JP5853474B2 - Inkjet recording device - Google Patents

Description

The present invention relates to Lee inkjet recording apparatus.

  An ink jet recording apparatus mounts a recording head composed of a plurality of ejection nozzles for ejecting ink on a carriage, and ejects ink while moving the carriage in a direction perpendicular to the conveyance direction of the recording medium (main scanning). By doing so, an image is formed.

  As a transfer method for transferring image data, which is data for driving an actuator provided in the recording head, from the control unit side to the driver IC of the recording head, generally, serial data transfer is used, and nozzles of the recording head are used. There is already known a method of outputting a transfer clock by the number (= actuator number) and storing it in the shift register of the driver IC.

  For example, Patent Document 1 includes a combination of each bit of a plurality of bits of gradation data per nozzle and a nozzle number for the purpose of transferring image data having a large number of gradations without increasing the number of signal lines. A configuration is disclosed in which the number of data signal lines necessary for the transfer is made constant regardless of the number of gradations of the image data by serially transferring the data.

  However, in order to store normal image data in the register in the driver IC by the conventional image data transfer method, a transfer period equal to the number of nozzles of the print head is required, and the print cycle is longer than the transfer period due to the carriage speed fluctuation. When the next recording timing occurs during transfer, the transfer error occurs, resulting in non-ejection, and an abnormal image (vertical white stripe) is formed.

  The present invention has been made in view of the above, and even when a period necessary for image data transfer to the recording head cannot be secured due to a change in carriage speed (main scanning speed) in the inkjet recording apparatus, Ensure that the quality of the output image can be secured to some extent, that is, the output image itself is treated as an abnormal image, but the degree of abnormality should not be recognized as abnormal at a glance, such as vertical white stripes. With the goal.

To solve the above problems and achieve the object, the present invention is an ink jet recording apparatus provided with an image data transfer device for transferring the image data to the record head, a detecting means for detecting the recording timing, the recording This is a means for serially transferring image data having a gradation of 2 bits or more corresponding to each nozzle to the recording head using timing as a trigger, transferring the upper bits of the image data corresponding to each nozzle first, After transferring all data, a transfer means for transferring the lower bit data of the image data, and when the next recording timing is detected by the detection means during the transfer of the lower bit data, the data transfer to the transfer means It was discontinued, when a transfer control means for starting the next data transfer, the transfer of data of the lower bits is canceled, original image The ejection droplet size determined by the upper and lower bits of the data is controlled based on the determined upper bit data or according to the determined upper bit data and a preset setting value. And a discharge droplet size control means.

  The image data transfer device is preferably mounted on an ink jet recording apparatus.

According to the present invention, the transfer order of the image data to be serially transferred is transferred in the first half of the data transfer period by transferring the upper bits of the image data for all nozzles first and then transferring the lower bits. When the next recording timing comes during data transfer, the current transfer is stopped and the next transfer is started . Subordinate bit when aborted transfer is indefinite, the discharged droplet size determined by the upper and lower bits of the original image data, based on a definite upper bit data, or a definite upper bit data Since the ejection droplet size is controlled according to the preset value , the output image is not an image with a high degree of abnormality such as vertical white stripes even if the period necessary for image data transfer cannot be secured, There is an effect that the quality of the output image can be secured to some extent.

FIG. 1 is a diagram illustrating a schematic mechanical configuration of an ink jet recording apparatus according to an embodiment. FIG. 2 is a block diagram showing an electrical configuration of the ink jet recording apparatus according to the embodiment. FIG. 3 is a block diagram illustrating a carriage including a recording head driving unit, a recording head control unit, and signals sent from the recording head control unit to the carriage. FIG. 4 is a timing chart of various signals related to the recording head drive. FIG. 5 is a diagram showing head drive signals (common drive signals and gradation control signals) in the same embodiment. FIG. 6 is a timing chart of the transfer order of image data to the recording head. FIG. 7 is a circuit diagram of the shift register of the recording head driving unit. FIG. 8 is a diagram for explaining a problem of the conventional image data transfer method. FIG. 9 is a timing chart showing the order of image data transfer to the recording head in the present embodiment. Figure 10 is a time complements operation (at break data transfer), a timing chart of various signals according to recording head driving. FIG. 11 is a diagram illustrating a circuit example of the shift register of the recording head driving unit in the embodiment. FIG. 12 is a timing chart in the circuit example shown in FIG. FIG. 13 is a diagram illustrating another circuit example (denoted as circuit example 2) of the shift register of the recording head driving unit in the embodiment. FIG. 14 is a timing chart in the circuit example 2 shown in FIG.

