JP2014054791A - Inkjet recording device and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording device capable of recording a bar code in which information can be read in high accuracy.SOLUTION: The inkjet recording device of the present invention, which can record a bar code on a recording medium, records a plurality of patches which have different densities, and reads each of the densities of the patches and a density of a non-recorded part in which ink is not applied on the recording medium. Based on the read densities of the patches and the density of the non-recorded part, the density of a plurality of bars which constitute the bar code is determined to be recorded in the determined density.

Description

  The present invention relates to an inkjet recording apparatus and an inkjet recording method capable of recording a barcode on a recording medium.

  An ink jet recording apparatus that performs recording by ejecting ink from a recording head can record high-definition images on various media. For this reason, inkjet recording apparatuses are often used not only for recording ordinary documents and images, but also for the purpose of recording shelf display labels, barcodes, tags, and the like. Since the bar code needs to be read by a bar code reader, it is important to increase the accuracy of the width of the black bar and the white bar in bar code recording. In particular, when the amount of information to be recorded within a predetermined barcode width increases, it is necessary to record each bar with high accuracy so that the reading rate does not decrease. In order to prevent the black bar of the bar code from becoming thicker due to ink bleeding etc., the barcode font table with the appropriate line width of the black bar and white bar is prepared to solve the decrease in the barcode reading rate. There is a recording device that does this.

  Further, when barcodes having the same line thickness (width) are recorded on a plurality of recording media, if the reflectance of light of each recording medium is different, there is a difference in the width of the barcode read by the reader. Arise. That is, the barcode recorded on the recording medium having a low light reflectance has a problem that the reading rate decreases because the reader reads the white bar thinner and the black bar thicker. On the other hand, Patent Document 1 discloses an ink jet recording apparatus that corrects and records the number of dots in the width direction of each black bar and white bar constituting a barcode in accordance with the light reflectance of a recording medium to be used. It is disclosed. According to this, a barcode composed of a black bar and a white bar having a width corresponding to the reflectance of the recording medium can be recorded.

JP 2006-323446 A

  However, in the inkjet recording apparatus, the width of the black bar and the white bar is adjusted by adjusting the number of dots in the width direction. For this reason, the adjustment amount with respect to a black bar and a white bar is too large, and there arises a problem that the bar width cannot be adjusted with high accuracy. In particular, in the case of a barcode having a small overall width, the adjustment of the bar width is performed in one line (in units, so the adjustment amount is large, the width cannot be adjusted with high accuracy, and the reading accuracy cannot be sufficiently improved. There is a problem.

  An object of the present invention is to provide an ink jet recording apparatus and an ink jet recording method capable of recording a barcode capable of reading information with high accuracy.

  In order to solve the above problems, an ink jet recording apparatus according to the present invention has the following configuration.

  That is, according to the first aspect of the present invention, a plurality of patches having different densities are provided in an ink jet recording apparatus that enables recording of a barcode including a plurality of dots by a recording unit that ejects ink on a recording medium based on recording data. Patch data supply means for supplying the recording means as patch data for forming the recording medium on the recording medium, the density of each patch formed on the recording medium, and ink applied in the recording medium A density of a plurality of bars constituting the bar code based on the density of each patch read by the reading means and the density of the non-recording portion. Determining means for determining, based on the patch data from the patch data supply means, the recording means Characterized by recording the plurality of bars at the concentrations determined me.

  According to the present invention, since the bar density of the barcode is changed based on the density of the recording part and the non-recording part in the recording medium, the bar width can be properly recognized by the reading unit, and the information can be accurately obtained. Can be recorded.

1 is a diagram illustrating a configuration of an ink jet recording apparatus according to an embodiment of the present invention. It is a block diagram which shows schematic structure of the control system of an inkjet recording device. It is a figure which shows an example of the structure of recording data. It is a figure which shows an example of the barcode recorded on the recording medium. It is explanatory drawing which shows the relationship between the bar width of a barcode, space width, and a nozzle pitch. It is a flowchart which shows the procedure of density | concentration acquisition of a black bar. It is a figure which shows an example of the test pattern for density | concentration measurement. It is explanatory drawing explaining bleeding of a recording dot. It is a flowchart which shows the procedure of correction parameter acquisition. It is a figure which shows an example of the test pattern for correction parameter acquisition. It is a flowchart which shows the procedure of the process from correction | amendment of barcode information to recording.

