JP2005349606A - Ink jet recorder and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recorder performing appropriate recording depending on the temperature of a recording head while suppressing self-temperature rise thereof, and to provide an ink jet recording method. <P>SOLUTION: In the recording operation by a recording head arranged with a plurality of ejection ports different in ink ejection, temperature of the recording head under recording is detected by a temperature sensor. If the detected temperature is lower than a predetermined reference temperature, such an ejection pattern as frequently using a small diameter nozzle of relatively low ink ejection in the recording head is employed when a predetermined quantity of ink is ejected. If the detected temperature is not lower than the reference temperature, such an ejection pattern as frequently using a large diameter nozzle of relatively high ink ejection in the recording head is employed thus creating ejection data. Ejection pattern is switched in units of line or page or in a predetermined unit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method using the apparatus, and more specifically, an ink jet recording apparatus including a discharge head having a relatively large amount of ink discharged at one time and a recording head having a relatively small number of discharge ports. The present invention relates to an ink jet recording method.

  An ink jet recording method ejects ink as droplets onto a recording medium from a plurality of ejection ports formed in a recording head, and the ink lands on the recording medium to form dots, thereby forming a predetermined image on the recording medium It is formed on top. Such an ink jet recording method is widely used in printers, facsimiles, copiers and the like because it is relatively easy to downsize the apparatus and can realize color recording at a low cost.

  A recording apparatus using such an inkjet recording method (hereinafter, also referred to as “inkjet recording apparatus”) is a bubble jet (registered trademark) as one of methods for ejecting ink from a plurality of ejection openings formed in a recording head. The method is used. In this bubble jet (registered trademark) system, a heating element which is an electric / thermal energy converter is provided in the vicinity of a discharge port, and an electric signal is applied to the heating element to generate heat during discharge. This thermal energy causes film boiling in the ink, and a predetermined amount of ink is ejected from the ejection port by the generation pressure of the bubbles. Other methods for ejecting ink from the ejection port include a piezo method using an electrical / mechanical converter such as a piezoelectric element.

  By the way, in the ink jet recording method, the halftone is expressed as follows. When recording dots of a certain size are used, a dot density control method for controlling the number of recording dots per unit area is used. However, graininess may be noticeable depending on the dot size and ink color, and in recent years, using a plurality of types of discharge ports with different discharge amounts, a plurality of types of recording dots with different dot sizes can be used to achieve a predetermined gradation. A dot diameter control method is also used. In this method, a plurality of types of ejection ports with different ejection amounts are arranged in advance on the recording head, and dots of a predetermined ink amount are driven by combining various ejection ports according to the applied ink amount per unit area. Since relatively small-diameter dots and relatively large-diameter dots are mixed in a predetermined area, each dot itself is less noticeable, and graininess can be suppressed.

  Further, a plurality of types of discharge ports having different discharge amounts can be selectively used according to the use of the recorded matter and the required image quality, and more appropriate recording can be performed. For example, in a text document or the like, characters can be clarified by increasing the density by printing dots having a relatively large diameter. Also, when emphasizing the recording speed, the time required for recording can be shortened by striking many dots having a relatively large diameter.

  However, there are the following problems in recording control in which the dot size is controlled according to the gradation of the recorded image. That is, in the bubble jet (registered trademark) type recording head, higher integration is relatively easy as compared to other types of recording heads. Accordingly, a recording head is formed in which small-diameter ejection openings with a small ejection amount are arranged. However, since an electrical / thermal converter is used, a part of the thermal energy for ink ejection heats the printhead, and as a result, the temperature of the printhead rises with use. Will occur. On the other hand, the viscosity of the ink decreases as the temperature rises, and bubbles tend to be formed. Therefore, even when ejecting from the same ejection port, the ejection amount tends to increase in the ejection operation at a high ink temperature. It is in. Therefore, in the bubble jet (registered trademark) system, the ink discharge amount changes depending on the environmental temperature or the self-temperature rise of the recording head. For this reason, depending on the condition of the recording head, such as when a plurality of sheets are continuously recorded, the ink ejection amount increases, and dots larger than necessary are formed.

  In other words, when the ink temperature is low, the discharge amount is small, and when the ink temperature is high, the discharge amount tends to increase. Therefore, the density of the recorded image that is the same image and changes with the temperature change of the recording head Will be different.

