JP6553972B2 - Image adjustment method and apparatus by color measurement - Google Patents

Description

  The present invention draws a test pattern for adjusting the drawing position and measures the color to detect a shift in the drawing position on the paper, and automatically adjusts the drawing position based on this. The present invention relates to an image adjustment method and apparatus by color measurement.

Particularly in bidirectional printing of a color ink jet printer, an intended beautiful image cannot be obtained unless the ejected ink is correctly landed on a predetermined position on the paper even when drawing from either direction. Similarly, even in the case of one-way printing, if the ejected ink deviates from the predetermined position on the sheet, it is not possible to obtain the intended clear image.
For this reason, conventionally, a test pattern for adjustment is drawn, and the image is observed by visual observation or magnifying with a loupe, and the ejection position is adjusted. Also, an adjustment value is obtained by taking an image with a camera / scanner and measuring the amount of deviation of the adjustment pattern.
In addition, there is known an image forming position adjustment and a color image forming apparatus using the image forming position adjustment that can perform high-speed automatic adjustment of the image forming position only by printing the alignment pattern once and measuring its average density (for example, Patent Document 1).
Also, the K-color parallel bars with tilt correction are printed on the forward path side of the carriage, and the parallel bars of each color are shifted between the K-color parallel bars by different shift amounts for each block, and printed on the return path side of the carriage. An image recording position adjustment method for detecting the density of parallel bars printed by an optical detection means and correcting a color color reciprocal deviation is conventionally known (see, for example, Patent Document 2).
Color image formation position adjustment that detects the change in the density of the printed test print pattern for adjustment with a near-infrared regular reflection type toner density sensor and corrects the print conditions to match the print output conditions of the darkest patch An apparatus is conventionally known (see, for example, Patent Document 3).

JP 2008-309931 A Unexamined-Japanese-Patent No. 2003-39761 JP, 2002-148890, A

The method of adjusting the ink ejection position of the color image forming apparatus by measuring the shift amount of the adjustment pattern by visual observation or using a camera / scanner has a problem that it takes time for accuracy and measurement. In addition, the method of measuring the density of the test pattern and adjusting the ejection position is, for example, when the ejection position is deviated by increasing the density by covering the white portion of the paper with ink by deviating the ejection position. However, in the case where green is made using cyan and yellow, colors such as cyan, yellow, and green appear when they are shifted to either of them, and it is difficult to understand with the determination criterion of density. Therefore, there is a problem that it is difficult to accurately measure the deviation amount of the test pattern.
The present invention aims to solve the above problems.

