JP2007292776A - Display board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of appearance of a display board caused by generation of gloss irregularities resulting from irregular reflection on the ink surface, concerning the display board formed by printing an image on the surface side of a resin substrate, by printing an ultraviolet curing ink by an ink jet method on the surface of the translucent resin substrate. <P>SOLUTION: The first black ink layer 6a, a blue ink layer 4a and a gray ink layer 5a are printed on the surface 7a of the resin substrate 7, and the second black ink layer 6b, the third black ink layer 6c and a white ink layer 9 are printed in due order in piles on the first black ink layer 6a, to thereby form a blue translucent part 4, a gray translucent part 5 and a black opaque part 6. Thereafter, a radical polymerization type UV clear to which acrylic beads, urethane beads, silicone beads or the like having the average particle size of 10-30 μm is over-coated on the ink layers. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a display panel of a display device, and is particularly suitable for use as an instrument panel of an instrument mounted on a vehicle such as an automobile.

  Conventionally, as a display device, there is a vehicle display device (vehicle instrument) equipped in a vehicle such as an automobile. In general, a display device for a vehicle includes an instrument panel (display panel) and a light source disposed on the back side of the instrument panel. The instrument panel has a design portion composed of scales, letters, and the like. And the part except the scale of a design part and a character is comprised by the opaque part which does not permeate | transmit light, for example, and the part of a scale and a character is comprised by the permeation | transmission part which permeate | transmits light. Thus, for example, at night, the instrument panel is illuminated with a light source, whereby the letters and scales on the instrument panel are displayed brightly.

  Here, the instrument panel is usually manufactured by printing a non-transparent portion (solid concealed image portion) on the surface of a resin transparent substrate such as polycarbonate, for example, by screen printing. In this screen printing, a screen (plate) on which a print image is drawn is produced from print data, and ink is printed on the substrate through this screen. Printing is performed at a time so that the print density of the non-transparent portion is increased. There is an advantage that you can.

  By the way, as a printing technique, there are digital printing techniques such as a laser printer electrophotographic system, a thermal transfer system, and an ink jet system as used in other fields such as the OA printer field in addition to the screen printing method. Since these can be directly drawn without producing a plate from print data, they are more suitable than screen printing in printing a small lot.

  Among such digital printing technologies, the ink jet method is a method of printing by spraying ink from electronically controlled head nozzles, and the device mechanism has a simple configuration, and the initial cost is low. Due to its high resolution, it is rapidly spreading in the field of OA printers.

  When manufacturing an instrument panel by screen printing as described above, there are the following problems. That is, since there are various types of vehicle instruments, displacements, grades, and the like for vehicle instruments, there are a wide variety of instrument panels and printed contents that are different from each other. For this reason, the screen printing method, which is a large-scale printing method, has a problem in that plate replacement, ink replacement, setting of conditions, etc. are required every time the instrument panel type is different.

  Further, the number of instrument panel lots is not a large number of copies as in paper printing, and as described above, even though the instrument panel is the same vehicle type, the design differs depending on the grade and the like, so the number is actually small. For this reason, a small number of instrument panel lots naturally rebounds on manufacturing costs. That is, when the instrument panel is manufactured by screen printing, the manufacturing cost is high. In particular, a very small amount of products such as prototypes and replenishment products are accompanied by plate making and printing plate production, resulting in problems such as higher manufacturing costs and longer production time.

  Therefore, as a countermeasure method for this problem, a method of manufacturing an instrument panel by printing using the above-described ink jet method can be considered.

  However, when the inkjet method used for printing in other fields is simply adopted for the production of instrument panels, there are the following problems.

  In the manufacture of an instrument panel, a transparent resin material such as polycarbonate or PET is generally used as a base material for the instrument panel. This is because the substrate is required to have light transmittance and heat resistance. In general, the ink used in the inkjet method includes water-based ink and solvent-based ink. This solvent-based ink is used for signage and the like, and is a long-life type ink.

  When printing is performed on a transparent resin substrate by an inkjet method using these inks, in the case of water-based ink, the above-described resin substrate is hydrophobic, so that the ink is repelled. In this case, the ink droplet on the substrate surface spreads out and overlaps with the adjacent ink droplet, thereby degrading the image quality. In addition, solvent-based inks also cause inconveniences such as repelling and melting and deforming the resin substrate.

