JPH04219247A - Recording device and control method of recording - Google Patents

Abstract

PURPOSE:To inhibit density unevenness, etc., without depending upon a recording picture pattern, and to enable the recording of a high grade in a recording device for conducting recording by using a recording head with a plurality of ink discharge openings. CONSTITUTION:The temperature distribution of a recording head with a plurality of discharge openings is detected by counting the number of discharge dots at every discharge opening (a step S4), and recording speed is decreased by lowering discharge frequency (a step S) when there are the discharge openings discharging ink at a number (N), where a temperature is increased, or more (a step S7). Accordingly, the discharge openings discharging ink at intervals longer than the progress of a temperature rise on recording are removed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording method for controlling recording according to the temperature distribution of a recording head equipped with a plurality of heating elements for recording, and a recording apparatus for carrying out the method. In particular, the present invention relates to a recording apparatus such as a printer, a copying machine, a facsimile machine, etc. used in office equipment in general, which employs inkjet recording in which the state of ink discharge dominates the recorded image.

0002

[Prior Art] In an inkjet device using a conventional inkjet recording head, a thermal energy recording method using film boiling has exceptional recording characteristics and resolution compared to a method using piezoelectric elements, and uses light energy, etc. It has been put into practical use as being superior to other thermal energy records.

By the way, although conventional wire dot printers and type printing printers do not use heating elements in the recording head, the responsiveness of the displacement mechanism itself deteriorates due to the heat generated by the solenoid and electromagnetic coil that drive the wire, making it impossible to record. It may happen. Various proposals have been made to solve this problem. For example, in order to solve this problem, Japanese Utility Model Application Publication No. 55-70256 discloses a device that enables the use of a solenoid by switching the printing method from bidirectional to unidirectional and allowing a large amount of heat dissipation period. . In addition, JP-A-57
Publication No. 157781 discloses similarly switching from bidirectional to unidirectional in order to radiate abnormal temperature rise caused by excitation current to the wire dot coil.

Originally, the heat generated by this type of solenoid or coil is due to long-term heat storage, and the recording speed is not very fast. Furthermore, the temperature determined therein is only an abnormally high temperature that makes it impossible to record, and cannot be used to determine temperature distribution.

On the other hand, in inkjet recording, in order to prevent the influence of ink viscosity that is affected by temperature changes in the external environment, an invention was developed in the United States to control the recording speed, recording frequency, and carriage movement speed according to the external environmental temperature. Patent No.
No. 4,544,931. Also,
U.S. Pat. No. 4,910,528 discloses a device that detects the temperature of an inkjet recording head using a heating element to determine recording conditions. However, in either case, there is only one head temperature sensor (an outside air detection sensor is not disclosed), and the partial temperature is simply the temperature of the entire head.

[0006]

[Problem to be solved by the invention] The problem with this heating element is that
This variation in ink ejection is particularly noticeable in inkjet recording in which a heat acting surface is formed within the recording head liquid path. The reason for this is that thermal energy is accumulated in the ink and liquid path constituent members, which tends to create areas with different temperatures. Generally, thermal heads used in thermal transfer recording do not have an ink liquid path, so the problem of heat accumulation is not a very big problem. However, this may become a problem in the future when using minute temperature differences to form high-quality, high-gradation images.

In any case, the conventional temperature control of the recording head using a single temperature sensor can prevent the occurrence of severe defects that would impede ejection. In a so-called multi-nozzle head arranged in such a manner, it has not been possible to effectively suppress the difference in the discharge amount of each of the plurality of liquid paths.

[0008] The background of the present invention will now be explained by explaining one reason why the discharge amount differs between the plurality of liquid paths.

FIG. 6 shows an inkjet recording apparatus equipped with an inkjet recording head with a resolution of 360 dpi (dots/inch) and 48 ejection openings, which can print 1500 characters.
This is a graph of the number of ejections from each ejection port when a typical English text document is recorded.

As is clear from this figure, even when recording a general English document, there is a significant difference in the number of ejections between the ejection ports. That is, as is clear from the inkjet ejection principle described above, the difference in the number of ejections is the difference in the number of times thermal energy is applied, which causes a temperature difference in the ink in each flow path. This temperature difference causes a difference in the foaming length of the bubbles even when driven with the same applied voltage and pulse width, resulting in a difference in the ejection amount between the respective ejection ports.

[0011] When a difference occurs in the discharge amount between the respective discharge ports, the following problems specifically occur.

