JP4402911B2 - Inkjet recording apparatus and method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus that performs recording by discharging ink from a recording unit to a recording material.

  As conventional image recording apparatuses, various printers, copiers, and the like are known depending on recording means. Such a recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a thermal transfer type, a laser beam type, and the like depending on the recording method of the recording means used. Among them, the ink jet type performs recording by ejecting ink onto a recording medium from an ink jet type liquid ejecting head (hereinafter referred to as a head) having a plurality of ejection openings for ejecting ink as an ejection medium as fine ink. The recording method is easy to downsize, high-definition images can be recorded at high speed, the running cost is low, the non-impact method is low noise, and multi-color ink is used. Thus, there is an advantage that it is easy to record a color image. (For example, page 2 of Patent Document 1, FIG. 5)

JP-A-6-44393

  However, in an ink jet recording apparatus, the ejection of secondary ink droplets (hereinafter referred to as satellites) generated when ink is ejected by applying a main pulse, which is unique to an ink jet printer, forms an unnecessary image on a recording medium. As a result, not only the printing quality of a recorded matter that requires high-quality recording, such as a barcode, but also the problem that the printed barcode cannot satisfy the standard may occur.

  FIG. 3 is a schematic diagram for explaining a customer barcode, which is one of barcodes that require high print quality.

  Customer barcodes are used in conjunction with the introduction of the new postal code system that started on February 2, 1998. Addresses are printed on postal items in the form of barcodes that can be easily read by a sorting machine. It is a bar code for making it possible to mechanize from reading to route assembly work.

  As shown in FIG. 3, a customer bar code 3000 includes a long bar 3001 that extends vertically, a semi-long bar (upper) 3002 that extends only upward, a semi-long bar (lower) 3003 that extends only downward, and One character is composed of four types of timing bars 3004, and a total of 23 characters are composed.

  The ratio of the bar width and the length of each bar (long bar, semi-long bar, timing bar) is standardized as 1: 3: 2: 1. When the barcode is printed, the barcode size A (valid at 8 ≦ A ≦ 11.5 points) is determined from the relative ratio of the bar length and the bar width, etc., and the barcode size is A point The effective range standard of the bar width is (0.50 × A ÷ 10) mm to (0.70 × A ÷ 10) mm, and the effective range standard of the bar height T is (3.40 × A ÷ 10). ) Mm to (3.60 × A ÷ 10) mm.

  Next, the principle on which satellites are formed will be described.

  FIG. 1 is a diagram illustrating a process in which an electrothermal transducer provided in an inkjet recording head nozzle is energized and ink droplets are ejected by rapid expansion of ink in the nozzle.

  FIG. 1A shows a state in which the nozzle 1000 is filled with ink 1001, and FIG. 1B shows a state in which energy is applied to the electrothermal transducer 1002 for an extremely short time. At this time, electrothermal conversion is performed. The ink in the vicinity of the body 1002 is rapidly heated to generate minute bubbles 1003.

  Next, as shown in FIG. 1C, the ink 1001 is rapidly vaporized, and microbubbles 1003 grow.

  FIG. 1D shows a state where the bubble 1003 is expanded to the maximum and the ink droplet 1004 is pushed out from the ejection port.

  FIG. 1E shows a state in which energization of the electrothermal transducer 1002 is completed and the bubble 1003 is rapidly shrunk by ink and becomes liquid.

  FIG. 1 (f) shows a state where the ink droplet 1004 is pushed out and flies in the direction of the arrow, and FIG. 1 (g) shows that the ink droplet 1004 is a main ink droplet 1005 and a spiral ink droplet (satellite) 1006. The state where and are formed is shown.

  Not only such an ink jet recording method but also a general ink jet recording method, when ink droplets are ejected, the tail when the main ink droplet is ejected is a small ink droplet due to the surface tension of the ink itself. Thus, it becomes a satellite separately from the main ink droplets necessary for original recording.

  It has been measured that this satellite flies to a position that is offset forward of the main droplet with respect to the transport direction.

  FIG. 2 is a schematic diagram showing a pattern in which this satellite lands on a recording medium. In this way, satellites have an adverse effect that, in particular, in recordings that require high-quality recording such as barcodes, unnecessary images are formed, so that the printing quality is lowered and sometimes the standards cannot be satisfied. .

