JP4645941B2 - Printing apparatus and printing method - Google Patents

Description

  The present invention relates to an ink jet printing apparatus and printing method, and more particularly to a printing apparatus and printing method for forming an image on a film attached to the surface of an internally illuminated signboard.

  Internally-lit signboards often seen in towns are equipped with a light source such as a fluorescent lamp inside, and by the lighting effect from the light source, characters and figures etc. (signboard designs) on the signboard surface are made conspicuous (the signboard) The person who sees it).

  Usually, a viewer uses such signboard design (specifically, formed on a translucent film made of polyethylene terephthalate (PET) or the like affixed to the signboard surface) at the above-mentioned illumination. The effect is seen by the transmitted light from the internal light source, but in the daytime it is seen by the reflected light from sunlight. Since the fluorescent light generally used as the light source is different from the spectral characteristics of sunlight, the appearance of both is naturally different.

  For the above reasons, a signboard design that looks natural in the daytime (when viewed with reflected light) may appear unnatural at night (when viewed with transmitted light). For example, this can be said to be a level that does not cause much problem when a signboard design is configured using a cutting sheet or the like with poor color expression, but there is a problem that unnaturalness is prominent in photographs with abundant color expression. Arise.

  The above problem may be solved by adopting a light source (for example, a halogen lamp) having characteristics close to that of sunlight. However, this type of light source has many disadvantages such as difficulty in uniformly illuminating the signboard surface, and is not practical in terms of cost.

  Furthermore, even if the above light source (light source whose spectral characteristic is close to that of sunlight) can be adopted, the color development characteristics of ink differ between transmission and reflection, so when viewed with reflected light, it is natural to see with transmitted light. The unnatural problem cannot be solved.

  The present invention solves the above-mentioned conventional problems, and when an image (original image) formed (printed) on a film used by being attached to the surface of an internally illuminated signboard is viewed with reflected light (for example, It is an object of the present invention to provide a printing apparatus and a printing method that can eliminate a difference in appearance (gap) when viewed with transmitted light (for example, at night).

The printing apparatus according to the present invention is an ink jet printing apparatus, in which an original image is printed on one surface of a film, and the transmitted light is transmitted from the other surface side of the film toward the one surface side. In order to eliminate the difference between the appearance due to reflected light and the appearance due to reflected light reflecting the original image from one side of the film, the color development characteristics of the transmitted light of the original image is reflected from the measured color extracted from each color. Transmitted light correction characteristic with a correction value set based on the difference between the color development characteristic during transmission and the color development characteristic during transmission, and transmitted light correction using the transmitted light correction characteristic based on the input original image data And a transmitted light correction image data generation unit for generating image data for printing, and a transmitted light correction image is printed on the other surface of the film based on the transmitted light correction image data.

The printing method according to the present invention is an ink jet printing method, in which an original image is printed on one side of a film and transmitted through the original image from the other side of the film toward one side. In order to eliminate the difference between the appearance due to reflected light and the appearance due to reflected light reflecting the original image from one side of the film, the color development characteristics of the transmitted light of the original image is reflected from the measured color extracted from each color. Generate transmitted light correction image data based on the input original image data by using transmitted light correction characteristics that have correction values set to correct based on the difference between the color development characteristics during transmission and the color development characteristics during transmission A step of generating transmitted light correction image data, and printing the transmitted light correction image on the other surface of the film based on the transmitted light correction image data.

  According to the above-described configuration, it is possible to print a transmitted light correction image that corrects the ink coloring characteristics when the original printed image is light-transmitted to approach the ink coloring characteristics when light is reflected. Therefore, by the printing apparatus and the printing method having the above-described configuration, for example, an original image is printed on one surface and a transparent light correction image corresponding to the original image is printed on the other surface (back surface). If you use a film with a characteristic for an internally-illuminated signboard (specifically, if the original image is printed so that the print side of the signboard is on the front side, etc.) It is possible to make the viewer recognize the original image.

  Further, if the configuration further includes a light source characteristic profile in which characteristic information relating to the light source of transmitted light is set, and the transmitted light correction image data is generated with reference to the light source characteristic profile, transmission with higher accuracy is achieved. Light correction image data can be generated.