  Hereinafter, embodiments of an ink jet recording apparatus and a recording method according to the present invention will be described in detail with reference to the drawings. The following embodiments do not limit the invention according to the claims of the present application, and all the combinations of features described in the embodiments are not necessarily essential to the solution means of the present invention. Absent. In FIG. 1 to FIG. 11, the same reference numerals are assigned to the same components.

[Configuration of Inkjet Recording Apparatus]
FIG. 1 is a diagram illustrating a configuration of an ink jet recording apparatus according to the present embodiment. The ink jet recording apparatus 10 is connected to a host computer 12. The inkjet recording apparatus 10 records on the recording medium P by ejecting ink from each of the recording heads 22K, 22C, 22M, and 22Y based on the recording data transmitted from the host computer 12. Although four recording heads are shown in FIG. 1, recording heads corresponding to other inks such as special color inks may be further mounted.

  The four recording heads 22K, 22C, 22M, and 22Y are arranged in parallel along the conveyance direction of the recording medium P (the direction of arrow A in the figure). Each recording head is arranged in the order of the recording heads 22K, 22C, 22M, and 22Y from the upstream in the transport direction. Each recording head has a nozzle array in which ejection openings, which are openings of nozzles that eject ink, are arranged along a direction (direction orthogonal to the drawing) that intersects the conveyance direction of the recording medium. This nozzle array is a so-called line type recording head in which nozzles are arranged over a range longer than the maximum width of the recording medium to be used (maximum length in the direction orthogonal to the transport direction). The inkjet recording apparatus 10 conveys the recording medium P without moving each recording head, and performs recording by ejecting ink from each of a plurality of nozzles arranged in the recording head. Ink is discharged from each nozzle by driving a discharge energy generating element provided in each nozzle. In this embodiment, an electrothermal conversion element (heater) is used as the discharge energy generating element, but an electromechanical conversion element or the like can also be used as the discharge energy generating element.

  When recording is performed, foreign matters such as dust and ink droplets may adhere to the surfaces (discharge port surfaces) 22Ks, 22Cs, 22Ms, and 22Ys on which the discharge ports of each recording head are formed. In this case, the ink ejection state may change and affect recording. A recovery device 40 is configured in the ink jet recording apparatus 10 so that ink can be stably ejected from each recording head. Since the recovery device 40 periodically cleans each ejection port surface, the ink ejection state from the nozzles of each recording head can be maintained satisfactorily. The recovery device 40 is provided with a cap 50 for removing ink staying on each ejection port surface facing the ejection port surface of each recording head. The cap 50 is provided independently of each recording head, and includes a blade (not shown), an ink removing member, a blade holding member, a cap, and the like.

  The recording medium P, which is roll paper, is supplied from the roll paper supply unit 24 and is transported in the direction of arrow A by the transport mechanism 26. The transport mechanism 26 includes a transport belt 26a for placing and transporting the recording medium P, a transport motor 26b for rotating the transport belt 26a, and a roller 26c for applying tension to the transport belt 26a. . When the recording medium P being conveyed at the time of recording reaches the lower portion of the recording head 22K, black ink is ejected from the recording head 22K to the recording medium P based on the recording data transmitted from the host computer 12. Color recording is performed by ejecting each color ink onto the recording medium P in the order of the recording head 22C, the recording head 22M, and the recording head 22Y.

  The ink jet recording apparatus 10 includes ink tanks 28K, 28C, 28M, and 28Y that store ink to be supplied to each recording head, a pump for replenishing each recording head, a pump for performing a cleaning operation, and the like. Is included.

