JP2003334941A - Inkjet recorder and method of inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To record a high quality image at a high resolution even when a small wave exists on a recording face. <P>SOLUTION: Image data from a host computer 801 is converted to data corresponding to a recording method specified for a printer by a data converting section 802, and the rasterized binary data is transferred to a head driving section 804. The head driving section 804 generates a driving signal in predetermined voltage, pulse width and timing in accordance with the data to perform the recording by driving each of nozzles on a recording head 102. When the recording is performed, a distance to a paper is measured by an optical paper gap sensor 107. A correction value of a deviation amount which is expected based on the obtained value is calculated by a calculating section 807, and then the ejection timing is corrected based on the correction value by an image signal correcting section 803. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus and an ink jet recording method, and in particular, unpredictable paper float (cockling) during recording.
The present invention relates to an inkjet recording apparatus and an inkjet recording method capable of performing recording control according to a change in the distance between a recording head and a recording medium.

[0002]

2. Description of the Related Art For example, as an information output device in a word processor, a personal computer, a facsimile or the like, there is a printer for recording desired information such as characters and images on a sheet-shaped recording medium such as paper or film.

Although various methods are known as recording methods for printers, ink-jets are used for the reasons such as non-contact recording on recording media such as paper, easy colorization, and high quietness. In recent years, the method has attracted particular attention, and as its configuration, a recording head that ejects ink according to desired recording information is mounted and recording is performed while reciprocally scanning in a direction perpendicular to the feeding direction of a recording medium such as paper. The serial recording method is generally used because it is inexpensive and easy to miniaturize.

In particular, ink-jet type serial printers have rapidly become popular because the resolution and color have been improved in recent years and the recording quality has been remarkably improved. In such an apparatus, by increasing the integration density of nozzles that eject ink droplets and reducing the amount of ink ejected per dot, it is possible to achieve higher resolution, while achieving an image quality that is closer to that of silver halide photography. In order to realize it, various technologies such as multi-tone recording using four color inks (cyan, magenta, yellow, black) as the basics and light inks having a low density are developed.

Further, with respect to a decrease in recording speed which is a concern as the image quality becomes higher, a good throughput can be obtained by a technique such as an improvement of the driving frequency and a bidirectional recording in which the recording is performed in the forward and backward passes of scanning. Has been obtained.

However, in the ink jet system,
Since an image is formed by adhering and absorbing ink droplets on a recording medium, various problems may occur depending on the recording medium used. For example, when using a very general plain paper or the like as a recording medium, paper floating or waviness due to expansion and contraction of fibers called cockling occurs on the paper surface in a region where much ink is absorbed,
This causes image distortion.

In particular, it is difficult to prevent the cockling from occurring because various factors such as the environmental temperature and humidity and the state of the recorded image affect not only the recording medium used but also the position and degree of occurrence of the cockling are predicted. Because I can't
Various countermeasures have been proposed for degrading image quality.

For example, as a method of preventing the occurrence of cockling itself, a method of electrostatically adhering a recording medium, and a method of suppressing image distortion due to cockling do not make image disturbance noticeable to human eyes. And the like are known.

However, these methods cannot completely suppress cockling and deterioration of image quality. In particular, when performing high-resolution recording as in recent years, even a slight deviation in the landing position of ink droplets corresponds to one or more pixel sizes, so more stringent accuracy is required, and the above method is satisfactory. I can't get the results I can.

As described above, in the ink jet type serial printer, a change in the relative distance between the recording head and the recording medium has a great influence on the image formed. On the contrary, this means that if the relative distance between the recording head and the recording medium can be detected in advance, it is possible to perform recording as intended even on a material having irregularities or a three-dimensional object. From such a viewpoint, there is a technique for measuring a relative distance between a recording head and a recording medium and controlling various parameters during recording according to the value to perform recording on an uneven or three-dimensional object. , JP-A 06-091878, JP-A 07-81065, JP-A 07-137398, JP-A 09-029958, and JP-A 09-
It is disclosed in Japanese Patent Publication No. 193368.

[0011]

However, the technique described in the above-mentioned publications has a sufficient effect even when applied to a serial type ink jet printer which performs high resolution recording by a recording head having a plurality of nozzle rows. I can't get it.

Of the above publications, Japanese Patent Laid-Open No. 06-09187
No. 8, JP-A-07-81065, and JP-A 07-
The respective publications of 137398 relate to a continuous type inkjet printer in which an ink droplet after ejection is charged and deflected based on recording data to perform recording. More specifically, Japanese Patent Laid-Open No. 06-091878 discloses controlling a dot recording position by changing a deflection voltage for dot deflection. JP-A-0
In JP-A-7-81065, either the distance between the nozzle and the recording medium or the thickness of the recording medium is measured,
It is disclosed that the flight direction of ink droplets or the relative distance between a head and a recording medium is controlled. Further, Japanese Patent Laid-Open No. 07-137398 discloses that at least one of the relative position between the head and the recording medium, the relative movement speed, and the flying speed of the ink droplet is controlled according to the obtained distance. Has been done.

Since all of these three publications are premised on being applied to a continuous type printer, the configuration for realizing the control method is quite large. Therefore, even if it is applied to an on-demant type serial printer, the size of the entire apparatus increases and the cost increases, which is not practical. Further, since neither of them is supposed to use a recording head having a plurality of nozzle rows or to perform bidirectional recording, it is applied to an ink jet type serial printer which records a high resolution image at a high speed. However, you cannot expect a sufficient effect.