  Hereinafter, an inkjet recording apparatus as an embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  First, a schematic mechanical configuration of the ink jet recording apparatus will be described with reference to FIG. FIG. 1 is a diagram illustrating a schematic mechanical configuration of an ink jet recording apparatus.

  The inkjet recording apparatus includes a carriage 1, a guide rod 2, a pulley 3, a main scanning motor 4, a timing belt 5, a recording head 6, an ink discharge nozzle 7, a conveyance belt 8, a sub-scanning motor 9, a pulley 10, a timing belt 11, The apparatus includes a transport roller 12, an encoder sensor 13, an encoder sheet 14, a maintenance unit 15, an idle discharge receiver 16, and the like.

  The carriage 1 is held by a guide rod 2 and scans in the main scanning direction via a timing belt 5 passed between the main scanning motor 4 and a pulley 3. The carriage 1 is mounted with a recording head 6 that discharges ink droplets of, for example, yellow (Y), cyan (C), magenta (M), and black (K), and is arranged on the recording head 6. Ink can be ejected from the ink ejection nozzle 7.

  In addition, the conveyance belt 8 rotates in the sub-scanning direction when the conveyance roller 12 is rotationally driven by the sub-scanning motor 9 via the pulley 10 and the timing belt 11.

  An image is formed on the surface of the recording medium on the conveying belt 8 by ejecting ink droplets at a necessary position while moving the carriage 1 in the main scanning direction. The position information of the carriage 1 is read by the encoder sensor 13 fixed to the carriage 1 while moving the pattern recorded on the encoder sheet 14 fixed to the casing at regular intervals, and the count is added / subtracted. Can be obtained at

  By performing the carriage movement in the main scanning direction and the ink ejection operation once, an image can be formed on a band having the same width as the length of the nozzle row. The recording medium is moved in the sub-scanning direction by driving the scanning motor 9 to move the conveyor belt 8 in a revolving manner, and the image forming operation for one band is repeated again. An image can be formed.

  A maintenance unit 15 that performs maintenance and recovery of the recording head 6 is disposed on the side of the conveyance belt 8 on one side of the carriage 1 in the main scanning direction, and an idle ejection receiver that performs idle ejection from the recording head 6 on the other side. 16 are arranged.

  Next, the electrical configuration of the ink jet recording apparatus according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing an electrical configuration of the ink jet recording apparatus of the present embodiment.

  The control unit 100 includes a CPU 101, a ROM 102, a RAM 103, a recording head control unit 104 that also serves as a common drive signal generation unit and a data transfer unit, a main scanning control unit 105, a sub scanning control unit 106, a host I / F 107, and the like.

  Firmware for controlling the entire inkjet recording apparatus and drive waveform data for generating a common drive signal to be sent to the recording head drive unit 111 that drives the recording head 6 are stored in the ROM 102. The RAM 103 is used as various buffers and a work memory and stores various data. When a print job (image data) is received from the host PC 110 via the host I / F 107, the CPU 101 stores this image data in the RAM 103.

  The main scanning control unit 105 detects the position of the carriage 1 in the main scanning direction based on the detection signal from the main scanning encoder 108, and controls the position of the carriage 1 by driving and controlling the main scanning motor 4. The main scanning control unit 105 can move the carriage 1 to an arbitrary position in the main scanning direction.

  The sub-scanning control unit 106 detects the rotation amount and rotation position of the conveying roller 12 based on the detection signal from the sub-scanning encoder 109 and drives and controls the sub-scanning motor 9 to move and stop the conveying belt 8. Perform position control. The sub-scanning control unit 106 can move the recording medium on the conveyor belt 8 to an arbitrary position in the sub-scanning direction.

  The recording head control unit 104 is linked to the position information of the carriage 1 obtained from the main scanning encoder 108 via the main scanning control unit 105, and is common based on image data stored in the RAM 103 and driving waveform data stored in the ROM 102. A drive signal and other control signals are transferred to each print head drive unit 111. Each recording head drive unit 111 drives the corresponding recording head 6 based on the image data transferred from the recording head control unit 104 and ejects ink droplets. In FIG. 2, four recording heads (1 to 4) 6 and the recording head driving unit 111 are illustrated.

  Subsequently, the configuration of the recording head driving unit 111 is shown, and the control of the recording head 6 in the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a block diagram illustrating the carriage 1 including the recording head driving unit 111, the recording head control unit 104, and signals sent from the recording head control unit 104 to the carriage 1, and FIG. 4 relates to recording head driving. It is a timing chart of various signals.

