JPH06246932A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To reduce unevenness in density generated according to service frequency of each discharge opening when recording is carried out with a recording head having a plurality of ink discharge openings. CONSTITUTION:In a case where driving of a recording head for discharging ink is carried out by a split pulse, a relation between a width of a preheat pulse among the split pulses and its discharge amount becomes what is given by a line (a) for a certain discharge opening group: it follows that given by a line (b') for another discharge opening group, discharge driving of both discharge opening groups is carried out by taking the width of the preheat pulse as Pab'. Thereby, a specific discharge amount Vdab' can be obtained for either discharge opening group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a plurality of ink ejecting portions,
For example, the present invention relates to an inkjet recording apparatus that performs recording using a recording head having an ejection port.

[0002]

2. Description of the Related Art Among ink jet recording apparatuses of this type, an apparatus using an ejection heater and ejecting ink by utilizing thermal energy generated by the ejection heater has an advantage that high-definition recording can be performed. , Is becoming more common. However, in an ink jet recording apparatus that uses such thermal energy, the ink amount Vd ejected from each ejection port often changes due to the following factors.

The number of drive pulses for each ejection port, that is,
Frequency of use of each discharge port Frequency of use of recording head, which is indicated by the ratio of use time and leaving time. Change in ink head pressure due to changes in ink remaining amount, changes in ink composition, etc. Changes in environment such as temperature and humidity. Foaming characteristics of (∂Vd / ∂P ₁
Among these, the difference in the discharge amount caused by the difference in the usage frequency (the number of input pulses) of each discharge port is remarkable (about 5).
~ 20% change).

Such a difference in the use frequency for each discharge port occurs in the following cases, for example. That is, in recent inkjet recording apparatuses, a plurality of recording modes in which a plurality of ejection ports are divided and used by one recording head are often used. In such a case, a remarkable difference occurs in the ejection port usage frequency in the recording head, which may cause the following problems.

If there is a significant difference in the frequency of use for each discharge port, the discharge amount will vary depending on the frequency of use (the discharge amount may increase or decrease).
Once the difference in the ejection amount in the print head occurs, the density is high in the ejection port portion where the ejection amount is large, and the density is low in the ejection port portion where the ejection amount is small. For this reason, in a so-called serial type recording apparatus, density unevenness in the recording width period of the recording head remarkably appears in the image. Further, in a so-called full-line type recording apparatus, for example, when 100 sheets of A4 size paper are longitudinally fed and then the same paper is horizontally fed, the use area of the ejection port is changed, so that the density becomes a boundary. A difference occurs.

Further, even when color recording is performed with four colors of cyan, magenta, yellow, and black, for example, a color image is changed in color tint, resulting in color unevenness and deterioration of image quality.

In order to reduce the density unevenness as described above as much as possible, the following method has been conventionally used.

1) An aging pulse is applied to the ejection heater at the time of shipment of the recording head, in the initial stage of use, etc. (the ejection amount at each ejection port is stabilized).

2) A preliminary pulse is applied to an unused ejection port portion during recording (the change in ejection amount is reduced).

[0010]

However, in the method of 1) above, the work steps and time at the time of shipment increase, resulting in an increase in cost and conversely impairing the durability of the discharge heater due to aging. Therefore, there is an adverse effect such as a decrease in reliability. Moreover, there was a problem in the duration of the effect due to aging, which was insufficient.

Further, the method 2) is not preferable since it causes an increase in recording time and an increase in ink consumption (especially in the case of the full line type), and its effect is not sufficient.

The present invention has been made to solve the above problems, and it is possible to record an image with reduced density unevenness by changing the driving condition according to the number of ejection pulses of each ejection port. It is an object of the present invention to provide a simple inkjet recording device.

[0013]

Therefore, according to the present invention,
In an inkjet recording apparatus that uses a recording head having a plurality of ejection portions for ejecting ink and ejects ink from the recording head onto a recording medium to perform recording, the ejection frequency of each of the plurality of ejection portions is detected. When the difference between the ejection frequency of the frequency detecting means and the ejection frequency detected by the frequency detecting means is equal to or more than a predetermined value, each of the plurality of ejection portions has an ejection frequency corresponding to the ejection frequency. In the relationship between the driving condition and the ejection amount, a driving condition selecting unit that selects a driving condition that makes the ejection amounts equal among the plurality of ejecting units, and each of the plurality of ejecting units according to the driving condition selected by the selecting unit. Drive means for driving to discharge ink.