On the other hand, Japanese Unexamined Patent Publication No. 09-029958 relates to an on-demant type serial printer, and its purpose is to perform highly accurate recording even when the recording surface of a recording medium is curved. In this publication, the ejection speed of ink droplets is controlled according to the measured value. More specifically, when the distance between the recording head and the surface to be recorded changes, the distance between the recording head and the surface to be recorded is prevented in order to prevent the characters from being distorted due to the density of the seating (landing) points. Is larger, the injection speed is faster, and by controlling in this way,
It is described that even if the gap between the recording head and the recording medium changes, the time from the ejection of the ink droplets until the ink is seated on the recording sheet becomes almost constant, and it is possible to prevent the distortion and density of the recording from occurring. .

However, the method described in this publication is effective when the surface to be recorded is largely curved, but has little effect on extremely small undulations such as cockling. Generally, in an on-demant type serial inkjet printer, if the relative moving speed between the print head and the print medium and the ink ejection frequency of the print head are constant, the distance between the print head and the print medium or the ink drop Regardless of the arrival time to the recording medium, the dot landing intervals are constant, and the landing positions are not uneven.

That is, when there is an extremely small undulation such as cockling, the density of the landing position becomes uneven depending on the rate of change (ie, inclination) of the distance when recording on a curved surface. It is necessary to control the interval (timing). Therefore, Japanese Patent Laid-Open No. 09-02
The method described in Japanese Patent Publication No. 9958 does not solve the image distortion due to cockling.

In Japanese Patent Laid-Open No. 09-193368, the distance from the ink jet recording head to the recording surface is measured at each ejection point, the displacement amount of the measured distance is obtained from this value, and ink is ejected based on the displacement amount. It is disclosed to control the volume or the discharge interval. According to this method, the dots can be arranged at the same intervals as in the case of recording on a smooth surface regardless of the unevenness of the surface of the recording medium, so that the dot positions do not become uneven.

However, when performing high-resolution recording, the number of ink droplets ejected to record one raster becomes very large, so that the distance from the recording head to the recording surface is increased at each ejection point. Is not realistic to measure.
Therefore, as described in other publications, those described in this publication,
It cannot be applied to a recording head having a plurality of nozzle arrays or a recording device for recording a high-resolution image by bidirectional recording.

The present invention has been made in view of the above situation, and it is possible to record an image with high resolution and high quality even if a minute waviness such as cockling is present on the recording surface. An object is to provide a recording apparatus and an inkjet recording method.

[0020]

In order to achieve the above object, a first ink jet recording apparatus of the present invention comprises a recording head having a plurality of recording elements arranged in a predetermined direction and ejecting ink droplets from each of them. A recording apparatus for performing recording by scanning a mounted carriage on a recording medium in a direction substantially orthogonal to the array direction of the recording elements, wherein a distance between an ejection surface of the recording element and a recording surface of the recording medium is set. A detection unit for detecting and a timing control unit for controlling the drive timing of the recording element according to the value of the distance detected by the detection unit are provided.

In a second ink jet recording apparatus of the present invention which achieves the above object, a carriage having a recording head arranged in a predetermined direction and having a plurality of recording elements for ejecting ink droplets from each of the recording heads is used. Is a recording device that performs recording by scanning on a recording medium in a direction substantially orthogonal to the array direction of, and detection for detecting the distance between the ejection surface of the recording element and the recording surface of the recording medium at at least two positions. Means, a computing means for calculating a displacement amount from the value of the distance detected at the at least two positions, a scanning speed control means for controlling the moving speed of the carriage according to the displacement amount, and the at least two From the value of the distance detected at the position, the paper distance calculating means for obtaining the average distance between the ejection surface of the recording element and the recording surface of the recording medium, and according to the value of the average distance, And a timing control means for controlling the drive timing of the serial recording element.

Further, the first ink jet recording method of the present invention which achieves the above object, is characterized in that the carriage having a recording head arranged in a predetermined direction and having a plurality of recording elements for ejecting ink droplets from each of the carriages is mounted on the carriage. A recording method of performing recording by scanning on a recording medium in a direction substantially orthogonal to the array direction of the recording elements, a detecting step of detecting a distance between an ejection surface of the recording element and a recording surface of the recording medium, A timing control step of controlling the drive timing of the recording element according to the value of the distance detected by the detection step.

According to a second ink jet recording method of the present invention for achieving the above object, a carriage having a recording head arranged in a predetermined direction and having a plurality of recording elements for ejecting ink droplets from each of the recording heads is used. Is a recording method in which recording is performed by scanning on a recording medium in a direction substantially orthogonal to the array direction of, and detection is performed by detecting the distance between the ejection surface of the recording element and the recording surface of the recording medium at at least two positions. A step of calculating a displacement amount from a value of the distance detected at the at least two positions; a scanning speed control process of controlling a moving speed of the carriage according to the displacement amount; From the value of the distance detected at the position, the paper distance calculating step for obtaining the average distance between the ejection surface of the recording element and the recording surface of the recording medium, and according to the value of the average distance, And a timing control step of controlling the drive timing of the serial recording element.

That is, in the present invention, the distance between the ejection surface of the recording element and the recording surface of the recording medium is detected, and the drive timing of the recording element is controlled according to the value of the distance. When the distance to the recording medium is detected at at least two positions, the displacement amount is calculated from the value of the distance detected at the two positions, and the moving speed of the carriage is also controlled according to the displacement amount.