In order to achieve the above object, according to the present invention, in a method for adjusting a drawing position in a scanning direction of a print head, a test pattern on which ink is superimposed is printed by a print head, and the printed test pattern is read by an optical device. It is characterized in that adjustment of the drawing position is performed based on the spectral difference and color difference appearing due to the deviation of the drawing position of the test pattern.
Further, the present invention is characterized in that the adjustment of the drawing position is performed based on the similarity of the measured value of the test pattern to the measured value of the printing medium (media).
Further, the present invention uses a spectrum value or a color measurement value as the measurement value, and the similarity is obtained by using a measurement value of the print medium (media) and a measurement value of a test pattern as a vector, and an angle between the vectors. It is characterized by being a cosine.
Further, the present invention uses a spectrum value or a color measurement value as the measurement value, and the similarity is a vector of the measurement value of the media and the measurement value of the test pattern, and the cosine value of the angle formed by the vectors is The drawing position is adjusted to be close to 1 or 1.
According to the invention, the optical device applies light emitted from the light source to the surface of the object to be measured from the opening of the case and guides reflected light reflected from the surface to the optical sensor from the opening to detect the reflected light. It is characterized by being a spectrophotometer.
In the invention, it is preferable that the test pattern has a horizontal width of at least 2 dots and is formed of vertical lines extending in a direction perpendicular to the horizontal width direction.
According to the present invention, a plurality of vertical lines of the test pattern are formed in the horizontal width direction of the vertical lines to form blocks, and the interval between adjacent blocks is configured to be one dot or several dots. It is characterized by
Further, the present invention is characterized in that the printing of the test pattern is completed by unidirectional printing in the main scanning direction across the printing medium (medium) with respect to the printing medium (medium) of the print head.
Further, the present invention is characterized in that the printing of the test pattern is completed by bidirectional printing in the main scanning direction across the printing medium (medium) with respect to the printing medium (medium) of the print head.
The present invention also moves the print head to the print medium (medium) in the main scanning direction across the print medium (media) and ejects ink from the print head to print dot unit information on the print medium (media). In a printer comprising a printing mechanism to be performed and a colorimeter for measuring the color of information printed on the printing medium, a computer or the controller connected to a controller of the printer,
Test pattern printing control for controlling the print head to print a test pattern in which a plurality of inks are overlapped by gradually changing the ink ejection position in the plus direction and the minus direction with reference to zero and printing the print medium (media) means,
Test pattern colorimetric means for controlling the colorimeter to measure the color of the test pattern;
Ink ejection position adjustment value generation means for generating an ink ejection position adjustment value based on a spectral difference or color difference of the test pattern appearing due to a displacement of the ink ejection position;
It is characterized in that it functions as
Further, the present invention is characterized in that the ink discharge position adjustment value generating means generates an ink discharge position adjustment value based on the similarity of the measured value of the test pattern to the measured value of the medium. is there.

  In the present invention, since the spectral difference and the color difference of the test pattern for adjusting the drawing position are measured using the colorimeter, the adjustment of the drawing position between the heads of different colors can be easily realized.

It is explanatory drawing of this invention. It is explanatory drawing of this invention. It is a graph which shows the spectrum of a test pattern. It is explanatory drawing of a test pattern. It is explanatory drawing of this invention. FIG. 1 is an external view of an inkjet printer. FIG. 1 is an external view of a part of an inkjet printer. It is explanatory drawing of a colorimeter. It is a graph which shows a spectral similarity. It is a graph which shows the spectrum of a test pattern. It is a graph which shows the spectrum of a test pattern. It is a graph which shows the spectrum of a test pattern. It is a graph which shows the spectrum of a test pattern. It is a graph which shows the spectrum of a test pattern. It is a graph which shows the spectrum of a test pattern. It is a graph which shows the spectrum of a test pattern. It is a graph which shows the spectrum of a test pattern. It is explanatory drawing of similarity. It is explanatory drawing of similarity. It is a graph which shows a spectrum transition. It is a graph which shows a spectrum transition. It is a graph which shows a spectrum transition.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 6 shows an overall schematic diagram of the inkjet printer. A printer 4 having a leg 1 includes a platen or other conveying path plate 8 that guides a printing medium (media) 6 such as paper in the printer body 3 in the front-rear direction (sub-scanning direction) of the body and an inkjet print head 10. A Y-axis rail 12 for guiding in the lateral direction (main scanning direction) is attached. A cover 14 for blocking the front of the Y-axis rail 12 is attached to the printer body 3 so as to be openable and closable.

  The cover 14 is normally closed, but to illustrate the inside of the cover 14, FIG. 6 shows the cover 14 in an open state. The controller of the inkjet printer 4 is connected to the computer 16, receives image data from the computer 16 via the input / output interface, ejects ink from the print head 10, and performs print processing on the print medium 6. The computer 16 generates original color image data to be printed out. A print head 10 having an ink discharge nozzle is movably attached to the Y-axis rail 12 supported horizontally to the floor surface of the printer 4 via a carriage.

