JP2007210327A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To execute a complementary recording operation with a simple constitution without causing a drastic degradation of a recording speed even when a nozzle of poor discharge occurs in one recording head in an inkjet recording device that forms an image while dividing image data corresponding to a plurality of the recording heads by using a plurality of line type inkjet recording heads to one color ink. <P>SOLUTION: When there is a nozzle of poor ink discharge in one recording head (102), the recording operation of which the nozzle takes charge is complemented by the corresponding nozzle of other recording head (for example, an auxiliary recording head 114). On that occasion, the same split image data are supplied to the one recording head and the other recording head. The recording action is made invalid to the one recording head only at the timing that the nozzle of poor discharge is driven. The recording action is made valid to the other recording head only at the timing that the corresponding nozzle is driven. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus (hereinafter referred to as a line type ink jet recording apparatus or simply an ink jet recording apparatus) using an ink jet recording head (hereinafter also referred to as a line head) in which nozzles are arranged over a range corresponding to the width of the recording medium to be conveyed. Say).

  For a general line type ink jet recording apparatus that uses one line head for one color ink, a plurality of line heads are used for one color ink, and image data is divided corresponding to the plurality of line heads. Thus, there is a line type ink jet recording apparatus that forms an image. In such a line type ink jet recording apparatus, a plurality of line heads share the image formation. Accordingly, a recording operation exceeding the maximum drive frequency of one line head, that is, recording at a speed proportional to the number of line heads can be performed, so that high-speed recording can be realized.

  In a line-type ink jet recording apparatus, there may be a case where a defectively ejected nozzle (hereinafter also referred to as a defective nozzle) cannot be ejected normally to one line head for some reason. In that case, for a general line-type ink jet recording apparatus, a response is made such that the recording is continued in a state where the recording quality cannot be guaranteed, or the recording is interrupted and the line head is replaced. On the other hand, in a line type ink jet recording apparatus using a plurality of line heads for one color ink, in addition to performing such measures, recording is continued using only a normal line head without defective nozzles. Correspondence becomes possible. In addition, when a defective nozzle is detected, interpolation is performed between a plurality of line heads corresponding to one color ink, that is, an ink ejection operation is performed so that normal nozzles in each of the plurality of line heads are used. There is also a technology to complement each other (Patent Document 1).

Japanese Patent Laid-Open No. 10-6488

  However, a line-type ink jet recording apparatus that uses a plurality of line heads for one color ink is originally configured to meet the demand for high-speed recording. However, in response to continuing recording using only normal line heads, the recording speed must be reduced to a speed proportional to the number of normal heads, and the high-speed recording requirement cannot be satisfied. In consideration of applying the technique disclosed in Patent Document 1 when a defective nozzle is detected, in order to perform a complementary discharge operation between normal line heads, re-development of print data or mask data It is necessary to perform generation, and a means for storing the generated mask data is required. Therefore, there has been a problem that the control mode and the configuration of the control system are complicated, and the circuit scale of the recording apparatus is increased.

  The present invention has been made in view of the above problems that occur in a line-type inkjet recording apparatus that uses a plurality of line heads for one color ink and divides image data corresponding to the plurality of line heads to form an image. It is a thing. An object of the present invention is to suppress a decrease in recording speed as much as possible even when a defective nozzle occurs, and to perform a complementary recording operation with a simple configuration.

To this end, the present invention comprises a plurality of ink jet recording heads in which nozzles for ejecting ink are arranged in a direction intersecting the transport direction of the recording medium, the ink of the same color being juxtaposed in the transport direction. An inkjet recording apparatus capable of recording by supplying divided image data obtained by dividing image data corresponding to the arrangement of the nozzles to the inkjet recording head,
When there is a nozzle with poor ink ejection in one of the ink jet recording heads, the ink jet recording head includes a complementing means for complementing the recording operation in charge of the nozzle with the corresponding nozzle of the other ink jet recording head
The complementing unit supplies the same divided image data to the one inkjet recording head and the other inkjet recording head, and the ink ejection failure nozzle is provided to the one inkjet recording head. The recording operation is invalidated only at the driving timing, and the recording operation is validated only at the timing at which the corresponding nozzle is driven for the other ink jet recording heads.

  Here, the other ink jet recording head may be prepared for the supplement.

  Alternatively, the other ink jet recording head may be an ink jet recording head in which nozzles other than the corresponding nozzles are defective in ink ejection.

  According to the present invention, when an ejection failure nozzle is generated in one recording head (line head), the same divided image data (raster data) is supplied to the line head and another line head. For the one line head, the recording operation is invalidated only at the timing when the defective nozzle is driven (for example, the timing of the time-division driving of the block including the defective nozzle). Therefore, the recording operation is valid only at the timing at which the corresponding nozzle is driven (for example, the timing of the time-division driving of the corresponding block). As a result, it is not necessary to generate mask data for performing the operation of complementing the defective nozzles, or to dispose mask data storage means. Here, if the other line heads are prepared for complementation, high-quality recording can be maintained without causing a decrease in recording speed. Further, if the other line head is a line head having a defective nozzle in a nozzle other than the corresponding nozzle, since the complement is performed between the one line head and the other line head, both of them are excluded. There is no significant drop in recording speed as in the case of recording.

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

(First embodiment)
FIG. 1 is a conceptual diagram showing a schematic configuration example of a recording system to which the present invention can be applied. Such a system includes a line-type ink jet recording apparatus 107 that performs a recording operation on a recording medium, and a host computer 106 that exchanges various data with the ink jet recording apparatus 107. The host computer 106 and the ink jet recording apparatus 107 are connected via a communication cable 108. Then, the image data processed by the host computer 106 and various data such as a cleaning command are transmitted to the ink jet recording apparatus 107, whereby recording and other necessary operations are performed in the ink jet recording apparatus 107. Further, the printer status such as error information of the inkjet recording apparatus 107 is transmitted to the host computer 106 so that the host computer 106 can recognize the status of the inkjet recording apparatus.