  FIG. 2 is a diagram showing the configuration of the control system. In FIG. 2, a controller 200 is a main control unit that controls the entire inkjet recording apparatus. For example, a CPU 201 in the form of a microcomputer, a ROM 202 that stores programs, required tables, and other fixed data, an area for developing recording data, A RAM 203 or the like provided with a work area or the like is included. The host computer 12 has a function as a recording data supply source. The host computer 12 takes the form of a computer or the like for creating and processing data such as an image related to recording, as well as an image reading apparatus. A reader unit or the like can also be applied, and recording data and other commands transmitted from here are transmitted to and received from the controller 200 via an interface (I / F). A head driver 204 and a motor driver 205D are connected to the output side of the controller 200.

  The head driver 204 is a driver that drives the discharge heaters of the recording heads 22K to 22Y according to the recording data. The head driver 204 is synchronized with a shift register that arranges print data corresponding to the position of the discharge heater, a latch circuit that latches print data output from the shift register, and a drive timing signal output from the latch circuit. In addition to a theoretical circuit element for operating the discharge heater, a timing setting unit for appropriately setting a drive timing for dot formation position alignment is provided. The motor driver 205D is a driver for driving the scanning motor 205.

  In the present embodiment, patch data and test pattern data, which will be described later, are stored in the host computer 12, but may be stored in the inkjet recording apparatus 10. Reference numeral 207 denotes a reading device (reading unit) that reads an image, a bar code, and the like recorded on a recording medium by a recording unit, and is configured by an imaging element such as a CCD.

[Structure of recorded data]
FIG. 3 is a diagram illustrating an example of a structure of recording data transmitted from the host computer 12. As shown in FIG. 3A, the recording data is largely composed of a start command 31, a content 35, and an end command 34. The start command 31 represents the recording setting contents for the entire recording area (for example, the entire document). In this example, the start command 31 includes, for example, an identification code for identifying a recording device, a recording reference position on the recording medium, an effective recording range in the recording medium, as shown in FIG. And the number of recorded sheets.

  The content 35 includes, for example, an attribute unit 32 for setting the type and position of each field such as an image or a character included in the document, and a data unit 33 for storing actual data representing recorded contents. . When the field type is a character (character), the attribute unit 32 includes an identification code, a font type, a character size, a character color, character decoration information, a character interval, as shown in FIG. Character rotation information is set. When the field type is an image (image), an identification code, a vertical and horizontal size, an image type, and a drawing color are set in the attribute unit 32.

  When the field type is a barcode, an identification code, a barcode type, a magnification, a barcode height, and barcode rotation information are set in the attribute unit 32. The inkjet recording apparatus 10 can recognize that the barcode information exists by referring to the attribute portion 32 of the recording data transmitted from the host computer 12. As shown in FIG. 3D, the data portion 33 includes a data length and data representing the contents.

  As shown in FIG. 3E, the end command 34 is composed of only an identification code to indicate the end of recorded data.

[Barcode configuration]
FIG. 4 is a diagram illustrating an example of a barcode recorded on a recording medium by the inkjet recording apparatus 10, (a) illustrates an example of a barcode recorded on the recording medium, and (b) illustrates a barcode. The recording state of the recording dots constituting the bar is schematically shown. In FIG. 4B, black circles indicate recording dots formed by landing of ink droplets, and a portion where the recording dots are formed becomes a recording portion. Further, for the sake of explanation, the white circle is described by virtually positioning the recording dot, and the portion with the white circle is a non-recording portion where ink droplets are not actually ejected. As shown in FIG. 5, the nozzle pitch of the recording head is strongly reflected in the bar width Lb and space width Ls of the barcode recorded by the inkjet recording apparatus 10.

FIG. 5 is a diagram for explaining the bar width Lb and the space width Ls of the bar code based on the nozzle pitch. As shown in FIG. 5, the general bar width Lb and space width Ls are calculated by the following formulas (1) and (2).
Lb = (nozzle pitch) × (number of dots−1) + dot diameter (1)
Ls = (nozzle pitch) × (number of dots + 1) −dot diameter (2)

  The bar code needs to satisfy certain conditions such as a certain standard and accuracy in order to be read accurately. That is, it is necessary that the ratio between the bar width Lb and the space width Ls constituting the barcode is within a certain standard range. In particular, when a small barcode is recorded, the error in the bar width has a greater influence on the ratio. Therefore, for a bar having a large difference between the bar width Lb and the space width Ls among the plurality of bars included in the barcode, the user sets the bar (black bar) width and the space (white bar) width on the host computer 12. To adjust the ratio to be within the standard range.

