JP2001096733A - Two way recording device, record correcting method for two way recording device, and computer-readable recording medium with record correction processing program for two way recording device recorded thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the recording quality by having an ink impact on a desired position even in the case an ink ejection speed is changed. SOLUTION: In the case an ink impact point on the first half way is displaced from an original impact point Pa to Q1 (or Q3), and an ink impact point in the second half way is displaced from an original impact point Pa to Q2 (or Q4) due to change of an ink ejection speed according to change of the ink temperature, the ink ejection timing in the second half way is corrected. Specifically, the ink ejection position is corrected by a displacement amount Z in the recording head 1 movement direction (or in the direction opposite to the movement direction) so that an ink is ejected at the corrected ink ejection position (imaginary line).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bidirectional recording device,
The present invention relates to a recording correction method for a bidirectional recording device and a computer-readable recording medium recording a recording correction processing program for the bidirectional recording device.

[0002]

2. Description of the Related Art In a recording apparatus which performs recording on a recording material by discharging ink from nozzles arranged in a recording head, a mechanism such as a thermostat for keeping the temperature of ink constant is usually low cost of the recording apparatus. It is not provided from the viewpoint of miniaturization, low power consumption, miniaturization, etc. Therefore, when the temperature of the environment in which the printing apparatus is used changes, the temperature of the ink mounted on the printing apparatus changes accordingly.

However, when the temperature of the ink changes, the viscosity of the ink changes accordingly, and the change in the viscosity of the ink changes the viscous load between the ink and the nozzle. That is, as the temperature of the ink increases, the viscosity of the ink decreases and the viscous load decreases. On the other hand, when the temperature of the ink decreases, the viscosity of the ink increases and the viscous load increases.

Irrespective of such a change in viscous load, if ink is ejected under the same driving conditions of the recording head (for example, a driving voltage applied to apply an ejection pressure to the ink), the temperature of the ink depends on the temperature of the ink. In addition, there is a problem that the amount of ink ejected from the nozzle changes. That is, even if the same drive voltage is applied, when the temperature of the ink rises,
Due to the decrease in viscous load, the ink ejection amount increases,
When the temperature of the ink decreases, there is a problem that the ink ejection amount decreases due to an increase in the viscous load.

In order to solve this problem, a conventional printing apparatus controls the drive voltage to decrease as the ink temperature rises, while increasing the drive voltage as the ink temperature decreases. Was adjusted so that the amount of ink ejected from the nozzle became constant regardless of the temperature.

[0006]

However, when the drive voltage is increased to increase the ink ejection pressure, the ink ejection speed from the nozzles is increased, while the drive voltage is decreased to decrease the ink ejection pressure. , The discharge speed of the ink from the nozzles is reduced. When the ink ejection speed changes, the flight time of the ink from the nozzle to the landing point (the arrival point of the ink on the recording material) changes.

However, in the conventional recording apparatus, the ink flight time is assumed to be substantially constant, and the ink ejection timing is also fixed. Therefore, when the flight time of the ink changes, the ink does not land on the target landing point, and there is a problem that a deviation occurs between the actual landing point and the target landing point.

Particularly, in a bidirectional printing apparatus that performs printing in both the forward and backward passes of the main scan of the print head, the ink droplets ejected in the forward pass and the ink drops ejected in the backward pass are opposite in the main scanning direction. Therefore, if the ink landing point shifts, even if both ink droplets should land on the same pixel position, they land on different pixel positions, thereby deteriorating the recording quality. was there.

In addition, since the deviation of the landing point on the forward path and the deviation of the landing point on the return path are added, there is a problem that the deviation of the landing point is doubled.

An object of the present invention is to cause ink to land at a desired position even when the ink ejection speed changes,
The purpose is to improve the recording quality.

[0011]

In order to achieve the above object, a bidirectional recording apparatus according to the first aspect of the present invention comprises a plurality of ink jet heads for discharging ink on a surface facing a recording material. Driving a recording head in which nozzles are arranged at a constant pitch in the sub-scanning direction, a reciprocating motion of the recording head in the main scanning direction, and an operation necessary for recording including ink ejection timing and ink ejection pressure from the nozzle. And a head drive control unit for controlling the head drive control unit. The head drive control unit drives the recording head in both the forward path and the return path of the main scanning of the recording head, and discharges ink from the nozzles to form dots on the recording material. While forming the ink droplets, the ink ejection pressure is adjusted according to the change in the ink viscosity due to the change in the ink temperature. In a bidirectional printing apparatus that drives and controls a recording head so that ink is ejected from a nozzle, the head drive control unit is configured to control the ink ejection pressure by adjusting the ink ejection pressure. A correction means is provided for correcting the ink discharge timing so as to reduce the mismatch between the ink landing point on the forward path and the ink landing point on the return path that should be matched at the position in the main scanning direction.

According to the present invention, the head drive control unit has a correction means, which is originally caused in the main scanning direction by a change in the ink discharge speed caused by adjusting the ink discharge pressure. The ink ejection timing is corrected so as to reduce the mismatch between the ink landing point on the forward path and the ink landing point on the return path that should be matched at the position. Therefore, according to the present invention, since the ink is ejected at the corrected ink ejection timing, it is possible to reduce the mismatch between the ink landing points of the two inks, and to ideally match the ink landing points. it can. As a result, the recording quality can be improved.