  In general, printing paper or the like used for printing in the field of OA printers has a dedicated ink receiving layer and is designed with an emphasis on affinity with water. Therefore, when printing on a transparent resin substrate by an ink jet method using water-based ink, a method of preventing the image quality of a printed image from being deteriorated by providing an ink receiving layer on the transparent resin substrate can be considered.

  However, since the ink receiving layer has a high affinity with water, whitening and peeling due to moisture absorption occur in a high humidity environment, and image quality maintenance and durability cannot be achieved at all. For this reason, in particular, in a vehicle instrument, it is not suitable to provide an ink receiving layer on the instrument panel of a vehicle instrument because the interior of the vehicle becomes humid during rainy weather.

  Therefore, when printing is performed on a material that does not soak in ink, such as a resin substrate, by the inkjet method, ink droplets applied to the substrate surface spread and mix with adjacent droplets. It is necessary to prevent bleeding (roughness of image quality). In such a case, it is necessary to firmly adhere an ink having a high color density onto the substrate.

  Therefore, the present inventors paid attention to an ultraviolet curable ink (hereinafter referred to as UV ink) as an ink used when an instrument panel is manufactured by printing by an inkjet method.

  This UV ink has a property of being cured when ultraviolet light is irradiated to the liquid ink. Therefore, when UV ink is used, printing is performed as follows. The UV ink is liquefied and ink droplets are landed on a transparent resin substrate by an ink jet method. Then, the ink is cured by irradiating the ink droplets landed on the substrate with ultraviolet rays.

  As a result of investigations by the present inventors, by shortening the time from the landing of the ink droplet to the irradiation of ultraviolet rays, the ink droplet is prevented from spreading on the substrate and deteriorating the image quality. I found out that I could do it. It has also been found that ink having a high color density can be firmly adhered to the substrate.

  In addition, since the ink jet method using UV ink can solidify the ink by ultraviolet irradiation as described above, it is necessary to dry the ink when water-based ink or solvent ink is used as the ink. There is an advantage that you can.

  By the way, according to the study by the present inventors, it was confirmed that an instrument panel can be manufactured by printing by an ink jet method using UV ink, as described above, but another problem described below occurred.

That is, when the ink layer is formed on the main surface on the side where the resin substrate is visually recognized by printing by the ink jet method using UV ink, if unevenness of the thickness of the ink jet ink layer occurs, Since it appears to have uneven gloss, it does not look good .

In view of the above points, the present invention provides a display board in which an ultraviolet curable ink is printed on a surface of a light-transmitting resin substrate by an inkjet method to print an image on the surface side of the resin substrate. An object is to suppress the appearance of the display panel from being deteriorated due to uneven gloss caused by irregular reflection of the surface.

In order to achieve the above object, in the present invention, an ultraviolet curable ink is attached to the surface (7a) of the translucent resin substrate (7) by an inkjet method, and then the ink is irradiated with ultraviolet rays. A display board obtained by printing an image on the resin substrate (7) using a printing method for curing the ink, wherein an ultraviolet curable clear is overcoated on the surface of the image. It is said.

Accordingly, since the image is visually recognized through the ultraviolet curable clear, the uneven thickness of the ink layer can be alleviated, and the uneven gloss due to the uneven thickness of the ink layer can be made inconspicuous.

As the ultraviolet curable clear, for example, a radical polymerization type to which at least one of acrylic beads, urethane beads, and silicone beads having an average particle diameter of 10 to 30 μm is added can be employed.

  In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

(First embodiment)
FIG. 1 is a front view of a display panel according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA ′ of the display panel in FIG. In the present embodiment, the manufacture of an instrument panel (meter dial) of a vehicle instrument will be described as an example.

  As shown in FIG. 2, the vehicle instrument includes an instrument panel 1 as a display board and a light source 2 such as an LED disposed on the back side of the instrument board 1. As shown in FIG. 1, the instrument panel 1 includes a design having a transparent light transmitting portion 3, a blue light transmitting portion 4, a gray light transmitting portion (smoke portion) 5, and a black opaque portion 6. ing. The blue translucent part 4 and the gray translucent part 5 correspond to the colored translucent part of the present invention, and the transparent translucent part 3, the blue translucent part 4 and the gray translucent part 5 correspond to the translucent part of the present invention. .