  A drive roller and a pinch roller are disposed on the machine side of the printer 4, and the print medium (media) 6 on the transport path plate 8 is nipped by the drive roller and the plurality of pinch rollers during printing, and the drive roller rotates. Is configured to be conveyed in the sub-scanning direction. A maintenance box 18 is provided on a part of the machine body of the printer 4, and a control panel 18 a connected to the controller is disposed on an upper surface portion of the front surface of the box 18. Support can be provided from this control panel.

 A maintenance box 20 used for maintenance, management, and maintenance of the print head 10 is provided on the other side of the machine, the side facing the printing area being open, and the box 20 extends forward in the maintenance box 20. An openable cover 22 is provided. In the maintenance box 20, since the white reference color is read by the colorimeter 24, when the cover 22 is closed, the structure is such that light from the outside does not enter from the gap of the cover 22, etc. As a dark room, it has the function of providing a stable state.

  In the maintenance box 20, as shown in FIG. 7, a stand 26 is provided, and a plate holder 27 is fixed thereto. The plate holder 27 detachably holds a plate 28 having a white reference colored surface 28 a colored with a white reference color for reference calibration. The print head 10 can move a carriage to the Y-axis rail 12 so that it can move to the print area on the transport path plate 8, the print head standby non-print area in the maintenance box 18, and the non-print area in the maintenance box 20. It is supported through.

The print head 10 is provided with a colorimeter attachment portion, and a connector portion for detachably connecting to the connector portion of the colorimeter 24 is provided. Between the front face of the print head 10 and the colorimeter 24 there is provided a detachable coupling means consisting of a pin and a corresponding pin hole. The colorimeter 24 used as a sensor in the present embodiment is configured so that it can also be used as a manual colorimeter that can be operated by hand.

  The reading unit 24 a of the colorimeter 24 is provided with a circular opening 44 that receives reflected light from the object to be measured. The storage device of the computer 16 connected to the controller of the printer 4 stores a program capable of processing image data necessary for printing by the ink jet printer 4, creation of print data of a color ink test pattern, and color ink. A program for transmitting the print data of the test pattern, a program for adjusting the dot position, and the like are installed.

Next, the configuration of the colorimeter will be described with reference to FIG.
FIG. 8 is an explanation of the internal structure of the spectrophotometer used for the application of the colorimeter 24. In the present embodiment, a spectrophotometer is used as a colorimeter. A plurality of light sources 36 made of light emitting diodes (LEDs) are arranged on the circumference at equal intervals on a circuit board 34 on which circuits such as a CPU, a memory, an input / output interface, a driver, and a receiving circuit are formed. . The plurality of light sources 36 are arranged inside the cover 38 so as to protrude downward toward the object to be measured.

  Inside the light shielding partition 42 for blocking the light of the light source 36, the light reflected from the surface of the object to be measured is directed from the opening 44 of the cover 38 into the chamber of the cover 38 for focusing A geometry converter 48 with a filter constituting an optical path geometry converter designed to do is arranged. In addition, inside the light shielding partition 42, a detection unit 52 including an optical sensor, an etalon, and a face plate is disposed above the geometry converter 48, and electrically connected to the reception circuit of the circuit unit of the circuit board 34. doing.

The detection unit 52 is attached to the circuit board 34, and the geometry converter 48 is held by the light shielding partition 42. The opening 44 of the cover 38 is formed in a circular shape so that the measurement object from the light source can be uniformly applied to the object to be measured.
Next, an operation for automatically performing the ink discharge position adjustment by drawing a test pattern for ink discharge position adjustment and measuring the color will be described.

  Inside the printer 4 is provided an ink discharge position adjusting mechanism which can set the correction of the ink discharge position in a predetermined range in the plus direction and the minus direction with reference to zero. FIG. 4 shows a drawing example of the ejection position adjustment test pattern drawn on the print medium. For this drawing, either of a bidirectional drawing method along the main scanning direction by the print head 10 shown in FIG. 5A and a one-way drawing method shown in FIG. 5B can be adopted. .