  In the ink jet recording apparatus according to this embodiment, four long ink jet recording heads (line heads) 101 to 104 in which nozzles are arranged over a range corresponding to the width of the recording medium to be conveyed are arranged in the recording medium conveying direction. They are juxtaposed and are usually recorded using these. Each of these line heads ejects black ink. Then, the image data of the same color (black) is divided in raster units corresponding to the nozzle arrangement of the line head and supplied as recording data (divided image data), so that the monochrome (black) image is shared and formed. . In the present embodiment, another line head 114 is further arranged, and is used to perform ink discharge that complements the defective nozzles generated in the line heads 101 to 104 (hereinafter, this line). Head is also called auxiliary line head). In addition, as the line heads 101 to 104 and the auxiliary line head 114, for example, as the energy used for discharging the ink, an electrothermal conversion element (discharge) that generates thermal energy that causes film boiling in the ink when energized. Heater).

  The recording medium 109 is transported along a predetermined transport path passing below each of the line heads 101 to 104 and 114 by a transport unit 110 including an endless transport belt or a transport roller driven by a motor. In this transport operation, when the front end portion of the recording medium 109 is detected by the recording medium sensor 111 disposed on the upstream side in the transport direction from the line head 101, recording on the recording medium 109 is performed at a predetermined timing with reference to the detection time. Operation starts.

  A light emitting unit 112 and a light receiving unit 113 are provided on one side and the other side of the line heads 101 to 104 and 114, respectively, which constitute a defective nozzle detection device. The light emitting unit 112 and the light receiving unit 113 have light emitting elements and light receiving elements arranged corresponding to the line heads 101 to 104 and 114. The light emitting elements are arranged so as to project light in the direction along the nozzle outlet array on the lower surface of the head, and the corresponding light receiving elements can receive this light. In the defective nozzle detection operation, an optical path from the light emitting element to the light receiving element is formed, and for example, the ink ejection operation is sequentially performed from the nozzle located on one side of the head to the nozzle located on the other side. The light receiving unit 113 detects whether or not a light shielding state has occurred. Here, it is possible to determine whether or not each nozzle has normally performed a discharge operation from the drive (discharge) timing of each nozzle and the detection timing of whether or not light shielding has occurred. Furthermore, when non-ejection is detected, a cleaning operation is performed to improve the ink ejection performance, and then a defective nozzle is further detected. It is also possible to determine that the nozzle is a defective nozzle.

  As the cleaning operation, for example, a cap capable of capping the nozzle forming surface of the head is provided, and ink is forcibly discharged from the nozzle by applying an appropriate pressure to the ink supply system to the head in the capped state. can do.

  Moreover, as a mode of defective nozzle detection, it is not necessarily performed automatically using the above-described defective nozzle detection device. For example, a predetermined test pattern may be printed, and the user may visually check the print result to identify a defective nozzle and set it in the recording system.

  The recording apparatus of FIG. 1 can be selected as a recording target regardless of whether the recording medium is in the form of continuous paper or cut sheet. Further, the recording medium may be a medium comprising a mount and a label or tag sheet carried thereon.

  FIG. 2 is a block diagram illustrating a schematic configuration example of a control system of the line type inkjet recording apparatus according to the present embodiment.

  In the figure, the control unit 201 includes a CPU 202, ROM 203, RAM 204, communication controller 208, image memory 205, head drive circuit 209, motor driver 210, input / output unit (I / O) 211, control circuit 212, and the like. .

  The CPU 202 performs various processes such as calculation, determination, and control according to a processing procedure described later with reference to FIG. The ROM 203 stores a control program corresponding to a processing procedure executed by the CPU 202 and other fixed data. The RAM 204 has a work area when the CPU 202 processes various data and an area used as a transmission / reception buffer. The communication controller 208 transmits and receives required data between the host computer 106 and the recording device 107 via the communication cable 108, and for example, a USB controller is used. Information communicated from the host computer 106 to the recording device 107 includes image data to be recorded, a command for instructing execution of printing (printing), and the like. Information communicated from the recording device 107 to the host computer 106 includes There are statuses of the recording device 107 and the like.

  The image memory 205 is used as a developing unit for image data to be recorded (printed). The head drive circuit 209 drives the electrothermal conversion elements of the line heads 101 to 104 and the auxiliary line head 114 at a specified timing during conveyance of the recording medium according to the image data. The motor driver 210 drives various motors 206 serving as a drive source for performing a cleaning operation for the line heads 101 to 104 and the auxiliary line head 114 and a necessary drive required for the recording operation. The I / O 211 is connected to a conveyance control interface (I / F) unit 207 for the conveyance unit 110 that feeds and conveys the recording medium, and outputs an on / off signal of the conveyance unit 110 and detection from the recording medium sensor 111. Input the signal.

  The control circuit 212 controls the image memory 205, the head drive circuit 209, the motor driver 210, and the I / O 211, and also controls the operations of the light emitting unit 112 and the light receiving unit 113 that constitute the defective nozzle detection device. Further, the control circuit 212 controls the display unit 213 arranged to notify the user of the status of the recording apparatus 107 and an error.

  The normal recording operation of the ink jet recording apparatus having the above configuration, that is, the shared recording operation by the line heads 101 to 104 for the divided image data will be described with reference to FIG. In FIG. 3, for the sake of explanation, each line head is shown as viewed from the side, and the recording medium is viewed from above. The same applies to FIGS. 8 and 9 described later.

  Recording on the recording medium 109 is performed based on a detection signal at the tip of the recording medium 109 and a horizontal synchronization signal synchronized with the conveyance. Here, the horizontal synchronization signal is a signal used to determine the sequential drive timing of each line head.