[0012] There is a correlation between the ejection amount and the dot area on the recording medium. As shown in FIG. 7, when ejection ports with a large ejection amount and ejection ports with a small ejection amount coexist, a difference occurs in the overlapping width of the formed dots, and for example, pseudo gradation, etc., in which gradation is expressed by the number of ejected dots, is recorded. In this case, it has been found that problems such as unevenness or black streaks appearing in areas where uniform density is expected to occur or conspicuous white streaks occur.

The present invention aims to solve this problem and provide an inkjet recording device that can reduce the difference in ejection amount between the ejection ports and suppress the occurrence of density unevenness, black streaks, and white streaks. It is.

Another object of the present invention is to provide a recording control method that detects, preferably predicts, the temperature distribution of a recording head and enables rapid recording with only short interruptions sufficient to equalize this distribution. and the provision of recording devices.

Still another object of the present invention is to provide a recording apparatus in which interruption time can be extremely shortened even in an inkjet recording apparatus using a bubble formation method using thermal energy.

[0016]

[Means for Solving the Problems] To this end, the present invention provides
A printhead having a plurality of ejection ports for ejecting ink, a detection means for detecting temperature distribution within the printhead related to printing operation, and control for controlling a printing speed by the printhead based on the detection. It is characterized by having the means.

[0017] Here, the detection means may include means for detecting the temperature distribution based on data relating to the number of ink ejections during a recording operation at each of the plurality of ejection ports.

The detection means may also include means for detecting the temperature distribution by detecting the temperature inside each of the plurality of discharge ports.

Further, the detection means includes means for detecting the temperature distribution based on data regarding the number of ink ejections during a recording operation at each of the plurality of ejection ports, and It may also include means for detecting the temperature distribution by detecting the temperature at the temperature.

In addition to the above configuration, the present invention also provides a discharge means for forcibly discharging ink from the plurality of ejection ports of the recording head by applying pressure, and a discharge means for forcibly discharging ink from the plurality of ejection ports of the recording head based on the detected temperature distribution. The apparatus further includes a second control means for driving the ejection means.

The present invention also provides a recording control method for recording on a recording medium using an inkjet recording head equipped with thermal energy generating elements respectively corresponding to a plurality of ejection ports, the method comprising controlling the temperature distribution of the recording head. a process of determining;
The present invention is characterized by comprising a step of determining whether to continue recording or to interrupt recording based on the determination result, and a step of starting recording after an interruption time determined in accordance with the recording interruption determination.

[0022] Here, the thermal energy generating element is an electrothermal transducing element that forms bubbles in the ink by an electric drive signal corresponding to a recording signal, and the interruption time can be 500 milliseconds or less. .

[0023] Furthermore, the determination can be made in accordance with the temperature detected by a temperature detection mechanism provided in each of a plurality of predetermined regions. Furthermore, the determination is determined by the duty ratio per unit time of the recording signal supplied to each of the plurality of predetermined regions and the total duty supplied to each of the plurality of predetermined regions; The time run by
The time can be 500 milliseconds or less.

[0024]

[Operation] According to the present invention, the temperature distribution detection means for detecting the temperature distribution of the recording head during recording and the recording speed control means for controlling the recording speed are used to eject 1 from each ejection port.
Because it can reduce fluctuations in ink droplets (discharge amount) per dot, it suppresses the occurrence of density unevenness, black streaks, white streaks, etc. on the recorded image, and enables high-quality recording regardless of the recording pattern. becomes possible.

[0025]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a perspective view showing an example of an inkjet recording apparatus to which the present invention can be applied.

First, the overall configuration of the recording device will be explained. In the figure, 1 is a recording medium (hereinafter referred to as a recording sheet) made of paper, plastic sheet, etc., and a plurality of sheets 1 are stacked in a cassette or the like. The paper sheets are fed one by one by a paper feed roller (not shown in FIG. 1). The sheet is further conveyed in the direction of arrow A by a first pair of conveying rollers 3 and a second pair of conveying rollers 4, which are arranged at a constant interval and each driven by an individual stepping motor (not shown).

Reference numeral 5 denotes an inkjet recording head for recording on the recording sheet 1. Ink is supplied from the ink cartridge 10 and is ejected from each ejection port in accordance with an image signal. The recording head 5 and ink cartridge 10 are mounted on a carriage 6, and a carriage motor 23 is connected to the carriage 6 via a belt 7 and pulleys 8a, 8b. Therefore, the carriage motor 23
The carriage 6 is driven to reciprocate along the guide shaft 9.