According to this structure, unpredictable paper floating due to cockling or the like occurs, and even if the distance between the ejection surface of the recording element and the recording medium changes, the recording dots do not shift in position and are of high quality. Images can be recorded in high resolution.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In the embodiments described below, a printer will be described as an example of a recording apparatus using the ink jet recording method.

In the present specification, "recording" (sometimes referred to as "printing") means not only the case of forming meaningful information such as characters and figures, but also the case of significant senselessness and human visual perception. Regardless of whether or not it is actualized so as to be possible, it also represents a case where an image, a pattern, a pattern, etc. is widely formed on a recording medium or the medium is processed.

The "recording medium" is not limited to paper used in a general recording apparatus, but is widely applicable to ink such as cloth, plastic film, metal plate, glass, ceramics, wood and leather. Things shall also be represented.

Further, "ink" (which may be referred to as "liquid") should be broadly construed in the same way as the definition of "recording (printing)", and is given on a recording medium, A liquid that can be used for forming an image, a pattern, a pattern, or the like, processing a recording medium, or treating an ink (for example, solidifying or insolubilizing a coloring agent in the ink applied to the recording medium).

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.
3 is a perspective view showing a state where the cover of the inkjet printer as the embodiment of FIG. Recording medium 106 inserted from paper feed port 111 of inkjet printer 100
Is fed by the feed roller 109 to the recording head unit 10
3 is conveyed to the recordable area. A platen 108 is provided below the recording medium 106 in the recordable area. The carriage 101 is configured to be movable in a direction (scanning direction) defined by two guide shafts, a guide shaft 104 and a guide shaft 105, and reciprocates in a recording area.

The carriage 101 is equipped with a recording head unit 103 including recording heads for ejecting color inks for image recording of a plurality of colors and ink tanks for supplying ink to the respective recording heads. Printer 100 of FIG.
Each of the plurality of colors of ink provided in the four colors is, for example, four colors of black (K), cyan (C), magenta (M), and yellow (Y). At the left end of the area where the carriage 101 can move, there is a recovery system unit in the lower part of the device, which caps the ejection port of the recording head except during the recording operation,
Ink is received at the time of preliminary ejection at a predetermined time interval during the recording operation. The position where the recovery system unit 110 is provided is called the home position.

FIG. 2 is a perspective view showing the structure of the recording head unit 103. Bk, C, and
A recording head 102 for ejecting M and Y and a tank for each color are mounted. A paper gap sensor 107 such as an optical sensor type displacement meter is attached to the tip, and measures the distance to the recording medium (hereinafter referred to as the paper gap) at the same height as the ejection port surface of the recording head. Each tank is connected to the recording head 102 via a connection portion with the recording head 102 and supplies ink of each color.

The structure of the recording head unit is not limited to the example shown in FIG. For example, the tanks of different colors may have an integrated structure, or the tank and the ejection head may have an integrated structure. Further, the displacement gauges may be attached to the side of the carriage or both sides of the front and rear, or may be compatible with six colors in which light density cyan or magenta ink tanks are simultaneously mounted.

FIG. 3 is a side view schematically showing a recording state of this embodiment. The recording medium 106 is partially lifted as shown in the figure due to the absorption and evaporation of the ink in the already recorded portion, and the sheet interval is not constant. The carriage 101 reciprocates in a direction orthogonal to the feeding direction of the recording medium indicated by an arrow in the figure to perform recording in both directions. At this time, the displacement gauge 107 at the tip of the recording head unit measures the distance between the surface of the recording medium and the surface of the recording medium, and the ejection timing from each color nozzle is controlled according to the value.

In the figure, the floating of the recording medium is exaggerated for ease of explanation, and the distance between sheets actually varies by about 1 mm or less.

FIG. 4 is a diagram showing a difference in recording position due to a change between sheets in bidirectional recording. In the figure, Ig
And Ib represent ink droplets ejected from the print head during forward printing and backward printing. Each ink droplet has an ejection speed Vd in a substantially vertical direction which is determined by the driving performance of the head and an inertial speed Vcr accompanying the movement of the carriage.
And two velocity components. The discharge speed Vd is constant regardless of the speed of the carriage and the traveling direction, but Vc
In the case of reciprocal recording, r is reversed in direction during forward recording and backward recording.

By design, as shown in FIG. 4A, the ejection timings of the both are adjusted so that the landing positions on the recording surface are aligned with respect to the reference sheet interval. However,
Even if ink is ejected from the recording head at the adjusted timing, if the distance between the head ejection surface and the recording medium (paper interval) changes, the time until the ink droplet reaches the recording surface of the recording medium 106 Are different from each other, and a shift due to the velocity component Vcr is generated by that amount.

FIG. 4B shows the case where the sheet interval is shorter than the set value, and FIG. 4C shows the case where the sheet interval is longer than the set value. In any of these cases, the ink droplet landing positions are different between the forward pass recording and the backward pass recording, and the intended recording cannot be performed. As a result, image distortion occurs and the recording quality deteriorates.

FIG. 5 is a diagram schematically showing the principle of the ejection timing control according to this embodiment. As described above, in the present embodiment, since the distance between the ejection surface of the recording head and the recording medium is always measured by the paper interval sensor 107, irregular floating of the paper surface can be detected. In the present embodiment, the ejection timing of ink droplets is generated in accordance with the detected inter-paper value.