  When the horizontal synchronization signal is detected, the data for one raster stored in the image memory 205 is transferred to the line head 101 located on the most upstream side in the recording medium conveyance direction, and one raster image 301 is recorded. Is done. Next, when a horizontal synchronization signal is detected, image data for the next one raster read from the image memory 205 is transferred to the line head 102 to form an image 302. When the next horizontal synchronizing signal is further detected, the image data for the next one raster read from the image memory 205 is transferred to the line head 103 to form a raster image 303. When the next horizontal synchronization signal is further detected, the image data for the next raster read from the image memory 205 is transferred to the line head 104 to form a raster image 304. Thereafter, similarly, the line heads 101 to 104 are sequentially used to record image data divided in units of rasters.

  As described above, in the present embodiment, the auxiliary line head 114 is not used for recording when all of the four line heads that discharge black ink are in a state where ink can be discharged in an appropriate state. That is, monochrome image data developed in the continuous area of the image memory 205 is sequentially read in units of rasters in synchronization with the horizontal synchronization signal, and sequentially supplied and set to the four line heads 101 to 104, so that the monochrome image data is read. Sharing records are made. As a result, a monochrome image is recorded at a frequency that is four times the maximum drive frequency of a single line head. As a result, the monochrome image is four times higher than when a single line head is used for the recording operation. Recording throughput can be obtained.

  In this embodiment, in each line head, time-division driving (block driving) is performed for each block grouped in units of a predetermined number of nozzles. Here, the configuration and control mode for block driving will be described.

  Each of the line heads 101 to 104 and the auxiliary line head 114 in this embodiment includes 2560 nozzles arranged in the raster direction (hereinafter, from nozzles located on one side to nozzles located on the other side. , Seg1 to seg2560 are referred to). One head is composed of four sections with nozzles seg1 to seg640, nozzles seg641 to seg1280, nozzles seg1281 to seg1960, and nozzles seg1961 to seg2560 as units. In each section, time-division driving in units of blocks is performed for the purpose of reducing the maximum power consumption, the voltage drop in the line head, or the like.

  FIG. 4 shows an example of the electrical configuration of the electrothermal conversion element in the section including the nozzles seg 1 to seg 640 in one head and its drive circuit, and FIG. 5 shows a timing chart of each part signal. FIG. 6 shows the correspondence between the signals for performing the block drive and the nozzles seg1 to seg640. These configurations and the like are the same for the other sections including the nozzles seg 641 to seg 1280, the nozzles seg 1281 to seg 1960, and the nozzles seg 1961 to seg 2560, and the nozzles indicated by the same block drive signal are the same timing even in other sections. It is driven by.

  In FIG. 4, reference numeral 222 denotes a power supply control transistor array that is connected to the drive power supply (VH) line of the electrothermal conversion elements provided in the nozzles seg1 to seg640 together with the electrothermal conversion elements. Turn continuity on / off.

  The decoder 224 generates a signal for defining the timing of block selection. The decoder 224 sequentially outputs eight timing signals in response to three input signals (3-bit parallel signals) BENB0 to BENB2, and the output is the transistor array 222. Is supplied to one of the four input terminals of each AND gate 223 connected to. ODD and EVEN are signals for selecting odd-numbered nozzles and even-numbered nozzles, and are supplied to the other one of the four input terminals of the AND gate 223 corresponding thereto. That is, 640 electrothermal transducers are divided into 16 blocks (BLK1 to BLK1) for each of the 40 electrothermal transducers based on 8 timing signals generated according to BENB0 to BENB2 and an ODD / EVEN selection signal. BLK16; FIG. 6) and time-division driving. In the following, a signal for selecting a block, which includes eight timing signals generated according to BENB0 to BENB2 and an ODD / EVEN selection signal, is referred to as a “block selection signal”.

  Image data (2560-bit data) DATA for one raster divided corresponding to the line head is serially transferred to a shift register 226 arranged in each section and connected in series in synchronization with the clock signal DCLK. The Then, when the data alignment corresponding to the nozzles is completed, the data is latched in the latch circuit 225 according to the latch signal DLT. The latched data is sent to the other one of the four input terminals of the AND gate 223.

  In FIG. 4, * PHX, * PHA, and * MH1 (* indicates negative logic) are pulses of the heat signal, and the electrothermal conversion element is energized at a timing defined by the logic state of the block selection signal. It defines the time to perform. These signals are input to the OR gate 227, and the OR output is sent to the other one of the four input terminals of the AND gate 223. The signal * MH1 corresponds to the nozzles seg1 to seg640. * MH2, * MH3, and * MH4 are supplied to the nozzles seg641 to seg1280, the nozzles seg1281 to seg1960, and the nozzles seg1961 to seg2560 in the other sections, respectively (FIG. 5). When there is data for performing an ejection operation, the electrothermal conversion element of each nozzle has a preceding heat pulse (prepulse) * PHA and a subsequent pulse (main pulse) * MH1 to * MH4. Double pulse driving is performed. In addition, when there is no data for performing the ejection operation, a heat pulse * PHX that defines a drive time that does not cause the ejection operation is supplied to reduce the temperature difference from the nozzle that performs the ejection operation, thereby reducing image unevenness. It is trying to suppress the occurrence of.

  The block selection signal and the heat signal are individually supplied to the line heads 101 to 104 and the auxiliary line head 114 from the control circuit 212 of FIG. 2, and can be controlled independently. Then, when the electrothermal conversion element of each nozzle is selected by the block selection signal, it is energized for a time specified by the presence or absence of data and a heat pulse. In the present embodiment, since one raster is divided into 16 times to perform the ejection operation, the maximum number of simultaneously driven nozzles per line head is 160.

  Next, a supplementary operation when a defective nozzle occurs using the above configuration will be described. The complementary operation of this embodiment is performed in units of blocks divided as described above using the auxiliary line head 114.