  In a long head in which a plurality of recording element substrates are arranged, only a specific recording element substrate is frequently used, and recording is performed using the entire head while the temperature of the plate is rising. In this case, the discharge amount is higher only in the portion of the plate where the temperature has been increased in the previous recording, and the density of the recording result is higher only in the portion recorded on the recording element substrate where the temperature is increasing. May cause.

  The present invention has been made to solve such a conventional problem. An ink jet recording apparatus and an ink jet recording method for suppressing the self-heating of the recording head and performing appropriate recording according to the temperature of the recording head. The purpose is to provide.

  The inkjet recording apparatus of the present invention includes a first ejection port for ejecting ink and a second ejection port for ejecting an amount of ink larger than the amount of ink ejected from the first ejection port. An ink jet recording apparatus that forms an image on a recording medium by ejecting ink onto the recording medium using a recording head, each of the recording heads acquiring temperature of the recording head, and each of the recording heads The ejection data creating means for creating ejection data corresponding to the ejection ports, and the ejection control means for controlling ink ejection at each ejection port of the recording head based on the ejection data, the ejection data creating means, The ejection ratio of the first ejection port and the second ejection port when ejecting a predetermined amount of ink is changed according to the temperature acquired by the temperature acquisition unit.

  The control method according to the present invention includes a first ejection port for ejecting ink, and a second ejection port for ejecting an amount of ink larger than the amount of ink ejected from the first ejection port. A control method in an ink jet recording apparatus for forming an image on a recording medium by ejecting ink onto the recording medium using a head, a temperature acquisition step for acquiring the temperature of the recording head, and the recording head An ejection data creation step for creating ejection data corresponding to each ejection port, and a ejection control step for controlling ink ejection at each ejection port of the recording head based on the ejection data. The discharge ratio of the first discharge port and the second discharge port for discharging a predetermined amount of ink is changed according to the temperature acquired by the temperature acquisition means.

  By using the present invention, the temperature of the recording head during recording can always be maintained within a certain range, so that by the recording head self-heating, an unnecessarily large amount of ink is ejected from each ejection port, and recording is performed. As a result, it is possible to prevent a phenomenon in which a density difference occurs depending on a region, and it is possible to form a high-quality image with a uniform density at all times.

  In addition, since the temperature of the recording head can always be maintained within a certain range with a simple control mechanism, there is no need to separately provide a sub-heater or the like for temperature control, which is economical.

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

(Embodiment 1)
FIG. 1 is a perspective view showing the ink jet recording apparatus of the present embodiment.

  An ink tank 1 is integrated with the recording head 2 and mounted on the carriage 3. The carriage 3 is movable along the guide rail 4 in the direction of arrow A.

  A recording medium (not shown) is fed from a paper feed tray 6 to a recording start position facing a discharge port surface of the recording head 2 by a paper feed roller (not shown). When the recording medium is fed, the carriage 3 scans the recording medium, and ink droplets are ejected from the ejection ports of the recording head 2 to the recording medium during the scanning. When the carriage moves from one end of the recording medium to the other end, the recording medium is conveyed by a predetermined amount in a direction perpendicular to the scanning direction of the carriage by a conveyance roller (not shown). In this way, an image is formed on the entire recording medium by alternately repeating the recording operation and the paper feeding operation.

  FIG. 2 is a perspective view showing the recording head.

  The recording head 2 is formed by integrating a tank holder unit 201 and a recording element unit 202. In the tank holder unit 201, an ink tank is mounted for each ink color, and communicates with the recording element unit 202 via an ink path. The recording element unit 202 arranges recording elements for each ink color.

  FIG. 3 is a schematic diagram showing the discharge port surface of the recording element unit.

  The recording element includes a small nozzle 203 having a discharge port with a relatively small discharge amount and a large nozzle 204 having a discharge port with a relatively large discharge amount. That is, the large nozzle (ejection port) ejects an amount of ink larger than the amount of ink ejected from the small nozzle, and these ejection ports are provided in the recording element unit. The nozzle rows are configured according to the ink color to be ejected in large / small, and from the left, light cyan small nozzle 203LC, light cyan large nozzle 204LC, light magenta small nozzle 203LM, light magenta large nozzle 204LM, cyan small nozzle. 203C, large cyan nozzle 204C, small magenta nozzle 203M, large magenta nozzle 204M, small yellow nozzle 203Y, large yellow nozzle 204Y, small black nozzle 203K, and large black nozzle 204K.