  The transparent translucent part 3 is a transparent part that transmits light, and constitutes a scale and characters. The blue light-transmitting portion 4 is a blue portion that transmits light, and is a display portion that displays the indication direction of the direction indicator. The gray light transmitting portion 5 is a gray (or black) portion that transmits light and is a display portion that indicates a shift position. The black impervious portion 6 is a black portion that does not transmit light, and is a scale or a background portion of characters.

  As shown in FIG. 2, the instrument panel 1 includes a transparent resin substrate 7, a surface matte layer 8 printed on the main surface (front surface) 7 a of the resin substrate 7, and a back surface 7 b of the resin substrate 7. Each of the ink layers 4a, 5a, 6a, 6b, 6c, and 9 is printed. In addition, the main surface 7a of the resin substrate 7 is a surface on the side visually recognized by the driver, and the back surface 7b is a surface on the opposite side.

  The resin substrate 7 is made of a transparent resin such as polycarbonate or PET. The surface matting layer 8 is for matting caused by external light on the main surface 7a of the resin substrate 7, and is made of a general matting material.

  Each of the ink layers 4a, 5a, 6a, 6b, 6c, and 9 constitutes the blue light-transmitting portion 4, the gray light-transmitting portion 5, and the black non-transmitting portion 6, and is made of UV ink.

  Specifically, the black opaque portion 6 includes a first black ink layer (first layer) 6a, a second black ink layer (second layer) 6b, and a third black ink layer (third layer) from the substrate side. 6c and white ink layer (fourth layer) 9 are laminated. That is, the black opaque part 6 is composed of three black ink layers 6 a to 6 c and one white ink layer 9.

  The first black ink layer 6a is a colored layer that is visually recognized by the driver, and mainly constitutes the outline of the black opaque portion 6 and is an ink layer for finishing the design. The second black ink layer 6b and the third black ink layer 6c are ink layers for increasing the density of black. The reason why the black opaque portion 6 is constituted by the three black ink layers 6a to 6c is that the black ink layer 6a alone is not sufficient to shield light. The three black ink layers 6a to 6c have different resolutions as will be described later.

  The white ink layer 9 is an ink layer for diffusing light from the light source 2.

  The blue light transmitting portion 4 is composed of one blue ink layer 4a, and the gray light transmitting portion 5 is composed of one gray ink layer 5a. In addition, the transparent translucent part 3 is a site | part in which each ink layer 4a, 5a, 6a, 6b, 6c, 9 is not printed among the transparent resin substrates 7. FIG.

  3A and 3B, among the three black ink layers 6a to 6c and the white ink layer 9 constituting the black opaque portion 6, the second black ink layer 6b, the third Trapping (release) 10 is formed on the black ink layer 6 c and the white ink layer 9.

  That is, the positions of the end portions 13 of the second black ink layer 6b, the third black ink layer 6c, and the white ink layer 9 in the vicinity of the boundary between the black opaque portion 6 and the light transmitting portions 3, 4, and 5 are It does not coincide with the position of the end portion 12 of the first black ink layer 6a, and is located on the side farther from the light transmitting portions 3, 4, and 5 than the end portion 12 of the first black ink layer 6a. 3A and 3B are enlarged views of the blue light transmitting portion 4 and the gray light transmitting portion 5 in FIG.

  In addition, as shown in FIG. 1, the instrument panel 1 is provided with an opening 11 to which a pointer (not shown) is attached in the black opaque portion 6. Also in the opening 11, the second black ink layer 6 b and the third black ink layer 6 c of the second and subsequent layers among the three black ink layers 6 a to 6 c and the white ink layer 9 constituting the black opaque portion 6. The white ink layer 9 has a relief (trapping) 10 formed thereon.

  The instrument panel 1 has a transparent light transmitting portion 3, a blue light transmitting portion 4, and a gray light transmitting portion 5 transmissively illuminated by the light source 2 from the back side where the ink layers 4a, 5a, 6a, 6b, 6c, 9 are formed. These are visible to the driver from the front of the instrument panel 1.