(C) of FIG. 5A shows a state in which the discharge position of the ink K2 is shifted in the negative direction with respect to the ink droplet K1 in the forward scan in the backward scan of the bidirectional printing; c) shows a state in which the ejection position of the ink droplet K2 is shifted in the plus direction with respect to the ink droplet K1 in the ejection of the unidirectional drawing. FIGS. 5A and 5B show a state in which the ink droplets K1 and K2 are accurately overlapped and the ink discharge position is not shifted. In the present embodiment, a case where a bidirectional drawing method is employed will be described.

  FIG. 4 shows an example in which the test pattern 54 for adjusting the discharge position is sequentially drawn with n-stage adjustment values in the positive and negative directions with reference to zero. The ink ejection position adjustment test pattern 54 is drawn using a plurality of inks. As shown in FIG. 1, the test pattern for discharge position adjustment shown in FIG. 4 is composed of a plurality of thick vertical lines L extending in the sub scanning direction, and each vertical line L has a plurality of adjacent dots d1 with a plurality of horizontal widths. d5.

In FIG. 1, a thick vertical line L extending in the sub-scanning direction in which five dots d1 to d5 are arranged in the horizontal width direction is shown, but the vertical line L actually used is six dots or Thus, a suitable plurality of dots can be arranged.
The test pattern 54 for adjusting the ejection position performs reading including the entire range in which the positions where the ink is ejected and the positions where the ink is not ejected are alternately adjacent in the reading range corresponding to the opening 44 of the colorimeter 24.

Although the figure is written with an emphasized concept, the relationship between the actual ejection position adjustment test pattern 54 and the colorimeter opening 44 includes a large number of lines because the opening 44 is larger than the resolution of the printer. In order to read the range, a lot of components from a portion that is not concealed with ink of the print medium (medium) are included.

In FIG. 1, the vertical line L constituting the test pattern for adjusting the discharge position has a horizontal width consisting of a plurality of dots d1, d2, d3, d4, d5, and adjacent narrow lines extending in a direction perpendicular to the horizontal width direction. It is composed of lines L1, L2, L3, L4, and L5, and the distance between the vertical line L and the vertical line L adjacent to the vertical line L is set to 1 dot or more. Therefore, even when a deviation of one cycle occurs at the discharge position due to the forward scan and the backward scan of the print head 10, this shift can be detected.

However, in the case where the vertical lines constituting the test pattern are narrow lines with a width of 1 dot, and the line interval is 1 dot, the dot arrangement cycle is 1 dot. In such a case, if a deviation of one cycle for one dot occurs in the test pattern, adjacent vertical lines overlap, and in the case of the same color, it is impossible to detect dot misalignment. On the other hand, in the present embodiment, as shown in FIG. 1, the test pattern 54 is constituted by a thick line L of 2 dots or more, and the interval between the adjacent vertical lines L is 1 dot or more (2 in the embodiment). Since it is set to dot), even if there is a one-dot deviation between the vertical line L of the test pattern 54 drawn by forward scanning and the vertical line L drawn by backward scanning, this deviation is detected. Is possible.

In the case of the present embodiment, even if a shift of one cycle for one dot occurs, if there are two dots or more away, there is still a gap there, and there is no contact with the adjacent vertical line. Further, even in the case of one dot, the adjacent vertical lines can be distinguished because they are adjacent at portions different in color. The vertical line L (Y) of the test pattern is drawn with the ink of Y (yellow) shown in FIG. 2A in the forward scan, and the vertical line L (C of the test pattern with the ink of C (cyan) in the backward scan. C) (Cyan) and Y (Yellow) as shown in FIG. 2 (B) if the dots are drawn in such a way that the dots are in the ideal state if the dots are drawn in such a way that the dots are ideal A test pattern 54 (CY) that is accurately combined is drawn. However, when the adjustment is not completed completely, dots of C (cyan) and Y (yellow) do not overlap as shown in FIG. 2 (C).