An ink jet recording apparatus which uses a recording head having a plurality of ejection portions for ejecting ink and ejects ink from the recording head to a recording medium to perform recording, wherein the number of ejection portions used is In an ink jet recording apparatus having a plurality of recording modes accompanied by changes, when the recording mode is changed, a relationship between a driving condition and a discharge amount for each of the plurality of discharge units according to the discharge frequency. In the driving method, a driving condition selecting unit that selects a driving condition that makes the ejection amounts equal among the plurality of ejection units, and a drive that ejects ink by driving each of the plurality of ejection units according to the driving condition selected by the selection unit. Means and are provided.

Furthermore, an ink jet recording apparatus which uses a recording head having a plurality of ejection portions for ejecting ink and ejects ink from the recording head onto a recording medium to perform recording, wherein the number of ejection portions used is In an inkjet recording apparatus capable of using a plurality of sizes of the recording medium with changes, when the recording medium is changed, each of the plurality of ejecting units has a drive for ejecting according to the ejection frequency. In terms of the relationship between the condition and the ejection amount, a driving condition selection unit that selects a driving condition that makes the ejection amounts equal among the plurality of ejection units, and drive each of the plurality of ejection units according to the driving condition selected by the selection unit. Drive means for ejecting ink.

Furthermore, an ink jet recording apparatus which uses a recording head having a plurality of ejection portions for ejecting ink and ejects ink from the recording head onto a recording medium to perform recording, wherein In an inkjet recording apparatus having a plurality of recording modes accompanied by changes, a frequency detection unit that detects the ejection frequency of each of the plurality of ejection units, and the ejection frequency of the ejection unit according to the ejection frequency and the state of the recording head. Table means for defining a driving condition for the table, and a table for selecting one table from the table means according to the ejection frequency for each of the plurality of ejection parts when the recording mode is changed. In accordance with the selection unit and the table selected by the table selection unit, each of the plurality of ejection units is driven to eject ink. Characterized in that comprises driving means.

Furthermore, an ink jet recording apparatus which uses a recording head having a plurality of ejection portions for ejecting ink and ejects ink from the recording head onto a recording medium to perform recording, wherein the number of ejection portions used is In an ink jet recording apparatus capable of using a plurality of recording mediums of various sizes accompanied with changes, a frequency detecting unit that detects the ejection frequency of each of the plurality of ejection units, and the ejection frequency and the recording head according to the state of the recording head. When the recording medium is changed and a table unit including a table that defines drive conditions for the ejection of the ejection unit, one of the table units is selected from the table unit according to the ejection frequency for each of the plurality of ejection units. Table selecting means for selecting one table, and driving for each of the plurality of discharge parts according to the table selected by the table selecting means. Driving means for ejecting the ink, characterized in that comprises a.

[0018]

According to the above construction, the driving condition is changed so that the discharge amount becomes equal even if the discharge amount difference between the used and unused discharge ports occurs with the change in the number of used discharge ports. .

[0019]

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

(Embodiment 1) FIG. 1 is a waveform diagram for explaining divided pulses for driving a recording head used in an embodiment of the present invention.

In this example, the recording head driving method and the recording method have the following features. A divided pulse driving method is used for driving the recording head. As shown in FIG. 1, V _OP is a driving voltage, P ₁ is a preheat pulse and its width, P ₂ is an interval time and its width, and P ₃ is a main heat. The pulse and its width are shown respectively. T
₁ , T ₂ and T ₃ have widths P ₁ , P ₂ and P _{3 respectively}
Shows the time to decide. V _OP constitutes the electrical energy required to generate thermal energy in the ejection heater, and is determined according to the area of the ejection heater, the resistance value, the film structure and the ink path structure of the recording head.

In the split pulse driving method, the pulses P ₁ , P
_A pulse is given in the order of ₂ and P ₃ . Preheat pulse P ₁
Is a pulse mainly for controlling the ink temperature in the ink passage provided with the ejection heater, and controls the pulse width P ₁ by temperature detection using the temperature sensor of the recording head. At this time, too much heat energy is applied to the ink passage to prevent the pre-foaming phenomenon from occurring. The interval time P ₂ is set in order to set a predetermined time interval so that the preheat pulse P ₁ and the main heater pulse P ₂ do not interfere with each other, and to make the temperature distribution of the ink in the ink path uniform. The main heat pulse P ₃ is for causing a bubbling phenomenon in the ink path and ejecting an ink droplet from the ejection port.

FIG. 2 is an exploded perspective view of the recording head unit used in this example.

The unit of this example is roughly divided into four parts as shown in FIG. That is, the recording head unit includes the recording head 1, the ink tank portion 4, and the carriage 2.
0 and cover 30.