  Furthermore, the degree of influence of satellites on print quality varies depending on the barcode printing direction (array direction). That is, as shown in FIG. 6A, when the barcode is recorded in the horizontal direction, the satellite has little influence on the print quality of the barcode. However, as shown in FIG. 6B, when the barcode is recorded in the vertical direction, the influence of the satellite on the quality of the barcode cannot be ignored.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet recording apparatus capable of recording a high-quality bar code (for example, a customer bar code) by correcting ejection characteristics in the ink jet recording apparatus.

In order to solve the above problems, the ink jet recording apparatus of the present invention is capable of ejecting ink droplets from the nozzles of a recording head in which a plurality of nozzles are arranged in a row, and is arranged in a direction perpendicular to the conveyance direction of the recording medium. In the ink jet recording apparatus that records an image including a barcode on the recording medium based on the recording data by the nozzle row, the recording medium is transported when the recording data includes data for recording the barcode. An arrangement direction discriminating means for discriminating whether an arrangement direction of the bar code with respect to a direction is a direction orthogonal to or parallel to a conveyance direction of the recording medium; If it is determined that the barcode arrangement direction is parallel to the transport direction, the width of the bar forming the barcode is reduced. Characterized in that it comprises a control means for the.
Further, the inkjet recording method of the present invention includes a step of ejecting ink droplets from the nozzles of a recording head in which a plurality of nozzles are arranged in a row, and the nozzle row arranged in a direction orthogonal to the conveyance direction of the recording medium. A method of recording an image including a barcode on the recording medium based on the recording data, and when the recording data includes data for recording a barcode, the conveyance direction of the recording medium An array direction determining step for determining whether the bar code array direction is a direction perpendicular to or parallel to the transport direction of the recording medium, and the array direction determining means transports the recording medium. When it is determined that the barcode arrangement direction is parallel to the direction, the width of the bar forming the barcode is recorded narrowly. Characterized in that it comprises a control step.

  As described above, according to the present invention, since the recording is performed by correcting the ejection characteristics so as to minimize the influence of the satellite in the ink jet recording, high-quality bar code recording can be performed.

  Hereinafter, an embodiment of an ink jet recording apparatus of the present invention will be described with reference to the drawings.

  In the present specification, the horizontal direction means a direction substantially perpendicular to the transport direction of the recording medium, and the vertical direction means a direction substantially parallel to the transport direction of the recording medium. It shall be said.

(First embodiment)
FIG. 4A is a schematic view showing an ink jet recording apparatus as an embodiment of the ink jet recording apparatus of the present invention, and FIG. 4B is a cross-sectional view showing the internal structure thereof.

  In FIG. 4A, reference numeral 4000 denotes an ink jet recording apparatus, 4001 denotes a feeder cover for accommodating a recording medium, and 4002 denotes an upper cover for opening and closing a head station and a recording medium conveying unit which will be described later. 4003 is a front cover for opening and closing a tank unit for storing ink as liquid supplied to a head of a head station described later, 4004 is a power switch unit of the recording apparatus, and 4005 is a recording unit It is an operation panel for setting, changing, and the like of an operation environment in the apparatus.

  As shown in FIG. 4B, the head station in this embodiment is a long type inkjet line head (K, C, M, Y) in which a plurality of recording elements are arranged in a straight line. They are arranged in parallel to each other in a direction perpendicular to the transport direction. Specifically, it is composed of a yellow line head Y, a magenta line head M, a cyan line head C, and a black line head K. The transport unit U, which is a transport means positioned below, transports the recording medium Pa stacked on the feeder unit F toward the recording position by the line head at a constant speed, and when each recording head reaches the recording position, each head Ink is ejected by (K, C, M, Y), and an image is recorded on the recording medium. Thereafter, the recording medium Pa is configured to be carried out on the stacker S. Below the transport unit U, a tank portion R for storing dedicated ink supplied to each head (K, C, M, Y) is detachably fixed.

  FIG. 5 is a block diagram showing a configuration of a control circuit of the ink jet recording apparatus shown in FIG. In FIG. 5, 5000 is an interface input from an external device such as a host computer, 5001 is an MPU of a processing unit, 5002 is a memory, MPU 5001 reads a program and executes the program, and a flow shown in FIG. A ROM 5003 for storing a control program (including a character font if necessary) is a DRAM for temporarily storing various data (such as the recording data and a recording signal supplied to the recording head). A gate array 5004 controls the supply of recording signals to the recording heads K, C, M, and Y, and also controls the transfer of data between the interface 5000, the MPU 5001, and the DRAM 5003. Reference numeral 5008 denotes a conveyance motor for conveying the recording medium. Reference numeral 5005 denotes a head driver that drives the recording heads K, C, M, and Y, and 5006 denotes a motor driver that drives the transport motor 5008.

