JP2011126091A - Inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus that can do accurate registration adjustment. <P>SOLUTION: The inkjet recording apparatus determines an influence of an external light. When the apparatus detects the influence, the appratus performs to fill a part of area that reflects the external light of the recording apparatus. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a recording apparatus, and more particularly to a recording apparatus that records a check pattern for performing registration adjustment between recording heads and a method for reading the recorded check pattern.

  An ink jet recording apparatus (hereinafter referred to as an ink jet recording apparatus) has an advantage that an ink discharge port of a recording head can be arranged at a high density, and a high-definition and high-quality image is recorded. Further, in an ink jet recording apparatus, a method of using a check pattern described later for inspection of a recording head is widely known. Many of the ink jet recording apparatuses are of a serial scan format, and recording is performed by ejecting ink to a predetermined position of a recording medium by a recording head mounted on a carriage scanning in the main scanning direction. When the recording for one scan is completed, the recording medium is conveyed in the sub-scanning direction to the next recording start position. As described above, in the ink jet recording apparatus, recording is performed by repeating the recording by the recording head and the transport operation of the recording medium.

  In a serial scan type recording apparatus, particularly in an apparatus using a plurality of recording heads, such as an apparatus that performs full-color recording, dots formed by ink ejected from the recording head are placed at substantially the same location on the recording medium, for example. By arranging, a high-definition image is formed. It is known that registration adjustment (hereinafter, also simply referred to as “registration adjustment”) is performed so that the positional relationship of overlapping dots among a plurality of recording heads can be maintained. As a conventional example of this registration adjustment, a predetermined check pattern is recorded on each recording medium by a recording head for each color, and the result of reading the recorded check pattern is determined based on the deviation between the respective patterns. Some adjust the recording timing.

  Such a carriage included in the ink jet recording apparatus includes a sensor light emitting unit and a sensor light receiving unit, and is configured to be able to mount an ink tank on which a recording head is mounted. The registration adjustment sequence uses a reflection type sensor composed of a light emitting unit and a light receiving unit, and detects the lightness and darkness of the check pattern while moving the carriage with respect to the check pattern recorded on the recording medium. Is realized.

  However, in the check pattern reading operation, the sensor light receiving unit may not be able to read a correct value due to the influence of not only the reflected light due to the lightness and darkness of the original check pattern but also external light outside the housing. Therefore, as means for eliminating the influence of external light, Patent Document 1 discloses that the sensor light emitting unit provided on the paper passing path is turned off to measure the influence of external light, and the influence of external light received by the sensor light receiving unit is The threshold value is determined by adding a predetermined value determined in advance. A method is disclosed in which the influence level of external light is determined based on this threshold value, and the influence of external light is subtracted from the input value of the sensor light receiving unit.

JP 09-249339 A

  However, in the conventional measurement method described above, the threshold value is supported for the shape of the exterior of the recording device, the material used for the exterior, reflection of external light on the recording medium during conveyance, and various changes in the recording environment. I have to let it. In addition, registration adjustment of an apparatus that performs high-definition recording such as an ink jet recording apparatus needs to determine the overlap of a very small amount of ink droplets, and must flexibly cope with environmental changes. In patent document 1, since it is detected at a specific position for such a wide range of changes, it cannot be said that the accuracy is sufficient.

  FIGS. 7A and 7B are diagrams schematically illustrating a state in which the external light 102 is reflected due to a difference in the conveyance state of the recording medium. At the position of the recording medium in FIG. 7A, the sensor is not affected by external light, whereas when the recording medium is conveyed over a certain level as shown in FIG. The light is reflected by the surface and reaches the sensor light receiving unit inside the recording apparatus. At this time, the sensor light receiving unit 405 receives light that is greater than or equal to the reflected light due to the density of the registration pattern, and receives a value obtained by adding the influence of the external light 404 to the reflected light with respect to the original light emission of the sensor. For this reason, the value of the registration adjustment check pattern may not be read accurately.

  Therefore, an object of the present invention is to provide an ink jet recording apparatus capable of performing accurate registration adjustment.

  Therefore, the inkjet recording apparatus of the present invention measures the influence of external light when reading by the recording means capable of recording the check pattern on the recording medium, the reading means for reading the check pattern recorded on the recording medium, and the reading means. In the ink jet recording apparatus provided with the measuring means, the recording means fills a portion of the recording medium where the external light is reflected when it is determined that there is an influence of external light as a result of the measurement by the measuring means. It is characterized by that.