FIG. 5A shows a case where the sheet interval is shorter than the set value. When ink droplets are ejected at the same timing as the normal sheet interval during the backward path recording, it becomes like Ib 'and the landing position shifts. However, in the present embodiment, when the sheet interval is shorter than the set value, the ejection timing at the time of the backward printing is delayed so that the landing position is adjusted as indicated by Ib. On the other hand, FIG. 5B shows a case where the paper interval is longer than the setting, and if ink droplets are ejected at the same timing as the normal paper interval during the backward printing, I
As shown in b ′, the landing position is displaced, but in the present embodiment, when the paper interval is longer than the setting, the ejection timing in the backward path recording is advanced and the landing position is adjusted as indicated by Ib.

FIG. 6 is a block diagram showing a control configuration of this embodiment for realizing such control. Binary or multivalued image data is sent from the device such as the host computer 801 connected to the printer to the printer body. The data conversion unit 802 performs various conversions on this data received via the interface according to the printing method peculiar to the printer, and then transfers the rasterized binary data to the head drive unit 804. Head drive unit 8
In 04, a drive signal is generated according to this data at a predetermined voltage, pulse width, and timing to drive each nozzle of the recording head 102 to perform recording.

The energy and pulse width required for driving are different depending on the individual heads, nozzles, or environment, and are thus corrected by the image signal correction unit 803 by a method such as table conversion so that ideal recording can always be performed. . The signals to be corrected include reciprocal recording and ejection timing for each color. At the time of shipment from the factory or at the time of shipment, a correction value (resist) is obtained and stored at a resolution of one pixel for each recording head, and during actual recording, the value is read and corrected.

The control of the ejection timing in this embodiment is as follows.
During the recording scan, the sheet distance is measured by the optical sheet sensor 107, the correction value of the deviation amount that can occur from the obtained value is calculated by the calculation unit 807, and the image signal correction unit 803 is calculated based on this correction value. Is performed by correcting the ejection timing. The correction by the image signal correction unit 803 is performed in a unit of pixel by adding a correction value to the resist.

In the present embodiment, the data detected by the paper interval sensor 107 is not used for the correction of the print timing during the same scan, but is used for the next print scan. This is because the paper interval data is reflected during the same scan because the load on the arithmetic processing is heavy and the real-time processing is difficult.
Therefore, in the present embodiment, the paper interval sensor 107 is provided at the tip of the recording head 102, and the area to be printed by the next scan can be detected almost accurately.

However, the mounting position of the sheet interval sensor is not limited to this configuration. The paper interval sensor may be attached in the scanning direction of the carriage, or may be provided before and after the nozzle row, and the paper interval may be determined from the average value of both.

FIG. 7 is a diagram showing a specific example of the correction table of this embodiment. Here, as the initial settings, the ink droplet ejection speed from the recording head is 12 m / sec, the carriage moving speed is 24.5 mm / sec, and the standard paper distance is 1.2 mm, and the resist during bidirectional recording is adjusted. 3 shows the value of the sheet interval detected when the sheet interval is shortened by cockling and the corresponding correction value of the resist.

In this case, when the distance between sheets is in the range of 1.2 to 0.9 mm, no correction is made, and when it is in the range of 0.9 to 0.4, recording is performed at a timing advanced by one pixel on either the forward or backward path. When the value is in the range of 0.4 to 0.0, recording is performed at a timing advanced by two pixels on either the forward path or the backward path.

However, if the paper interval becomes zero, the ejection surface of the recording head comes into contact with the surface of the recording medium, which may damage the ejection surface. Therefore, the paper interval is actually 0.2 mm.
When the following is detected, it is preferable to notify the user or automatically perform a process such as stopping the recording.

Generally, the printer is designed with a margin between the initial sheets so that the contact with the ejection surface does not occur even if some cockling occurs. However, conversely, if the paper interval itself can be adjusted in a plurality of steps by a method such as a paper interval lever or automatic adjustment, the initial paper interval can be set narrower. With this configuration, a narrow paper interval is set in a normal area where cockling does not occur, and high-quality images are recorded by paper interval detection and registration correction, while cockling occurs and the ejection surface is likely to contact the recording surface. It is possible to control to record as a wider sheet interval and registration correction. In the present embodiment, a manual paper gap lever that can be adjusted in two stages of a thick paper position for thick paper and a normal position is provided.

As a modified example of the present embodiment, when 0.2 mm or less is detected in the paper distance detection at the standard position, recording is interrupted and the user is notified that it is necessary to switch to the thick paper position. Alternatively, the sheet interval may be newly measured at the switched position, appropriate registration correction may be performed, and recording may be restarted.

Further, in the above description, it has been stated that the vertical distance (height) of the paper interval sensor 107 is set to be the same as the ejection surface of the recording head, and the paper interval is measured. It is not limited to. Actually, the height of the paper interval sensor may be closer to or farther from the ejection surface than the recording surface as long as the accurate relative distance between them can be grasped. In the former case, it is possible to prevent contact between the paper surface on which cockling has occurred and the ejection surface by the paper distance sensor contacting the paper surface first, and in the latter case, the mist of ink ejected from the recording head is prevented. There is an advantage that it is possible to prevent contamination of the paper interval sensor due to

As described above, according to this embodiment,
The paper interval sensor attached to the print head detects the paper interval in the area to be printed in the next scan in the raster direction, calculates the registration correction amount at the time of reciprocal printing at each point, and ejects it at the next printing. Timing is corrected. As a result, in a printer that performs bidirectional recording, even when unpredictable paper floating occurs due to cockling or the like, it is possible to obtain a high-quality image at high speed without misalignment of recording dots.