  The operation outline of the control circuit will be described. When recording data input by a user enters an interface 5000 at an input unit of a host computer (not shown), it is analyzed by the control unit (for example, the arrangement direction of barcodes to be recorded). Image data is expanded in the DRAM 5003, whether the image data is in the horizontal direction or the vertical direction. Image data is converted into a recording signal for recording between the gate array 5004 and the MPU 5001. Then, the motor driver 5006 is driven, and the recording heads K, C, M, and Y are driven according to the recording signal sent to the head driver 5005 to perform the recording operation.

  Next, a customer barcode recording method by the ink jet recording apparatus in the present embodiment will be described with reference to FIG.

  When the interface 5000 receives recording data including a customer barcode from a host computer (not shown), the MPU 5001 reads the data as described above, expands the customer barcode image data into the DRAM 5003, and performs a recording operation according to the image data. Is called.

  First, the bar code is determined in step 10001, and if YES, the process goes to the direction determination step. 6A is a schematic diagram for explaining the relationship between satellites and barcodes when a customer barcode is recorded in the horizontal direction, and FIG. 6B is a diagram for explaining the relationship between each satellite and barcode when recording the customer barcode in the vertical direction. In the case where the satellite described above does not occur, an ideal customer barcode should be printed if the bar width of the customer barcode is configured with X dots and the bar length is configured with 3X. However, actually, when customer barcodes are recorded in the horizontal direction and the vertical direction with the above-described dot configuration, satellites as shown in FIGS. 6A and 6B are generated.

  Here, 6000 in FIG. 6 is the above-described satellite (the size is α), and it can be seen that an unnecessary image is formed in the transport direction. That is, as shown in FIG. 6A, when a customer barcode is recorded in the horizontal direction, the desired bar length is 3X dots, whereas the recording result is 3X + α dots. The image formed by the satellite does not significantly affect the quality of the barcode. On the other hand, as shown in FIG. 6B, when the customer barcode is recorded in the vertical direction, the desired bar width is X dots, whereas the recording result is X + α dots, so that satellites are formed. The image greatly affects the quality of the customer barcode.

  FIG. 7 shows the dot configuration of the customer barcode according to the first embodiment of the present invention.

  In this embodiment, as shown in FIG. 7B, when the satellite has a great influence on the quality of the customer barcode, that is, when the customer barcode is recorded in the vertical direction in the direction determination step, step 10003 is performed. Thus, in consideration of the image formed by the satellite, printing is performed with a reduced bar width for one dot. On the other hand, when the customer barcode is recorded in the horizontal direction as shown in FIG. 7A, since the satellite has little influence on the barcode size in step 10005, the influence of the satellite is ignored and the customer barcode is ignored. Configure. If it is not a bar code, it is determined in step 10006 whether or not a character is printed, and printing is performed according to the width of the character. If the printing end is determined in step 10004, the process is terminated. If the printing is not completed, the process returns to step 10002 to resume printing.

  As described above, according to the present invention, the configuration of the recorded data of the customer barcode developed in the DRAM is changed according to the printing direction according to the printing direction (array direction) of the customer barcode designated by the host computer. This minimizes the effect of satellites on print quality and enables high-quality customer bar code recording.

(Second Embodiment)
The hardware configuration in the present embodiment will be described using the block diagram of the first embodiment. The ink droplet ejection process in the ink jet printing of the present embodiment is as described above, and the ink is foamed by applying energy by a pulse signal to the electrothermal transducer to obtain an ink ejection liquid.

  FIG. 8 is a waveform diagram showing a pulse waveform applied to the electrothermal transducer of the recording head of the present embodiment. In (a), a recording timing signal 8000 and recording data are first input to a head driving circuit (head driver). In accordance with the recording timing signal 8000, the sub heat pulse 8001 having the voltage V1 and the width T1 is applied to the electrothermal transducer 1002 in (b). At this time, foaming contributing to the ejection of ink droplets does not occur in the vicinity of the electrothermal transducer 1002 in the nozzle 1000. That is, ink ejection does not occur. The sub heat pulse heats the ink in the nozzle 1000 and particularly serves to lower the viscosity of the ink. Subsequently, after the time T2 has elapsed with the voltage being 0, the main heat pulse 8002 having the voltage V2 and the width T3 is applied to the electrothermal transducer 1002. Here, the voltages of the sub heat pulse 8001 and the main heat pulse 8002 are equal. That is, V1 = V2. Further, the main heat pulse 8002 is longer than the sub heat pulse width 8001, and T1 <T2. The main heat pulse 8002 has a voltage and width that are sufficient for the applied electrical energy to cause foaming in the nozzle 1000 and ink to be ejected from the nozzle 1000.