According to a second aspect of the present invention, there is provided the bidirectional printing apparatus according to the first aspect, wherein the correcting means corrects the ink ejection timing in one of the forward path and the backward path of the main scanning of the recording head. It is characterized by the following.

According to the present invention, the correction means corrects the ink ejection timing in one of the forward path and the backward path of the main scanning of the recording head.
Compared with the case where the correction is performed in both directions, the number of corrections is reduced to half, and the processing and time required for the correction can be reduced.

Further, in the correction of only one of the forward path and the return path, the deviation amount obtained by adding the deviation of the forward path and the deviation of the return path is corrected at once, whereas in the correction of both the forward path and the return path, the correction of each path is performed. The deviation amount (approximately one half of the total deviation amount between the forward path and the return path) is corrected. Therefore, when correction can be performed only with a discrete amount instead of a continuous amount, and when the deviation amount and the discrete correction amount do not completely match, it is better to perform correction only on one of the forward path and the return path. However, the difference between the correction amount and the deviation amount can be made smaller in many cases than in the case where the correction is performed by both of them, and the deviation can be corrected more.

According to a third aspect of the present invention, in the bidirectional recording apparatus according to the first or second aspect, the correction means includes a temperature measurement means for measuring an ink temperature, and a correction amount of the ink temperature and the ink ejection timing. Correction data storage means for storing correction data defining the relationship with the ink temperature measured by the temperature measuring means, and a correction amount based on the correction data stored in the correction data storage means. Discharging timing changing means for changing the ink discharging timing according to the determined correction amount.

According to the present invention, there is provided correction data storage means for storing correction data defining the relationship between the ink temperature and the correction amount of the ink discharge timing, and the ink discharge timing is corrected by the correction data. Therefore, it is not necessary to measure the ink ejection speed, which is difficult to measure during recording, and the ink ejection timing can be corrected by measuring the ink temperature, which is easy to measure even during recording.

Further, in general, the temperature measuring means is already mounted in the conventional recording apparatus for controlling the drive voltage to be changed in accordance with the change in the ink temperature (ink viscosity). Therefore, an increase in manufacturing cost can be suppressed.

The correction data is obtained in advance for each bidirectional recording apparatus by a test or the like before shipment from a factory or the like, and is stored in the correction data storage means.

According to a fourth aspect of the present invention, there is provided the bidirectional recording apparatus according to the third aspect, wherein the ink landing point on the outward path which should be coincident in the position in the main scanning direction when the bidirectional recording apparatus is shipped. And a shipping ink temperature storing means for storing a shipping ink temperature which is an ink temperature when the ink ejection timing is adjusted so that the ink landing point in the return path coincides with the ink landing point. A plurality of types are provided corresponding to the plurality of shipping ink temperatures, respectively, wherein the ejection timing changing means uses the correction data to correspond to the shipping ink temperature stored in the shipping ink temperature storage means. Correction data to be selected, and the ink ejection timing is changed based on the selected correction data.

According to the present invention, a plurality of types of correction data are provided corresponding to a plurality of shipping ink temperatures having different values, respectively, and the ejection timing changing means uses the correction data from the shipping data. The correction data corresponding to the shipping ink temperature stored in the hour ink temperature storage means is selected, and the ink ejection timing is changed based on the selected correction data.

Therefore, when the ink temperature at the time of shipment is different, even when the correction amount for the ink temperature changed from the ink temperature at the time of shipment is different, it is possible to perform appropriate correction according to the ink temperature at the time of shipment. As a result, the ink ejection timing can be corrected more accurately.

According to a fifth aspect of the present invention, there is provided the bidirectional recording apparatus according to the third or fourth aspect, wherein the correction data stored in the correction data storage means includes a plurality of ink temperature ranges each having a different temperature range. And table data in which ink ejection timing correction amounts in each of the plurality of ink temperature ranges are associated with each other, wherein the ejection timing changing means includes an ink temperature including the ink temperature measured by the temperature measuring means. The correction amount corresponding to the area is selected from the table data.

According to the present invention, the correction data is associated with a plurality of ink temperature ranges each having a different temperature range and a correction amount of the ink ejection timing in each of the plurality of ink temperature ranges. It is configured as table data. Then, the ejection timing changing means obtains a correction amount by selecting a correction amount corresponding to the ink temperature range including the ink temperature measured by the temperature measuring means from the table data.

Therefore, according to the present invention, the correction amount corresponding to the temperature range including the measured ink temperature is selected in the table data.
The correction amount can be obtained quickly and easily.

According to a sixth aspect of the present invention, in the bidirectional recording apparatus according to the third or fourth aspect, the correction data stored in the correction data storage means derives a correction amount of an ink ejection timing from an ink temperature. Wherein the ejection timing changing means substitutes the ink temperature measured by the temperature measuring means into the calculation formula to obtain a correction amount.