  The original image and the transmitted light correction image corresponding to the original image do not necessarily have to be printed on the same film (for example, they may be printed on different films, and the two prints may be used together) ), Adopting a configuration in which the printing of the original image and the printing of the transmitted light correction image are simultaneously performed, the controllability is improved, and the printing position accuracy of the original image and the transmitted light correcting image is improved.

  In addition, in the printing apparatus and the printing method of each configuration described above, an illumination unevenness profile in which illumination unevenness information related to a light source of transmitted light is set and a transmitted light amount characteristic created based on the transmitted light amount of each ink color are prepared in advance. Based on the original image data, the illumination unevenness profile and the transmitted light amount characteristics are used to generate transmitted light amount adjustment data, and predetermined illumination is ejected based on the transmitted light amount adjustment data, thereby preventing the illumination unevenness. A configuration for forming an ink film can also be added.

  When the film on which the ink film is formed by the printing apparatus and the printing method configured as described above is used for an internally illuminated signboard, uneven illumination can be reduced, and the visibility of the printed original image is further improved.

  Note that the predetermined ink corresponds to an ink (for example, white ink) that has a characteristic of blocking transmitted light without affecting the appearance of the original image with reflected light.

  As described above, according to the printing apparatus and the printing method of the present invention, a transmitted light correction image that eliminates the gap in appearance between when the printed original image is viewed with reflected light and when viewed with transmitted light is printed. For example, if a transparent film such as PET made by printing the original image and the transmitted light correction image is used for an internally illuminated signboard, the viewer can express natural colors day and night. The original image printed on the can be recognized. In addition, since an ink film that reduces illumination unevenness can be formed, the visibility of the printed original image is further improved by using the film on which the ink film is formed for an internally illuminated signboard.

  Hereinafter, a printing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

[First embodiment]
FIG. 1 is a schematic configuration diagram of a printing apparatus 1 according to the first embodiment of the present invention. The printing apparatus 1 of the present embodiment is an inkjet color printer, and ejects ink (droplets) of predetermined colors (in this embodiment, cyan (C), magenta (M), yellow (Y)), Original images (characters, figures, symbols, patterns, or combinations of these) are formed (printed) on the film F.

  The film F on which the original image is printed is used as a display function for an internally illuminated signboard installed outdoors. Specifically, it is affixed on the surface panel (portion through which light is transmitted) of the internally illuminated signboard with the A surface as the surface. A viewer who sees such an internally illuminated signboard generally recognizes the original image printed on the A side by reflected light from sunlight in the daytime (FIG. 2 (A)), and at night. This is recognized by the transmitted light from an internal light source (for example, a fluorescent lamp) (FIG. 2 (b)).

  Of course, the film F can be printed appropriately, and since it has the above uses, it is required to have transparency, durability (water resistance, heat resistance) and the like. A film made of polyethylene terephthalate (PET) is exemplified as a material that satisfies these requirements.

  The printing apparatus 1 can be roughly classified into a processing unit A that prints on the A side of the film F and a processing unit B that prints on the B side. Although not shown, the printing apparatus 1 also includes a control unit such as a CPU that controls the entire apparatus including the processing unit A and the processing unit B.

  The processing unit A includes a head unit 2 configured by inkjet heads 2C, 2M, and 2Y of each color (C (cyan), M (magenta), and Y (yellow)) having a plurality of nozzles that eject ink. Using the LUT (look-up table) 1, the driver 3 that performs ink ejection control of the heads 2C, 2M, and 2Y and the original image data (RGB data) of the image (original image) to be printed on the A side are printed. It has a color data conversion unit 4 that converts image data (CMY data).

In the LUT 1, CMY data corresponding to RGB data is set in advance for the entire range (for example, 0 to 2 ²⁴ ) that the RGB data can take. Therefore, the color data conversion unit 4 can basically acquire CMY data for A-side printing only by referring to the LUT 1 (that is, without complicated calculations). Note that both the original image data and the LUT 1 are generally developed and used in a semiconductor memory such as a RAM (not shown). However, since the LUT 1 requires high-speed access, an SRAM (Static RAM) or the like is required. It is desirable to deploy to high-speed memory.