  FIG. 7 is a flowchart illustrating an example of a complementary operation procedure executed when a defective nozzle is detected. When a defective nozzle is detected by the defective nozzle detection device (step S601), it is determined whether complementation using the auxiliary line head 114 is possible (step S606). This determination can be performed, for example, by the following steps.

  That is, it is first determined whether or not all the nozzles belonging to the block in the auxiliary line head 114 corresponding to the block of the line head including the defective nozzle that has occurred can be ejected normally. If ejection can be performed normally, complementation using the auxiliary line head 114 is performed. However, if there is a defective nozzle in the block of the auxiliary line head, it is determined whether the auxiliary line head section to which the defective nozzle belongs corresponds to the section of the line head to which the defective nozzle belongs. If not supported, complementation using the auxiliary line head 114 is performed, whereas if supported, supplementation using the auxiliary line head 114 is disabled. That is, when a defective nozzle is detected in a certain line head, it is determined whether both of the block and section to which the nozzle belongs overlap with both of the block and section to which the defective nozzle in the auxiliary line head belongs. Only, supplementation using the auxiliary line head 114 is disabled.

  If the supplement using the auxiliary line head 114 is possible, a setting for performing a supplement processing as described later is performed (step S607), and this procedure is terminated. On the other hand, if the supplementation using the auxiliary line head 114 is not possible, it is determined whether or not the recording can be executed (step S608). The determination can be performed as follows. That is, if all the line heads have defective nozzles, and all the defective nozzles belong to the corresponding blocks and sections (overlapping in the transport direction), it is determined to be impossible, and otherwise determined to be possible. To.

  If recording can be performed, it is determined whether or not it is necessary to reduce the conveyance speed of the recording medium in correspondence with the number of remaining line heads that can normally perform recording (step S603). It is necessary to decelerate, for example, when the number of usable line heads is less than four. In this case, the remaining line heads and the conveyance speed corresponding to the maximum drive frequency of each line head are set. Then, regardless of whether or not the conveyance speed needs to be reduced, image data division number changing processing corresponding to the number of remaining line heads is performed, and this procedure ends.

  On the other hand, if it is determined in step S608 that recording cannot be performed, the recording operation is stopped, the display unit 213 of the ink jet recording apparatus is driven to display an error, and an error signal is sent to the host computer 106 side. And displays an error on the display on the host computer 106 side (step S609). At this time, detailed error information such as the position of the line head where the defective nozzle has occurred can be presented, and an instruction on how to deal with the user can be included. If it is determined in step S603 that it is necessary to reduce the conveyance speed of the recording medium, the conveyance speed is reduced, that is, the recording speed is reduced via the display unit 213 of the inkjet recording apparatus or the display on the host computer 106 side. It is also possible to notify. In addition, when such a reduction in recording speed occurs, the user is inquired as to whether or not this is acceptable, and if it is acceptable, the recording is continued, and if not, an error message is presented. Is possible.

  Next, the complementary operation when a defective nozzle is detected will be described more specifically. Here, it is assumed that a defective nozzle is detected in the line head 102, and the defective nozzle belongs to BLOCK1 in the section of seg1 to seg640 (see FIG. 6).

  In this case, if there is no defective nozzle in BLOCK1 in the section of seg1 to seg640 in the auxiliary line head 114, it can be determined that the supplementation is possible using the nozzle group belonging to BLOCK1 in the section of the auxiliary line head 114. Further, if there is a defective nozzle in BLOCK1 in the section of seg1 to seg640 in the auxiliary line head 114, it is determined that complementation using the auxiliary line head 114 is impossible.

  FIG. 8 is an explanatory diagram of a complementary operation using the auxiliary line head 114, and FIGS. 9 and 10 are timing charts of signals in each part in the line head and the auxiliary line head in which a defective nozzle is detected, respectively.

  When the conveyance operation of the recording medium 110 is started and the leading edge of the recording medium is detected by the recording medium sensor 111, a horizontal synchronization signal synchronized with the conveyance of the recording medium is started to be transmitted. The horizontal synchronizing signal is generated by converting the output signal of a means (not shown) provided in the conveyance path, for example, a rotary encoder. For example, if the resolution of the recording head is 600 dots / inch (reference value), the dot pitch is Each time the recording medium 110 advances by 42.3 (μm), one horizontal sync signal is sent out. If the design value of the distance from the recording medium sensor 111 to the line head 101 located on the most upstream side is 2 inches, 1200 pulses until the recording medium sensor 111 detects the leading edge of the recording medium and reaches the line head 101. The horizontal sync signal is sent out.

  Further, when the recording start position reaches the lower side of the line head 101, the data of the first raster stored in the image memory 205 is transferred, and the image of the first raster is recorded. Thereafter, the line head 101 performs intermittent image recording such that one raster recording is performed every time the horizontal synchronizing signal advances by four pulses.

  Subsequently, when the second raster position from the top reaches the lower side of the line head 102, the image of the second raster from the top is recorded. If the design value of the distance between the line heads is 1 inch, the recording by the line head 102 is started after about 600 pulses of horizontal synchronizing signal are counted from the start of recording by the line head 101. become. Thereafter, the line head 102 performs intermittent image recording such that recording of one raster is performed every time the horizontal synchronizing signal advances by four pulses.

  Similarly, every time about 600 pulses of the horizontal synchronizing signal are sent, recording in the intermittent raster portion is filled in the order of the downstream line heads 103, 104, and 114, and an image starts to be completed.

  Description will be made by paying attention to portions of rasters 701 to 704 in the middle of image recording.