The recording head 1 has a base plate 13 and a substrate (not shown) bonded near the front end of the base plate 13, and an ejection heater (electrothermal conversion element) for generating thermal energy used for ejection is provided on the substrate. ) And electrode wiring, as well as a temperature detecting element and the like are formed by the same process as the semiconductor manufacturing process. The grooved top plate 10 is bonded to the above-mentioned substrate corresponding to the portion where the discharge heater and the like are arranged, and thus ink paths, discharge ports and the like corresponding to the respective discharge heaters are formed. A front plate is formed vertically and integrally with the front end portion of the top plate 10, and this portion constitutes a discharge port arrangement surface. The base plate 13 is provided with a connector 16 for electrically connecting the circuit formed on the substrate and the apparatus body control circuit. The recording head 1 is capable of ejecting four types of ink, as will be described later, and each ejection port array is arranged so as to form a linear ejection port array 11.

The carriage 20 is slidably provided with a guide shaft 21 (only a part of which is shown in FIG. 2) provided in the main body of the apparatus, and is driven by a drive mechanism (not shown) to guide the guide shaft. It is possible to move along 21.
The recording head 1 is mounted on the carriage 20 so that the connector 16 thereof is inserted into the connector upper portion K22 provided on the carriage 20.

The ink tank section 4 corresponds to four kinds of inks of yellow (Y), magenta (M), cyan (C) and black (BK).
It has Y, 4M, 4C and 4BK. this house,
The black ink tank 4BK has other tanks 4Y,
It has a larger ink capacity than 4M and 4C. In these ink tanks, the connection holes 3 provided in each of the ink tanks are connected to the connection pipes 2 of the recording head 1 to form the recording head 1.
It is possible to supply ink to the ink. Each connecting pipe 2 is connected through the supply paths 15Y, 15M, 15C and 15BK,
It is connected to each liquid chamber. Ink tanks 4Y, 4M, 4C
And 4BK include the carriage 20 together with the recording head 1.
Be attached to.

The cover 30 is provided with a member for positioning and fixing when the recording head 1 and the ink tanks 4Y, 4M, 4C and 4BK are mounted on the carriage 20, and is used for fixing the recording head and the like. A shaft 37 provided on a part of the cover 30 is rotatably supported by a bearing 24 of the carriage 20, so that the cover 30 can be opened / closed by the rotation when the recording head or the like is replaced.

FIG. 3 is a plan view showing details of the substrate of the recording head 1 shown in FIG.

The recording head 1 of this embodiment is capable of ejecting different kinds of ink with one recording head, and 24, 24, 24 and 64 inks for yellow, magenta, cyan and black inks, respectively. Equipped with individual discharge ports. Therefore, as shown in FIG. 3, discharge heaters (electrothermal conversion elements) corresponding to the number of discharge ports are formed on the substrate. The discharge heater group corresponding to each ink type has a space of 8 discharge ports for each of yellow, magenta, and cyan. Further, the cyan and black discharge heater groups have a space for 16 discharge ports. Further, temperature sensors 18 are formed at both ends and the center of the substrate.

The maximum drive frequency of the recording head of the present example shown above is f _r = 8.0 kHz, and the drive frequency during normal recording is 5.4 kHz. It also has a resolution of 360 dpi. In this recording head, 64 black ink ejection ports are divided into 8 blocks and driven. That is, one block of ejection port is
Every other 1, 9, 17, 25, 33, 41, 49, 57
The heaters of these ejection ports are simultaneously driven as the second ejection port, and then the second, second, ..., Eighth block including eight ejection ports selected in the same manner are sequentially driven. The driving conditions in this case are: head temperature T _H = 25.0 (° C.), applied voltage V _OP = 25.6 (V), pulse width P ₁ = 1.50 (μs)
ec), P ₂ = 2.0 (μsec), P ₃ = 3.00
(Μsec), and a stable ink ejection state can be obtained. The ejection characteristic at this time is that the ink ejection amount V _D = 80.0
(Ng / dot), discharge speed V = 14.0 (m / se
c).

The cyan 24 ejection port is divided into 3 blocks, the magenta 24 ejection port is divided into 3 blocks, and the yellow 24 ejection port is divided into 3 blocks, and they are similarly driven. The driving conditions for these inks are head temperature T _H = 25.0 (° C.),
Applied voltage V _OP = 25.6 (V), pulse width P ₁ = 1.0
0 (μsec), P ₂ = 2.0 (μsec), P ₃ =
It is 3.00 (μsec), and a stable ink ejection state can be obtained. The ejection characteristic at this time is that the ink ejection amount V _D =
40.0 (ng / dot), discharge speed V = 14.0 (m
/ Sec).