The diagram on the left side of FIG. 2C shows the state of the test pattern 54 (CY) due to overcorrection in the minus direction. The diagram on the right side of FIG. 2C shows the state of the test pattern 54 (CY) due to overcorrection in the plus direction.
When the test pattern in such a state is measured, the characteristics of the spectrum of each ink appear in the obtained spectrum. The spectrum is shown in the graph in FIG.

  A curve a in the graph of FIG. 3 shows the spectrum of the yellow test pattern 54Y of FIG. 2, where the horizontal axis represents the wavelength (unit: nm) and the vertical axis represents the reflectance. The curve b of the graph shows the spectrum of the test pattern 54C of Cyan (cyan) in FIG. 2, and the curve C of the graph is a mixture of colors of yellow (yellow) and Cyan (cyan) dots shown in FIG. ) Of the test pattern 54 (CY).

Initially, this value is stored in advance in a memory or the like as a reference value. At this time, the combination of the wavelength and the reflectance constituting the spectrum is digitized and stored (hereinafter, this stored combination data is referred to as a spectrum value). On the other hand, the curve d of the graph is the spectrum of the test pattern 54 (CY) in which the dots of Cyan (cyan) and Yellow (yellow) ink are shifted.

The spectrum of the test pattern 54 (CY) in which the ink ejection position is shifted is shorter than the waveform of the spectrum of the curve C of the test pattern of Green (green), which is characteristic of each spectrum of Cyan (cyan) and Yellow (yellow). Since the high-wavelength and long-wavelength portions become obvious, the waveform level of the curve d of the test pattern 54 (CY) increases. Therefore, such a feature can be detected to generate a positional deviation adjustment value.

Specifically, first, based on the spectrum when there is no deviation between the Cyan (cyan) and Yellow (yellow) ink ejection positions, the ejection positions are shifted at regular intervals in the positive and negative directions within the adjustable range of the apparatus. In this case, a spectrum obtained by color measurement is treated as a spectrum value, and the relative relationship is stored in the apparatus as a parameter in association with positional deviation information at regular intervals. In other words, a plurality of combinations (data sets) of positional deviation information and spectral values are stored in the device. Then, in practice, a test pattern is printed and measured in order to confirm how much the print head deviates from the reference.

Next, the spectrum value obtained by measuring the test pattern is compared with each spectrum value stored in advance in the device (hereinafter, the spectrum value obtained by measuring the test pattern and the spectrum stored in advance in the device The difference from the value is called the spectral difference). Then, as a comparison result of a plurality of spectrum differences to be obtained, one having a spectrum difference of zero is selected, a data set associated with it is extracted, and displacement information (adjustment value) recorded in the data set is output. Then, the discharge position is corrected.

If there is no spectral difference of zero, the spectral difference is selected to be the smallest of the plurality of spectral differences. Then, a data set associated with it is extracted, positional deviation information (adjustment value) recorded in the data set is output, and the discharge position is corrected.

  Note that the color values to be measured may vary depending on the printing medium (media) used. Therefore, multiple spectral values and data sets are stored for each printing medium (media) to be used. The parameters may be changed depending on the medium. However, as with UV (ultraviolet curing) ink, when the ink is cured by every operation and has a feature that does not mix, the order of ink discharge (order of colors to be discharged) when drawing a test pattern is Since there is a possibility of greatly affecting the colorimetric result, the order in which the color is stored in the apparatus in advance and the order in which the test pattern is printed for adjusting the print head position need to be the same order.

  In FIG. 4A, one test pattern 54 corresponds to one adjustment value, but is not particularly limited to this configuration, and as shown in FIG. 4B, a plurality of test patterns 54 in the main scanning direction. The test pattern 54 may correspond to one adjustment value. In this case, when a plurality of test patterns are used, the average value of the measurement values is adopted as the corresponding adjustment value. FIG. 4B shows the case of three, but in the case of many cases such as ten, it is preferable to take an average value excluding the maximum value and the minimum value. The adjustment value is set to a value obtained by shifting the dot position in the positive and negative directions with respect to the non-adjustment position “0” on the basis of a unit that can be adjusted by the apparatus.