  The recording head control unit 104 supplies image data SD (serial data) corresponding to the number of nozzles (= the number of actuators) of the recording head 6 to the recording head driving unit 111 during the period t1 in FIG. The data is transferred to the shift register 201 by SCK.

  When the transfer of the image data SD from the recording head control unit 104 is completed, the image data that has been transferred to the shift register 201 by the transfer data latch signal SLn in the period t2 in FIG. 202).

  After latching the image data, a drive waveform for causing the ink droplets of each gradation value to be ejected from the ink ejection nozzle 7 is output from the recording head control unit 104 to the common drive signal Vcom during the period t3 in FIG. At this time, the drive waveform mask pattern MN transits to select a drive pulse included in the common drive signal in accordance with the timing of the drive waveform of the common drive signal for gradation control.

  In the recording head driving unit 111, the gradation control signal MN and the latched image data are logically calculated by the gradation decoder 203, and the analog switch 205 can operate the logic level voltage signal of the gradation decoder 203 by the level shifter 204. Converted to a different level. Then, by opening and closing the analog switch 205 by the output of the gradation decoder 203 given through the level shifter 204, each actuator 206 in the recording head 6 receives a drive signal (drive waveform) VoutN corresponding to the nozzle. Ink ejection based on the image data is performed from each nozzle by each actuator 206.

  Here, the head drive signal (common drive signal and gradation control signal) in this embodiment is shown in FIG. 5, and the relationship between the head drive signal and the ejected ink droplets will be described.

  The common drive signal Vcom input to the recording head 6 is composed of a collection of a plurality of drive pulses, and the ejection ink droplet size for the image data of each nozzle is determined by the combination of the drive pulses. This drive pulse is selected by the drive waveform mask pattern MN. Then, the drive pulse of the common drive signal selected by the drive waveform mask pattern MN is output to the actuator 206 as a gradation control signal. The example shown in FIG. 5 is a case where the image data is 2 bits, and four types of drop sizes of 0 to 3 can be selected.

(A) Droplet size 0: Actuator 206 is finely driven by outputting drive pulse <1> (in this case, ink droplets are not ejected).

(B) In the case of the droplet size 1: A droplet is formed by the recording head 6 by outputting the drive pulse <4>.

(C) Droplet size 2: Medium droplets are formed in the recording head 6 by outputting drive pulses <3> and <4>.

(D) Droplet size 3: Large droplets are formed by the recording head 6 by outputting drive pulses <2>, <3>, and <4>.

  Table 1 below shows the relationship between image data and ejected ink droplets (ejection droplet size).

  Next, transfer of image data from the recording head control unit 104 to the recording head driving unit 111 will be described with reference to FIGS. 6 and 7. FIG. 6 is a timing chart of the transfer order of image data to the recording head 6, and FIG. 7 is a circuit diagram of the shift register 201 of the recording head driving unit 111. 6 and 7 are examples in the case where the number of nozzles = 160 nozzles.

  The image data is transferred using the signal line SD [1] in order of the nozzle 160 to the nozzle 1 for the upper bits of the image data for each nozzle, and the nozzle 160 to the nozzle 1 for the lower bits of the image data for each nozzle. Are transferred using the signal line SD [0] in this order. Therefore, the image data for the nozzle 160 that is first transferred with 160 SCK pulses is transferred to the right end of the shift register 201 shown in FIG. In order to obtain normal image data in each register in the shift register 201, SCK pulses corresponding to the number of nozzles are required (160 pulses in this case), and transfer cannot be stopped halfway.

  Next, the problem of the conventional image data transfer method will be described with reference to FIG. FIG. 8 is a diagram for explaining a problem of the conventional image data transfer method.

  As described above, in order to store normal image data in the shift register 201 in the recording head driving unit 111, a transfer period corresponding to the number of nozzles of the recording head 6 is required. In the conventional image data transfer method, as shown in FIG. 8, when the recording cycle becomes shorter than the transfer period due to the carriage speed fluctuation, and the next recording timing occurs during the transfer, the recording timing becomes invalid. There is a period in which the recording head 6 is not driven because data transfer is not performed for one recording period. In such a case, there is a problem that the output image becomes a serious abnormal image that looks like vertical white stripes.

  Because of such a problem, in this embodiment, image data is transferred as follows. FIG. 9 is a timing chart showing the order of image data transfer to the recording head 6 in this embodiment.