  According to the present invention, the ink jet recording apparatus is configured to detect a portion of the recording medium where the external light is reflected by the recording unit when it is determined that there is an external light effect as a result of the measurement by the measuring unit that measures the influence of the external light. Fill. Thus, an ink jet recording apparatus capable of performing accurate registration adjustment can be realized.

It is the front view which showed schematic structure of the serial type inkjet recording device. It is the perspective view which showed the carriage mounted in an inkjet recording device. FIG. 2 is a block diagram illustrating a configuration example of a control system of the ink jet recording apparatus. It is a flowchart showing the flow which detects the influence of external light. 10 is a flowchart when reading a registration adjustment check pattern. FIG. 6 is a diagram illustrating an ink ejection surface of a carriage. (A), (b) is the figure which showed typically a mode that external light reflected.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing a schematic configuration of a serial type ink jet recording apparatus (hereinafter also simply referred to as a recording apparatus) applicable to the present embodiment. The carriage 32 is supported by the guide shaft 27 and the linear encoder 28 so as to reciprocate along the main scanning direction (X direction). The carriage 32 reciprocates along the guide shaft 27 by driving the carriage motor 30 and moving the drive belt 29. In addition, an ink jet recording head (hereinafter also simply referred to as a recording head) is detachably mounted on the carriage 32. A plurality of ejection units (hereinafter also referred to as nozzles) for ejecting ink are arranged in the recording head. By ejecting ink from the nozzles, the recording head can perform recording. The liquid path formed in each nozzle of the recording head is provided with a heating element (electrothermal converter) that generates thermal energy for discharging ink in the liquid path. Further, this serial type ink jet recording apparatus is provided with a transport mechanism for transporting the recording medium P such as plain paper, high-quality exclusive paper, OHP sheet, glossy paper, glossy film, postcard and the like. This transport mechanism has a transport roller (not shown), a paper discharge roller 25, a transport motor 26, and the like, and is transported intermittently in the sub-scanning direction (arrow Y direction) as the transport motor 26 is driven.

  A discharge signal and a control signal sent from a controller unit, which will be described later, are sent to the recording head and the transport mechanism via the flexible cable 23, and each recording head and the transport mechanism operate according to the discharge signal and the control signal. . The heat generating element of the recording head is driven based on the position signal of the carriage 32 output from the linear encoder 28 and the discharge signal, and ejects ink droplets from the nozzles by the thermal energy generated during the drive, onto the recording medium P. Let it land. Further, the transport mechanism transports the recording medium P by a certain amount in the sub-scanning direction between the main scanning of the recording head based on the control signal. An image is formed on the entire recording medium P by repeating scanning a plurality of times by the recording operation by the recording head and the transport operation by the transport mechanism. In addition, a recovery unit 34 having a cap portion 35 that can seal and open the ejection port formed in the recording head is installed at the home position of the carriage 32 set outside the recording area.

  FIG. 2 is a perspective view showing the appearance of a carriage mounted on an ink jet recording apparatus to which this embodiment can be applied. The carriage 32 is mounted with ink tanks 304a to 304e that store different colors of ink therein, and each ink tank is provided with a recording head. In addition, the carriage 32 includes a sensor light emitting unit 302 and a sensor light receiving unit 303, and can detect the density of the check pattern recorded on the recording medium P.