Next, a density unevenness correction control method using the preheat pulse P ₁ of the drive pulses (the same control is possible using P ₂ ) will be described.

FIG. 4 shows the relationship between the preheat pulse P ₁ and the ejection amount V _{D under} the condition that the head temperature is constant at T _H.
Here, the discharge amount V _D linearly increases up to a predetermined width P _{1LMT with} respect to the increase of the pulse width P ₁ , and thereafter the foaming due to the main heat pulse P ₃ is disturbed due to the pre-foaming phenomenon or the like, and P _{After 1MAX} , it tends to decrease.

The relationship between the head temperature T _H and the ejection amount V _{D under the} constant preheat pulse P ₂ is shown in FIG. Here, the discharge amount indicates a tendency to increase linearly with an increase in the head temperature T _H.

The coefficients of the linearity regions shown in FIGS. 4 and 5 are as follows:

[0037]

[Equation 1] Preheat pulse dependence coefficient of discharge amount K _P = ΔV
_DP / ΔP ₁ (ng / μs · dot) Head temperature dependence coefficient of ejection amount K _TH = ΔV _DT / ΔT _H (n
g / C · dot).

In the head structure shown in FIG.

[0039]

[Equation 2]

By making effective use of these two relations, as will be described later, even if the discharge amount difference between the discharge ports occurs, it is possible to use the discharge ports that are used and the discharge ports that are not used. Instead, the ink ejection amount can be always kept constant.

The recording operation of the present example to which the recording head and the density unevenness correction control are applied as described above will be described below.

(In case of color recording mode) In this mode, recording is performed using 24 ejection ports of each ink color (BK, C, M, Y).

FIG. 6 is a schematic diagram showing the relationship between the main scan of the recording head and the paper feed in the color recording mode.

As shown in the figure, for example, in the first pass of the printing area, printing is performed by 24 ejection ports of black ink by the first main scanning (first scanning).
Sequentially, 8 cyan ink ejection ports in the 2nd scan, 16 cyan ejection ports in the 3rd scanning, 24 magenta ink ejection ports in the 4th scanning, and 16 yellow ink ejections in the 5th scanning.
Recording is performed by each of the eight ejection ports and eight ejection ports of the yellow ink in the sixth scan. Thus each path is
Printing is performed by six main scans of the print head, and paper is fed by 24 ejection ports during each main scan (in the figure, it is shown that the print head has moved). .

At this time, of the 64 ejection openings for black ink, only the upper 24 ejection openings are always used.

In the color recording mode, the pre-pulse width P ₁
The ejection amount is controlled so as to keep the ejection amount constant while changing the value according to the head temperature T _H. 8 and 9 are diagrams for explaining this pulse width modulation (PWM) control method. Figure 8 is an explanatory view for explaining a discharge amount control when the head temperature T _H is changed by the self-heating of the recording head according to ink discharge for the surrounding environmental temperature or recording, an example of the sequence in FIG. 9 Shown respectively. That is, when the head temperature T _H is in the PWM region (T ₀ < _TH < _TL ) shown in FIG. 8, the head temperature is detected as shown in FIG. 9 (S40
1) The temperature change is judged based on the past head temperature (S402, S403). Accordingly, the pulse width P in the range of pulse widths (1) to (11) shown in FIG.
₁ is changed (S404, S405, S406).

The pulse width modulation may be performed on either P ₁ or P ₂ , and instead of the temperature detection by the temperature sensor, a known method such as heat storage detection by recording dot count may be used.

The driving conditions of the ejection port for each ink of this example are as follows.

BK drive condition; P ₁ : PWM control (P ₁ = 1.50 when T _H = 25 ° C.)
(Μsec)) P ₂ : 2.00 (μsec) P ₃ : 3.00 (μsec) (However, change according to individual difference of print head) At this time, ejection amount: V _d = 80.0 ± 4 0.0 (ng / d
ot).

C, M, Y drive conditions; P ₁ : PWM control (P ₁ = 1.00 when T _H = 25 ° C.)
(Μsec)) P ₂ : 2.00 (μsec) P ₃ : 3.00 (μsec) (however, change according to individual difference of print head) At this time, ejection amount: V _d = 40.0 ± 3 0.0 (ng / d
ot).

(In the case of monochrome recording mode) In this mode, recording is carried out by using 64 ejection openings of black ink. As a result, 2 used in the color mode
The recording speed can be improved by newly adding 40 discharge ports to 4 discharge ports. The recording method in the monochrome mode is shown in FIG.