  Next, a method for manufacturing the instrument panel 1 having such a configuration will be described. The instrument panel 1 is manufactured by creating a design image with a computer and printing the image on a substrate by an inkjet method using UV ink based on the created image.

  At this time, the following is used as a manufacturing apparatus. In creating an image, for example, image processing software manufactured by Adobe is used. In addition, as a printing machine, for example, a UV curable ink jet apparatus (ink jet head, UJF605C manufactured by MIMAKI ENGINEERING, UV irradiation light source simultaneous drive type, maximum resolution 1200 DPI, CMYKKKWW, attached with 8 heads) is used.

  In this printing machine, a light source for irradiating ultraviolet rays is mounted on an inkjet head, and after ejecting ink droplets from nozzles of the head, the ejected ink droplets can be irradiated with ultraviolet rays immediately. In this embodiment, the time from when the ink droplets are ejected from the nozzles of the ink jet head to when the ultraviolet rays are irradiated is, for example, within 1 second.

  For example, the head does not print an image with the target resolution by irradiating the ink once, but prints an image with the target resolution by ejecting the ink multiple times to the same part by reciprocating the head. It is supposed to be. For example, when the resolution of the head is 150 DPI, an image of 1200 DPI can be obtained by irradiating the head with ink 8 times (8 pushes).

  In this specification, printing is performed once until an image having a target resolution is obtained. That is, when printing a 1200 DPI image, if the head resolution is, for example, 150 DPI, printing is performed once when ink is ejected eight times, and if the head resolution is 1200 DPI, ink is ejected once. This is a single print.

  In addition, as the UV ink (ultraviolet curable ink), for example, an acrylic radical polymerization type, an epoxy cationic polymerization type, or the like can be used.

  Specifically, the instrument panel 1 is manufactured as follows. After the image is created on the computer, this image data is input to the printing machine. At this time, as shown in FIG. 4, the resolution of each ink layer, the appropriate amount of ink (not shown), the color, the dot ratio, and the like are designated. FIG. 4 is a chart showing a first example of the resolution, color, and halftone dot ratio of the ink layer in each of the black opaque portion 6, the blue transparent portion 4, and the gray transparent portion 5.

  For example, for the first ink layer, the resolution is set to 1200 DPI and the appropriate amount of ink is specified to 6 pl (picoliter). The first black ink layer 6a is K (black): 100%, the blue ink layer 4a is C (cyan): 80%, the gray ink layer 5a is C: 30%, M (magenta): 30%, Y ( Yellow): 30%, K: 30%.

  For the second, third, and fourth ink layers 6b, 6c, and 9, the resolution is specified as 600 DPI, and the appropriate amount of ink is specified as 12 pl. The second and third black ink layers 6b and 6c of the second and third layers are designated as K (black): 100%, and the white ink layer 9 of the fourth layer is designated as W (white): 100%.

  Then, a resin substrate 7 is prepared, and the blue light-transmitting portion 4 of the resin substrate 7 is formed on the back surface 7b of the resin substrate 7 by an inkjet method using UV ink by using a printing machine in which the image data is input. The first ink layers 4a, 5a, and 6a are directly printed on the regions where the gray light transmitting portion 5 and the black opaque portion 6 are to be formed. At this time, the resolution is 1200 DPI and the appropriate amount of ink liquid is 6 pl. Moreover, the formation planned area | region of the blue translucent part 4, the gray translucent part 5, and the black non-transparent part 6 is equivalent to the image formation planned area | region of this invention.

  As a result, as shown in FIG. 2, the first black ink layer 6a, the blue ink layer 4a, and the gray ink layer 5a are simultaneously printed on the back surface 7b of the resin substrate 7. The first black ink layer 6 a is formed in a region of the resin substrate 7 excluding the regions where the light transmitting portions 3, 4, and 5 are to be formed.

  Subsequently, the second and third black ink layers 6 b and 6 c are printed on the area where the black opaque portion 6 is to be formed. That is, as shown in FIG. 2, the second and third black ink layers 6b are superimposed on the first black ink layer 6a on the resin substrate 7 on which the first ink layers 4a, 5a and 6a are printed. , 6c are printed. At this time, the resolution is 600 DPI and the appropriate amount of ink is 12 pl. Note that printing with this resolution changed is performed by the printing apparatus itself changing to the specified resolution.