According to the present invention, since the correction data is stored as data representing a calculation formula for deriving the correction amount of the ink ejection timing from the ink temperature, the correction amount for each ink temperature is stored. The storage amount can be reduced as compared with the case.

According to a seventh aspect of the present invention, in the bidirectional printing apparatus according to any one of the third to sixth aspects, the correction data is such that the amount of ink droplets ejected from a nozzle differs depending on a printing mode. In this case, a plurality of types are provided corresponding to each recording mode, and the ejection timing changing means selects correction data corresponding to a print mode at the time of recording from the correction data, and converts the selected correction data into the selected correction data. The ink ejection timing is changed based on the timing.

According to the present invention, when the amount of ink droplets ejected from the nozzle differs depending on the recording mode, a plurality of types of correction data are provided corresponding to each recording mode. Selects the correction data corresponding to the print mode at the time of recording from the correction data, and changes the ink ejection timing based on the selected correction data.

Therefore, even if the correction amounts differ due to the different recording modes (that is, the ink droplets ejected from the nozzles), the ink ejection timing can be appropriately corrected according to the recording mode. In addition, the ink ejection timing can be corrected more accurately.

According to an eighth aspect of the present invention, there is provided the bidirectional recording apparatus according to any one of the third to seventh aspects, wherein the bidirectional recording apparatus is identical in position in the main scanning direction when the bidirectional recording apparatus is shipped. An ink discharge speed storage unit for storing an ink discharge speed at the time of shipment, which is an ink discharge speed when the ink discharge timing is adjusted so that the ink landing point on the forward path to be made coincides with the ink landing point on the return path; A plurality of types of correction data are provided corresponding to each of the plurality of shipping ink ejection speeds having different values.
The correction data corresponding to the factory ink discharge speed stored in the ink discharge speed storage means is selected from the correction data, and the ink discharge timing is changed based on the selected correction data. And

According to the present invention, a plurality of types of correction data are provided corresponding to a plurality of shipping ink ejection speeds having different values, respectively. The correction data corresponding to the factory-set ink discharge speed stored in the ink discharge speed storage means is selected from the correction data, and the ink discharge timing is changed based on the selected correction data.

Therefore, according to the present invention, even when the ink ejection speed at the time of shipment differs for each bidirectional printing apparatus, the ink ejection timing is appropriately corrected for each bidirectional printing apparatus. And finer correction can be performed.

According to a ninth aspect of the present invention, there is provided the bidirectional recording apparatus according to any one of the third to eighth aspects, wherein the correction amount is such that the main scanning of the recording head before the correction is performed by the correction means. This is a difference value between the ink ejection position in the direction and the corrected ink ejection position, and is represented by a negative value when the ink ejection timing is advanced and a positive value when the ink ejection timing is delayed. It is characterized by the fact that

According to the present invention, the correction amount is a difference value between the ink discharge position in the main scanning direction of the recording head before correction by the correction means and the ink discharge position after correction. Generally, the data amount of the correction data can be reduced as compared with the case where the corrected ink ejection position is used as the correction data.

Further, the correction amount is represented by a negative difference value when the ink discharge timing is advanced, and a positive difference value when the ink discharge timing is delayed. The ink ejection position after the correction can be obtained only by adding the correction amount to the ejection position. Since the corrected ink ejection timing is when the recording head passes the corrected ink ejection position, the corrected ink ejection timing can be determined easily and at high speed.

Further, the ink discharge position can be detected by a detector (for example, a linear encoder) for detecting the position of the recording head in the main scanning direction. This detector is usually provided in the recording apparatus. Therefore, a new detector for detecting the ink discharge position is not required, and the increase in manufacturing cost can be suppressed.

According to a tenth aspect of the present invention, in the ninth aspect of the present invention, in the ninth aspect, the difference value is defined as the minimum distance when the minimum distance at which the ink ejection position can be changed is set to 1. It is characterized by being expressed by an integer multiple.

Some bidirectional printing apparatuses can change the ink ejection position only in discrete amounts (digital amounts), not in continuous amounts (analog amounts). In such a bidirectional printing apparatus, the change of the ink ejection position is performed at an integral multiple of the minimum value of the discrete amount.

According to the invention described in this claim, in such a bidirectional printing apparatus, the difference value is set such that the minimum distance (that is, the minimum value of the discrete amount) at which the ink ejection position can be changed is one. Since the distance is expressed as an integral multiple of the minimum distance, the correction amount can be easily expressed. Generally, a numerical value is represented by an integer rather than a decimal number, so that the data amount is reduced. Therefore, the data amount representing the correction amount can be reduced.

According to a recording correction method for a bidirectional recording apparatus according to the present invention, the surface facing the recording material is
A recording head in which a plurality of nozzles for ejecting ink are arranged at a constant pitch in the sub-scanning direction, a reciprocating movement of the recording head in the main scanning direction, an ink ejection timing and an ink ejection pressure from the nozzle. And a head drive control unit for driving and controlling operations necessary for printing, the head drive control unit driving the print head in both forward and backward paths of main scanning of the print head, and ejecting ink from the nozzles. Then, the dots are formed on the recording material, and the ink ejection pressure is adjusted according to the change in the ink viscosity with the change in the ink temperature. A printing correction method for a bidirectional printing apparatus for controlling the printing head so that the ink is ejected from a nozzle. The ink temperature is measured by the measuring means, and the correction amount of the ink ejection timing corresponding to the measured ink temperature is obtained from the correction data defining the relationship between the ink temperature and the correction amount of the ink discharge timing corresponding to the ink temperature. The ink discharge timing is changed based on a correction amount obtained from the correction data.