  FIG. 9 is a graph plotting the characteristics of the pulse width T1 of the sub heat pulse 8001 and the ink ejection volume. As can be seen from FIG. 9, the ink ejection volume changes according to the pulse width T <b> 1 of the sub heat pulse 8001. That is, the ink ejection volume is proportional to the ink dyeing area for the recording medium including the satellite.

  Therefore, in the present embodiment, when a customer barcode is recorded in the vertical direction, a drive circuit 5005a as shown in FIG. 11 is provided in the head driver in FIG. 5, recording data is input, and direction data is further input. Depending on the direction data, the pulse shown in FIG. 8b or 8c is generated. Therefore, when printing in the vertical direction, as shown in FIG. 8C, the dots of the first line of each bar constituting the customer barcode are formed small. By making the pulse width T1 of the sub heat pulse 8001 smaller than the normal pulse width and reducing the ink ejection volume, the ink dyeing area including the satellite is reduced, and printing is performed.

  Here, the head line means a line of recording dots arranged at a boundary position when the barcode is switched from a space to a bar.

  The first and subsequent lines are applied with a normal pulse width T1 as shown in FIG. In the case of recording in the horizontal direction, the satellite has little influence on the customer barcode. Therefore, when forming the dot of the first line, it is applied with the normal pulse width T1 as shown in FIG. 8B.

  As described above, according to the present invention, when the customer barcode is recorded in the vertical direction, the pulse applied to the electrothermal transducer 1002 according to the order of the recording dots constituting each bar of the customer barcode. By controlling the width and reducing the ink dyeing area, it is possible to minimize the influence of the satellite on the print quality and enable high-quality customer barcode recording.

  In the embodiment described above, the ink ejection volume is controlled by controlling the pulse width T1 of the sub heat pulse 8001, but the present invention is not limited to this. For example, the characteristic that the ink ejection volume changes according to the pulse width T2 of the main heat pulse 8002 is generally known, and the influence of the satellite on the print quality may be minimized by using the characteristic.

  In addition, it is generally known that the ink ejection volume changes in accordance with the pause time T2 of the pulse between the sub heat pulse 8001 and the main heat pulse 8002. The characteristics are used to minimize the influence of the satellite on the print quality. May be.

(Third embodiment)
Since the hardware configuration in this embodiment is the same as that in the first embodiment, the description thereof is omitted. In addition, the ink droplet ejection principle in the present embodiment is the same as that in the second embodiment, and a description thereof will be omitted.

  A recording method of the ink jet recording apparatus in the present embodiment will be described. The so-called multi-drop method, in which a plurality of ink droplets are overlapped and recorded at the same location on the recording medium, is already widely known, and the ink jet recording apparatus in the present embodiment also employs this recording method. is doing.

  An outline of the operation in the present embodiment will be described with reference to FIG. When recording data input by a user enters an interface 5000 at an input unit of a host computer (not shown), the control unit analyzes the recording data, and image data is “not discharged”, “discharged only once”, “only discharged”, “ The recording data is converted into a recording signal for recording between the gate array 5004 and the MPU 5001. Then, the motor driver 5006 is driven and the head driver is developed. The recording heads K, C, M, and Y are driven in accordance with the recording data sent to 5005, and a recording operation is performed, at which time the ink ejection operation is performed according to the recorded recording data of the DRAM. No ”,“ Eject ink only once ”, and“ Discharge ink twice ” In proportion to the number of ink ejections, together with the recording density of the recording paper becomes darker, ink stained area becomes wider in proportion to the number of ink ejections.

  Therefore, in this embodiment, when the satellite has a great influence on the quality of the customer barcode, that is, when the customer barcode is recorded in the vertical direction, in order to minimize the dot droplets formed by the satellite, The first line ejects ink only once, thereby reducing the ink dyeing volume and reducing the ink dyeing area including satellites. Further, the line after the first line ejects ink twice to record a customer barcode having a high printing density and a high reflectance. On the other hand, when recording in the horizontal direction, the satellite has little effect on the customer barcode, so to form all lines including the first line of each bar, the ink is ejected twice and the print density is high. Record a highly reflective barcode.