  As described above, the barcode reader recognizes the white bar width narrower than the actually recorded thickness as the light reflectance of the recording medium is lower, and the black bar width than the actually recorded thickness. Also tend to recognize thicker. That is, the width for recognizing the white bar and black bar of the barcode varies depending on the light reflectance of the recording medium. The lower the reflectance of the recording medium, the narrower the white bar and the wider the black bar. Tend to. This is because the barcode reader measures the barcode with black and white reflectance, the reflectance of the recording medium is low, and when the difference between the reflectance of the white bar and the black bar is small, the edge recognition of the bar is recognized. The reason is that it becomes dull and the black bar is read thickly.

[Black bar density setting]
FIG. 6 is a flowchart showing the density processing procedure for determining the density of the black bar in the present embodiment. In this flowchart, in step S <b> 101, the density measurement test pattern is recorded by the inkjet recording apparatus 10. In the present embodiment, as shown in FIG. 7, a density measurement test pattern having a plurality of patches whose densities are changed at predetermined intervals is recorded by the inkjet recording apparatus 10. Thereafter, in step S102, the recorded test pattern is read by a reading device such as a scanner. In this case, since the density of black is calculated from the reciprocal of the reading value of green (G), the reading device mode is selected from the three primary color (RGB) modes of red (R), green (G), and blue (B). .

  In step S103, an average value of the green (G) values of the recording medium of the image data read by the reading device and each patch is obtained, and the reciprocal thereof is calculated. The green (G) when the difference (density difference) between the light reflectance of the white bar as the non-recording portion and the black bar as the recording portion is 50 percent (%) of the reflectance (density) of the non-recording portion. ) Is the reciprocal of the read value. Further, a patch having a reciprocal value of the acquired recording medium and a difference value of each patch closest to the threshold is set as the density of the black bar.

  Further, in the inkjet recording apparatus 10, when recording a barcode, ink droplets land on the recording medium to form recording dots, as in the case of recording other images. At this time, when a plurality of dots that have landed on the recording medium are adjacent to each other, as shown in FIG. 8, a phenomenon occurs in which adjacent recording dots are connected to each other and bleed in a direction in which no ink exists. The bleeding distance varies depending on the width of the black bar to be formed.

  In addition, as shown in FIG. 8, the ink applied to the recording medium may permeate (bleed) in the direction parallel to the recording surface (enlargement direction), but may cross the recording surface. In some cases, the ink permeates in the direction of recording, that is, in the thickness direction of the recording medium. In this case, the area of the portion to which ink is applied (recording portion) on the recording surface is reduced, the width of each black bar of the barcode is reduced, and the width of the white bar is increased. .

  As described above, when the control for simply adjusting each bar width is performed in accordance with the light reflectance of the recording medium, the bar width fluctuates (increases or decreases) due to ink bleeding, and the bar width. There is a possibility that the ratio between Lb and space width Ls may be outside the standard range. Therefore, in the present embodiment, the black bar density is controlled based on the light reflectance of the recording medium, and correction processing is performed to correct the number of dots in the width direction of each bar according to the blur of the recording medium. Then, the barcode is recorded on the recording medium with the corrected recording data.