According to the present invention, the same operation and effect as those of the first and third aspects of the present invention can be achieved.

According to the twelfth aspect of the present invention, there is provided a computer-readable recording medium having recorded thereon a recording correction processing program for a bidirectional recording apparatus, comprising a plurality of recording media for ejecting ink on a surface facing a recording material. A recording head in which nozzles are arranged at a constant pitch in the sub-scanning direction;
A head drive control unit for driving and controlling operations required for recording including reciprocation of the recording head in the main scanning direction and ink ejection timing and ink ejection pressure from the nozzles, wherein the head drive control unit The recording head is driven in both the forward path and the return path of the main scanning of the head to discharge ink from the nozzles to form dots on a recording material, and to discharge ink in accordance with a change in ink viscosity with a change in ink temperature. A recording correction processing program for a bidirectional recording apparatus, which controls the driving of the recording head so as to adjust the pressure and eject substantially the same amount of ink from the nozzles for ink droplets forming dots of the same size. A recording medium on which the ink temperature is measured by a temperature measuring means for measuring the ink temperature; A procedure for obtaining a corresponding correction amount of the ink ejection timing from correction data that defines the relationship between the ink temperature and a correction amount of the ink discharge timing corresponding to the ink temperature; and a correction amount obtained from the correction data. And a procedure for changing based on the

According to the present invention, the same operation and effect as those of the first and third aspects of the present invention can be achieved. In addition, as long as the bidirectional recording device is capable of reading and executing a program recorded on the recording medium according to the present invention, any of the bidirectional recording devices can have the above-described effects.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram for explaining a main part of a bidirectional printing apparatus according to the present invention and a synthetic speed V of an ink discharge speed Vi and a print head moving speed Vs. The recording head 1 of this bidirectional recording apparatus (the whole is not shown) has a plurality of nozzles 3 for discharging ink toward the recording material 2 on a surface facing the recording material (paper or the like) 2. . These nozzles 3 are arranged at a constant pitch in the sub-scanning direction.

The recording head 1 has a thermistor (not shown) for measuring the ink temperature. Strictly, this thermistor does not measure the temperature of the ink ejected from the nozzles, but is provided inside the recording head and measures the temperature around the recording head 1 (environmental temperature). However, since the temperature of the ink ejected from the recording head 1 also follows this environmental temperature, there is no problem even if the temperature measured by the thermistor is regarded as the ink temperature. Therefore, in the present embodiment, the temperature measured by the thermistor is treated as the ink temperature.

The head drive controller 7 controls the reciprocation of the recording head 1 between the forward direction 5 and the backward direction 6 of the main scanning, and also controls the ejection of ink from the nozzles 3. These controls are performed by the internal storage device (RO) of the head drive control unit 7.
M, RAM, hard disk drive, etc .: a program stored in a storage medium (not shown), or a recording medium (floppy disk, CD-ROM,
(MO disk, magnetic tape, etc.) 9 and may be executed by a processor (not shown) of the head drive control unit 7 executing this program, or incorporated in the head drive control unit 7. May be realized by a hardware circuit. The correction processing of the ink ejection timing, which will be described in detail later, is also realized by a program or a hardware circuit, similarly to this control.

The ink droplets ejected from the nozzles 3 by the drive control of the head drive control unit 7 have an ink ejection speed (a speed component perpendicular to the recording surface) Vi and a moving speed (a reciprocating motion of the recording head 2 in the main scanning direction). Vs), which is a speed component perpendicular to the ink ejection speed Vi. Therefore, the ink flies toward the recording surface 2 at the composite speed V of these speeds Vi and Vs, and reaches the landing point P which is the arrival point on the recording material 2.
Lands on a.

For this reason, the head drive control unit 7 controls the position Pf (hereinafter referred to as “ink discharge”) just before the recording head 1 passes just above the landing point Pa so that the target pixel coincides with the landing point Pa. Ink is ejected at the time when the ink passes through the position.). The distance X between the impact point Pa and the ink discharge position Pf is given by the following equation, where d is the distance (paper gap) between the recording head 1 and the recording material 2: X = | Pa−Pf | = (d / Vi) · Vs (1)

Here, since the velocities Vi and Vs and the distance d are known, the distance X can be obtained from these found values. Therefore, when the target pixel, that is, the landing point Pa is determined, the ink ejection position Pf is determined by determining the position at a distance X from the landing point Pa to the position in front of the recording head 1 in the traveling direction. And
The position of the recording head 1 in the main scanning direction is detected by a linear encoder (not shown), and when the time when the recording head 1 passes the ink ejection position Pf is detected, ink is ejected at this time.