[Second Embodiment] The second embodiment of the present invention will be described below. In the first embodiment, the recording head is reciprocally scanned to perform bidirectional recording. However, in the present embodiment, the recording head is provided with a plurality of nozzle rows for each ink, and high-speed scanning is performed in one direction. The resolution is recorded. The configuration of this embodiment is basically the same as that of the first embodiment described above, and here, only the parts different from the first embodiment will be described.

FIG. 8 is a diagram showing the nozzle arrangement for one ink of the recording head of this embodiment. In the print head of this embodiment, in order to form an image with a resolution of 1200 dpi, two nozzle rows arranged at a 600 dpi pitch are shifted by a half pitch in the nozzle arrangement direction and arranged in parallel in the scanning direction. This means that a certain amount of nozzle spacing is required for accurate ejection,
This is a configuration for achieving both high resolution of 1200 dpi.

Here, for convenience, the left side is referred to as an even nozzle row and the right side is referred to as an odd nozzle row. Even-numbered nozzle rows and odd-numbered nozzle rows are similarly configured with a predetermined distance. However, due to manufacturing variations, the ejection speeds and ejection angles of the ink droplets may be slightly different between the even nozzle rows and the odd nozzle rows.

As described in the first embodiment, the ejection angle of the ink droplet is determined by the ejection direction from the nozzle and the moving speed of the carriage, but the ejection angle from the nozzle is not always on the recording surface (platen). It is not a right angle. The angle may be intentionally set, or the angle may vary during the manufacturing process of the recording head. This may be due to the characteristics of the ink, or even the same ink may differ between the odd and even columns.

In the present embodiment, in order to correct such variations, registration correction between two nozzle rows arranged in parallel in the scanning direction is performed in the same manner as the registration correction for reciprocal printing in the first embodiment. To do.

FIG. 9 is a diagram showing the relationship between the paper interval and the recording position of the ink droplets ejected from the two nozzle rows.
In the figure, Io and Ie represent ink droplets ejected from odd and even nozzle rows, respectively. Each ink droplet has two velocity components, an ejection velocity in a substantially vertical direction that is determined by the driving performance of the head and an inertial velocity associated with the movement of the carriage.

By design, as shown in FIG. 9 (a), the ejection timings of the both are adjusted so that the landing positions on the recording surface are aligned with respect to the reference sheet interval. However,
Even if ink is ejected from the recording head at the adjusted timing, if the distance between the head ejection surface and the recording medium (paper interval) changes, the time until the ink droplet reaches the recording surface of the recording medium 106 Is different, and the shift due to the velocity component is caused accordingly.

FIG. 9B shows the case where the paper interval is shorter than the setting, and FIG. 9C shows the case where the paper interval is longer than the setting. In any of these cases, the ink droplet landing positions are different between the forward pass recording and the backward pass recording, and the intended recording cannot be performed. As a result, image distortion occurs and the recording quality deteriorates.

FIG. 10 is a diagram schematically showing the principle of the ejection timing control according to this embodiment. As in the first embodiment, in the present embodiment, the distance between the ejection surface of the recording head and the recording medium is constantly measured by the paper interval sensor.
Anomalous floating on the paper surface can be detected. In the present embodiment, the ejection timing of ink droplets is generated in accordance with the detected inter-paper value.

FIG. 10A shows a case where the paper interval is shorter than the set value. When ink droplets are ejected from even-numbered nozzles at the same timing as the normal paper interval, it becomes like Ie 'and the landing position is reached. However, in the present embodiment, when the sheet interval is shorter than the set value, the ejection timing of the even nozzles is delayed and the landing position is adjusted as indicated by Ie. On the other hand, FIG. 10B shows the case where the sheet interval is longer than the setting,
When the ink droplets are ejected from the even-numbered nozzles at the same timing as the normal paper interval, the ink droplets become like Ie ′ and the landing position shifts. However, in this embodiment, the ejection timing of the even-numbered nozzles when the paper interval is longer than the setting. Advance and align the impact position as indicated by Ie.

The correction as described above is effective not only between the even-numbered columns and the odd-numbered columns but also between the recording heads ejecting ink of different colors.

The control configuration of this embodiment is the same as that of the first embodiment and can be represented by FIG. Correction value (registration) between even-numbered nozzles and odd-numbered nozzles of each color and correction value (registration) between each color that was stored at the time of shipment from the factory
Is read at the time of actual recording and is corrected and recorded for each pixel. The inter-sheet distance is measured at the same time when the optical inter-sheet sensor 107 performs the print scan, and the calculation unit 807 calculates the correction value of the deviation amount that can occur from the obtained value, and the image signal correction unit according to this. At 803, the ejection timing is corrected. Similar to the first embodiment, the correction at this time is performed on a pixel-by-pixel basis by adding a value to the correction value of the resist.

The table referred to in the correction processing by the image signal correction unit 803 is not limited to one as in the first embodiment, but a plurality of tables are required. This is because if the ejection angle differs for each nozzle row, different correction values are required even for the same sheet interval. Therefore, ideally, it is necessary to have a correction table for each color between odd and even colors and a correction table for each color, but in reality, since the ejection accuracy between even and odd columns is similar for each color, Not all correction tables need be prepared.

Also in this embodiment, as in the first embodiment,
The data detected by the paper interval sensor 107 is not used for correction of the print timing during the same scan, but is used for the next print scan. This is because the paper interval data is reflected during the same scan because the load on the arithmetic processing is heavy and the real-time processing is difficult. Therefore, in the present embodiment, the paper interval sensor 107 is provided at the tip of the recording head 102, and the area to be printed by the next scan can be detected almost accurately.