  When the raster 702 position reaches the lower part of the recording head 102, the image data of the corresponding raster is read from the image memory 205 and transferred to the line head 102. At this time, by appropriately controlling the block selection signal and the heat signal, driving of nozzles belonging to BLOCK 2 to 16 in the sections of seg 1 to seg 640 and BLOCK 1 of the sections of seg 641 to seg 1280, seg 1281 to seg 1960 and seg 1961 to seg 2560 are performed. The driving of all nozzles belonging to 16 is made effective. That is, only the main pulse MH1 is invalidated at the timing of BE0 = 0, BE1 = 0, BE2 = 0, ODD = 1, and EVEN = 0 of the line head 102 (FIG. 9). As a result, the raster portion 702 (dot group indicated by a black circle) is formed. At this point, the corresponding block 705 in which there is a defective nozzle proceeds without being recorded, but after the raster 702 has passed through the recording head 102, when the horizontal synchronizing signal is sent for about 1800 pulses, the lower part of the auxiliary line head 114 To reach.

  Since the same data as the image data read for the recording head 102 is read in advance in the same order in the auxiliary line head 114, the image data of the raster 702 is read from the image memory 205, and the auxiliary line head 114 114.

  At this time, by appropriately controlling the block selection signal and the heat signal, only the driving of the nozzles belonging to BLOCK1 in the section of seg1 to seg640 is enabled. That is, only the main pulse MH1 is enabled at the timing of BE0 = 0, BE1 = 0, BE2 = 0, ODD = 1, and EVEN = 0 of the auxiliary line head 114 (FIG. 10). As a result, a raster image portion (hatched dots) 705 is formed and the image is complemented.

  Next, the operation when it is determined that there is a defective nozzle in BLOCK1 in the section of seg1 to seg640 in the auxiliary line head 114 and it is determined that complementation using the auxiliary line head 114 is impossible.

  Here, it is assumed that the remaining line heads 101, 103, and 104 do not include defective nozzles, and it is determined that recording can be continued by these three line heads. In this case, it is determined from the period of the horizontal synchronization signal whether the current conveyance speed of the recording medium 109 is capable of recording by the remaining three line heads. If the recording speed is not recordable, the conveyance speed is controlled to be reduced to a recordable speed. Note that the maximum recordable conveyance speed is proportional to the number of recording heads, and the maximum recordable speed corresponding to the number of each recording head is set in a table in advance in the control program, and may be read and used as appropriate. After the recordable speed is set, the number of divisions of the image data is changed from “4” to “3”.

  FIG. 11 shows the result of recording by the three line heads 101, 103 and 104 capable of recording the portions of the rasters 801 to 803 during the image recording.

  When the recording start position reaches the lower side of the line head 101, the data of the first raster stored in the image memory 205 is transferred, and the image of the first raster is recorded. Thereafter, the line head 101 performs intermittent image recording such that one raster recording is performed every time the horizontal synchronizing signal advances by three pulses.

  Subsequently, when the second raster position from the top reaches the lower side of the line head 103, the image of the second raster from the top is recorded. Since the design value of the distance between the line heads is 1 [inch], the recording by the line head 103 is started after about 1200 pulses of the horizontal synchronizing signal are counted from the start of recording by the line head 101. It will be. Thereafter, the line head 103 performs intermittent image recording such that recording of one raster is performed every time the horizontal synchronizing signal advances by three pulses.

  Further, when about 600 pulses of the horizontal synchronizing signal are transmitted, the image is started to be completed by the recording of the line head 104.

  As described above, when the complementary operation using the auxiliary line head 114 is impossible, the recording speed is reduced by performing recording using the remaining line heads, that is, normal line heads having no defective nozzles. An image is formed without degrading the quality.

  As described above, in this embodiment, an auxiliary line head is used, and complementation is performed in units of blocks in a section that corresponds spatially, that is, positionally corresponds in the transport direction, based on the timing of the block selection signal. I made it. As a result, a complementary operation can be performed by controlling the reading and transfer of raster-unit image data developed in the image memory and the signal state of the heat signal (main heat pulse). This eliminates the need for re-development of image data, mask data generation, mask data storage means, etc. for performing defective nozzle complementing operations, and does not cause a decrease in recording speed, so that high-quality recording can be achieved with a simple configuration. The effect that can be maintained is obtained.

  Further, in the present embodiment, even when supplementation by the auxiliary line head is impossible, the number of divisions of the image data is changed in accordance with the number of line heads capable of executing the recording operation, and an appropriate number corresponding to the number is obtained. The recording medium conveyance speed was set. Thereby, it is possible to form an image without reducing the recording quality while minimizing the decrease in the recording speed.

  In the above embodiment, the operation when a defective nozzle is detected by one line head other than the auxiliary line head has been described, but the present invention is not limited to the above. When defective nozzles are detected by two or more recording heads other than the auxiliary line head, if the blocks where the defective nozzles are generated do not overlap, the auxiliary line head is used to achieve high quality without reducing the recording speed. Recording is possible.

  In the above example, four line heads are used for normal recording and one auxiliary line head is used. However, these numerical values are merely examples, and it is a matter of course that an appropriate number can be used.

  In addition, in the above-described embodiment, the dedicated auxiliary line head is fixedly provided. However, a plurality of line heads that function as auxiliary line heads may be appropriately changed. That is, for example, for every certain amount of image recording, a plurality of line heads that are used as auxiliary line heads can be prepared cyclically or randomly. Alternatively, when a defective nozzle is generated in one line head, this is set as an auxiliary line head in the next recording, and the previously prepared auxiliary line head is switched to the line head used for normal recording. It is also possible. After that, if a defective nozzle occurs in any of the line heads, the block where the defective nozzle is generated is compared with the block to which the defective nozzle belongs but is set as an auxiliary line head. Can be processed.

(Second Embodiment)
FIG. 12 is a conceptual diagram showing a schematic configuration example of a recording system according to the second embodiment of the present invention. Here, about each part comprised similarly to 1st Embodiment, the same code | symbol is attached | subjected to the corresponding location. As is apparent from this figure, the system according to the present embodiment is not provided with an auxiliary line head, and is provided with only four line heads 101 to 104 that are normally used for recording.