  Corresponding to each nozzle, a heater which is an electrothermal converter is provided. When the ink is ejected, the heater generates heat, and air bubbles are instantaneously generated in the ink. A predetermined amount of ink is ejected by the generation pressure of the bubbles. As described above, in this embodiment, the bubble jet (registered trademark) method is used as the ink ejection method. However, the present invention is not limited to this, and any other method such as a piezo method may be used.

  FIG. 4 is a block diagram showing an electrical configuration of the ink jet recording apparatus according to the present embodiment.

  A system controller 401 controls the entire recording apparatus. The recording data from the host computer 406 is once stored in the reception buffer 407 and sent to the system controller. The recording control unit 410 generates ejection data corresponding to each nozzle of the recording head based on the recording data. The generation of the discharge data is performed by a conversion table stored in the ROM 408. The converted ejection data is ejected by driving the heater of each nozzle by the recording head driver 411. On the other hand, a drive command is also sent from the system controller 401 to the driver 402 of each drive unit. In response to this drive command, each driver 402 drives each motor 403 to perform a paper feed operation or the like.

  Further, a temperature sensor 422 for detecting the temperature of the recording head is provided. The temperature sensor 422 detects the temperature of the recording head, and sends a detection result to the system controller 401. The system controller 401 uses different ejection data conversion tables when generating ejection data according to the detection result. In the embodiment, a configuration using a sensor for detecting temperature will be described as an example. However, in the present invention, a configuration capable of acquiring temperature may be provided. For example, in order to acquire temperature, you may employ | adopt the structure which estimates and calculates | requires temperature by calculation based on recording data.

  Next, the ejection data generation will be described in detail.

  As described above, the recording head of the present embodiment includes two types of recording elements, a large nozzle and a small nozzle. The recording control unit creates ejection data in which a predetermined amount of ink is applied to a predetermined region by combining large nozzles and small nozzles based on the recording data. The discharge data is generated according to the discharge data conversion table.

  Here, in general, the amount of heat generated when ejecting the same ink amount is larger for a nozzle (small nozzle) that ejects a smaller amount of ink, and for a nozzle (large nozzle) that ejects a larger amount of ink. Tend to be smaller. For this reason, when a predetermined amount of ink is ejected to a predetermined area, the ejection of the recording head is smaller when ejected with only a small nozzle than when ejected with only a large nozzle or both large and small nozzles. The temperature rise will be accelerated. In other words, if only a specific nozzle row, particularly only a specific small nozzle row, is frequently used, the temperature of the small nozzle row portion rises, resulting in a temperature difference from other portions of the print head. Therefore, when applying a predetermined amount of ink to the recording medium, the temperature rise rate of the recording element substrate is suppressed by using large nozzles and small nozzles separately, and the temperature is controlled to be as uniform as possible throughout the recording head. To do.

  Specifically, the discharge data is generated using the following discharge data conversion table.

  The temperature sensor detects the temperature of the recording head every time the recording head performs one reciprocating scan on the recording medium. This may be detected for each ink color, or for the entire recording head. Then, the recording control unit generates ejection data for one scan by using different ejection data conversion tables depending on whether the detected temperature is higher or lower than a preset reference temperature.

When the detected temperature is lower than the reference temperature, the number of times each nozzle is used for a given area is the number of times the large nozzle is used X <the number of times the small nozzle is used Y
An ejection data conversion table that satisfies the above relationship is used.

On the other hand, when the detected temperature is equal to or higher than the reference temperature, the number of times each nozzle is used for the predetermined area is
Number of uses of large nozzle X> Number of uses of small nozzle Y
An ejection data conversion table that satisfies the above relationship is used. That is, when the print head temperature is lower than the reference temperature, printing is performed by frequently using small nozzles in the next scan so that the print head temperature approaches the reference temperature, while the print head temperature is When the temperature is equal to or higher than the reference temperature, the large nozzle is frequently used in the next scanning in order to suppress a further temperature increase. This ejection data conversion table may be used for each ink color, or may be used in common for all ink colors.