When the bidirectional printing apparatus is manufactured and then shipped from a factory, the ink ejection position Pf is the same as the ink landing point on the outward path that should coincide with the position in the main scanning direction under the environmental temperature of the factory. The adjustment is performed so that the ink landing point on the return path matches. The environmental temperature of the factory at the time of shipment (at the time of adjustment), that is, the ink temperature at the time of shipment (hereinafter referred to as “shipping ink temperature”) is stored in the internal storage device of the head drive control device 7.

Next, correction of the ink ejection timing will be described. FIGS. 2A and 2B are explanatory diagrams for explaining the correction of the ink ejection speed timing. FIG. 2A shows that the ink ejection speed at the time of recording is higher than the speed at the time of shipment from a factory (hereinafter referred to as “shipping ink ejection speed”). (B) shows the correction when the ink discharge speed at the time of recording is lower than the ink discharge speed at the time of shipment.
In these figures, the recording head 1 and the ink landing point in the forward path are located above the recording material 2 and the return point is located in the lower side so that the landing point on the outward path and the landing point on the return path can be easily understood. Respectively show the recording head 1 and the ink landing point.

As described in the section of the prior art, the ink discharge speed increases as the ink temperature decreases, and decreases as the ink temperature increases. Therefore, when ink is ejected at a constant ink ejection timing regardless of a change in the ink ejection speed as in the conventional bidirectional printing apparatus, as shown by solid lines in FIG. There is a gap between them.

That is, when the ink temperature is lowered, FIG.
As shown by the solid line in (a), the ink lands at positions Q ₁ (forward path) and Q ₂ (return path) on the near side of the original landing point Pa when viewed from the recording head 1. For this reason, a displacement occurs between the two impact points. This deviation becomes that the deviation PAQ ₂ during the backward and shift PAQ ₁ in the forward is added. If the moving speeds of the recording head 1 in the main scanning direction in the forward path and the return path are the same, generally, PaQ ₁ = PaQ
Since the _2, the shift amount Z becomes Z = 2PaQ _1. On the other hand, when the ink temperature rises, as shown by the solid line in FIG. 2B, the ink moves to positions Q ₃ (forward path) and Q ₃ beyond the original landing point Pa as viewed from the recording head 1.
₄ (Return) landed. For this reason, the deviation amount Z is Z = 2
PaQ ₃ is obtained.

FIG. 3 shows the ink temperature (environmental temperature) [° C.] and the deviation Z [μ] measured for a plurality of conventional recording heads.
[m]. When the ink temperature during printing is lower than the shipping ink temperature (in the case of FIG. 2A), the shift amount is assumed to be positive, and when the printing ink temperature is higher than the shipping ink temperature (FIG. 2B). ) Is expressed as negative. Lines L ₁ is a graph of the mean value of the deviation amount. Linear _{L 2} is the standard deviation sigma +3 multiplied by the straight line _{L 3} are multiplied by the standard deviation sigma -3, 99.7 as a distribution
% Represents an area for securing%.

In this embodiment, the shift amount Z is reduced,
Alternatively, in order to eliminate the ink ejection timing, the ink ejection timing in the return path is corrected according to the change in the ink temperature during printing, and the ink is ejected at the corrected ink ejection timing.

More specifically, when the ink temperature decreases, as shown by the imaginary line in FIG. 2A, the ink discharge position at the time of printing on the return path is adjusted to the ink discharge position adjusted at the time of shipment from the factory. This is corrected in such a way that the ink ejection timing is delayed by displacing in the moving direction (hereinafter referred to as “shipping ink ejection position”). On the other hand, when the ink temperature rises, as shown by the imaginary line in FIG. 2B, the ink ejection position at the time of printing in the return path is displaced in the direction opposite to the moving direction from the ink ejection position at the time of shipment. , The ink ejection timing is advanced.

[0058] In the correction in the backward only displaced in different impact point Q ₁ or Q ₃ are the impact point Pa of ink landing point is adjusted at the factory. However, this displacement merely moves the recorded image as a whole by the distance PaQ ₂ or PaQ ₃ (typically, several μm to several tens μm as will be described later) in the main scanning direction. Since the landing point coincides with the ink landing point in the return path, there is no adverse effect on the recording quality.

FIG. 4 is table data showing an example of the correction amount of the ink ejection timing. FIG.
The three types of ink droplets, a small dot ink droplet (for example, 13 picoliters), a medium dot ink droplet (for example, 27 picoliters), and a large dot ink droplet (for example, 40 picoliters) are used. 5 is an example of table data for a print mode in which a print head capable of discharging prints with one type of ink droplet for a small dot. FIG.
Is the ink drop for small dots (for example, 6 picoliters)
This is an example of table data for a print mode in which only ink droplets are ejected, a medium dot is formed by hitting this ink droplet twice on the same pixel, and a large dot is formed by hitting it three times. As described above, by providing the table data indicating the correction amount for each recording mode, even if the correction amount differs for each recording mode, it is possible to perform appropriate correction according to the recording mode. The ejection timing can be corrected more accurately.