  The control system of such a system is also configured in the same manner as in FIG. However, this corresponds to the fact that the auxiliary line head 114 is not provided.

  Further, the normal recording operation of the recording system is the same as the operation described with reference to FIG. 3 in the first embodiment, that is, the shared recording operation by the line heads 101 to 104 performed in a state where the auxiliary line head 114 is not used. It becomes.

  Also in the present embodiment, the block driving is performed in each line head, and the configuration for that and the mode of control during normal recording are the same as those in the first embodiment described with reference to FIGS. It is the same.

  Next, a supplementary operation when a defective nozzle occurs using the above configuration will be described. The complementing operation of the present embodiment is performed in units of blocks divided as described above.

  FIG. 13 is a flowchart illustrating an example of a complementary operation procedure executed when a defective nozzle is detected. When a defective nozzle is detected by the defective nozzle detection device (step S701), it is determined whether there is only one line head in which the defective nozzle is generated (step S702).

  If there is only one, recording is performed using the remaining three line heads that can perform normal recording, and it is determined whether or not it is necessary to reduce the conveyance speed of the recording medium according to the number (three). (Step S703). That is, when the number of line heads not including defective nozzles is reduced, the maximum recording speed when recording is performed with four line heads according to the maximum recordable frequency that can be recorded with the remaining line heads. Must be low speed. Therefore, it is determined whether or not the recording operation can be executed with the currently set conveyance speed. The deceleration is necessary when the maximum recording speed is initially set. In this case, the conveyance speed corresponding to the remaining line heads and the maximum drive frequency of each line head is set. Thereafter, regardless of whether or not the conveyance speed needs to be reduced, image data division number change processing corresponding to the number of line heads to be used is performed (step S705), and this procedure ends.

  If there are two or more line heads with defective nozzles in step S702, it is determined whether or not complementation using the relationship between the line heads is possible (step S706). This determination can be performed, for example, by the following steps.

  That is, first, it is determined whether or not the blocks including the defective nozzles overlap each other in the relationship between the line heads including the defective nozzles. If they do not overlap, it is determined that supplementation is possible immediately. On the other hand, if they overlap, it is determined whether the sections to which the defective nozzle belongs correspond to each other. Then, if it does not correspond, the complement is performed, and if it corresponds, the complement is disabled. That is, when a defective nozzle is detected in two or more line heads, it is determined whether both the block and the block to which the nozzle belongs are overlapped, and complementation is disabled only when they overlap.

  If complementation is possible, the setting for performing the complementing process which will be described later is performed (step S707), and this procedure ends. On the other hand, if complementation is not possible, it is determined whether or not recording is possible (step S708). The determination can be performed as follows. That is, if all the line heads have a defective nozzle and the defective nozzle belongs to the corresponding block (overlapping in the transport direction) and the section, it is determined as impossible, otherwise it is determined as possible. .

  If it is determined in step S708 that it is possible, the process proceeds to step S703, and a conveyance speed reduction process or the like is executed. On the other hand, if it is determined in step S708 that recording cannot be performed, the recording operation is stopped, the display unit 213 of the ink jet recording apparatus is driven to display an error, and an error signal is sent to the host computer 106 side. And displays an error on the display on the host computer 106 side (step S709). At this time, detailed error information such as the position of the line head where the defective nozzle has occurred can be presented, and an instruction on how to deal with the user can be included. If it is determined in step S603 that it is necessary to reduce the conveyance speed of the recording medium, the conveyance speed is reduced, that is, the recording speed is reduced via the display unit 213 of the inkjet recording apparatus or the display on the host computer 106 side. It is also possible to notify. In addition, when such a reduction in recording speed occurs, the user is inquired as to whether or not this is acceptable, and if it is acceptable, the recording is continued, and if not, an error message is presented. Is possible.

  Next, the recording operation when a defective nozzle is detected will be described more specifically. Here, it is assumed that defective nozzles are detected only in the line head 102, and the remaining line heads 101, 103, and 104 do not include defective nozzles.

  In this case, it is determined from the period of the horizontal synchronization signal whether the current conveyance speed of the recording medium 109 is capable of recording by the remaining three line heads. If the recording speed is not recordable, the conveyance speed is controlled to be reduced to a recordable speed. Note that the maximum recordable conveyance speed is proportional to the number of recording heads, and the maximum recordable speed corresponding to the number of each recording head is set in a table in advance in the control program, and may be read and used as appropriate. After the recordable speed is set, the number of divisions of the image data is changed from “4” to “3”.

  Thereafter, a recording operation is performed by the three recordable heads 101, 103, and 104. For example, this is the same as the operation described with reference to FIG. 11 in the first embodiment, that is, the shared recording operation by the line heads 101, 103, and 104 performed in a state where the auxiliary line head 114 is not used.

  That is, in this embodiment, if only one line head has a defective nozzle, printing is performed using the remaining three line heads. In this case, when the maximum recording speed using four line heads is initially set, the recording speed decreases from that speed, but a raster unit is used using a normal line head that does not include defective nozzles. Thus, an image is formed without deteriorating the recording quality.

  However, after that, for example, it is assumed that a defective nozzle is detected also in the line head 103. In this case, in step S706 described above, it is determined whether or not complementation is possible in the mutual relationship between the line heads 102 and 103 in which the defective nozzle has occurred. Here, it is assumed that the sections and blocks to which the defective nozzles detected in the line head 102 and the line head 103 belong do not overlap. Then, the defective nozzle complementing operation in the line head 102 and the line head 103 can be performed by appropriately controlling the respective driving.