As described above, according to this embodiment,
The paper interval sensor attached to the print head detects the paper interval in the area to be printed in the next scan in the raster direction, calculates the registration correction amount at the time of reciprocal printing at each point, and ejects it at the next printing. Timing is corrected. As a result, in a printer that performs recording with a recording head having a plurality of nozzle rows, even if unpredictable paper floating due to cockling or the like occurs, high-resolution, high-quality images with no positional deviation of recording dots can be obtained. Obtainable.

[Third Embodiment] The third embodiment of the present invention will be described below. In this embodiment, the correction processing is performed by controlling the ejection timing described in the first and second embodiments, and at the same time, recording on a three-dimensional object can be performed more positively. The configuration of this embodiment is basically the same as that of the first embodiment, and here, the first
Parts different from the embodiment will be described.

For a three-dimensional object having a more swelling or tilting than the ordinary cockling, even if a recording head having only one line of a single color is used, recording dots are sparsely and densely when recording with a constant driving frequency. , A uniform image cannot be obtained.
This will be described with reference to FIG.

FIG. 11A shows a state in which ink droplets are ejected at even intervals on a smooth recording surface and land. Here, for ease of explanation, it is assumed that the ink droplets are ejected at a right angle to the recording surface. In this way, when the carriage and the recording surface are parallel, the ejection interval d and the landing interval d match.

However, as shown in FIG. 11B, when the recording surface has the inclination angle α, the landing interval d ′ is d ′ = arc cos (α)> d with respect to the ejection interval d. The dot spacing becomes wider than that of the non-tilted portion. Therefore, in the present embodiment, in order to make the landing interval of the ink droplets constant (d) even when the recording surface is inclined, the drive frequency of the recording head is not changed and is changed according to the inclination. Slow down.

FIG. 12 is a diagram schematically showing the principle of control in which the landing interval of ink droplets is made constant in this embodiment. In order to set the ejection interval to the same value d with respect to the recording surface having the inclination angle α as in the case where the recording surface is not inclined, the ejection position is advanced by d (1-cosα) compared to the case where there is no inclination. To discharge. Therefore, the carriage speed may be slowed down so that the ejection timing has a constant cycle at that position.

Although the lateral velocity component of the ejected ink droplet is not taken into consideration in the above description, the actual ink droplet is
As described above, it has a combined component of the angle and speed at the time of ejection from the recording head and the moving speed of the carriage at the time of ejection. Therefore, when actually controlling the carriage speed, it is necessary to control in consideration of these. In any case, in the present embodiment, the intervals of the recording dots are made constant regardless of the angle of the recording surface only by adjusting the speed of the carriage without changing the drive frequency of the recording head.

In this embodiment, the speed control of the carriage as described above is performed, and the correction processing is performed by the control of the ejection timing described in the first and second embodiments. This not only makes the ink droplet landing intervals uniform, but also when performing high-resolution recording of a color image using bidirectional recording and a recording head having a plurality of nozzle rows.
The distortion of the image recorded on the inclined portion or the uneven portion is reduced.

Also in the present embodiment, the adjustment of the positional deviation between the nozzle rows in both directions and between the plurality of nozzle rows is performed as the registration correction for each pixel as described in the first and second embodiments. In this embodiment, the moving speed of the carriage is adjusted to control the landing position, but the drive frequency is not changed.
It can be combined with the first and second embodiments, and the advantage of registration correction is also effective.

Unlike the above embodiment, in this embodiment,
In addition to the absolute distance between sheets for registration correction, it is necessary to measure the amount of displacement (tilt) between sheets for speed control of the carriage. In this case, the displacement amount is preferably measured in a narrow range such as a portion corresponding to the length (width) of the recording head in the scanning direction.

FIG. 13 is a diagram schematically showing a state in which the amount of displacement (tilt) between sheets is measured in this embodiment. As shown in the figure, the recording head unit 103 of the present embodiment has paper distance sensors 1401 and 1402 such as optical sensors mounted on both sides of the recording head with respect to the moving direction of the carriage. The inclination of the recording surface is obtained from the difference between the sheets obtained from these two sensors. The absolute value between the sheets is calculated as the average value of both. According to this configuration, it is possible to detect the amount of displacement between sheets and the distance between sheets in a narrow area corresponding to the width of the recording head.

FIG. 14 is a block diagram showing the control configuration of this embodiment for realizing such control. 2 from the device connected to the printer such as the host computer 801
Value or multivalued image data is sent to the printer body. The data conversion unit 802 performs various conversions on this data received via the interface according to the printing method peculiar to the printer, and then transfers the rasterized binary data to the head drive unit 804. The head drive unit 804 uses a predetermined voltage, pulse width,
A drive signal is generated at a timing to drive each nozzle of the recording head 102 to perform recording.

Since the energy and pulse width required for driving vary depending on the individual head, nozzle, or environment, correction processing is performed by the image signal correction unit 803 by a method such as table conversion so that ideal recording can always be performed. . The signals to be corrected include reciprocal recording and ejection timing for each color. At the time of shipment from the factory or at the time of shipment, a correction value (resist) is obtained and stored at a resolution of one pixel for each recording head, and during actual recording, the value is read and corrected.