In this case, as shown in FIG. 10, between the 24 ejection ports used in the color mode and the 40 ejection ports used only in the monochrome mode, the number of pulses is, for example, 10 ^7. When a difference in pulse use frequency occurs, a discharge amount difference ΔV _d (n _p , t) corresponding to the difference in the number of discharge pulses occurs, as shown in FIG. 11. That is, the amount of ink ejected from 24 ejection ports (recording ejection port) and the amount of ink ejected from 40 ejection ports (non-recording ejection port portion) are constant with a pulse number difference of a predetermined number or more. Make a difference. When used in this state, density unevenness is remarkably generated as shown in FIG. 12A, and this density unevenness becomes more remarkable in the low density portion.

In order to prevent such density unevenness, in this example, the drive pulse is set near the preheat pulse P _{1MAX in the} region close to the saturated state of foaming shown in FIG. 4 to maintain the ejection amount in the supersaturated state. Thus, the discharge amount difference ΔV _d (n _p , n _p , between the used portion (24 pieces) and the unused portion (40 pieces)
t) is eliminated to prevent the occurrence of uneven density (FIG. 12).
(See (B)).

In this case, the driving conditions for the 64 black ink ejection ports are as follows.

[0055] _{P 1: 2.00 (μsec) P} 2: 2.00 (μsec) P 3: 3.00 (μsec) ( however, be modified in individual difference of the recording head) In this case, the discharge amount: V _d = 85.0 ± 8.0 (ng / d
ot) Hereinafter, the ejection control for bringing the ejection amount into the supersaturated state will be described with reference to FIG.

In the figure, in the normal color mode, the ejection amount V _d0 is set so that P ₁ is P ₁₀ . The line a shows the relationship between the pulse width and the ejection amount at this time. Here, if the frequency of use changes, the preheat pulse width P required to obtain the same amount of ink ejection amount V _d0.
The value of ₁ changes. The change in the relationship between the pulse width P ₁ and the discharge amount V _d due to the change in the use frequency is represented by the line b,
It is shown in b'and c, c '. In the figure, lines b and b'are P
_The case where the _1- dependence slope changes and the lines c and c ′ show the case where the P ₁ dependence shifts in parallel.

For example, the case where the line a is changed to the line b'will be described as follows.

1) 24 used in color recording mode
When only one ejection port has a pulse width P ₁ = P ₁₀ , for example, the ejection amount changes to V _{db ′} , the ejection amount increases by ΔV _{d ′ -a,} and a density difference occurs.

2) When 64 discharge ports are used under this condition in the monochrome mode, the density is increased by the discharge amount increase amount ΔV _b'-a only in the 24 discharge ports.

3) In order to prevent such a density difference, 6
The driving conditions for the four ejection ports are P ₁ = P _{ab '} . That is, by driving with the preheat pulse at the intersection of the lines a and b ′, the ejection amount becomes V _d = V _{dab ′,} and no difference occurs, so that the density difference can be prevented.

In other cases as well, the driving feeling P of the portion where the ejection characteristics of the unused portion and the used portion of the ejection port intersect is similarly set.
_{By using ac ′} , P _ac , and P _ab , it is possible to make the discharge amounts equal and suppress the occurrence of density difference.

FIG. 13 is a diagram showing the density change for each print duty when the drive conditions are changed as described above by using the print head having the difference in ejection amount (difference in use frequency).

It can be seen that the longer the pulse width of the preheat pulse P ₁ is, the smaller the density difference between the used portion and the unused portion of the ejection port becomes, and finally the density difference disappears.

As described above, it is possible in principle to eliminate the density unevenness caused by the difference in the frequency of use and the storage state.

(Embodiment 2) The recording head used in this embodiment relates to a color printer using the same recording head as in Embodiment 1 above.

In this device, 2
Dedicated PW for each of 4 outlets and 40 outlets
Equipped with M table, each outlet (24 and 40
It has a circuit for detecting the total number of ejection pulses.

As a result, according to the total number of ejection pulses, the optimum PWM table is selected from the relationship between the number of ejection pulses and the ejection amount obtained in the experiment shown in FIG. It is configured to correct the difference in quantity.

The feature of this method is that the discharge amount is fixed as a result of the control in the first embodiment, and a slight increase in the discharge amount causes a density difference between the color mode and the monochrome mode. For this reason, in this example, the density difference that occurs when the mode is switched is suppressed by selecting the table according to the total number of ejection pulses. In the present method, only the total number of ejection pulses is used as a factor for changing the ejection amount, but other factors that affect the changes in the ejection amount such as leaving time and temperature may be used as a function.

The change (selection) of the PWM table is performed by calculating the difference in the total number of ejection pulses by the CPU and comparing the number with the PWM table shown in FIG.