  Further, the white ink layer 9 is printed on the third black ink layer 6c. At this time, the resolution is 600 DPI and the appropriate amount of ink liquid is 12 pl. These printings correspond to multiple printings at two or more resolutions of the present invention. The printing of the second and third black ink layers 6b and 6c and the white ink layer 9 described above corresponds to printing on the same portion of the resin substrate (7) of the present invention. The first black ink layer 6a, the second black ink layer 6b, the third black ink layer 6c, and the white ink layer 9 correspond to a plurality of ink layers of the present invention.

  Here, in the black opaque part 6, it is the first black ink layer 6a that is visually recognized by the driver or the like, and these ink layers 6b, 6c, and 9 are not visually recognized by the driver or the like. Therefore, in this embodiment, since the first black ink layer 6a is printed at a high resolution, the resolution of the second, third black ink layers 6b, 6c and the white ink layer 9 is set to be higher than that of the first black ink layer 6a. Even if the image quality is lowered, the same image quality as that of the instrument panel 1 manufactured by conventional screen printing can be obtained.

  Further, when printing the second and third black ink layers 6b and 6c and the white ink layer 9, as shown in FIG. 2, these ink layers 6b corresponding to the end portions 12 of the first black ink layer 6a, The end portions 13 of 6c, 9 are shifted from the end portion 12 of the first black ink layer 6a in the direction away from the regions where the light transmitting portions 3, 4, 5 are to be formed, and these ink layers 6b, 6c, 9 To print.

  That is, the ink layers 6b, 6c, and 9 are formed so that the region where the ink layers 6b, 6c, and 9 are not formed is larger than the region where the first black ink layer 6a is not formed. That is, a relief (trapping) 10 is provided in these ink layers 6 b, 6 c, 9.

  At this time, although not shown in the region where the opening 11 for attaching the pointer to the rotary inner unit is not shown, the same applies to the second and third black ink layers 6b and 6c and the white ink layer 9. Provide relief. That is, the region where these ink layers 6 b, 6 c, 9 are not formed is made larger than the opening 11. In other words, the ink layers 6b, 6c, and 9 are formed so that the positions of the end portions of the ink layers 6b, 6c, and 9 are located away from the region where the opening 11 is to be formed.

  The first black ink layer 6a corresponds to the first ink layer of the present invention, and the second black ink layer 6b, the third black ink layer 6c, and the white ink layer 9 are the second and subsequent layers of the present invention. It corresponds to an ink layer.

  Then, the surface matte layer 9 is printed on the main surface 7a of the resin substrate 7 by a known printing means. Thereafter, the opening 11 is formed in the instrument panel 1 by punching (die-cutting) the area of the instrument panel 1 where the opening 11 is to be formed.

  In this way, the instrument panel 1 shown in FIG. 1 is manufactured. The instrument panel 1 manufactured in this way is housed in a housing composed of a casing and a facing plate together with a pointer, a rotating inner unit, a light source and the like (not shown) to manufacture a vehicle instrument.

  Next, features of the present embodiment will be described.

  (1) First, for reference, FIGS. 5 and 6 show the cross-sectional structure and printing conditions of the instrument panel 1 when a plurality of stacked ink layers are formed at the same resolution, unlike the present embodiment.

  As shown in FIGS. 5 and 6, in the black ink layer constituting the black opaque portion 6, the resolution of the second and subsequent black ink layers 6b, 6c, and 6d is set to be the same as that of the first black ink layer 6a of the first layer. When the same 1200 DPI was used, four black ink layers were required. Therefore, the total number of ink layers formed in the black opaque portion 6 was five layers.

  The time required to form each ink layer at this time was about 200 seconds per layer and about 1000 seconds in total for the five layers.

  On the other hand, in the present embodiment, as shown in FIG. 2, the first black ink layer 6a, the blue ink layer 4a, and the gray ink layer 5a are printed on the back surface 7b of the resin substrate 7 to obtain the first The second black ink layer 6b, the third black ink layer 6b, and the white ink layer 9 are printed in order on the black ink layer 6a.