Under the above configuration, the recording head 5 is
While moving in the direction, ink is ejected onto the recording sheet 1 according to the image signal to record an image, and the recording head 5 is moved as necessary.
returns to the home position, uses the recovery system 2 to eliminate clogging of the ejection port, improves the ejection condition, and drives the pair of conveyor rollers 3 and 4 to move the recording sheet 1 along the arrow A.
Convey one line in the direction. By repeating this process, desired recording is performed on the recording sheet 1. The recovery system means 2 includes a cap that can be joined to the ejection port forming surface of the recording head 5, and a pump that communicates with the cap and applies a suction force to the ejection port forming surface.

A control system for driving each part of the recording apparatus described above will now be explained.

FIG. 2 shows an example of the configuration of the control system, for example, a CPU 20a such as a microprocessor;
ROM that stores control programs and various data for a.
20b and a RAM 2 which is used as a work area for the CPU 20a and temporarily stores various data.
0c, etc., an interface 21, an operation panel 22, each motor (carriage drive motor 23, paper feed motor drive motor 24, first conveyance roller pair drive motor 25, 2 transport roller pair drive motor 26) and a driver 2 for driving each motor.
7 and a recording head drive driver 28.

The control unit 20 receives various information (for example, character pitch,
(character type, etc.), and an image signal from the external device 29 is input. Further, the control section 20 outputs ON/OFF signals and image signals for driving each of the motors 23 to 26 via the interface 21, and drives each section using the image signal.

Further, information on the number of ejections made from each ejection port per unit time is sent to the control unit 20 via the interface 21 by the timer 30 and counter 32.
will be forwarded to.

In the above configuration, the degree of increase in ink temperature in and around each channel varies greatly depending on the number of ejections per unit time, but in this embodiment, the temperature does not rise above the set temperature. Take control to prevent this from happening.

A configuration for controlling the temperature so that the temperature does not rise above the set temperature will be explained below with reference to experimental results.

[0036] Resolution 400dpi (dots/inch),
It has a head with 128 ejection ports and a recording speed of 4.
In an experiment using an inkjet recording device that records at 000 [dots/sec/ejection port], the following results were obtained:
The ink temperature near the liquid path increases by approximately 10°C (ΔT=10
℃).

In terms of the reflection density on the recorded image, this is an increase of about 10% compared to the reflection density when the temperature is not raised.

[0038] If the heated head (ink) is left without recording, it will return to its original temperature (temperature in equilibrium with the outside air temperature).

[0039] ■ If recording is continued with the temperature raised,
The head (
Ink) temperature is fixed.

[0040] Here, if the rate of change in reflection density recorded by the target device is set to within 10%, the ejection interval "N" will be within ΔT = 10°C depending on the balance between temperature rise and temperature fall. (dots/unit time), this ejection interval "N" is stored in advance in the ROM 20b, and the data on the number of ejections for each nozzle transferred from the counter 32 every unit time and the "N" are calculated. The number of discharges per unit time is ``N'' for any one discharge port.
'', the temperature rise in the vicinity of the liquid path can be suppressed by controlling the recording speed to decrease, that is, by controlling the ejection interval.

FIG. 3 shows an example of a recording operation procedure by the recording apparatus having the above configuration.

First, when a recording command is input in step S1, the timer 30 and counter 32 are reset (step S2), and recording is started (step S3). At this time, the counter 32 counts the number of ejections from each ejection port (step S4). The control unit 20 receives information from the timer 30 and monitors whether a unit time has elapsed (
Step S5), if the unit time has not elapsed and there is a command to record the next line (step S6), step S3
The process returns to step S5 and performs the recording operation again, and if there is no recording command, the process returns to step S5 to continue monitoring whether the unit time has elapsed.

Here, after the unit time has elapsed, the number of discharges from each discharge port is compared with the discharge interval "N" at which the temperature rise can be suppressed (step S7), and if there is no discharge port that has discharged more than "N", then The process returns to step S1 and waits for a recording command. If “N
If there is a discharge port that discharges more than 50%, a preset table (50
The recording speed is reduced (step S8) according to the interrupt condition (interruption condition of 0 msec or less), and the process returns to step S1 to wait for a recording command.

Note that lowering the recording speed specifically means lowering the ejection frequency for recording (increasing the ejection interval) and, in the case of a serial printer type device like this example, reducing the recording head speed. The goal is to reduce the scanning speed accordingly. On the other hand, when the present invention is applied to a so-called full multi-type print head in which ejection ports are arranged over a range corresponding to the width of the print medium, the ejection frequency is lowered and the conveyance speed of the print medium is lowered. That's fine.