An example of the PWM table changing sequence will be described below.

According to the experiment by the applicant, the ejection amount from the 40 ejection ports in the unused portion gradually decreased according to the ejection pulse number. Therefore, for example, the PWM shown in FIG.
The table Tpa is changed to the table Tpb.

Generally, the optimum PWM table Tpi (i = a, b, b ′, c,
c ′) may be selected. The control method will be briefly described below.

1) As shown by the line c'in FIG. 4, when the discharge amount of the discharge ports (24) used is increased, the preheat pulse when the head temperature T _H = 25.0 ° C. The value of the width P ₁ is set to the standard driving condition (P ₁ = 1.50 (μse
c)) to be P ₁ = 1.25 (μsec),
Standard discharge rate V _Do = 80.0 (ng /
Dot).

2) On the contrary, as shown in the line c in FIG. 4, when the discharge amount at the discharge port used is decreased, the value of the preheat pulse width P ₁ at the head temperature T _H = 25.0 ° C. Is longer than the standard driving condition (P ₁ = 1.50 (μsec)) to P ₁ = 1.75 (μsec), and the discharge amount is reduced to the standard discharge amount V _D0 = 80.0 (ng / dot). Approach to.

3) As shown by the line b'in FIG. 4, when the P ₁ dependency coefficient of the discharge port used increases, the preheat pulse width P when the head temperature T _H = 25.0 ° C.
The variation width value of ₁ (0.125 (μsec)) is shortened to 0.100 (μsec), and the discharge amount is kept constant to approach the standard discharge amount V _D0 = 80.0 (ng / dot). .

4) On the contrary, as shown by the line b in FIG. 4, when the P ₁ dependency coefficient of the discharge port used is decreased, the preheat pulse width P when the head temperature T _H = 25.0 ° C.
The change width value of ₁ (0.125 (μsec)) is made longer to 0.150 (μsec), and the discharge amount is kept constant to approach the standard discharge amount V _D0 = 80.0 (ng / dot). .

The above series of operations selects the table having the relationship between the table Tpi and the preheat pulse width P ₁ from the table shown in FIG. 14 according to the ejection amount state. Even if the ejection amount varies depending on the number of pulses, by switching to a table according to the number of ejection pulses, it is possible to set the standard ejection amount V _D0 always even when the recording mode is changed as well as the environmental temperature. .

(Embodiment 3) A third embodiment of the present invention relates to a color copying machine using a so-called full line type recording head. Here, a means for correcting the ejection amount difference caused by the recording paper used will be described.

In the full line type recording apparatus, for example,
Density unevenness phenomenon (so-called A
Similarly to (B density unevenness), when 100 sheets of A4 paper are longitudinally fed and then the same size of paper is laterally fed, by suddenly using the ejection port of an unused portion, The same problem as the phenomenon described above occurs in the width recording area. In other words, since the use area of the ejection port changes due to the change of the paper or the conveyance width of the paper, there is a case where the used ejection port and the unused ejection port are used at the same time for recording, and the above-mentioned problems occur.

This apparatus employs a method of switching the driving condition according to the paper size and paper feed direction selected by the user and the total number of ejection pulses for each paper.

That is, a dedicated PWM table is provided in advance according to each paper size, and a circuit for detecting the total number of ejection pulses of each ejection port (unused portion and used portion) is provided.

Thus, according to the total number of ejection pulses, the optimum PWM table is selected from the relationship between the number of ejection pulses and the ejection amount, which is obtained in advance by an experiment as shown in the second embodiment, and the usage frequency is selected. difference configured to correct the ejection amount difference generated by not only changing the pulse width P _1, the expansion and ejection stability of the control region by performing simultaneously the change of the driving voltage Vop can be further improved.

FIG. 15 is a schematic perspective view showing a main part of an ink jet recording apparatus which can use the recording head shown in FIG.

In FIG. 15, the recording head 1 has a surface facing the recording paper 57, Y, in the conveying direction of the recording paper 57.
Each of the M, C, and BK ink ejection ports (not shown) is provided in a row. Further, the recording head 1 is provided with an ink path (not shown) communicating with each of these ejection ports, and is used for ejecting ink on the substrate constituting the recording head 1 corresponding to each ink path. An electrothermal conversion element that generates the generated heat energy is formed. The electrothermal transducing element generates heat by an electric pulse applied to the electrothermal transducing element in accordance with drive data, which causes film boiling in the ink, and the ink is ejected from the ejection port as bubbles are generated by the film boiling. Is ejected. Each ink path is provided with a common liquid chamber for each ink color that communicates with them in common, and the ink stored therein is supplied to the ink path according to the ejection operation in each ink path. It

The carriage 20 carries the recording head 1 and the ink tank 4, and slidably engages with a guide rail 21 extending parallel to the recording surface of the recording paper 57.
As a result, the recording head 1 can move along the guide rail 21, and recording is performed by ejecting ink toward the recording surface at a predetermined timing with this movement. After the above movement, the recording paper 57 is conveyed by a predetermined amount in the direction of the arrow in the figure, and the above movement is performed again to perform recording.
By repeating such an operation, the recording paper 57 is
Records will be made sequentially.