  At this time, as shown in FIG. 4, the resolution of the first ink layers 4a, 5a, 6a is 1200 DPI, and the resolution of the second and subsequent ink layers 6b, 6c, 9 is 600 DPI. In general, in a printing method using an inkjet method, the time required for one printing is shorter as the resolution of an image is lower. In this embodiment, when the resolution is 600 DPI, the time required to form the ink layer is about 70 seconds per layer. The time required to form all the ink layers was about 410 seconds.

  Thus, according to the present embodiment, the time required for forming the second and subsequent ink layers 6b, 6c, and 9 can be shortened. Therefore, according to the present embodiment, the time required to form all the ink layers can be shortened compared to when all the ink layers are printed at a high resolution of 1200 DPI.

  (2) Also, in this embodiment, when printing at a resolution of 600 DPI, the appropriate amount of ink is set to 12 pl, and the appropriate amount of liquid is increased as compared with the printing of the ink layers 4a, 5a, 6a of the first color layers. Yes.

  That is, in the present embodiment, in forming the second and subsequent ink layers, the amount of droplets sprayed by inkjet can be increased by reducing the resolution. This is because when the resolution is high, the distance between adjacent dots is small, so it is necessary to reduce the appropriate amount of liquid so that the dots do not overlap, but when the resolution is low, the distance between adjacent dots Because is big.

  Here, as shown in FIGS. 5 and 6, when the resolution of the second and subsequent black ink layers 6b, 6c, and 6d is 1200 DPI, which is the same as that of the first black ink layer 6a, In the printing machine to be used, the appropriate amount of ink is 6 pl. For this reason, in order to obtain a desired density that does not transmit light in the black opaque portion 6, four black ink layers are necessary.

  The total film thickness of the four black ink layers 6a to 6d at this time was 40 to 60 μm because the film thickness per layer was 10 to 15 μm when black ink was printed at 6 pl.

  On the other hand, when black ink is printed at 12 pl, the film thickness per layer can be 15 to 20 μm.

  Therefore, in this embodiment, the film thickness of the first black ink layer 6a of the first layer is 10 to 15 μm, and the film of the second black ink layer 6b and the third black ink layer 6c of the second layer and the third layer. The thickness is 15 to 20 μm, respectively. For this reason, as shown in FIG. 6, the total film thickness of the black ink layer in the present embodiment is 40 to 55 μm, as in the case where printing is performed with the same resolution and the same appropriate liquid amount.

  As described above, in the present embodiment, when printing the ink layers 6b, 6c, and 9 after the second layer, not only the resolution is lower than that of the first ink layer 6a, but also an appropriate amount of ink liquid. Is larger than that of the first ink layer 6a.

  Thereby, it is possible to reduce the number of black ink layers necessary for forming the black opaque portion 6 made of an ink layer having a desired film thickness. As a result, the time required for printing can be shortened compared to the case where the resolution and the appropriate amount of ink liquid of the second and subsequent ink layers 6b, 6c, and 9 are the same as those of the first ink layer 6a.

  (3) In this embodiment, when the second and third black ink layers 6b and 6c and the white ink layer 9 are printed, the ink layers 6b, 6c and 9 are allowed to escape as shown in FIG. Trapping) 10 is provided for printing.

  In this embodiment, after the first black ink layer 6a for finishing is printed on the resin substrate 7, the second black ink layer 6b for adding color density, etc. is printed on the first black ink layer 6a. . At this time, there is no problem if the positions of the end portions of the respective ink layers coincide with each other. However, a printing error occurs in the printing process of each of the ink layers 6a, 6b, and 6c, and the end portions of the first black ink layer 6a. The position may be shifted from the position of the end of the other ink layers 6b, 6c, 9 such as the second black ink layer 6b.

  In this case, since the position of the end portion of the first black ink layer 6a becomes a boundary with the transparent light transmitting portion 3, the blue light transmitting portion 4, and the gray light transmitting portion 5, the other ink layers 6b, 6c, and 9 When printing is performed up to the positions of the respective light-transmitting portions 3, 4, and 5, the other ink layers 6 b, 6 c, and 9 are visually recognized by the driver and the like, resulting in a defective product.