  FIG. 14 is an explanatory diagram of the complementary operation using the relationship between the line heads in which defective nozzles are generated. The timing chart of each signal in the line heads 102 and 103 in which the defective nozzle is generated is the same as that in FIGS. 10 and 9 referred to in the first embodiment. Here, the defective nozzles detected in the line head 103 are those of seg 65 belonging to BLOCK 1 in the sections of seg 1 to seg 640 (see FIG. 6), and the defective nozzles detected in the line head 102 are those sections and blocks. It shall not overlap with the partition and block to which it belongs.

  When the horizontal synchronization signal is detected, data for one raster stored in the image memory 205 is transferred to the line head 101 located on the most upstream side in the recording medium conveyance direction, and an image 901 of one raster is recorded. Is done.

  Next, when a horizontal synchronization signal is detected, the image data for the next one raster read from the image memory 205 is transferred to the line head 102. At this time, by appropriately controlling the block selection signal and the heat signal, only the driving of the nozzles belonging to BLOCK1 in the section of seg1 to seg640 is enabled. That is, only the main pulse MH1 is enabled at the timing of BE0 = 0, BE1 = 0, BE2 = 0, ODD = 1, and EVEN = 0 of the line head 102 (see FIG. 10). As a result, a raster 902 portion (hatched dots) 905 is formed. This is a portion where the line head 103 cannot perform recording. At this time, the nozzles belonging to the blocks other than the block and the blocks are not driven including the blocks and blocks to which the defective nozzle generated in the line head 102 belongs.

  When the next horizontal synchronization signal is detected, the same data as the data for one raster transferred to the line head 102 is transferred to the line head 103. At this time, by appropriately controlling the block selection signal and the heat signal, driving of nozzles belonging to BLOCK 2 to 16 in the sections of seg 1 to seg 640 and BLOCK 1 of the sections of seg 641 to seg 1280, seg 1281 to seg 1960 and seg 1961 to seg 2560 are performed. The driving of all nozzles belonging to 16 is made effective. That is, only the main pulse MH1 is invalidated at the timing of BE0 = 0, BE1 = 0, BE2 = 0, ODD = 1, and EVEN = 0 of the line head 102 (see FIG. 9). As a result, a raster portion 902 (a dot group indicated by a black circle) is formed, and complementation is performed including a portion where the line head 102 cannot perform recording.

  When the next horizontal synchronization signal is further detected, the image data for the next raster read from the image memory 205 is transferred to the line head 104 to form a raster image 903.

  Thereafter, the line heads 101 to 104 are similarly used, and an image is formed without greatly reducing the recording quality and the recording speed.

  As described above, in the present embodiment, the blocks in the section that use the relationship between the line heads in which defective nozzles are generated and that correspond spatially based on the timing of the block selection signal, that is, positionally correspond in the transport direction. Added completion in units of. As a result, a complementary operation can be performed by controlling the reading and transfer of raster-unit image data developed in the image memory and the signal state of the heat signal (main heat pulse). This eliminates the need for re-development of image data, generation of mask data, mask data storage means, etc. for performing the complementary operation of defective nozzles, and provides an effect of maintaining high-quality recording with a simple configuration.

  In the present embodiment, as described above, when defective nozzles are generated by two line heads, the nozzles of normal blocks complement each other to record one raster image data, and four lines are recorded. The recording is performed every three rasters by the head. Therefore, even if a defective nozzle is generated by two line heads, recording can be executed at the same recording speed as when the three line heads are normal. That is, there is an effect that recording can be continued without lowering the recording speed to a speed proportional to the number of normal heads as in the conventional case, that is, without causing a significant decrease in the recording speed. .

  In the above embodiment, the operation when a defective nozzle is detected by two line heads has been described. However, when a defective nozzle is detected by three or more recording heads, if the blocks where the defective nozzles are generated do not overlap, the recording will not be possible at all or the recording speed will not be significantly reduced. It is possible to perform high recording. That is, even if there are defective nozzles in all four line heads, it is possible to continue recording as long as the blocks in which the defective nozzles are not overlapped in all the line heads. For example, if the blocks where defective nozzles are generated in all line heads are different, or if the blocks where defective nozzles are generated overlap only between two line heads, the blocks where defective nozzles are generated overlap. Recording can be executed at the same recording speed as when two line heads are normal by utilizing the relationship between a pair of line heads that are not present.

  In addition, complementation is performed in the relationship between the line heads in which defective nozzles are generated. However, when defective nozzles are generated in one line head, other normal line heads are used and the same complement as described above. An operation may be performed.

  Furthermore, in the above-described embodiment, a description has been given of processing when a defective nozzle is initially generated in one line head and then a defective nozzle is generated in another line head. However, if a defective nozzle is detected in two or more line heads from the beginning, the recording medium conveyance speed associated with the complementary operation can be set at that time.

  In addition, in the above example, four line heads are used for normal recording. However, this numerical value is an example, and it is a matter of course that an appropriate number can be used.

(Other)
In the first embodiment, an auxiliary line head is prepared, and when a defective nozzle is generated in the line head used for normal recording, the recording operation of the line head is complemented by the auxiliary line head. When the complement is impossible, recording is continued using only a normal line head. In the second embodiment, the recording operation for one line head is complemented using the relationship between two line heads having defective nozzles without preparing an auxiliary line head. However, these embodiments can be appropriately combined. For example, when an auxiliary line head is prepared and a defective nozzle is generated in a certain line head, if the recording operation cannot be supplemented by the auxiliary line head, complementation is performed using another line head. can do.

  In the ink jet recording apparatus according to each of the above-described embodiments, a line head in which nozzles are arranged over a range corresponding to the width of the recording medium to be conveyed is used. However, the arrangement range of the nozzles is not limited to this, and may satisfy at least a part of the width of the recording medium. Also, the nozzle arrangement direction may be a direction that intersects the recording medium conveyance direction.