As shown in FIG. 9, the present embodiment is characterized in that image data is serially transferred in the order of “transfer upper bit data for all nozzles and then transfer lower bit data for all nozzles”. As a result, all the upper bit data largely related to the image quality are determined in the first half of the data transfer period, so even when the next recording timing comes during the latter lower bit transfer (this means that the movement of the carriage 1 is the encoder). It can be detected by detecting with the sensor 13), the data transfer being transferred can be stopped, and the next data transfer can be started. The ejection droplet size that becomes indefinite due to the lower bit data that becomes indefinite when data transfer is stopped is complemented based on the value of the upper bit that has already been established. Table 2 below shows the relationship between the image data and the ejected ink droplets by this image data transfer method.

  When the upper bit is 0 and the lower bit is indefinite, the expected original droplet size is “no droplet” or “small droplet”, but in this case, “ink non-ejection” or “ink ejection” It can be said that it is a choice. In the printing area of the ink jet recording apparatus, the ratio of the area of white data (ink non-ejection) is large, and in this case, it is desirable to complement “no drop”. On the other hand, when the upper bit is 1 and the lower bit is indefinite, the expected droplet size is “medium droplet” or “large droplet”. When the complement method is fixed regardless of the register setting value, etc., it is supplemented to “medium drop” in consideration of the ink consumption that is wasted when supplementing the image data, which is originally a medium drop, to a large drop. It is desirable to do.

  When the upper bit is 1 and the lower bit is indefinite, the expected droplet size is “medium droplet” or “large droplet”, which is suitable for complementing the print head 6 or the head drive signal. And the quality of the output image desired by the user. Therefore, a configuration in which the print head control unit 104 is provided with a complementary setting register (not shown) so as to be settable is more preferable than the example in Table 2 above. This setting can be set at the time of print setting from the host PC 110, for example.

  In Table 3 below, when the complementary set value is 0, the medium droplet is complemented, and when the interpolation set value is 1, the large droplet is complemented. In Table 3 below, “−” in the complementary setting indicates that the complementary setting value is not involved in determining the ejection droplet size.

Next, FIG. 10 shows the time complements operation (at break data transfer), a timing chart of various signals according to recording head driving. This figure is a timing chart based on the relationship shown in Table 3 above.

  In the complement operation, as shown in the figure, the recording head controller 104 outputs the drive waveform mask pattern MN [1] with the same signal transition as MN [0], and MN [3] is the same signal as MN [2]. Operates to output on transition. As a result, during the complementary operation, regardless of whether the image data is 00 or 01, the drive waveform applied to the actuator 206 is the drive waveform of image data at normal operation = 00 (no droplets), and the image data is 10 11, the drive waveform is a drive waveform (medium droplet) of image data = 10 during normal operation.

  Here, FIG. 11 shows a circuit example (denoted as circuit example 1) of the shift register 201 of the recording head driving unit 111 in this embodiment, and FIG. 12 shows a timing chart in the circuit example 1 shown in FIG. Indicates.

  In the circuit example 1 of FIG. 11, the image data transfer clock supplied to the shift register 201 is divided into two systems, SCK1 that outputs a pulse only in the first half of the data transfer period and SCK2 that outputs a pulse only in the second half of the data transfer period. ing. Transfer data SD [0] transfers data from nozzle 1 to nozzle 80, and transfer data SD [1] transfers data from nozzle 81 to nozzle 160. The number of signal lines between the recording head control unit 104 and the recording head driving unit 111 increases as the image data transfer clock becomes a plurality of systems, but the circuit scale of the shift register 201 in the recording head driving unit 111 does not increase. It has become.

  Next, FIG. 13 shows another circuit example (denoted as circuit example 2) of the shift register 201 of the recording head driving unit 111 in this embodiment, and FIG. 14 shows the circuit example 2 shown in FIG. A timing chart is shown.

  In the circuit example 2 of FIG. 13, the image data transfer clock sck1 of the high-order bit shift register 201 is an internally generated gated output from the OR logic circuit that inputs the image data transfer clock SCK and the transfer data latch signal SLn from the outside. This is a clock and outputs pulses only in the first half of the data transfer period (by the number of pulses that is 1/2 the number of nozzles). The transfer data latch signal SLn becomes L (low) at the recording timing, and becomes H (high) when the transfer of the upper bit data of all the nozzles is completed. The latch 202 at the rear stage of the shift register 201 performs a latch operation at the falling edge of the transfer data latch signal SLn. With this configuration, in the first half of the data transfer period, the upper bits of the image data are transferred to the portion corresponding to the upper bits of the shift register 201 by the internally generated image data transfer clock sck1. The lower bit of the image data is transferred to the portion corresponding to the lower bit of the register 201 by the image data transfer clock SCK. Compared to circuit example 1 shown in FIG. 11, circuit example 2 increases the circuit scale by adding a logic circuit in shift register 201, but the signal line between printhead control unit 104 and printhead drive unit 111. This can be realized without increasing the number.