[0045] By performing the control as described above, there is no discharge port that discharges at intervals longer than the temperature rise during recording, so that variations in the foaming length of the bubbles from channel to channel, that is, the discharge amount from each channel, are eliminated. Variations can be prevented. Therefore, occurrence of uneven density, black streaks, white streaks, etc. can be prevented, and high image quality can be achieved.

[0046] Furthermore, the ejection interval "N", which maintains a balance between temperature rise and temperature fall, may also be affected by the outside temperature where the recording apparatus is placed. Therefore, "N" may be set as a function of the outside temperature f(t)=Nt.

Furthermore, in FIG. 2, the recording signal input from the external device 29 is sent to the control unit 2 via the interface 21
The recording signal (code) is sent to the RAM 20c (receiving buffer) of No. 0, and is converted into a heat signal to the electrothermal converter corresponding to each liquid path. Here, in this embodiment, control is performed after ejection is performed and the ink temperature near the liquid path rises, but a counting operation is performed at the time of conversion to a heat signal, and appropriate control is performed before the temperature rises. The recording speed may also be set. Further, data on the number of ejections performed last time or the time before the previous time per unit time may be used as a reference for recording speed control.

In any case, by detecting the ink temperature distribution near the liquid path based on the data regarding the number of ejected dots, and controlling the ejection interval by controlling the recording speed according to the detection, It is possible to control the degree of increase in ink temperature near the liquid path and reduce the difference in ejection amount between the respective ejection ports. As a result, regardless of the printing pattern, it is possible to prevent the occurrence of density unevenness, black streaks, white streaks, etc. on the printed image, and to perform printing with high image quality.

In any case, the embodiment of the present invention can operate against minute irregularities in temperature distribution that do not reach the conventionally known abnormal temperature, so that the abnormal temperature does not reach the normally recorded temperature as in the conventional case. No long-term non-recording time required. In addition, it is possible to significantly improve the recording unevenness that occurs until the temperature reaches an abnormal temperature, which is the case in the past, so it is possible to achieve image formation that is superior to the conventional recording control according to temperature.

In FIG. 2, reference numerals 100 to 105 are each unit used to execute control which will be described later as a more detailed example, and their functions will be described later.

(Second Embodiment) Next, another embodiment for detecting the ink temperature distribution within the head will be described.

In the first embodiment, the temperature of ink in the flow path was estimated by counting the number of ejections from each ejection port per unit time, but the temperature of all the liquid paths may be directly measured as described below.

FIG. 4 is an explanatory diagram of a predetermined flow path configuration in the multi-nozzle recording head according to this example.

When a drive signal is applied between X and Y in the figure,
The electrothermal converter 34 generates heat, and the flow path 3 passes through the protective film 36.
Thermal energy is transferred to the ink I in the ink 3, film boiling occurs and bubbles B are generated, and in response to this, ink droplets D are ejected from the ejection ports. Here, the voltage drop at the resistance change detection type temperature sensor 35, which is not affected by the thermal influence of the electrothermal converter 34 and is placed sufficiently close to the liquid path, is expressed as Y and Z in the figure.
to detect the ink temperature. Since this configuration is provided for all liquid paths, more accurate information can be obtained. Based on this, the temperature distribution of the head can be determined more accurately, and by performing the same recording speed control as in the above example, a more stable image can be formed.

[0055] In conventional temperature detection using a single temperature sensor, temperature changes in only a portion of a large number of flow paths are detected, and the entire flow path is uniformly controlled based on this. The error was large. Therefore, although the occurrence of severe ejection failures could be avoided, it was not possible to deal with density unevenness caused by differences in ejection amount for each ejection port.

However, in this embodiment, the recording head is divided into the largest partial areas and each of these areas is detected. That is, since the temperature is detected and controlled for each flow path, variations in the amount of ink ejected from each ejection port can be reduced, and high-quality printing can be achieved.

In this embodiment, the temperature of all flow paths is detected, but depending on the purpose of the recording device, for example, if it is a character printer that mainly records a program list or records documents, etc. For example, as is clear from Fig. 6, it is easy to assume that there are discharge ports with a high discharge frequency and discharge ports with a low discharge frequency, so it is possible to estimate only the necessary portions, such as multiple (two or more) regions that dominate the temperature distribution. Detection (in this case, duty may be used instead of temperature) may be performed. When the main purpose is to improve the seam, use the discharge port numbers (1 to 8) and (41 to 48) in Figure 6.
), and the overall density can be determined by comparing the ejection port numbers (13 to 16) and the ejection port numbers (35 to 38). Of course, the combination is not limited to these.