  Furthermore, in the above example, in each line head, time-division driving (block driving) is performed for each block grouped in units of a predetermined number of nozzles. However, at the time of complementation, the same divided image data is supplied to one recording head and the other recording head, and the recording operation is performed only on the timing at which the ejection failure nozzle is driven. In the light of the idea of the present invention that, for other recording heads, the recording operation is enabled only at the timing at which the corresponding nozzle is driven, it is sufficient that the nozzle is driven in a time-sharing manner. It is not always necessary to perform block driving in which a predetermined number of nozzles are grouped as a unit. In other words, the number of nozzles included in one block can be determined as appropriate.

  In the above embodiment, the case of recording a monochrome image using black ink has been described. However, a plurality of line heads are provided for ink other than black ink, and a color image is recorded while appropriately dividing the image data. In this case, the present invention can be applied. In this case, of course, the number of types of colors to be used can be determined as appropriate.

  In addition, in the above-described embodiment, an inkjet recording apparatus using an inkjet recording head having an electrothermal conversion element that generates thermal energy as energy used for ejecting ink has been described. However, it goes without saying that the present invention is also applicable to an ink jet recording apparatus using an ink jet recording head having a piezoelectric element that generates other energy, for example, mechanical energy.

1 is a conceptual diagram illustrating a schematic configuration example of a recording system to which a first embodiment of the present invention can be applied. FIG. 2 is a block diagram illustrating a schematic configuration example of a control system of the line-type inkjet recording apparatus according to the first embodiment of the present invention. It is a conceptual diagram for demonstrating the normal recording operation | movement of the inkjet recording device shown in FIG. FIG. 3 is a circuit diagram showing an electrical configuration example of an electrothermal conversion element in a predetermined section and its drive circuit in one head of the ink jet recording apparatus shown in FIG. 2. 5 is a timing chart of signals at various parts for performing block driving of the circuit shown in FIG. 4. It is explanatory drawing which shows a response | compatibility with the signal for performing a block drive, and a nozzle. 5 is a flowchart illustrating an example of a complementary operation procedure executed when a defective nozzle is detected in the first embodiment of the present invention. In the 1st Embodiment of this invention, it is a conceptual diagram for demonstrating the complementary operation | movement using the auxiliary line head performed at the time of a defective nozzle detection. It is a timing chart of each part signal in a line head in which a defective nozzle was detected. It is a timing chart of each part signal in an auxiliary line head. FIG. 6 is a conceptual diagram for explaining an operation when recording is performed without using an auxiliary line head when a defective nozzle is detected in the first embodiment of the present invention. It is a conceptual diagram which shows the schematic structural example of the recording system which can apply the 2nd Embodiment of this invention. It is a flowchart which shows an example of the complementary operation | movement procedure performed at the time of defective nozzle detection in the 2nd Embodiment of this invention. In the 2nd Embodiment of this invention, it is a conceptual diagram for demonstrating the complementary operation | movement performed at the time of a defective nozzle detection.

Explanation of symbols

101-104 Line head 105 Image memory 106 Host computer 107 Recording device 109 Recording medium 110 Conveyance unit 111 Recording medium detection sensor 112 Light emitting unit of defective nozzle detection device 113 Light receiving unit of defective nozzle detection device 114 Auxiliary line head 201 Control unit 202 CPU
205 Image Memory 206 Various Motors 207 Transport Control Interface 209 Head Drive Circuit 210 Motor Driver 211 Input / Output Unit (I / O)
212 control circuit 301-304, 701-705, 801-803, 901-903 raster image

Claims (6)

A plurality of ink jet recording heads in which nozzles for performing ink ejection are arranged in a direction intersecting the transport direction of the recording medium are juxtaposed with respect to the same color ink in the transport direction. An inkjet recording apparatus capable of recording by supplying divided image data obtained by dividing image data corresponding to the arrangement of the nozzles,
When there is a nozzle with poor ink ejection in one of the ink jet recording heads, the ink jet recording head includes a complementing means for complementing the recording operation in charge of the nozzle with the corresponding nozzle of the other ink jet recording head,
The complementing unit supplies the same divided image data to the one inkjet recording head and the other inkjet recording head, and the ink ejection failure nozzle is provided to the one inkjet recording head. An ink jet recording apparatus, wherein a recording operation is invalidated only at a driving timing, and a recording operation is validated only at a timing at which the corresponding nozzle is driven for the other ink jet recording head.   The inkjet recording apparatus according to claim 1, wherein the other inkjet recording head is prepared to perform the complement. When recording the divided image data, the inkjet recording head is divided into a plurality of blocks including a plurality of nozzles, and driving means for driving in a time division manner is provided.
The complementary means invalidates the recording operation only at the timing of the time-division driving of the block including the ink ejection defective nozzle with respect to the one inkjet recording head, and with respect to the other inkjet recording head. 3. The ink jet recording apparatus according to claim 2, wherein the driving unit is controlled so as to enable the recording operation only at the timing of the time-division driving of the block including the corresponding nozzle.   The ink jet recording apparatus according to claim 1, wherein the other ink jet recording head is an ink jet recording head in which nozzles other than the corresponding nozzles are defective in ink ejection. When recording the divided image data, the inkjet recording head is divided into a plurality of blocks including a plurality of nozzles, and driving means for driving in a time division manner is provided.
The complementary means invalidates the recording operation only at the timing of the time-division driving of the block including the ink ejection defective nozzle with respect to the one inkjet recording head, and with respect to the other inkjet recording head. Controlling the driving means so as to enable the recording operation only at the timing of the time-division driving of the block including the corresponding nozzle,
The inkjet recording apparatus according to claim 4, wherein the nozzles that are defective in ejection in the other inkjet recording head are included in a block other than the block in which the corresponding nozzle is included.   6. The ink jet recording apparatus according to claim 1, wherein the recording operation is validated or invalidated depending on whether or not a driving signal for causing the ink ejection is supplied.

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