  The above function of the processing unit A may be considered as a general function of a conventional ink jet printer. Next, the configuration and function of the processing unit B, which is a characteristic part of the printing apparatus 1 according to this embodiment of the present invention, will be described.

  The processing unit B includes a head unit 5 having three color (C, M, Y) inkjet heads 5C, 5M, and 5Y having a plurality of ink ejection nozzles, and a driver that controls ink ejection of the head unit 5. 6. Transmitted light from the original image data using the color data converter 7 for converting the transmitted light correction image data (RGB data) into CMY data for printing using the LUT 2 and the light source characteristic profile and transmitted light correction table. It has a transmitted light correction image data generation unit 8 for generating correction image data.

  The LUT 2 is a table in which CMY data corresponding to RGB data is set in advance as in the LUT 1 and is developed in a semiconductor memory such as a RAM (SRAM is desirable) and used in the color data conversion unit 7. The difference between LUT1 and LUT2 is basically due to the difference in the characteristics of the head units 2 and 5. Therefore, when the characteristics of both are the same, the contents of LUT1 and LUT2 are also the same. In such a case, only one of the tables (for example, LUT1) can be used in combination.

  The transmitted light correction image data generated by the transmitted light correction image data generation unit 8 is RGB image data of an image printed on the B surface of the film F (transmitted light correction image). The purpose of printing such a transmitted light correction image on the B side of the film F is to correct the color development characteristic of the image printed on the A side (original image) by the transmitted light so that it approximates the color development characteristic of the reflected light. It is. In other words, it can be said that the purpose is to eliminate the difference (gap) between the appearance of the original image by reflected light and the appearance of transmitted light.

  In order to generate transmitted light correction image data from original image data, a transmitted light correction table and a light source characteristic profile are used. The transmitted light correction table (transmitted light correction characteristics) is a kind in which correction values corresponding to each color (R, G, B corresponding to each ink color of the inkjet heads 2C, 2M, 2Y in this embodiment) are set. LUT. The correction value derivation method will be described in detail. For the sample color extracted from each ink color (C, M, Y), the color development characteristics during reflection and the color development characteristics during transmission are actually measured by a colorimeter. (Specifically, a stimulus value (X, Y, Z) for the viewer to feel color is measured using a sensor having color sensitivity characteristics similar to that of the human (viewer) eyes) Find the correction value to absorb the gap. Correction values other than the measurement color are obtained by regression analysis (linear interpolation) based on each measurement result.

  The light source characteristic profile is a file (also referred to as a kind of LUT) in which the light source characteristics of an internally illuminated signboard using the film F are described in RGB. Specifically, the characteristics of a light source (for example, a fluorescent lamp) used in the internally illuminated signboard are measured in advance using a colorimeter (for example, a luminance sensor, an RGB sensor, etc.), and each color is measured from sunlight. A color balance deviation is set. Such a light source characteristic profile is prepared for each type of light source, and can be selected and used.

  The transmitted light correction table and the light source characteristic profile are developed and used in a semiconductor memory such as a RAM (a high-speed memory such as an SRAM if necessary).

  The transmitted light correction image data generation unit 8 refers to the transmitted light correction table and the light source characteristic profile for each pixel of the original image data using the RGB data as a key, and acquires the corresponding correction value and light source characteristic value. The transmitted light correction image data is generated by multiplying them.

  The color data conversion unit 7 converts the generated transmitted light correction image data into CMY data for printing by referring to the LUT 2. Then, based on the CMY data, the driver 6 controls the ejection of the ink jet heads 5C, 5M, and 5Y of the head unit 5 so that the transmitted light correction image is printed on the print B surface.

  Note that the same timing signal is input to the driver 3 and the driver 6 to synchronize the scanning timing of the head units 2 and 5 and the timing of ink ejection from each inkjet head. Therefore, the printing of the A side and the B side proceeds simultaneously, and it is possible to precisely align the A side print image (original image) and the B side print image (transmission light correction image).