  As described above, according to the present invention, according to the printing direction (arrangement direction) of the customer barcode, the printing density is controlled by the number of ejections of ink ejected to the same location, and the satellite is printed by reducing the ink dyeing area. The effect on quality can be minimized and high-quality bar code recording can be realized.

(Other embodiments)
The embodiments described above are not only implemented exclusively, but can be implemented by combining, for example, the second embodiment and the third embodiment. In the above embodiment, only the customer barcode is discussed, but the same applies to other barcodes, and the barcode is not limited to the customer barcode.

  Although various embodiments of the present invention have been described, those skilled in the art will recognize that the spirit and scope of the present invention are not limited to the specific descriptions and drawings in the present invention, and are all within the scope of the claims of the present application. It will be understood that this will cover the various modifications and changes described.

(A)-(g) is the schematic explaining the ink discharge process in the inkjet recording device concerning embodiment of this invention. It is the schematic explaining the satellite in the inkjet recording device concerning embodiment of this invention. It is the schematic explaining a customer barcode. (A) is a perspective view of the inkjet recording device concerning embodiment of this invention, (b) is typical sectional drawing of the inkjet recording device concerning embodiment of this invention. 1 is an electrical block diagram of an ink jet recording apparatus according to an embodiment of the present invention. It is a schematic diagram explaining the relationship between a satellite and a customer barcode, (a) shows the case where a barcode is recorded in the horizontal direction, and (b) shows the case where a barcode is recorded in the vertical direction. It is a schematic diagram explaining the dot structure of the customer barcode concerning the 1st Embodiment of this invention, (a) shows the Example at the time of recording a barcode in a horizontal direction, (b) is a perpendicular direction It is a figure which shows the Example at the time of recording a barcode in the. (A)-(c) is a wave form diagram of the pulse signal applied to the electrothermal converter which concerns on the 2nd Embodiment of this invention. It is a graph which shows the relationship between the pulse signal applied to the electrothermal converter which concerns on the 2nd Embodiment of this invention, and the discharge volume of ink. 3 is a flowchart according to the first embodiment of the present invention. It is a figure which shows the generator of the pulse signal applied to the electrothermal converter which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

1000 Nozzle 1001 Ink 1002 Electrothermal converter 1003 Bubble 1004 Ink 1005 Main droplet 8000 Recording timing signal 8001 Sub heat pulse 8002 Main heat pulse K Inkjet recording head (black)
C Inkjet recording head (cyan)
M Inkjet recording head (magenta)
Y Inkjet recording head (yellow)
R Ink cartridge S Stacker U Conveyance unit Pa Recording medium F Feeder unit

Claims (6)

Ink droplets can be ejected from the nozzles of a recording head in which a plurality of nozzles are arranged in a row, and the recording is performed based on recording data by the nozzle rows in which the nozzle rows are arranged in a direction perpendicular to the conveyance direction of the recording medium. In an inkjet recording apparatus that records an image including a barcode on a medium ,
When the recording data includes data for recording a barcode, the barcode arrangement direction with respect to the recording medium conveyance direction is a direction perpendicular to or parallel to the recording medium conveyance direction. Array direction discriminating means for discriminating whether or not
Control means for narrowing the width of the bar forming the bar code when the arrangement direction discriminating unit discriminates that the bar code arrangement direction is parallel to the transport direction of the recording medium . An ink jet recording apparatus.   The inkjet recording apparatus according to claim 1, wherein the control unit changes the recording data. 3. The ink jet recording apparatus according to claim 1 , wherein the control unit records a narrow width of the bar by reducing the number of times of ejecting the ink droplets . 4. 2. The bar according to claim 1, wherein the bar is formed by arranging the dots, and the control means records the width of the bar to be narrow by reducing the number of rows of dots. Item 4. The ink jet recording apparatus according to any one of Items 3 . The inkjet recording apparatus according to claim 1, wherein the barcode includes a customer barcode. Based on the recording data, a bar is placed on the recording medium by ejecting ink droplets from the nozzles of the recording head in which a plurality of nozzles are arranged in a row and the nozzle row arranged in a direction orthogonal to the conveyance direction of the recording medium. In an inkjet recording method comprising a step of recording an image including a code ,
When the recording data includes data for recording a barcode, the barcode arrangement direction with respect to the recording medium conveyance direction is a direction perpendicular to or parallel to the recording medium conveyance direction. An array direction determining step for determining whether or not
And a control step of recording a narrow width of the bar forming the bar code when the arrangement direction discriminating unit discriminates that the bar code arrangement direction is parallel to the conveyance direction of the recording medium . An ink jet recording method.

Images