In FIG. 4, the hatched portion of the test pattern 54 and the portion separated by the opposite line indicate the displacement of the ink ejection position, and indicate that the non-overlapping ink color appears as it is at each end. For example, the adjustment value portion of “0” in FIG. 4 is an ideal situation in which the displacement of the ejection position is zero, but this state appears at the test pattern 54 of the adjustment value of +1. Since it is sufficient to adjust the adjustment value of to the state of adjustment value + 1, the discharge position is changed as such.

Next, an operation for measuring the color of the test pattern 54 printed on the print medium 6 will be described.
The colorimeter 24 for which the white reference adjustment has been completed is moved upward from the end of the test pattern in order, and the value is stored in a memory or the like in the reading device one by one.

The computer converts the measurement data of the colorimeter 24 into spectral values and stores individual values. Next, the program stored in the computer is compared with a reference parameter stored in advance based on the spectrum value stored in the memory, and it is determined which adjustment value has a displacement of the ejection position close to zero. Then, the value is used for adjusting the discharge position to correct the deviation of the ink discharge position, and the computer functions as an ink discharge position adjustment value generation unit that generates an ink discharge position adjustment value. Then, the value is used in subsequent printing by the printer. The reflection of the adjustment value to the printer may be automatically reflected, or may be displayed on a panel or a personal computer or the like and confirmed manually.

  In the present embodiment, digitization of color is realized using spectral values, that is, reflectance with respect to wavelength, but the present invention is not limited thereto. A Lab color system (or L * a * b * color system) expressed by lightness and chromaticity instead of a spectrum value may be used as a measured value, and an LCh table expressed by lightness and chroma as measured values. Other conventionally known color system indicators such as a color system (or L * C * h color system) can be used. In this case, the spectrum difference in the embodiment described above can be replaced with the name of color difference and applied.

The present invention is not particularly limited to the adjustment of the drawing position of the ink jet printer, and can be applied to an electrophotographic color image printer that transfers a color toner image onto a sheet.
In this specification, printing and printing are used in the same meaning.
Next, another embodiment of the drawing adjustment method using the similarity will be described with reference to FIGS.

First, in order to facilitate understanding of the present embodiment, the spectrum value and the similarity will be described.
The spectrum value is represented by a curve A connecting reflectances measured at n wavelength points as shown in FIG. In FIG. 18A, the horizontal axis represents wavelength points and the vertical axis represents reflectance. The numerical values of the n reflectances are written as follows.
A = (A1, A2, A3..., An-1, An)

In this way, A can be considered as one point in the n-dimensional space as shown in FIG. Since points can also be thought of as vectors, one spectrum points to one point in n-dimensional space and can be regarded as a vector passing through the origin.
FIG. 18 illustrates a case where n = 4 and A = (A1, A2, A3, A4) = (0, 5, 0, 6, 0, 5, 0, 8), and particularly FIG. B) shows a vector passing through the point A and the origin (0, 0, 0, 0) in the four-dimensional space.

Similarly, two spectral values correspond to two vectors in the same n-dimensional space. Here, when it is desired to find the closeness of the shape of a curve of two spectra, it is used that two spectral values are two vectors in an n-dimensional space. The fact that the shape of the spectrum value is close means that the angle between the two vectors is small with respect to the origin of the n-dimensional space, so that if the angle is obtained, the closeness of the spectrum value can be expressed. Become.