  FIG. 3 is a block diagram illustrating a configuration example of a control system of the ink jet recording apparatus according to the present embodiment. The data input unit 71 receives image data and control data transmitted from an external device 80 such as a host computer. The operation unit 72 performs data input or setting operation. The CPU 73 performs various types of information processing and recording control, and the storage medium 74 stores various types of data. In this storage medium 74, a recording information storage unit 74a that stores mainly information relating to the type of the recording medium P, information relating to ink, image recording information such as information relating to the environment such as temperature and humidity during recording, and various controls. A program storage unit 74b for storing a program group is included. Further, the RAM 75 temporarily stores processing data and input data of the CPU 72. The data processing unit 76 performs predetermined image processing including color conversion and binarization processing on the input image data. The image recording unit 77 executes image output by a recording head, a transport mechanism, or the like. The bus line 78 transmits address signals, data, control signals, and the like in the apparatus. Examples of the external device 80 include an image input device such as a scanner and a digital camera, or a personal computer. Multi-value image data (for example, RGB 8-bit data) output from the scanner, digital camera, or the like, or multi-value image data stored in a hard disk of a personal computer or the like is input to the image data input unit 71. The operation unit 72 also includes various keys for setting various parameters and inputting a recording start instruction. The CPU 73 controls the entire inkjet recording apparatus according to various programs in the storage medium. As a program stored in the storage medium 74, there is a program for operating the ink jet recording apparatus according to a control program or an error processing program, and all the operations of the present embodiment are executed according to this program. As the storage medium 74 for storing the program, a ROM, FD, CD-ROM, HD, memory card, magneto-optical disk, or the like can be used. The RAM 75 is used as a work area for executing various programs stored in the storage medium 74, a temporary save area for error processing, and a work area for image processing. In the RAM 75, after copying various tables in the storage medium 74, the contents of the tables can be changed, and image processing can be performed while referring to the changed tables. The image processing unit 76 performs color separation processing for converting input multi-value image data (for example, 8-bit RGB data) into multi-value data for each ink color (for example, 8-bit CMYBk data) for each pixel. Further, the image processing unit 76 quantizes the multi-value data of each color into K-value (for example, 17-value) data for each pixel, and the gradation value “K” (gradation) indicated by each quantized pixel. A process of setting a dot arrangement pattern corresponding to values 0 to 16) is performed. Here, the multi-value error diffusion method is used for the K-value processing, but the present invention is not limited to this, and an arbitrary halftone processing method such as an average density storage method or a dither matrix method may be used. Is also possible. Further, after performing the K-value conversion process, a dot arrangement patterning process is performed for each unit area corresponding to the dot arrangement pattern according to each gradation value. Then, in four recording scans by the recording head, a thinning process is performed on the binary print data generated by the dot arrangement patterning process to distribute the print data to each print scan using the thinning mask pattern. Note that a plurality of recording scans by the recording head include one recording scan performed by a recording head having two or more nozzle rows.

  By repeating these processes, binary recording data representing ejection and non-ejection for each nozzle of the recording head is created. Then, the image recording unit 77 ejects ink based on the binary recording data created by the image data processing unit 76 to form a dot image on the recording medium P.

  Hereinafter, a series of operations in the recording apparatus to which the present invention is applicable will be described with reference to flowcharts. FIG. 4 is a flowchart showing a flow for detecting the influence of external light.

  First, in order to measure the influence of external light received by the sensor in step S701, the sensor light emitting unit 302 attached to the carriage 32 is turned off, and in step S702, the carriage 32 is moved to cause the sensor light receiving unit 303 to perform one scan. Measure the influence of external light. At that time, the registration adjustment check pattern is simultaneously recorded.

  Thereafter, the process proceeds to step S703, and the maximum value of the influence of external light measured by the sensor light receiving unit 303 in the movement of the carriage 32 in one scan is obtained and stored. In step S704, it is determined whether or not the maximum value obtained in step S703 is larger than a predetermined value. If it is determined in step S704 that the value of the external light input to the sensor light receiving unit 303 is not influenced or is small enough not to be affected, the process proceeds to step S706. At this time, it is not necessary to store the value read by the sensor, and the read value can be discarded. If it is determined in step S704 that the influence of external light due to the measurement result cannot be ignored, the process proceeds to step S705 to store the transport position in the sub-scanning direction. At this time, the input value read by the sensor is simultaneously stored.

  In step S706, it is determined whether the registration adjustment recording is completed. If not completed, the recording medium P is transported in the sub-scanning direction to the next recording start position in step S707, and the process returns to step S702. Continue recording measurement and registration adjustment check patterns. If the registration adjustment pattern has been recorded, the process proceeds to a registration tone pattern reading sequence to be described later.

  In this manner, the operations in steps S702 to S706 are repeated, and check pattern recording / conveyance is repeated to record a check pattern for one page.

  FIG. 5 is a flowchart when the registration adjustment check pattern is read. When the registration adjustment pattern recording is completed, in step S801, the recording medium P is back-fed to the registration adjustment check pattern reading start position. Thereafter, in step S802, when the back feed is completed, the sensor light emitting unit 302 is turned on. In step S803, after the check pattern is conveyed to the reading position, the value stored in step S703 in the flowchart of FIG. 7 is read in order to determine whether or not it is affected by external light during the next reading. In step S804, the influence of external light is determined based on the value called in step S803. If it is determined in step S804 that it is not affected by outside light, the process proceeds to step S806. If it is determined in step S804 that it is affected by outside light, the process proceeds to step S805.