  As described above, by printing the transmitted light correction image corresponding to the original image printed on the A surface on the B surface, the color development characteristic due to the transmitted light of the original image can be corrected. As a result, the reflected light of the original image can be corrected. The gap between the appearance due to and the appearance due to transmitted light can be eliminated.

[Second Embodiment]
FIG. 3 is a schematic configuration diagram of the printing apparatus 10 according to the second embodiment of the present invention. In addition to satisfying the configuration of the printing apparatus 1 of the first embodiment, the printing apparatus 10 has a configuration of a processing unit C described later. Hereinafter, the function of the processing unit C will be mainly described.

  The processing unit C uses the inkjet head 11 having a plurality of nozzles for ejecting the transmitted light amount adjustment ink, the driver 12 that performs ink ejection control of the inkjet head 11, the illumination unevenness profile, and the transmitted light amount adjustment table, as an original image. A transmitted light amount adjustment data generation unit 13 that generates transmitted light amount adjustment data from the data is provided.

  In the present embodiment, the transmitted light amount adjustment ink is white ink that looks white when reflected, but has a characteristic of blocking transmitted light.

  The illumination unevenness profile is a file (also referred to as a kind of LUT) in which illumination unevenness information regarding an internally illuminated signboard in which the film F is used is set. Specifically, a difference from the average transmitted light amount is set for each coordinate (pixel) of the print area. The average amount of transmitted light is derived in advance based on the measurement result obtained by measuring the amount of light transmitted through the signboard surface panel (more specifically, the portion where the film F is attached) during internal illumination.

  In the transmitted light amount adjustment table (transmitted light amount characteristics), the transmitted light amount adjustment value corresponding to each color (R, G, B corresponding to each ink color of the inkjet heads 2C, 2M, 2Y in this embodiment) is set. It is a kind of LUT. The adjustment value will be described in detail. First, representative colors of each ink color (C, M, Y) are selected, and the amount of transmitted light is actually measured for these ink colors. As for the transmitted light amount of other ink colors, the transmitted light amount is obtained by regression analysis (linear interpolation) or the like based on the measurement result, and the average transmitted light amount is obtained from these results. The difference between the average transmitted light amount and the transmitted light amount of each ink color is the adjustment value for each ink color. Based on such adjustment values, by adjusting the amount of transmitted light by ejecting white ink to the pixel position of each ink color that forms the original image, the difference in the amount of transmitted light for each ink type can be absorbed. Therefore, it is possible to reduce illumination unevenness and display a more preferable image.

  The illumination unevenness profile and the transmitted light amount adjustment table are developed and used in a semiconductor memory such as a RAM (a high-speed memory such as an SRAM if necessary).

  The transmitted light amount adjustment data generation unit 13 refers to the illumination unevenness profile for each pixel of the original image data, acquires the illumination unevenness information of the corresponding pixel, and uses the RGB data of the corresponding pixel as a key to create the transmitted light amount adjustment table. Refer to and obtain the corresponding adjustment value. Then, the transmitted light amount adjustment data is generated by adding them. Here, the transmitted light amount adjustment data is specifically the discharge amount of the white ink in the corresponding pixel.

  Further, the transmitted light amount adjustment data generation unit 13 searches for a pixel having the smallest transmitted light amount in the transmission light amount adjustment data generation, and performs adjustment based on the pixel. By adjusting in this way, it is possible to generate transmitted light amount adjustment data so that the transmitted light amount of the entire film F is maximized (in other words, the entire transmitted light amount is not reduced unnecessarily). .

  As described above, according to the printing apparatus 10 of the present embodiment, ejection control is performed so that the amount of transmitted light of the film F is substantially uniform with no influence at the time of reflection and ink having the characteristic of blocking transmitted light (white ink). By doing so, an ink film of the ink applied to the film F is formed. When a film on which such an ink film is formed is used for an internally illuminated signboard, uneven illumination can be reduced, so that the visibility of the printed original image can be improved.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention.

  For example, in the first embodiment, the printing of the A side and the B side is performed at the same time. However, the embodiment of the present invention is not limited to this, and only the transmitted light correction image can be printed alone.