These two table data are correction data when the ink temperature at shipment is 25 ° C. or higher, correction data when the ink temperature is 15 ° C. or higher and lower than 25 ° C.
It consists of three pieces of correction data when the temperature is lower than ° C. Thus, the table showing the correction amount for each ink temperature range at the time of shipment
By providing the data, even when the correction amount differs depending on the ink temperature at the time of shipment, appropriate correction can be performed according to the ink temperature at the time of shipment, and the ink ejection timing can be corrected more accurately.

The correction data in each shipping ink temperature range includes an ink temperature range at the time of recording and a correction amount in the ink temperature range. This correction amount indicates a difference value indicating how much the ink discharge position at the time of recording in the return path is displaced from the ink discharge position at the time of shipping, and is the minimum unit (for example, 2880) by which the recording head 1 can change the ink discharge position. 1 / [inch] = about 9 [μm])
Assuming that α is 1, it is represented by a numerical value that is an integral multiple of α. The correction amount having a positive sign means that the ink discharge position at the time of recording in the return path is displaced in the moving direction from the ink discharge position at shipping, and the correction amount having a negative sign indicates the ink amount at the time of recording in the return path. This means that the ejection position is displaced in the direction opposite to the moving direction from the ink ejection position at the time of shipment.

For example, when the minimum unit α is 9 [μm] and the correction amount is +2, the ink discharge position at the time of recording is 18 [μm] more in the moving direction than the ink discharge position at the time of shipment.
[m] is displaced, and ink is ejected when the recording head 1 passes this displaced ink ejection position.
When the correction amount is 0, the ink ejection position at the time of recording is not corrected, and the ink ejection position at the time of shipment is set to the recording head 1.
Is ejected when passes.

The deviation can be corrected only by an integral multiple of the minimum unit α, which is a discrete amount, because the operation speed of the head drive control unit 7 (for example, the head drive control unit 7
This is because the position of the recording head can be specified only by a discrete amount according to the operation clock frequency of the processor (CPU or the like) included in the above. Therefore, when the operation speed of the head drive control unit 7 becomes higher (for example, the frequency of the operation clock of the processor becomes higher), the value of the minimum unit α also becomes smaller, and the correction can be performed more effectively. Can be.

This correction amount is obtained as follows. First, the ink ejection speed at each ink temperature is determined based on the graph representing the ink ejection speed measured at each ink temperature shown in FIG. 5, and the deviation Z is calculated from the obtained ink ejection speed as follows: Z = 2Vs _{· d · (1 / Vi P} -1 / Vi B) obtained by (2). Here, Vi _B represents the factory ink ejection velocity, Vi _P represents the ink ejection speed obtained from 5 (i.e. the ink ejection speed at the time of recording in the return path).

Subsequently, an integer n that minimizes the absolute value | Z−n · α | of the difference between the shift amount Z and the integral multiple n · α (n is an integer) of the minimum unit α is obtained. The value of the integer n is the correction amount.

The table data may be created in advance before shipment, and may be stored in the internal storage device of the head drive control unit 7 at the time of shipment, or may be recorded on the recording medium 9.
It may be read from the recording medium 9 at the time of recording.

In the present embodiment, the correction is performed on the return path, but the correction can be similarly performed on the outward path. Further, the correction can be performed both on the outward route and the return route. However, when the correction is performed in the minimum unit α as described above, generally, it is possible to more effectively reduce the deviation by performing the correction only on one of the return path and the forward path.

For example, when the minimum unit α = 9 [μm] and the deviation amount Z = 10 [μm], when the correction is performed only on one of the return path and the forward path, the deviation amount is 10 [μm].
m], 9 [μm] is corrected, and the shift amount is 1 [μm].
Can be reduced to On the other hand, when the correction is performed on both the forward path and the return path, the deviation amount on each path is 10 [μ].
m], that is, 5 [μm], which is a half of [m], so that this deviation is reduced to a minimum unit of 9 [μm] in both the forward path and the return path.
4 [μm] in each of the forward path and the return path
Of 8 [μm] remains without being corrected.
As described above, generally, the correction amount can be reduced by performing the correction only on one of the outward path and the return path.

Next, the procedure of the ink ejection timing correction process will be described with reference to FIG. First, table data corresponding to the recording mode designated by the user or the recording mode set by the bidirectional recording apparatus is selected (step S1).

Subsequently, the factory ink temperature stored in the internal storage device of the head drive control section 1 is read, and the table data corresponding to the read factory ink temperature is selected in step S1. Selected from the table data (step S2).

Subsequently, at the start of recording, the ink temperature is measured by the thermistor (step S3), and step S2
A correction amount corresponding to the recording ink temperature range including the measured ink temperature is selected from the table data selected in step S4 (step S4).

After the selection of the correction amount, the ink discharge position (the ink discharge position at the time of recording) obtained by adding the selected correction amount to the shipping ink discharge position is obtained (step S5).
Then, recording is performed while discharging ink according to the calculated ink discharge position at the time of recording. The processing in step S3 may be performed before steps S1 and S2, or may be performed between steps S1 and S2.