  Here, the positional relationship between the sensor and the ink ejection unit in the carriage 32 will be described. FIG. 6 is a view of the carriage 32 as viewed from below, and depicts the ink ejection surface. A reflective sensor including a sensor light emitting unit 302 and a sensor light receiving unit 303 with respect to the conveyance direction of the recording medium P is disposed behind the ink ejection unit 601 with respect to the conveyance direction. For this reason, it is configured such that ink can be ejected to the already read check pattern simultaneously with the reading of the next check pattern.

  In this embodiment, when it is determined that the reflection of external light affects the reading of the check pattern, black ink is ejected to the already read check pattern adjacent to the check pattern to be read and the check pattern is changed. Fill. As a result, the reflection of external light is reduced to reduce the influence of external light when the check pattern is read.

  Returning to the flowchart of FIG. 5 again, in step S805, the check pattern is painted from the top in order to eliminate the influence of external light. In step S806, the check pattern is read. Note that when the process proceeds from step S804 to step S806, there is no or little influence of external light, and thus reading is performed in a state where there is no filled portion. In step S807, it is determined whether reading of the check pattern has been completed. If not completed, the process moves to step S808 to carry the recording medium. In this way, the operations and conveyances of steps S803 to S806 are repeated, and the registration adjustment check pattern for one page is read.

  In the present embodiment, black is used as the fill color of the registration adjustment check pattern. However, the fill color is not limited to black, and any color may be used as long as it suppresses reflection. The density of the ink to be filled can also be changed according to the influence of external light, or can be applied with the same density from the place where the influence of external light appears.

  In the present embodiment, the already read check pattern is painted, but the painted area can be painted not only on the check pattern but also on a solid portion of the recording medium P that is not recorded.

  Further, in the present embodiment, the external light is measured while the registration adjustment check pattern is recorded. However, the recording medium P set in the recording apparatus is ejected little by little without being recorded, thereby measuring the influence of the external light. You can also It is also possible to measure the influence of external light at a specific place by fixing the position of the carriage without scanning the carriage. Furthermore, the measurement of external light and the registration adjustment check pattern may not be recorded simultaneously. Also in step S805, the registration adjustment check pattern may not be read and painted at the same time. After reading the check pattern, the registration adjustment check pattern can be filled.

  Further, even in the read external light value, all the influences of the external light are stored in this embodiment, but the transport position in the sub-scanning direction and the sensor input value from the place where the influence of the external light comes out are stored. You can also keep it.

  As for the sensor to be used, the same sensor is used for external light measurement and registration adjustment detection in this embodiment. However, the sensor for measuring the influence of external light and the sensor for reading the check pattern are different sensors. It doesn't matter.

  Further, in the present embodiment, a method has been described in which recording is continued until registration registration check pattern recording is completed for one page, and after the recording is finished, backfeed is performed to read the check pattern for one page. However, the check pattern can be recorded and read alternately. After recording the registration adjustment check pattern and measuring the influence of external light, the influence degree of external light is determined. At the same time, back feed is performed, and if there is no influence of external light, only the registration pattern is read, and if the influence of external light is large, the check pattern can be read while being painted.

  In this way, the presence / absence of the influence of external light is determined. Reduce. Thus, an ink jet recording apparatus capable of performing accurate registration adjustment can be realized.

32 Carriage P Recording medium 302 Sensor light emitting unit 303 Sensor light receiving unit

Claims (7)

An inkjet comprising: a recording unit capable of recording a check pattern on a recording medium; a reading unit that reads the check pattern recorded on the recording medium; and a measuring unit that measures the influence of external light during reading by the reading unit In the recording device,
As a result of measurement by the measuring unit, when it is determined that there is an influence of external light, the recording unit fills a portion of the recording medium where the external light is reflected.   2. The ink jet recording apparatus according to claim 1, wherein in the filling by the recording means, the density at the time of painting increases as the influence of external light increases in the measurement by the measuring means.   The inkjet recording apparatus according to claim 1, wherein the recording unit fills the check pattern.   The ink jet recording apparatus according to claim 1, wherein the filling by the recording unit and the reading of the check pattern by the reading unit are performed simultaneously.   The inkjet recording apparatus according to claim 1, wherein the measurement of the influence of external light by the measuring unit and the recording of the check pattern by the recording unit are performed simultaneously.   6. The value read by the reading unit is discarded when it is determined that there is no influence as a result of the measurement of the influence of external light by the measuring unit. The ink jet recording apparatus described.   7. The recording medium according to claim 1, wherein the recording means does not fill the recording medium when it is determined that there is no influence as a result of measuring the influence of external light by the measuring means. An ink jet recording apparatus according to any one of the above.

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