Furthermore, when recording is performed every predetermined width by serial scanning, density unevenness becomes particularly noticeable at the joints between the predetermined widths. This is a serial scan recording.
The line recorded at the lowest ejection port in the n-th scan and the line recorded at the n+th
The line recorded at the topmost ejection port in the first scan forms a seam on the recorded image, so if there is a temperature difference between the bottommost ejection port and the topmost ejection port, density unevenness will occur as described above. It is.

Therefore, as shown in FIG. 5, two temperature sensors (for example, resistance change detection type temperature sensor 35) are provided at both ends of the arrangement range of the liquid path 33 on the base plate 37, and the voltage drop of the temperature sensor is plotted. Detected between middle Y' and Z',
The above-described control may be performed when the detected temperature difference exceeds a predetermined value.

Furthermore, the temperature distribution may be obtained by a combination of the temperature detection section based on the number of ejections per unit time and the temperature detection section using a temperature sensor, which were employed in the first embodiment, and recording control may be performed. This is particularly effective when it is difficult to arrange a temperature sensor near the flow path due to constraints such as the configuration of the head. Furthermore, the temperature of the target area may be detected more accurately by using a temperature sensor and the number of times of ejection.

(Third Embodiment) Next, a description will be given of an embodiment that more effectively prevents the rise in ink temperature within the nozzle.

In the two embodiments described above, the ejection amount from each ejection port was controlled by changing the recording speed to balance the temperature increase due to ejection and the temperature decrease due to heat dissipation. This control is particularly effective when the temperature is below abnormality, but when the temperature exceeds abnormality, it is possible to return to recording in a shorter time than before;
It may exceed msec. This embodiment is a mode for exceeding such an abnormal temperature, and uses the recovery system 2 shown in FIG. 1.

The temperature increase due to ejection is a phenomenon that occurs in a narrow area near the liquid path, and it is unlikely that the ink inside the ink cartridge 10 will be affected. Therefore, the temperature detection means based on the data related to the number of discharges as in the first embodiment or the second
By the temperature detection means using the sensor as in the embodiment, when it becomes necessary to take measures to prevent temperature rise, the carriage 4 is returned to the suction recovery position, and by performing a suction operation, the heated ink is sucked out from inside the head and refreshed. By that,
It becomes possible to lower the temperature quickly and reliably.

Therefore, it is extremely effective to switch between the recording speed control method of the embodiment described above and the main recovery mode to control the ink temperature drop in the vicinity of the flow path.

Here, the recovery system 2 may be one in which an inkjet recording device is permanently installed, which has a function of eliminating clogging of the ejection ports. To give an example, recovery system 2
is driven forward and backward relative to the recording head 5, and includes a cap means for sealing the front surface of the recording head in the forward position, and a pump means for sucking ink from the ink discharge port through the cap means. That is, by operating the pump with the recording head sealed by the cap means, negative pressure is generated within the cap means, and ink is sucked out from the nozzles.

(Other Configuration of Control System) FIG. 11 is a block diagram showing another configuration of drive control means 200 from the host 100 to the inkjet recording head 5 of the present invention. 204 is a conventional central control means. In this example, two areas of the recording head 5, namely the first
The recording section 57 and the second recording section 52 are used as target regions for determining temperature distribution. In this example, 1 is normally block driven.
Each block is designated as a first and second recording section. It is preferable to control this block unit because the accuracy of the duty ratio is ensured. Of course, the control target may be controlled every two blocks or every three blocks.

[0067] Reference numeral 201 denotes a block serving as a duty determining means for determining the drive signal supplied to the first recording section 51, which determines 1) the duty per unit time, and 2) the total
Continue to measure the duty. Similarly, 202 is
The drive signal supplied to the first recording unit 52 is determined.

203 sends the duty determination data measured in blocks 201 and 202 to central control means 204.
This is a stop time judgment block for total duty and duty ratio. Like this block, there is a dedicated dut for each of the corresponding first and second recording units.
By providing the y determination means, data can be extracted as needed. This duty determination means includes a first,
It is also possible to supply temperature data from each sensor of the second recording section. Note that the normal inkjet recording speed is 200 mm/sec to 400 mm/s.
It is clear that the above-mentioned interruption time is extremely small compared to ec, which proves the superiority of the present invention.