The above-mentioned conveyance of the recording paper 57 is carried out by a pair of conveying rollers 54 arranged above and below the recording surface.
And 55 are rotated. Further, a platen 56 for maintaining the flatness of the recording surface is provided on the back side of the recording surface of the recording paper 57.

The above-mentioned movement of the carriage 20 is
For example, a belt (not shown) attached thereto can be driven by a motor, and rotation of the transport rotors 54 and 55 can be similarly performed by transmitting the rotation of the motor to them.

FIG. 16 is a block diagram showing the control arrangement of the ink jet recording apparatus shown in FIG.

In FIG. 16, the CPU 100 executes control processing, data processing, etc. of the operation of each part of the apparatus. ROM
The processing procedure and the like are stored in 100A, and RA
M100B is used as a work area for executing the above processing.

Ink ejection in the recording head 1 is CP
U100 supplies the drive data and drive control signal of the electrothermal converter to the head driver 1A. Further, as described above, the CPU 100 controls the temperature (ink temperature) of the recording head 1 according to the embodiment of the present invention, so that the electrothermal conversion element is driven to such an extent that ejection does not occur (preheat). Pulse application), and supplies the drive data and drive control signal. Further CPU1
Reference numeral 00 controls the rotation of the carriage motor 20B for moving the carriage 2 and the paper feed (PF) motor 50B for rotating the conveying rollers 54, 55 via motor drivers 20A and 50A, respectively.

(Others) The present invention is provided with a means (eg, electrothermal converter or laser beam) for generating thermal energy as energy used for ejecting ink, particularly in the ink jet recording system. The present invention brings about excellent effects in a recording head and a recording apparatus of the type in which the state of ink is changed by the heat energy. This is because such a system can achieve high density recording and high definition recording.

Regarding its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal in a one-to-one correspondence
It is effective because bubbles can be formed inside. Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid (ink) with excellent responsiveness can be achieved. 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 constitution of the recording head, in addition to the combination constitution of the ejection port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned specifications, US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of 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 port of an 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 structure corresponding to the ejection port is disclosed in Japanese Patent Laid-Open No. 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 which can be recorded by the recording apparatus. 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 in the above example, the recording head fixed to the main body of the apparatus, or the electrical connection to the main body of the apparatus or the ink from the main body of the apparatus by being attached to the main body of the apparatus. 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 integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add an ejection recovery means of the recording head, a preliminary auxiliary means and the like because the effects of the present invention can be further stabilized. Specifically, heating is performed by using a capping unit, a cleaning unit, a pressure or suction unit for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type or number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces 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 above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet system, it is common to control the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change of the ink from the solid state 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 thermal energy such as ink that is liquefied by applying thermal 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 No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the 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, as a form of the ink jet recording apparatus of the present invention, besides the one used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function are provided. It may be a form or the like.

[0100]

As described above, according to the present invention,
Even if a difference in the discharge amount occurs between the used and unused discharge ports due to the change in the number of used discharge ports, the driving conditions are changed so that the discharge amounts become equal.

As a result, it is possible to suppress the occurrence of density unevenness in the recorded image, and it is possible to eliminate the cyclic density unevenness of the image, which was particularly noticeable in the serial system.

[Brief description of drawings]

FIG. 1 is a waveform diagram showing divided pulses for driving a recording head according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing the structure of the recording head according to the embodiment of the invention.

FIG. 3 is a plan view showing a substrate that constitutes the recording head.

FIG. 4 is a diagram showing a relationship between a preheat pulse of the divided pulses and an ejection amount.

FIG. 5 is a diagram showing the relationship between the temperature of the recording head and the ejection amount.

FIG. 6 is a schematic diagram showing a recording method in a color recording mode using the recording head.

FIG. 7 is a schematic diagram showing a monochrome mode recording method in the same manner.

FIG. 8 is a diagram for explaining PWM control used in an embodiment of the present invention.

FIG. 9 is a flowchart showing an example of the PWM control sequence.

FIG. 10 is a schematic diagram showing a usage range of a black ink ejection port of the recording head.