In the present embodiment, the optical sheet interval sensor 140 is used.
In 1 and 1402, the recording interval is measured at the same time as the recording scan. The obtained two values are sent to the calculation unit 807, and the average value and the displacement amount of both are calculated here. The correction speed of the carriage is calculated from the displacement amount, and a correction signal is sent to the carriage motor driver 1301. Similar to the first and second embodiments, a correction value for the deviation amount is calculated from the average value between the sheets, and the image signal correction unit 803 corrects the ejection timing based on the calculated correction value. The correction at this time is performed pixel by pixel by adding a value to the resist.

Also in this embodiment, as in the above embodiment, the scanning for detecting the sheet interval and the scanning for actually recording the image may be different.

As described above, according to this embodiment,
By detecting the distance between papers and the amount of displacement by two paper distance sensors mounted on both sides of the head, and controlling the speed of the carriage and the ejection timing, the density of dots and the displacement between colors are uneven even on a three-dimensional object having irregularities. It is possible to record a good color image with no image.

[Other Embodiments] In the above embodiments, particularly in the ink jet recording system, means for generating thermal energy as energy used for ejecting ink (for example, electrothermal converter or laser light). ) And using a method of causing a change in the ink state by the thermal energy, it is possible to achieve high density recording and high definition recording.

Regarding its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, liquid (ink)
By applying at least one drive signal to the electrothermal transducer arranged corresponding to the sheet or liquid path in which is stored, which corresponds to the recorded information and gives a rapid temperature rise exceeding nucleate boiling. Since the electrothermal converter is caused to generate heat energy to cause film boiling on the heat-acting surface of the recording head, as a result, bubbles in the liquid (ink) corresponding to the drive signal in a one-to-one relationship can be formed. It is valid.

Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection openings to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid (ink) with excellent responsiveness can be achieved.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned specifications, The present invention also includes the configurations described in US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the heat-acting surface is arranged in a bending region. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a structure in which a common slot is used as a discharge portion of a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is discharged. A configuration based on Japanese Patent Application Laid-Open No. 59-138461, which discloses a configuration corresponding to each section, may be adopted.

Further, as a full line type recording head having a length corresponding to the width of the maximum recording medium which can be recorded by the recording apparatus, the length can be increased by combining a plurality of recording heads as disclosed in the above-mentioned specification. Either of the structure satisfying the requirement or the structure as one recording head integrally formed may be used.

In addition to the cartridge type recording head in which an ink tank is integrally provided in the recording head itself described in the above embodiment, the recording head is electrically attached to the apparatus main body by being attached to the apparatus main body. A replaceable chip-type recording head that enables various connections and supply of ink from the apparatus main body may be used.

Further, it is preferable to add recovery means for the recording head, preliminary means, etc. to the structure of the recording apparatus described above, because the recording operation can be made more stable. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or sucking means, electrothermal converters or heating elements other than these, or preheating means by a combination thereof. Further, provision of a preliminary ejection mode for performing ejection different from recording is also effective for stable recording.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but the recording head may be integrally formed or a plurality of combinations may be used. Alternatively, the device may be provided with at least one of full-color mixed colors.

In the above-described embodiments, the explanation is made on the premise that the ink is a liquid, but even if the ink solidifies at room temperature or lower, one that softens or liquefies at room temperature is used. Or, in the inkjet method, it is general that the temperature of the ink itself is adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is in a stable ejection range.
It suffices that the ink is in a liquid state when the use recording signal is applied.

In addition, in order to positively prevent the temperature rise due to thermal energy from being used as the energy for changing the state of the ink from the solid state to the liquid state,
Alternatively, in order to prevent the ink from evaporating, an ink that solidifies in a standing state and liquefies by heating may be used. In any case, by applying heat energy, such as ink that is liquefied by applying heat energy according to the recording signal and liquid ink is ejected, or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used.

In this case, the ink is described in JP-A-54-5.
6847 or Japanese Unexamined Patent Publication No. 60-71260, such that it is opposed to the electrothermal converter in the state where it is held as a liquid or solid in the recesses or through holes of the porous sheet. May be In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

Even when the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus including one device (for example, a copying machine, a facsimile). Device).

Further, an object of the present invention is to supply a storage medium (or recording medium) recording a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply a computer of the system or apparatus ( Needless to say, this can also be achieved by the CPU or MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Also,
By executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instructions of the program code.
Needless to say, this also includes the case where the above-mentioned processes perform part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, based on the instruction of the program code. Needless to say, this also includes a case where a CPU or the like included in the function expansion card or the function expansion unit performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

[0099]

As described above, according to the present invention, even when unpredictable paper floating due to cockling or the like occurs and the distance between the ejection surface of the recording element and the recording medium changes,
It is possible to record a high-quality image with no positional deviation of recording dots with high resolution.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an inkjet printer as a preferred embodiment of the present invention.

FIG. 2 is a perspective view of a recording head unit applicable to the printer of FIG.

FIG. 3 is a side view schematically showing a recording state of the first embodiment.

FIG. 4 is a diagram showing a relationship between a change between sheets and a recording position in bidirectional recording.

FIG. 5 is a diagram schematically showing the principle of ejection timing control according to the first embodiment.

FIG. 6 is a block diagram showing a control configuration of the first embodiment.

FIG. 7 is a diagram showing a specific example of a correction table according to the first embodiment.

FIG. 8 is a diagram showing a nozzle arrangement for one ink according to the second embodiment.

FIG. 9 is a diagram showing a relationship between a sheet interval and a recording position of ink droplets ejected from two nozzle rows.

FIG. 10 is a diagram schematically showing the principle of ejection timing control according to the second embodiment.