(Detailed Specific Example) Next, a practical specific example will be described in detail using the configuration using each part 100 to 105 in FIG. 2 and FIGS. 8 to 10.

The purpose of the control in this specific example is to prevent "joint lines" that occur at joints in the main scanning direction in serial printers. This prevents the difference in temperature between the upper and lower ends of the discharge port group, that is, the difference in discharge amount between the upper and lower ends, which is one of the main causes of this "connection streak."

Specific numerical examples are shown in the table below.

[0072]

[Table 1]

When a print code is input in step st1 of FIG. 8, the print code is converted into a binary ejection code (step st2). To explain this in detail using FIG. 2, an external device 100 such as a personal computer
The print code input from is stored in the reception buffer 103 in the gate array 101 for duty calculation. The print code stored in the reception buffer 103 is converted into a binary ejection code of "eject"/"not eject" for each ejection port, and is transferred to the print buffer 102. At this time, the ejection duty (du) of the upper half ejection port group is set in the line duty input buffer 105 of FIG. 2, and the ejection duty (dd) of the lower half ejection port group is set in the line input buffer 104 of FIG. st3, st4), starts printing (step st5), and the CPU 20a inputs the line input buffers 104, 105 at an arbitrary timing.
The ejection duty of the upper half ejection port group and the ejection duty of the lower half ejection port group can be detected by referring to .

After printing one line, the duty ratio calculation routine calculates x1, and the total-duty calculation routine calculates x2 (steps st6, st7), calculates the carriage rest time (t), and adjusts the carriage according to the calculated values. control the scanning of Specifically, in this embodiment, the pause time (t) of the carriage is calculated using the following multiple regression equation.

t=ax1+bx2+c (however, a, b, c are constants and in this example
a=b=100,c=0
x
1 and x2 are variables (details will be given below)) and the duty ratio (x1) is calculated as follows by a duty ratio calculation routine including steps st61 to st66 shown in FIG.

If the ratio of the duty of the upper half outlet group to the duty of the lower half outlet group is less than 1.5, x1=0,
When the duty ratio is 2.0 or more, x1=2, otherwise x1=1.

That is, when (du>dd), (du/d
d<1.5 ) or when (dd>du), if (dd/du<1.5) then (x1=0)
When (du>dd) (du/dd
≧2.0) or when (dd>du) (
dd/du≧2.0 ) then (x1=2)
When (dd>du) (1.5≦d
If d/du<2.0), set (x1=1).

Total-duty (x2) is total-d including steps st71 to st76 shown in FIG.
The uty calculation routine calculates as follows.

If the sum of the duty of the upper half discharge port group and the duty of the lower half discharge port group is 10% or less, x2 = 0,5
If it is 0% or more, set x2=2, otherwise set x2=1.

That is, if (du+dd<0.1), then (
x2=0) (dd+du≧0.5) then (x2=2
) (0.1 ≦du+dd<0.5 ) then (x2=
1).

[0081] Here, the regression equation will be explained.

[0082] In a serial type inkjet printing apparatus in which the printing head performs printing by scanning, the carriage downtime (t) to make the streaks at the joints caused by scanning inconspicuous depends on the ejection duty of the upper ejection port and the lower ejection port. The larger the duty ratio of the discharge duty, the greater the difference in discharge amount between the upper discharge port and the lower discharge port, and it takes a relatively longer time to cool down.

Furthermore, when the total duty is large, heat storage in the head increases and the ejection amount increases. If a printing pause occurs for a long time after a large amount of heat is accumulated (such as when transferring an image), uneven printing will occur before and after the pause.

[0084] The above regression equation is a multiple regression equation using the above two items as explanatory variables that cause connecting streaks due to scanning.
The pause time (t) of the carriage is determined as an objective variable.

The constants "a, b" of each explanatory variable represent the weight of each explanatory variable, and in this embodiment, they are equivalent and both are 100. In this embodiment, the head temperature is controlled by the carriage downtime, but it may be controlled by the head drive frequency, printing direction, suction recovery operation, or a combination of these.

Although the duty of the upper half discharge port group and the duty of the lower half discharge port group were used to detect the duty, a method using part of the upper discharge port group and part of the lower discharge port group may also be used. Alternatively, it may be a method of detecting and controlling duties at three or more locations.

Further, in this embodiment, the pause time of the carriage is calculated using a first-order multiple regression equation, but other regression methods may be used.