  In this way, by detecting the temperature of the print head and using the ejection data conversion table properly depending on whether the detected temperature is higher or lower than the reference temperature, the temperature rise of the print head can always be kept within a certain range and printing can be performed. It is possible to control so as not to change the temperature of the recording head within a certain time. As a result, it is possible to provide a high-quality recording result in which there is no region of sudden density change that is detected as density unevenness.

  In this embodiment, the temperature of the recording head is actually measured by the temperature sensor. However, the present invention is not limited to this, and the temperature change of the recording head is estimated based on the recording data. Accordingly, the ejection data conversion table may be used differently.

In the present embodiment, the temperature of the recording head is detected every time the recording head is scanned, that is, every time one line is recorded, and the temperature detection result is reflected in the next recording scan. For example, when recording is performed continuously, the temperature of the recording head is detected every time one page is recorded, and the ejection data conversion table may be switched in units of pages.

(Embodiment 2)
The present invention can be applied even when the recording head has a length corresponding to the paper width of the recording medium.

  FIG. 5 is a perspective view showing the discharge port surface of the long head.

  Reference numeral 501 denotes a recording element substrate for ejecting ink, and 502 denotes a flexible cable for supplying power to the recording element substrate 501. The cartridge H has a plurality of recording element substrates 501 arranged in order to increase the recording speed. Here, a plurality of recording element substrates are arranged in a staggered manner to form a so-called line head in which nozzles are substantially arranged in the paper width direction of the recording medium. Naturally, a line in which nozzle rows are arranged in one or two rows is formed. It may be a head. The arrows in the figure indicate the ink ejection direction. In this case, one color of ink is ejected from one housing, and only the necessary ink colors are provided according to the purpose of recording such as color recording. During recording, the recording medium is conveyed in a direction perpendicular to the direction in which the nozzle rows are arranged.

  The recording element substrate has a large nozzle and a small nozzle arranged in a row. Needless to say, the arrangement of the large nozzles and the small nozzles is not limited to this, and may take any form such as two rows.

  In such a recording head, after only a specific recording element substrate is frequently used, in a situation where all the recording element substrates are used, recording corresponding to the previously used recording element substrate is performed. The area may have a higher density than other recording areas. The present invention is effective for suppressing such density unevenness.

  The electrical configuration of the apparatus is the same as that of the first embodiment.

  As described above, the same amount of ink and the amount of heat generated when ejecting are larger for nozzles that eject smaller amounts of ink (small nozzles), and for nozzles that eject larger amounts of ink (large nozzles) Tend to be smaller. Therefore, the temperature of each recording element substrate is detected at regular intervals, and the ejection data conversion table is properly used depending on whether the detected temperature is equal to or higher than a predetermined reference temperature.

That is, when the temperature of the printing element substrate is lower than the reference temperature, the number of times each nozzle is used for a predetermined area is the number of times the large nozzle is used X <the number of times the small nozzle is used Y
An ejection data conversion table that satisfies the above relationship is used.

On the other hand, when the temperature of the recording element substrate is equal to or higher than the reference temperature, the number of times each nozzle is used for the predetermined area
Number of uses of large nozzle X> Number of uses of small nozzle Y
An ejection data conversion table that satisfies the above relationship is used.

  The temperature detection of the recording element substrate may be performed every time one line is recorded, or may be performed every time several lines are recorded. Furthermore, detection may be performed in units of one page.

  In this way, the recording element substrate having a relatively high temperature becomes a discharge pattern in which large nozzles are frequently used in order to suppress the temperature rise, and the recording element substrate having a relatively low temperature is comparable to other recording element substrates. Thus, the discharge pattern frequently uses small nozzles so that the temperature becomes the same temperature. In this way, the temperature of adjacent recording element substrates can be kept within a certain range, and the difference in the amount of ink ejected between the substrates can be reduced, so that a high-quality recording result with a uniform density can be obtained. it can.

  In both Embodiments 1 and 2, the temperature of the recording head can always be maintained within a certain range with a simple control mechanism, so that it is economical that there is no need to separately provide a sub-heater for temperature control.