FIG. 11 is a diagram schematically showing a difference in dot spacing recorded on a flat surface and an inclined surface.

FIG. 12 is a diagram schematically showing the control principle of the third embodiment.

FIG. 13 is a diagram schematically showing a state in which a displacement amount between sheets is measured in the third embodiment.

FIG. 14 is a block diagram showing a control configuration of a third embodiment.

[Explanation of symbols]

100 printers 101 carriage 102 recording head 103 recording head unit 107 Paper interval sensor 801 Host computer 802 Image data conversion unit 803 Image signal correction unit 804 Head drive unit 807 operation unit

Continued front page    (72) Inventor Yuji Konno             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Norihiro Kawadoko             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Tetsuya Eedura             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Tetsuhiro Maeda             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2C056 EA07 EB37 EC07 EC17 EC37                       FA03 FA11                 2C057 AF30 AG14 AL22 AM17 BA03                       BA13

Claims (14)

[Claims] 1. A carriage, on which a recording head having a plurality of recording elements arranged in a predetermined direction and ejecting ink droplets from each of the recording heads, is mounted, is scanned on a recording medium in a direction substantially orthogonal to the arrangement direction of the recording elements. A recording device for performing recording by performing recording according to a value of the distance detected by the detection unit that detects the distance between the ejection surface of the recording element and the recording surface of the recording medium, An inkjet recording apparatus comprising: a timing control unit that controls a drive timing of an element. 2. The recording device is configured to perform recording in both directions in which the carriage reciprocates, and the timing control means causes the two ink droplets ejected in both directions to land within a predetermined range on the recording medium. The inkjet recording apparatus according to claim 1, wherein the drive timing is controlled according to the first aspect of the present invention. 3. The recording head has a plurality of recording element arrays arranged in the same direction, and the timing control means causes the ink droplets ejected from each recording element array to fall within a predetermined range on the recording medium. The inkjet recording apparatus according to claim 1, wherein the drive timing is controlled so that the ink is landed inside. 4. The inkjet recording apparatus according to claim 1, wherein the predetermined range is a size of one pixel having a maximum resolution that can be recorded by the recording apparatus. 5. A carriage, on which a recording head having a plurality of recording elements arranged in a predetermined direction and ejecting ink droplets from each of the recording heads is mounted, is scanned on a recording medium in a direction substantially orthogonal to the arrangement direction of the recording elements. A recording device that performs recording by performing the recording, the detecting device detecting a distance between the ejection surface of the recording element and a recording surface of the recording medium at at least two positions, and a distance detected at the at least two positions. A calculation unit that calculates a displacement amount from a value, a scanning speed control unit that controls a moving speed of the carriage according to the displacement amount, and an ejection of the recording element from a value of a distance detected at the at least two positions. Distance calculating means for obtaining the average distance between the recording surface and the recording surface of the recording medium, and a timing control means for controlling the drive timing of the recording element according to the value of the average distance. Ink jet recording apparatus comprising: a and. 6. The detection means is mounted on the carriage, and detects the distance between the ejection surface of the recording element and the recording surface of the recording medium during scanning. The inkjet recording device according to any one of 1. 7. The ink jet recording apparatus according to claim 6, wherein the value of the distance detected by the detecting unit during scanning is used for recording control in the subsequent scanning. 8. The recording head according to claim 1, wherein the recording head has a plurality of recording element arrays corresponding to a plurality of color inks, and is configured to perform color recording. An inkjet recording device according to claim 1. 9. The recording head is a recording head for ejecting ink by utilizing thermal energy, and is provided with a thermal energy converter for generating thermal energy applied to the ink. Item 9. The inkjet recording device according to any one of items 1 to 8. 10. A carriage on which a recording head having a plurality of recording elements arranged in a predetermined direction and ejecting ink droplets from each of the carriages is mounted is scanned on a recording medium in a direction substantially orthogonal to the arrangement direction of the recording elements. A recording method for performing recording by performing the recording, wherein the detection step of detecting the distance between the ejection surface of the recording element and the recording surface of the recording medium, and the recording according to the value of the distance detected by the detection step. And a timing control step of controlling the driving timing of the element. 11. Recording is performed in both directions in which the carriage reciprocates, and the timing control step controls the drive timing so that two ink droplets ejected in both directions land within a predetermined range on the recording medium. The inkjet recording method according to claim 10, wherein 12. The recording head has a plurality of recording element arrays arranged in the same direction, and in the timing control step, ink droplets ejected from each recording element array are in a predetermined range on the recording medium. 11. The ink jet recording method according to claim 10, wherein the drive timing is controlled so as to land inside. 13. The ink jet recording method according to claim 10, wherein the predetermined range is a size of one pixel having the maximum recordable resolution of the recording method. 14. A carriage, on which a recording head having a plurality of recording elements arranged in a predetermined direction and ejecting ink droplets from each of the recording heads, is mounted, is scanned on a recording medium in a direction substantially orthogonal to the arrangement direction of the recording elements. A recording method for performing recording by performing the recording, the detecting step of detecting a distance between the ejection surface of the recording element and a recording surface of the recording medium at at least two positions, and a distance detected at the at least two positions. A calculation step of calculating a displacement amount from the value, a scanning speed control step of controlling the moving speed of the carriage according to the displacement amount, and an ejection of the recording element from the value of the distance detected at the at least two positions. Distance between the recording surface and the recording surface of the recording medium, and a timing control for controlling the drive timing of the recording element according to the value of the average distance. Ink jet recording method characterized by comprising a degree.