Here, it is possible to use an index called "similarity" used in statistical calculation and the like, and this "similarity" is used in this case. The degree of similarity is an extension to a n-dimensional space of a calculation for obtaining a cosine (COS) value of an angle between two vectors in a three-dimensional space as follows.
A = (A1, A2, A3,..., An-1, An),
B = (B1, B2, B3..., Bn−1, Bn)
When
Degree of similarity = A · B / | A || B | = Σ (Ak × Bk) / √ (ΣAk ² ) √ (ΣB
k ² )
It becomes. However,
A · B = Σ (Ak × Bk) = A1 × B1 + A2 × B2 + A3 × B3 +... + An−1 × Bn−1 + An × Bn
| A | = √ (ΣAk ² ) = √ (A1 ² + A2 ² + A3 ² +... + An−1 ² + A
n ² )
| B | = √ (ΣBk ² ) = √ (B1 ² + B2 ² + B3 ² +... + Bn-1 ² +
Bn ² )

This value takes a value of 0 to 1, indicating that 1 is the most similar, that is, the same, and 0 indicates the least similar (see FIG. 19). Therefore, the closer the value is to 1, the more similar.
In this embodiment, the basic idea is to determine that the color of the printed matter changes depending on the value of the adjustment position based on the difference in the spectrum value, and this idea is applied to the idea of similarity used in statistical calculations and the like. The degree of adjustment is determined from the similarity.

  20 to 22 are graphs of the spectrum transition of Black (Black), Blue (Blue), and Red (Red), and when the adjustment position is actually changed using the spectrum data used in the color difference determination. , How the spectrum value changes is expressed in a three-dimensional diagram. 20 to 22, the spectrum curve W indicates the spectrum value of the media. The X coordinate axis indicates the wavelength (nm), the Y axis indicates the adjustment position (μm), and the Z axis indicates the reflectance.

From these graphs, it can be seen that the shape of the spectrum when the adjustment position is matched has a slightly higher reflectivity than when it is not matched. This is because when it is correct, the reflectance from the print medium is increased. From a different point of view, it means that the reflectance is close to the spectral value of the print medium, although it is slight. The present embodiment utilizes this feature. Therefore, in the present embodiment, the difference between whether or not the spectrum value of the print medium (medium) is close or not is expressed by the similarity.

FIG. 10 shows the spectral value of the printed material of Red (red). In FIG. 10, the curve graph a is the spectral value of the print medium (medium), and the curve graph b is the spectral value of Red at the adjustment position 265 [μm]. The curve graph c shows the red spectral value at the adjustment position −265 [μm], and the curve graph d shows the red spectral value at the adjustment position 0 [μm]. 11 shows the spectrum of the printed matter of Blue, FIG. 12 shows Black, FIG. 13 shows Composite Black, FIG. 14 shows Cyan, FIG. 15 shows Green, FIG. 16 shows magenta (magenta) spectrum, and FIG. 17 shows yellow (yellow) spectrum values.

In each figure, the symbols a, b, c, and d are common. Each of these figures shows that the spectral value d at the adjustment position of 0 [μm] is close to the spectral value a of the media as compared with the adjustment positions −265 [μm] and 265 [μm]. When the adjustment position is adjusted to the correct position, the dots to be printed are arranged at the correct position, so that more light is reflected from the print medium (media) and the spectral value of the print medium (media) is Becomes closer, and when not adjusted correctly, the light reflected from the print medium (media) is less, so it deviates from the spectral value of the print medium (media).

In this embodiment, the similarity is used to determine the degree of closeness to the media spectrum value. The similarity takes a value of 0 to 1, and is close to 1 if similar, and close to 0 otherwise. That is, if the similarity is close to 1, it is close to the media spectrum value, close to the correct adjustment position, conversely close to 0, it can be determined that the adjustment position deviates from the media spectrum value.