  Therefore, when the ink layers 6b, 6c and 9 are printed by providing the second and third black ink layers 6b and 6c and the white ink layer 9 with the relief 10 as in the present embodiment, printing is performed. Even if a slight printing error occurs, the ink layers 6b, 6c, and 9 can be prevented from being printed up to the positions of the light transmitting portions 3, 4, and 5. As a result, generation of defective products can be suppressed. The size of the relief 10 can be arbitrarily set.

  (4) In the present embodiment, similarly, when the second and third black ink layers 6b and 6c and the white ink layer 9 are printed, the opening 11 for attaching the pointer to the rotating inner unit is planned to be formed. Also in the area, a relief is provided.

  When the opening 11 is formed by punching (die cutting) in the area of the black opaque portion 6, punching is performed on the first, second, and third black ink layers 6a, 6b, and 6c and the white ink layer 9. If it does, a big impact (damage) will be given to these ink layers 6a, 6b, 6c, and 9. For this reason, there is a possibility that these ink layers 6a, 6b, 6c, and 9 may be peeled off or burrs or chips may be generated by punching.

  On the other hand, in the present embodiment, since the relief is provided as described above and the second and subsequent ink layers are formed, only the first black ink layer 6a is punched and the opening portion is formed. 11 will be formed.

  For this reason, according to the present embodiment, it is possible to reduce damage given to the ink layer at the time of punching, as compared with the case where the second and subsequent ink layers are formed without providing relief. As a result, it is possible to prevent the ink layer from peeling off, burrs, and chipping from occurring during punching.

  In the first example, the case where the resolution of the second and subsequent ink layers 6b, 6c, and 9 is printed as 600 DPI is described as an example. However, the resolution of these ink layers can be further reduced.

  FIG. 7 shows printing conditions in the second example of the present embodiment. As shown in FIG. 7, the resolution of the second and subsequent ink layers 6b, 6c, and 9 can be set to 300 DPI. In this case, the printing time required for each ink layer 6b, 6c, 9 after the layer was about 30 seconds, and the time required to form all the ink layers was about 290 seconds.

  Thus, the printing time can be further shortened by further reducing the resolution of the second and subsequent ink layers 6b, 6c, and 9. Also at this time, the appropriate amount of ink can be changed. In this case, for example, it is preferable that the appropriate amount of ink is 24 pl.

(Second Embodiment)
In the first embodiment, the case where the black opaque portion 6 is formed by performing printing a plurality of times on the formation scheduled region of the black opaque portion 6 in the resin substrate 7 has been described as an example. As described above, the blue light-transmitting portion 4 and the gray light-transmitting portion 5 can also be formed by printing a plurality of times in the regions where the blue light-transmitting portion 4 and the gray light-transmitting portion 5 are to be formed.

  8 and 9 show a cross-sectional structure and printing conditions of the instrument panel 1 in the first example of the second embodiment, respectively. Hereinafter, differences from the first embodiment will be mainly described.

  In the first example of the present embodiment, as shown in FIG. 8, unlike the first embodiment, the blue light-transmitting portion 4 and the gray light-transmitting portion 5 are each composed of two blue ink layers 4 a, 4 b and two layers. The gray ink layers 5a and 5b.

  And when manufacturing the instrument panel 1 of such a structure, printing conditions are changed as follows with respect to the printing conditions of FIG. That is, as shown in FIG. 9, when forming the first ink layers 4a, 5a, 6a, the halftone dot ratio of the first blue ink layer 4a is C: 40%, and the halftone dots of the first gray ink layer 5a. The rate is changed to C: 15%, M: 15%, Y: 15%, K: 15%. When the second ink layer is formed, the second blue ink layer 4b and the second gray ink layer 5b are formed together with the second black ink layer 6b. The halftone dot ratios of the second blue ink layer 4b and the second gray ink layer 5b are the same as those of the blue ink layer 4a and the gray ink layer 5a, respectively. The resolution of the second ink layer 4b, 5b, 6b is set to 1200 DPI.