As described above, in the above-described embodiment, the transfer order of two or more bits of image data to be serially transferred is “transfer the upper bits of all nozzles and then transfer the lower bits of all nozzles”. in, to confirm the upper bits of all the nozzles in the first half of the data transfer period, when the next recording timing has come during the second half of the lower bit transfer, higher bits to abort the transfer of image data, and confirm values based on, or in accordance with the value of the upper bit has been finalized and the preset value, has become characterized by controlling the discharge droplet size. By controlling in this way, the output image does not become an image with a high degree of abnormality such as vertical white streaks even in a state where a period necessary for image data transfer cannot be secured due to fluctuations in the carriage speed (main scanning speed). For example, the quality of the output image can be ensured to some extent. In addition, as another effect, the restriction of speed fluctuation in the control of the carriage speed (main scanning speed) can be relaxed, and as a result, the cost of the apparatus main body can be reduced.

DESCRIPTION OF SYMBOLS 1 Carriage 2 Guide rod 3 Pulley 4 Main scanning motor 5 Timing belt 6 Recording head 7 Ink ejection nozzle 8 Conveyance belt 9 Sub scanning motor 10 Pulley 11 Timing belt 12 Conveyance roller 13 Encoder sensor 14 Encoder sheet 15 Maintenance unit 16 Empty ejection receptacle 100 Control unit 101 CPU
102 ROM
103 RAM
104 Print Head Control Unit 105 Main Scan Control Unit 106 Sub Scan Control Unit 107 Host I / F
108 Main scanning encoder 109 Sub scanning encoder 110 Host PC
201 Shift register 202 Latch 203 Gradation decoder 204 Level shifter 205 Analog switch 206 Actuator

JP 2007-069373 A

Claims (8)

In the ink jet recording apparatus provided with an image data transfer device for transferring the image data to the record head,
Detecting means for detecting recording timing;
A means for serially transferring image data having a gradation of 2 bits or more corresponding to each nozzle to the recording head using the recording timing as a trigger, wherein the upper bits of the image data corresponding to each nozzle are transferred first, Transfer means for transferring the lower bit data of the image data after transferring all the bit data;
A transfer control means for stopping the data transfer and starting the next data transfer when the detection means detects the next recording timing during the transfer of the lower bit data;
When the transfer of the lower bit data is stopped , the droplet size originally determined by the upper bits and the lower bits of the image data is determined based on the determined upper bit data or the determined upper bit data. An inkjet recording apparatus comprising: an ejection droplet size control unit that controls the ejection droplet size according to a preset value . 2. The ink jet recording apparatus according to claim 1, wherein the ejection droplet size controlled by the ejection droplet size control means varies depending on the value of the determined upper bit data. The discharged droplet size control means, if the combination of the lower bit data which is the value and the indefinite upper bit data, provided to selectively discharge / non-discharge of ink droplets, ejection towards serving as ink discharge failure The inkjet recording apparatus according to claim 2, wherein the droplet size is controlled . In control by the discharged droplet size control means, if the combination of the lower bit data which is the value and the indefinite upper bit data are both ejecting ink droplets, it was to select the ink drop size, drop size The ink jet recording apparatus according to claim 2, wherein the droplet size is controlled in a smaller direction. In control by the discharged droplet size control means, the ink-jet recording according to claim 4, characterized in that whether to control the discharged droplet size to either of the smaller or larger the droplet size the user has arbitrarily settable Equipment . The ejection droplet size control by the ejection droplet size control means is used when driving the recording head based on the determined upper bit data or according to the determined upper bit data and a preset set value. 2. The ink jet recording apparatus according to claim 1, wherein the driving waveform mask pattern signal for masking the common driving signal is operated to select a driving waveform of each nozzle. The transfer means stores a clock to a shift register for storing image data mounted in a recording head driving unit for driving the recording head, a clock for storing upper bit data, and lower bit data. 7. The ink jet recording apparatus according to claim 1, wherein a clock for supplying the same is supplied independently. The transfer means uses a transfer data latch signal as an enable signal for the clock for storing upper bit data to a shift register for storing image data mounted in a print head drive unit that drives the print head. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is internally generated in the recording head drive unit as a clock that is shared and operates only during a period in which upper bit data is transferred.

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