1 is a perspective view showing an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view of a recording head mounted on the ink jet recording apparatus of FIG. 1. FIG. 3 is a schematic diagram illustrating a discharge port surface of the recording head in FIG. 2. FIG. 2 is a block diagram showing an electrical configuration of the ink jet recording apparatus of FIG. 1. It is a perspective view which shows the recording head which is other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ink tank 2 Recording head 3 Carriage 4 Guide rail 6 Paper feed tray 201 Tank holder unit 202 Recording element unit 203 Small nozzle row 204 Large nozzle row 401 System controller 402 Driver 403 Motor 406 Host computer 407 Reception buffer 408 ROM
409 Buffer 410 Recording control unit 411 Head driver

Claims (8)

A recording head including a first ejection port for ejecting ink and a second ejection port for ejecting an amount of ink larger than the amount of ink ejected from the first ejection port is used as a recording medium. An ink jet recording apparatus that forms an image on a recording medium by ejecting ink,
Temperature acquisition means for acquiring the temperature of the recording head;
Discharge data creating means for creating discharge data corresponding to each discharge port of the recording head;
A discharge control means for controlling ink discharge at each discharge port of the recording head based on the discharge data;
The ejection data creation means changes the ejection ratio of the first ejection port and the second ejection port when ejecting a predetermined amount of ink according to the temperature acquired by the temperature acquisition unit. Inkjet recording apparatus.   The ejection data creation unit is configured to eject the first ejection port at a higher ejection ratio when ejecting a predetermined amount of ink if the temperature of the recording head acquired by the temperature acquisition unit is lower than a predetermined reference temperature. 2. The inkjet according to claim 1, wherein when the data is generated and the reference temperature is equal to or higher than the reference temperature, the discharge data is generated such that a discharge ratio of the second discharge port is increased when a predetermined amount of ink is discharged. Recording device.   The inkjet recording apparatus according to claim 1, wherein the temperature acquisition unit acquires the temperature of the recording head every time a predetermined amount of recording is performed by the recording head. The recording head has a plurality of recording element substrates arranged with the first discharge port and the second discharge port,
The temperature acquisition means acquires the temperature of each of the plurality of recording element substrates,
The ejection data creation means changes the ratio of the first ejection port to the second ejection port for each of the recording element substrates based on the temperature of the recording element substrate acquired by the temperature acquisition unit. The ink jet recording apparatus according to claim 1.   The inkjet recording apparatus according to claim 1, wherein the temperature acquisition unit acquires the temperature using a sensor that detects the temperature. A recording head having a first ejection port for ejecting ink and a second ejection port for ejecting an amount of ink larger than the amount of ink ejected from the first ejection port is used as a recording medium. A control method in an ink jet recording apparatus that forms an image on a recording medium by ejecting ink,
A temperature acquisition step of acquiring the temperature of the recording head;
A discharge data creation step of creating discharge data corresponding to each discharge port of the recording head;
A discharge control step for controlling ink discharge at each discharge port of the recording head based on the discharge data,
The ejection data creation step is characterized by changing a ejection ratio of the first ejection port and the second ejection port when ejecting a predetermined amount of ink according to the temperature acquired by the temperature acquisition unit. Control method to do.   In the ejection data creation step, when the temperature of the recording head acquired in the temperature acquisition step is lower than a predetermined reference temperature, an ejection in which the ejection ratio of the first ejection port is increased when ejecting a predetermined amount of ink. When the data is generated and the temperature of the recording head is equal to or higher than a predetermined reference temperature, the discharge data is generated so that the discharge ratio of the second discharge port becomes high when discharging a predetermined amount of ink. The control method according to claim 6. The ejection data creation step creates ejection data based on a predetermined first ejection pattern if the temperature of the recording head acquired in the temperature acquisition step is lower than a predetermined reference temperature, and the temperature of the recording head is predetermined If the temperature is equal to or higher than the reference temperature, discharge data is created based on a second discharge pattern different from the first discharge pattern,
The first discharge pattern is a discharge pattern that increases a discharge ratio of the first discharge port, and the second discharge pattern is a discharge pattern that increases a discharge ratio of the second discharge port. 6. The control method according to 6.

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