[Obtain barcode correction parameters]
FIG. 9 is a flowchart showing a procedure for acquiring correction parameters for correcting each bar width of the barcode in the present embodiment. In FIG. 9, first, in step S201, a correction parameter acquisition test pattern as shown in FIG. 10 is recorded. In the present embodiment, the correction parameter acquisition includes 35 black bars Bb having a width of 1 to 35 dots at predetermined intervals and a reference line Ir for knowing the position of the black bar of each width. The test pattern for recording is recorded by the inkjet recording apparatus 10. In addition, although the fluctuation range of the width of the black bar is 1 to 35 dots, it is not limited to this. Further, the recorded test pattern is read by a reading device such as a scanner. The resolution of the reading device needs to be at least the resolution of the recording density in order to obtain a bar that is thicker than the input image due to bleeding. Next, the read test pattern for obtaining correction parameters is analyzed, and the thickness of each black bar width is measured. The number and position of the width forming dots of each black bar are recognized by the distance from the reference line Ir. Finally, the width B of the black bar is obtained as a linear function of the number of dots forming the width (A).
B (thickness of black bar width) = a × A (number of width forming dots) + b (3)

  The slope a and intercept b of this linear function (3) are acquired as correction parameters.

  FIG. 11 is a flowchart showing a procedure for correcting the barcode and recording the barcode on the recording medium in the present embodiment.

  In FIG. 11, in step S <b> 301, data relating to the barcode as shown in FIG. 3, for example, data such as the type of barcode and the number of dots in the width direction of the reference bar are acquired. Also, the acquisition of the correction parameter information in step S302 is performed according to the flowchart shown in FIG. Thereafter, in step S303, the black bar width dot number design is performed as follows.

[Black bar width design]
The number of width dots for forming the black bar width of each ratio is calculated using the acquired correction parameter.
Black bar width = V x {(a x NB) + b} ..... Equation (4)
Black bar width dot count (N) = (Bar width-b) ÷ a
= {(a × V × NB) + b × (V-1)} ÷ a
= (V × NB) + {(b / a) (V-1) ..... Formula (5)
V: ratio, a: slope, b: intercept, NB: thinnest black bar width dot number

  Next, in step S304, the number of white bar width dots is designed as follows.

[White bar width design]
When the bar code is a black bar and a white bar, for example, a quaternary bar code such as EAN128, the bar width is 1: 2: 3: 4 with respect to the minimum bar width. It is defined in the standard to be. Also, it is necessary that the black bar and white bar of the same ratio are close in width. The difference between the black bar width calculated using the correction parameter and the black bar width of the input image is divided by the resolution to calculate the number of dots. Next, the white bar is sandwiched between the black bars at both ends, and tends to be thinner than the black bar of the same ratio due to the ink oozing from the black bars at both ends. Therefore, a state of a white bar having the lowest reflectivity is assumed to be sandwiched between black bars which are the thickest (ratio 4 in the case of a quaternary barcode and thick in the case of a binary barcode). The number of dots required for the white bar width in this state to be equal to the black bar width is calculated. The calculated blur amount of the black bar of the same ratio and the number of dots of the blur amount from the maximum bar are used as the correction amount and added to the number of dots of the black bar of the same ratio.
Number of blur dots in each ratio black bar = {(a × Bv + b)-(P × Bv)} ÷ (resolution)
= {a {(V × NB) + (V-1) (b / a)} + b -P {V × NB + (V-1) (b / a)}} ÷ (resolution)
= {(V × NB) (a -P) + (V × b) -P (V-1) (b / a)} ÷ (resolution) (6)
Maximum number of black bar bleeding dots = {(a x B _large + b)-(P x B _large )} / (resolution)
= {a {(4 × NB) +3 (b / a)} + b -P {4 × NB + 3 (b ÷ a)}} ÷ (resolution)
= {(4 × NB) (a -P) + (4 × b) -3P (b ÷ a)} ÷ (resolution) (7)
P: Distance between nozzle centers, B: Number of black bar width dots, B _large : Number of thickest bar width dots

  The number of dots in the width direction of each black bar and white bar of the generated barcode recording data is corrected based on the above equation (5), and the corrected recording data is transmitted to the recording apparatus 10. The recording apparatus records a barcode on the target recording medium based on the received recording data, and ends this process.

  Note that the host computer 12 performs all the operations shown in the above-described equations (1) to (7) and the determination processing and determination processing in the flowcharts shown in FIGS.