  Further, the original image and the corresponding transmitted light correction image are not necessarily printed on the same film, and may be printed on different films. In this case, the same effect as in the above embodiment can be obtained by pasting both prints together.

  In addition, the inkjet head 11 in the second embodiment may be configured to eject ink onto the B surface, which is the back surface, instead of ejecting ink onto the A surface (original image print surface).

  In addition to the transmitted light correction table, which is a kind of LUT as in the above embodiment, the transmitted light correction characteristics may be embodied by a predetermined calculation formula derived based on the measurement result, for example. Good. Similarly, the transmitted light amount characteristic may be embodied by a predetermined calculation formula or the like.

1 is a schematic configuration diagram of a printing apparatus according to a first embodiment of the present invention. 5A and 5B are diagrams illustrating a difference between day and night when an image printed by the printing apparatus according to the embodiment is viewed, in which (a) illustrates the daytime and (b) illustrates the night view. It is a schematic block diagram of the printing apparatus which concerns on 2nd embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,10 ... Printing apparatus, 2, 5 ... Head unit, 2C, 2M, 2Y, 5C, 5M, 5Y, 11 ... Inkjet head, 3, 6, 12 ... Driver, 4, 7 ... Color data converter, 8 ... Transmitted light correction image data generation unit, 13... Transmitted light amount adjustment data generation unit

Claims (8)

An inkjet printing apparatus,
The original image is printed on one side of the film, and the original image is reflected from one side of the film, and the way the light is transmitted through the original image from the other side of the film toward the one side. In order to eliminate differences in appearance due to reflected light, the color development characteristics of the original image transmitted by light are corrected based on the difference between the color development characteristics during reflection and the color development characteristics during transmission of the measured color extracted from each color. Transmitted light correction characteristics with correction values set,
A transmitted light correction image data generation unit that generates transmitted light correction image data using the transmitted light correction characteristics based on the input original image data;
A printing apparatus for printing a transmitted light correction image on the other surface of the film based on the transmitted light correction image data. A light source characteristic profile in which characteristic information related to the light source of transmitted light is set;
The printing apparatus according to claim 1, wherein the transmitted light correction image data generation unit generates the transmitted light correction image data with reference to the light source characteristic profile.   The printing apparatus according to claim 1, wherein the printing of the original image and the printing of the transmitted light correction image are performed simultaneously. Illumination unevenness profile in which illumination unevenness information relating to the light source of transmitted light is set;
A transmitted light amount characteristic created based on the transmitted light amount of each ink color;
A transmitted light amount adjustment data generating unit that generates transmitted light amount adjustment data using the uneven illumination profile and the transmitted light amount characteristic based on the original image data;
The printing apparatus according to claim 1, wherein an ink film that prevents the illumination unevenness is formed by ejecting predetermined ink based on the transmitted light amount adjustment data. An inkjet printing method,
The original image is printed on one side of the film, and the original image is reflected from one side of the film, and the way the light is transmitted through the original image from the other side of the film toward the one side. In order to eliminate differences in appearance due to reflected light, the color development characteristics of the original image transmitted by light are corrected based on the difference between the color development characteristics during reflection and the color development characteristics during transmission of the measured color extracted from each color. A transmitted light correction image data generation step for generating transmitted light correction image data based on the input original image data by using the transmitted light correction characteristic in which the correction value is set;
A printing method comprising printing a transmitted light correction image on the other surface of the film based on the transmitted light correction image data. In the transmitted light correction image data generation step,
6. The printing method according to claim 5, wherein the transmitted light correction image data is generated by further referring to a light source characteristic profile in which characteristic information relating to a light source of transmitted light is set.   7. The printing method according to claim 5, wherein printing of the original image and printing of the transmitted light correction image are performed simultaneously. By using the illumination unevenness profile in which the illumination unevenness information related to the transmitted light source is set and the transmitted light amount characteristic created based on the transmitted light amount of each ink color, the transmitted light amount adjustment data is obtained based on the original image data. A transmission light amount adjustment data generation step to generate,
The printing method according to claim 5, wherein an ink film that prevents the illumination unevenness is formed by ejecting predetermined ink based on the transmitted light amount adjustment data.

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