(Others) The present invention particularly relates to means for generating thermal energy as energy used to eject ink, in an inkjet recording system.
For example, the present invention provides an excellent effect in a recording head or recording apparatus that is equipped with an electrothermal converter (for example, an electrothermal converter, a laser beam, etc.) and uses the thermal energy to cause a change in the state of the ink. This is because such a system can achieve higher recording density and higher definition.

For its typical configuration and principle, see, for example, US Pat. Nos. 4,723,129 and 4,740.
Preferably, it is carried out using the basic principles disclosed in the '796 specification. This method is the so-called on-demand type.
It is applicable to both continuous types, but in particular, in the case of on-demand type, it is applicable to the electrothermal converter placed corresponding to the sheet holding the liquid (ink) or the liquid path. , by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise exceeding nucleate boiling, the electrothermal transducer generates thermal energy to produce film boiling on the thermally active surface of the recording head. liquid (ink) that corresponds one-to-one to this drive signal.
This is effective because it can form air bubbles inside. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one droplet. It is more preferable to use this drive signal in a pulse form, since the growth and contraction of bubbles can be carried out immediately and appropriately, making it possible to eject liquid (ink) with particularly excellent responsiveness. This pulse-shaped drive signal is described in US Pat. No. 4,463,359 and US Pat.
345262 are suitable. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

[0090] In addition to the configuration of the recording head that is a combination of ejection ports, liquid paths, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44 disclose a configuration in which a heat acting part is arranged in a bending region.
A configuration using the specification of No. 59600 is also included in the present invention. In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge part for a plurality of electrothermal converters, and a hole that absorbs pressure waves of thermal energy is disclosed. The effects of the present invention are also effective even with a configuration based on Japanese Patent Application Laid-open No. 138461/1985 which discloses a configuration corresponding to the discharge section. That is, regardless of the form of the recording head, according to the present invention, recording can be performed reliably and efficiently.

Furthermore, 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 that can be recorded by a recording apparatus. Such a recording head may have either a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration as a single recording head formed integrally.

In addition, even in the case of a serial type as in the above example, the recording head is fixed to the device main body, or it is attached to the device main body to connect electrically with the device main body and to prevent ink from flowing from the device main body. The present invention is also effective when using a replaceable chip-type recording head that can be supplied with ink or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself.

Further, it is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, etc. to the configuration of the recording apparatus of the present invention because the effects of the present invention can be further stabilized. Specifically, these include heating the recording head using a capping means, a cleaning means, a pressure or suction means, an electrothermal transducer, a separate heating element, or a combination thereof. For example, there may be mentioned a pre-heating means for performing the ejection, and a pre-ejection means for ejecting other than recording.

Regarding the type and number of recording heads to be mounted, for example, in addition to one type that corresponds to a single color of ink, there are also types and numbers of recording heads that are installed to correspond to a plurality of inks of different recording colors and densities. A plurality of them may be provided. That is, for example, the recording mode of the recording apparatus is not limited to a recording mode for only a mainstream color such as black, but may also be a recording mode in which the recording head is configured integrally or in a combination of multiple colors, Alternatively, the present invention is extremely effective for an apparatus equipped with at least one of the full-color recording modes using color mixing.

In addition, in the embodiments of the present invention described above, the ink is explained as a liquid, but it is also possible to use an ink that solidifies at room temperature or lower, and that softens or liquefies at room temperature. Generally speaking, in inkjet systems, the temperature of the ink itself is adjusted within the range of 30°C or higher and 70°C or lower to keep the viscosity of the ink within a stable ejection range. Sometimes, ink in liquid form may be used. In addition, in order to actively prevent temperature rise due to thermal energy by using the energy to change the state of the ink from a solid state to a liquid state, or to prevent ink from evaporating, it is possible to solidify and heat the ink when left standing. An ink that is liquefied by water may also be used. In any case, by applying thermal energy in accordance with the recording signal, the ink is liquefied and the liquid ink is ejected, or the ink has already begun to solidify by the time it reaches the recording medium. The present invention is also applicable when using ink that is liquefied for the first time. Ink in such cases is disclosed in Japanese Patent Application Laid-open No. 54-56847 or Japanese Patent Application Laid-open No. 60-71.
In a state where it is held as a liquid or solid in the porous sheet recesses or through holes, as described in Japanese Patent No. 260,
It may also be configured to face the electrothermal converter. In the present invention, the most effective method for each of the above-mentioned inks is to implement the above-mentioned film boiling method.