  By the way, in the above embodiment, the bar of the barcode is a black bar recorded in black. However, the bar of the barcode is not limited to being recorded with black ink, but may be recorded with ink of other colors. Is also possible. For example, in an ink jet recording apparatus having a recording head capable of ejecting inks of colors other than the four colors such as cyan, magenta, yellow, and black (for example, red, blue, and green), a bar is formed with any one of the special color inks. A code may be recorded. Further, even if the ink is provided with only four colors of ink such as cyan, magenta, yellow, and black, a color barcode can be formed by mixing two colors of cyan, magenta, and yellow. Also in this case, it is possible to apply the density setting process, the correction process, and the like of the present embodiment.

  In the above embodiment, the full-line type ink jet recording apparatus that performs recording by holding the recording head in a fixed position and moving only the recording medium has been described as an example. It is also applicable to the device. For example, the present invention can also be applied to a serial type ink jet recording apparatus that performs recording by scanning a recording head in a direction crossing the moving direction of the recording medium.

DESCRIPTION OF SYMBOLS 10 Inkjet recording device 22K, 22C, 22M, 22Y Recording head 22Ks, 22Cs, 22Ms, 22Ys Discharge port surface 201 Main controller 202 Memory 203Y, 203M, 203C, 203K Image memory 205 Recording head drive circuit

Claims (8)

In an inkjet recording apparatus that enables recording of a barcode composed of a plurality of dots by a recording unit that ejects ink on a recording medium based on recording data.
Patch data supply means for supplying patch data for forming a plurality of patches with different densities on the recording medium as recording data;
Reading means for reading the density of each patch formed on the recording medium and the density of a non-recording portion to which no ink is applied in the recording medium;
Determining means for determining the density of a plurality of bars constituting the barcode based on the density of each patch read by the reading means and the density of the non-recording portion;
With
The ink jet recording apparatus, wherein the recording unit records the plurality of bars at a density determined by the determination unit based on patch data from the patch data supply unit.   And a correction means for correcting the number of dots in the width direction of the bar and the number of dots in the width direction of a space formed between a plurality of adjacent bars according to the recording density of the bar. The ink jet recording apparatus according to claim 1.   The determining unit obtains a density difference between the non-recording portion and each patch, and determines a density of a patch having the density difference closest to a predetermined threshold as a density common to a plurality of bars constituting the barcode. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is an ink jet recording apparatus.   4. The ink jet recording apparatus according to claim 1, wherein the threshold value is set such that the density difference is 50% of the density of the non-recording portion. The correction means includes
Obtaining means for obtaining correction parameters corresponding to the type of the recording medium;
Using the correction parameter acquired by the acquisition means, calculating means for calculating the width of the bar and the width of the space;
The inkjet recording apparatus according to any one of claims 2 to 4, further comprising: The acquisition means includes
Test pattern data supplying means for supplying test pattern data for recording a bar with a plurality of different dot widths as recording data to the recording means;
Measuring means for measuring the width of each bar of the test pattern recorded on the recording medium by the recording means based on the test pattern data from the test pattern data supply means;
The number of dots in the width direction of each bar determined based on the test pattern data,
The inkjet recording apparatus according to claim 5, wherein the correction parameter is acquired from a correlation equation for obtaining a correlation with the width of the bar measured by the measuring unit. The calculation means is set at the time of recording so that the width of all bars of the barcode after recording is closest to a predetermined size based on the information on the type of barcode and the width of the reference bar. Bar calculation means for calculating the number of dots in the width direction of each bar;
Space calculation means for calculating the number of dots in the width direction of each space set at the time of recording so that the width of each space after recording is closest to the width of each bar after recording;
An ink jet recording apparatus according to claim 5 or 6, further comprising: In an inkjet recording method that enables recording of a barcode consisting of a plurality of dots by ejecting ink onto a recording medium based on the recording data,
A patch data supply step of forming a plurality of patches having different densities on the recording medium;
A reading step of reading the density of each patch formed on the recording medium and the density of a non-recording portion to which no ink is applied in the recording medium;
A determining step of determining the densities of a plurality of bars constituting the barcode based on the density of each patch read by the reading process and the density of the non-recording portion;
With
An ink jet recording method comprising: recording the plurality of bars at a density determined by the determination unit based on patch data from the patch data supply unit.