FIG. 7 is a graph showing the relationship between the ink temperature and the amount of deviation when the ink ejection timing is corrected. The straight lines L ₄ , L ₅ and L ₆ of this graph are similar to the straight lines L ₁ , L ₂ and L ₃ shown in FIG. ₃ , respectively. Comparing the graph shown in FIG. 7 with the graph shown in FIG. 3 in which the correction is not performed, it can be seen that the slope of the straight line is small and the deviation amount is small. As described above, according to the present embodiment, the deviation can be reduced (ideally reduced to zero) by correcting the ink ejection timing.

It should be noted that, as in the present embodiment, the correction amount is not determined in advance and stored as table data, but the equation of the function representing the straight line in FIG. 5 and the calculation of the equation (2) are performed. The correction amount can also be obtained by configuring the processing as a program or a hardware circuit and performing the calculation processing by substituting the ink temperature at the time of recording into these equations when performing the correction.

In some cases, the ink discharge speed at the time of shipment differs for each print head. In this case, a plurality of types of table data can be prepared for each of the ink discharge speeds at the time of shipment. For example, table data corresponding to an ink ejection speed at shipment from 6 [m / s] to less than 7 [m / s], 7 [m / s] to 8 [m / s].
s], table data corresponding to 8 [m / s] or more and less than 9 [m / s], 9
Four types of table data such as table data corresponding to [m / s] or more and less than 10 [m / s] can also be prepared. At the time of shipping, the shipping ink discharge speed is stored in an internal storage device of the head drive control unit 7, and at the time of recording, correction can be performed by selecting table data based on the stored shipping ink discharge speed. it can.

Furthermore, the correction amount of the table data can be represented not by the difference value of the ink ejection position but by the difference value of time, and the ink ejection timing can be corrected by adjusting the ink ejection time.

[0077]

According to the present invention, since the ink is ejected at the corrected ink ejection timing, the mismatch between the ink landing points of the two inks can be reduced, and ideally, the ink landing points can be matched. As a result, the recording quality can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a main part of a bidirectional printing apparatus according to the present invention and a combined speed V of an ink ejection speed Vi and a print head moving speed Vs.

FIGS. 2A and 2B are explanatory diagrams for explaining the correction of the ink discharge speed timing. FIG. 2A shows the correction when the ink discharge speed at the time of recording becomes faster than the ink discharge speed at the time of shipment.
(B) shows the correction when the ink discharge speed at the time of recording is lower than the ink discharge speed at the time of shipment.

FIG. 3 is a graph showing a relationship between an ink temperature measured for a plurality of conventional print heads and a shift amount Z;

4A and 4B are table data showing an example of the correction amount of the ink ejection timing. FIG. 4A shows three types of ink droplets for a small dot, a medium dot, and a large dot. This is an example of table data for a recording mode in which recording is performed with one type of small dot ink droplet in a recording head capable of discharging a small amount of ink droplets. FIG. This is an example of table data for a recording mode in which a medium dot is formed by hitting the ink droplet twice on the same pixel and a large dot is hit by hitting the ink droplet three times.

FIG. 5 is a graph showing an ink ejection speed measured at each ink temperature.

FIG. 6 is a flowchart illustrating an ink ejection timing correction process.

FIG. 7 is a graph showing the relationship between the ink temperature and the amount of deviation when the ink ejection timing is corrected.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 2 Recording material 3 Nozzle 7 Head drive control part 8 Recording medium reading device 9 Recording medium

Claims (12)