In addition, the inkjet recording apparatus of the present invention can be used as an image output terminal for information processing equipment such as a computer, a copying machine combined with a reader, or a facsimile machine having a transmitting/receiving function. It may also take a certain form.

[0097]

[Effects of the Invention] As explained above, according to the present invention,
By providing a temperature distribution detection means for detecting, estimating, and determining the temperature distribution of the recording head during recording, and a recording speed control means for controlling the recording speed according to the determination by the means,
Ink droplet per dot ejected from each ejection port (
Variations in ejection amount) can be reduced for multiple areas of the print head or constantly, regardless of the print pattern.
It is possible to suppress the occurrence of density unevenness, black streaks, white streaks, etc. on a recorded image, and to perform recording with high image quality.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of an inkjet recording apparatus to which the present invention can be applied.

FIG. 2 is a block diagram showing a configuration example of a control system of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 3 is a flowchart showing an example of the recording operation control procedure.

FIG. 4 is a schematic diagram of a recording head according to another embodiment of the invention.

FIG. 5 is a schematic diagram of a recording head according to still another embodiment of the present invention.

FIG. 6 is an explanatory diagram for explaining variations in the number of ejections for each ejection.

FIG. 7 is an explanatory diagram for explaining the state of dot formation due to variations in ejection amount.

FIG. 8 is a flowchart of specific control means performed in response to data from the host input side in FIG. 2;

FIG. 9 is a flowchart showing a subroutine for determining a duty ratio in the flowchart shown in FIG. 8;

FIG. 10: total- in the flowchart shown in FIG.
3 is a flowchart showing a duty determination subroutine.

FIG. 11 is an explanatory diagram of an embodiment of temperature distribution determination based on recorded information for each predetermined plurality of regions according to the present invention.

[Explanation of symbols]

1 Record sheet 2 Recovery system 5 Recording head 6 Carriage 10 Ink cartridge 20 Control section 23-26 Motor 30 Timer 32 Counter 33 Liquid path 34 Electrothermal converter 35 Temperature sensor

Claims (12)

[Claims] 1. A print head having a plurality of ejection ports for ejecting ink, a detection means for detecting temperature distribution within the print head related to a print operation, and a print head configured to perform printing by the print head based on the detection. 1. A recording device comprising: control means for controlling speed. 2. The detection means includes means for detecting the temperature distribution based on data regarding the number of ink ejections during a recording operation at each of the plurality of ejection ports. recording device. 3. The recording apparatus according to claim 1, wherein the detection means includes means for detecting temperature inside each of the plurality of ejection ports to detect the temperature distribution. 4. The detection means includes means for detecting the temperature distribution based on data related to the number of ink ejected during a recording operation at each of the plurality of ejection ports, and 2. The recording apparatus according to claim 1, further comprising means for detecting the temperature distribution by detecting the temperature in the recording apparatus. 5. A discharge means for forcibly discharging ink from the plurality of ejection ports of the recording head by applying pressure, and a second control for driving the discharge means based on the detected temperature distribution. 5. The recording device according to any one of 1 to 4, further comprising means. 6. The recording head includes an electrothermal transducer for generating thermal energy that causes film boiling in the ink as energy used for ejecting the ink, corresponding to each of the plurality of ejection ports. The recording apparatus according to claim 1, further comprising an inkjet recording head having an inkjet recording head. 7. The control means provides a stop time of 500 milliseconds or less based on the detection to the relative moving speed of the carriage on which the recording head is placed and the recording medium on which recording is performed by the recording head. The recording device according to claim 1, wherein the recording device is a recording device. 8. A recording control method for recording on a recording medium using an inkjet recording head equipped with thermal energy generating elements respectively corresponding to a plurality of ejection ports, the method comprising: determining a temperature distribution of the recording head; , a step of determining whether to continue recording or interrupting recording based on the determination result, and a step of starting recording after an interruption time determined according to the recording interruption determination. Recording control method. 9. The thermal energy generating element is an electrothermal transducing element that forms bubbles in the ink by an electric drive signal corresponding to a recording signal, and the interruption time is 500 milliseconds or less. The recording control method according to claim 8. 10. The recording control method according to claim 8, wherein the determination is made according to a temperature detected by a temperature detection mechanism provided in each of a plurality of predetermined areas. 11. The determination is determined by the duty ratio per unit time of the recording signal supplied to each of the plurality of predetermined regions and the total duty supplied to each of the plurality of predetermined regions. The recording control method according to claim 8. 12. The recording control method according to claim 11, wherein the time for executing the determination is 500 milliseconds or less.