FIG. 9 is a graph showing the change in similarity when the adjustment position is actually changed. In FIG. 9, the horizontal axis indicates the adjustment position (unit: μm), and the vertical axis indicates the spectral similarity. In FIG. 9, a is K (black), b is CompositeBlack (mixed black), c is Y (yellow), d is M (magenta), e is B (blue), f is G ( Green) and g are C (cyan), and h is a spectrum curve of each color of R (red). It can be clearly seen from the figure that the similarity is maximum when the adjustment position is near 0 [μm]. Based on these data, the controller of the computer or printer determines the vicinity of 0 [μm] as a correct adjustment position based on the drawing adjustment program. That is, the drawing adjustment method according to the present invention is to adjust the drawing position to the maximum value such that the degree of similarity is 1 or close to 1.
Here, the print medium (media) refers to paper, plastic sheet, cloth, cloth, and the like.

1 Leg 3 Machine 4 Printer 6 Print Media
8 Transport path board 10 Print head 12 Y-axis rail 14 Cover 16 Computer 18 Maintenance box 20 Maintenance box 22 Open / close cover 24 Colorimeter 26 Stand 28 Plate 34 Circuit board 36 Light source 38 Cover 42 Shading partition 44 Opening 48 Geometry converter 52 detection unit 54 test pattern

Claims (9)

In the method of adjusting the drawing position in the scanning direction of the print head, a test pattern in which ink is superimposed is printed by a print head, the printed test pattern is read by an optical device, and a spectrum that appears due to a shift in the drawing position of the read test pattern The drawing position is adjusted based on the difference or the color difference, and the drawing position is adjusted based on the similarity of the measured value of the test pattern to the measured value of the print medium (medium). Image adjustment method by colorimetry.   Spectral values and color measurement values are used as the measurement values, and the similarity is a cosine of an angle formed by the vectors formed by measuring the print medium (media) and the test pattern. The drawing adjustment method by colorimetry according to claim 1.   Spectral values and color measurement values are used as the measurement values, and the similarity is a vector of the media measurement value and the test pattern measurement value, and the cosine value of the angle formed by the vectors is close to 1 or 1. The method according to claim 1, wherein the adjustment of the drawing position is performed as follows.   The optical device applies light emitted from a light source to the surface of the object from the opening of the case, and guides the reflected light reflected from the surface to the light sensor from the opening to detect the reflected light. The drawing adjustment method by colorimetry according to claim 1, wherein:   2. The image adjustment method according to claim 1, wherein the test pattern has a horizontal width of at least two dots or more and includes vertical lines extending in a direction perpendicular to the horizontal width direction.   A plurality of vertical lines of the test pattern are formed in a horizontal width direction of the vertical lines to form blocks, and an interval between adjacent blocks is configured to be one dot or several dots. A drawing adjustment method by the color measurement according to claim 1.   2. The measurement according to claim 1, wherein the printing of the test pattern is completed by unidirectional printing in the main scanning direction across the printing medium (medium) with respect to the printing medium (medium) of the print head. Drawing adjustment method by color.   2. The colorimetric measurement according to claim 1, wherein the printing of the test pattern is completed by bidirectional printing in the main scanning direction across the printing medium (medium) with respect to the printing medium (medium) of the print head. The drawing adjustment method by. A printing mechanism that prints information in dot units on the print medium (media) by moving the print head in the main scanning direction across the print medium (media) relative to the print medium (media), and discharging ink from the print head; In a printer comprising a colorimeter for measuring the color of information printed on the print medium, a computer or the controller connected to a controller of the printer is provided.
Test pattern printing control for controlling the print head to print a test pattern in which a plurality of inks are overlapped by gradually changing the ink ejection position in the plus direction and the minus direction with reference to zero and printing the print medium (media) means,
Test pattern colorimetric means for controlling the colorimeter to measure the color of the test pattern;
Ink ejection position adjustment value generation means for generating an ink ejection position adjustment value based on a spectral difference or color difference of the test pattern appearing due to a displacement of the ink ejection position;
Function as
A drawing adjustment device by colorimetry, wherein the ink discharge position adjustment value generation unit generates an ink discharge position adjustment value based on a similarity of a measurement value of a test pattern to a measurement value of the medium.

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