[Claims] 1. A recording head in which a plurality of nozzles for ejecting ink are arranged at a constant pitch in a sub-scanning direction on a surface facing a recording material, and a reciprocation of the recording head in a main scanning direction. A head drive control unit for driving and controlling an operation necessary for printing including movement and ink ejection timing and ink ejection pressure from the nozzles, wherein the head drive control unit controls the forward scan and the return scan of the main scan of the recording head. The recording head is driven by both of them, and the ink is ejected from the nozzles to form dots on the recording material, and the ink ejection pressure is adjusted according to the change in the ink viscosity due to the change in the ink temperature. In a bidirectional printing apparatus which drives and controls a printing head so that substantially the same amount of ink is ejected from nozzles for ink droplets forming dots of The head drive control unit is configured to adjust a position between an ink landing point on the forward path and an ink landing point on the return path, which should be coincident with each other in the main scanning direction, due to a change in the ink ejection speed caused by adjusting the ink ejection pressure. A bidirectional printing apparatus, comprising: a correction unit that corrects an ink ejection timing so as to reduce a mismatch. 2. A bidirectional printing apparatus according to claim 1, wherein said correction means corrects an ink ejection timing in one of a forward scan and a return scan of a main scan of the print head. 3. The correction data storage device according to claim 1, wherein said correction means stores temperature data for measuring ink temperature and correction data defining a relationship between the ink temperature and a correction amount of ink ejection timing. Means for determining a correction amount based on the ink temperature measured by the temperature measuring means and the correction data stored in the correction data storage means, and changing the ink discharge timing based on the determined correction amount. And a means. 4. The ink jet printer according to claim 3, wherein at the time of shipment of the bidirectional printing apparatus, ink is ejected such that the ink landing point on the forward path, which should be matched at the position in the main scanning direction, and the ink landing point on the return path. A shipping ink temperature storing means for storing a shipping ink temperature which is an ink temperature when the timing is adjusted, wherein the correction data corresponds to each of a plurality of shipping ink temperatures having different values. The ejection timing changing means selects correction data corresponding to the shipping ink temperature stored in the shipping ink temperature storage means from the correction data, and based on the selected correction data. A two-way recording apparatus for changing the ink ejection timing. 5. The method according to claim 3, wherein the correction data stored in the correction data storage means includes a plurality of ink temperature ranges having different temperature ranges, and an ink ejection timing in each of the plurality of ink temperature ranges. The ejection timing changing means selects a correction amount corresponding to an ink temperature range including the ink temperature measured by the temperature measuring means from the table data. Is,
A bidirectional recording device characterized by the above-mentioned. 6. The discharge timing changing means according to claim 3, wherein the correction data stored in the correction data storage means is a data representing a calculation formula for deriving a correction amount of an ink discharge timing from an ink temperature. Wherein a correction amount is obtained by substituting the ink temperature measured by the temperature measuring means into the calculation formula. 7. The correction data according to claim 3, wherein a plurality of types of correction data are provided corresponding to each recording mode when the amount of ink droplets ejected from a nozzle differs according to the recording mode. Wherein the ejection timing changing means selects correction data corresponding to a recording mode at the time of recording from the correction data, and changes the ink ejection timing based on the selected correction data. Characteristic bidirectional recording device. 8. The ink landing point on the forward path and the ink landing point on the return path, which should match at the position in the main scanning direction, when shipping the bidirectional printing apparatus, according to any one of claims 3 to 7, Further comprising an ink ejection speed storage means for storing an ink ejection speed at the time of shipment, which is an ink ejection speed when the ink ejection timing is adjusted so that the two coincide with each other. A plurality of types are provided corresponding to the respective ink ejection speeds. The ejection timing changing means converts correction data corresponding to the factory ink ejection speed stored in the ink ejection speed storage means from the correction data. A bidirectional printing apparatus for selecting and changing the ink ejection timing based on the selected correction data. 9. The apparatus according to claim 3, wherein the correction amount is a difference between an ink discharge position in the main scanning direction of the recording head before correction by the correction unit and an ink discharge position after correction. A bidirectional printing apparatus characterized in that it is a difference value, and is represented by a negative value when the ink ejection timing is advanced, and by a positive value when the ink ejection timing is delayed. 10. The method according to claim 9, wherein the difference value is expressed by an integral multiple of the minimum distance when the minimum distance at which the ink ejection position can be changed is set to 1.
A bidirectional recording device characterized by the above-mentioned. 11. A recording head in which a plurality of nozzles for ejecting ink are arranged at a constant pitch in a sub-scanning direction on a surface facing a recording material, and a reciprocation of the recording head in a main scanning direction. A head drive control unit for driving and controlling an operation necessary for printing including movement and ink ejection timing and ink ejection pressure from the nozzles, wherein the head drive control unit controls the forward scan and the return scan of the main scan of the recording head. The recording head is driven by both of them, and ink is ejected from the nozzles to form dots on the recording material.
Adjusts the ink ejection pressure according to the change in ink viscosity with the change in ink temperature, and drives the recording head so that approximately the same amount of ink is ejected from the nozzles for ink droplets that form dots of the same size. What is claimed is: 1. A recording correction method for a bidirectional recording apparatus, comprising: measuring a temperature of an ink by temperature measuring means for measuring an ink temperature; and determining a correction amount of an ink ejection timing corresponding to the measured ink temperature. And a correction amount defining the relationship between the correction amount of the ink ejection timing corresponding to the ink temperature and the ink ejection timing is changed based on the correction amount obtained from the correction data. The recording correction method of the device. 12. A recording head in which a plurality of nozzles for ejecting ink are arranged at a constant pitch in a sub-scanning direction on a surface facing a recording material, and a reciprocation of the recording head in a main scanning direction. A head drive control unit for driving and controlling an operation necessary for printing including movement and ink ejection timing and ink ejection pressure from the nozzles, wherein the head drive control unit controls the forward scan and the return scan of the main scan of the recording head. The recording head is driven by both of them, and ink is ejected from the nozzles to form dots on the recording material.
Adjusts the ink ejection pressure according to the change in ink viscosity with the change in ink temperature, and drives the recording head so that approximately the same amount of ink is ejected from the nozzles for ink droplets that form dots of the same size. A recording medium on which a recording correction processing program of a bidirectional recording apparatus to be controlled is recorded, wherein a procedure of measuring an ink temperature by a temperature measuring means for measuring an ink temperature, and a step of ejecting an ink corresponding to the measured ink temperature Obtaining a timing correction amount from correction data defining a relationship between the ink temperature and an ink ejection timing correction amount corresponding to the ink temperature;
A computer-readable recording medium recording a recording correction processing program for a bidirectional recording apparatus, comprising: a step of changing an ink ejection timing based on a correction amount obtained from the correction data.