FIG. 11 is a diagram showing the relationship between the ejection amount and the difference in the total number of recording pulses for each usage range of the black ink.

12A and 12B are schematic diagrams of recording results showing occurrence and prevention of density unevenness.

FIG. 13 is a diagram showing the relationship between the reflection density and the preheat pulse width to explain the effect of one embodiment of the present invention.

FIG. 14 is a schematic diagram showing a PWM table used in another embodiment of the present invention.

FIG. 15 is a schematic perspective view showing an example of an inkjet recording apparatus that can use the recording head.

FIG. 16 is a block diagram showing a control configuration of the recording apparatus.

[Explanation of symbols]

 1 Recording Head 4, 4Y, 4M, 4C, 4BK Ink Tank 10 Temperature Sensor 20 Carriage 20B Carriage Motor 50B Paper Feed Motor 100 CPU 100A ROM 100B RAM

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 9012-2C B41J 3/04 104 F

Claims (6)

[Claims] 1. An inkjet recording apparatus for recording by using a recording head having a plurality of ejection portions for ejecting ink, the ink being ejected from the recording head onto a recording medium. When the difference between the ejection frequency of the ejection frequency of the ejection detection unit and the ejection frequency of the ejection units detected by the frequency detection unit is equal to or greater than a predetermined value, each of the ejection units determines the ejection frequency. In terms of the relationship between the ejection condition and the ejection amount, the ejection section has a plurality of ejection sections.
Drive condition selecting means for selecting a drive condition for equalizing the discharge amount, and drive means for driving each of the plurality of discharge parts to discharge ink according to the drive condition selected by the selecting means. Inkjet recording device. 2. An ink jet recording apparatus for recording by using a recording head having a plurality of ejection portions for ejecting ink, and ejecting ink from the recording head to a recording medium, the number of ejection portions being used. In an ink jet recording apparatus having a plurality of recording modes accompanied by changes, when the recording mode is changed, a relationship between a driving condition and a discharge amount for discharging each of the plurality of discharging units according to the discharging frequency. A driving condition selecting means for selecting a driving condition for equalizing the ejection amount among the plurality of ejecting parts, and a drive for ejecting ink by driving each of the plurality of ejecting parts according to the driving condition selected by the selecting means. An ink jet recording apparatus comprising: 3. An ink jet recording apparatus for recording by using a recording head having a plurality of ejection portions for ejecting ink, the ink being ejected from the recording head onto a recording medium, the number of ejection portions being used. In an inkjet recording apparatus capable of using a plurality of sizes of the recording medium with changes, when the recording medium is changed, a drive for ejection that each of the plurality of ejection units has according to the ejection frequency In terms of the relationship between the conditions and the ejection amount, a driving condition selection unit that selects a driving condition that makes the ejection amounts equal among the plurality of ejection units, and drive each of the plurality of ejection units according to the driving condition selected by the selection unit. An ink jet recording apparatus comprising: a driving unit that ejects ink. 4. An inkjet recording apparatus for recording by using a recording head having a plurality of ejection portions for ejecting ink and ejecting ink from the recording head onto a recording medium. In an inkjet recording apparatus having a plurality of recording modes accompanied by changes, a frequency detection unit that detects the ejection frequency of each of the plurality of ejection units, and the ejection of the ejection units according to the ejection frequency and the state of the recording head. Table means including a table that defines driving conditions for controlling the recording conditions, and when the recording mode is changed, the table means is set to 1 depending on the ejection frequency for each of the plurality of ejection portions from the table means.
An ink jet recording apparatus comprising: a table selection unit that selects one table; and a drive unit that drives each of the plurality of ejection units to eject ink according to the table selected by the table selection unit. 5. An ink jet recording apparatus which uses a recording head having a plurality of ejection portions for ejecting ink and ejects ink from the recording head onto a recording medium to perform recording. In an inkjet recording apparatus capable of using a plurality of sizes of the recording medium with changes, a frequency detecting unit that detects the ejection frequency of each of the plurality of ejection units, and the ejection frequency and the state of the recording head according to the ejection frequency. When the recording medium is changed, a table unit including a table that defines drive conditions for ejection of the ejection unit, and one of the table units according to the ejection frequency for each of the plurality of ejection units is selected from the table unit.
An ink jet recording apparatus comprising: a table selection unit that selects one table; and a drive unit that drives each of the plurality of ejection units to eject ink according to the table selected by the table selection unit. 6. The recording head generates thermal energy by the driving, generates bubbles in the ink by using the thermal energy, and ejects ink based on the generation of the bubbles. Item 6. The inkjet recording device according to any one of items 1 to 5.