  In the present embodiment, as described above, the halftone dot ratio of the first and second blue ink layers 4a and 4b is set to half the halftone dot ratio of the blue ink layer 4a in the first embodiment. Similarly, the halftone dot ratio of the second gray ink layers 5a and 5b is half the halftone dot ratio of the gray ink layer 5a in the first embodiment.

  By printing under such conditions, it is possible to form the blue light-transmitting portion 4 and the gray light-transmitting portion 5 having the same color density as that of the first embodiment (desired color density).

  Next, features of the present embodiment will be described.

First, in a method of printing by an inkjet method using UV ink, ink droplets that have landed on a resin substrate do not penetrate into the resin substrate and are laminated on the surface of the resin substrate. For this reason, compared with the water-based inkjet etc. which print on paper, the film thickness of a dot (ink droplet) becomes large and a feeling of thickness comes out.

  Here, the colored light-transmitting portion is a colored portion that transmits light. This colored light-transmitting portion is formed by lowering the halftone dot ratio (the ratio of dots to the print area) in printing by the inkjet method.

  Therefore, since the dot ratio is low in the colored transparent portion, the distance between adjacent dots is widened, and the dot film thickness is more easily recognized than in the non-transmissive portion. For this reason, in a colored translucent part, the granularity (rough feeling) becomes strong and the problem that appearance deteriorates arises.

  In addition, when printing colored transparent portions, there arises a problem in image quality that streak lines of operation lines called banding, which are generated due to head feeding error, are conspicuous in a dark color. This banding is a problem that occurs even in an OA printer. When the accuracy of paper feeding is poor, the joint of printed images can be seen. As described above, when printing is performed by the inkjet method, the appearance of the image is deteriorated as compared to when printing is performed by screen printing.

  In addition, as a general countermeasure method for the problem (2) in which the above-described appearance is deteriorated, a method of providing an ink receiving layer on a print object and causing ink droplets to blur to reduce graininess, light magenta, There is a method of reducing the conspicuousness of dots by using a light intermediate color such as light cyan. In other words, there is a method for dealing with a decrease in the appearance of a printed image due to color error dispersion.

  However, in the method of providing the ink receiving layer, not only the material cost and the forming process are increased, but also the viscosity of the UV ink is higher than that of the water-based ink, so that the UV ink does not penetrate into the receiving layer and the image quality improvement effect is not obtained so much. .

  Further, in the method using the light-based ink, a nozzle for the light-based ink is required. Therefore, when using an ink jet apparatus that does not include the nozzle for the light-based ink, it is necessary to increase the number of nozzles. For this reason, there arises a problem that the production cost is increased due to the increase in the number of nozzles and the maintenance cost. Therefore, it is desired to solve the above problems without providing an ink receiving layer or using light-based ink.

In the present embodiment, as described above, the blue light-transmitting portion 4 and the gray light-transmitting portion 5 are formed by printing twice instead of printing once. The density (halftone dot ratio) at the time of the first and second printing is a density obtained by dividing the desired density (target value) by the number of times of printing (twice).

  At this time, the ink layer formed in the first printing and the second printing has a light color (small dot ratio). When printing an ink layer of dark color (high dot ratio), banding will be noticeable. However, when printing a light ink layer, even if banding occurs, the ink layer will be dark. Compared with inconspicuous.

  Therefore, according to the present embodiment, even when banding occurs when the blue light-transmitting portion 4 and the gray light-transmitting portion 5 are printed, the blue light-transmitting portion is formed with one ink layer as in the first embodiment. The presence of banding can be made inconspicuous compared to the case where the 4 and the gray light-transmitting portions 5 are formed.

Also, in the present embodiment, the blue light-transmitting portion 4, and the gray light-transmitting portion 5 is formed by printing twice rather than one printing. As described above, when the same portion of the resin substrate 7 is printed multiple times, some errors occur in the printing position. In this case, the positions of the dots of the first printed image and the dots of the next printed image are different, and the resolution is increased in a pseudo manner.

  The reason why the colored light-transmitting portion has a strong graininess is that the colored light-transmitting portion transmits light so that the dot ratio is small, that is, the interval between dots is large and the dots are easily visible. On the other hand, according to the present embodiment, the resolution can be increased in a pseudo manner, that is, the interval between the dots can be reduced, so that the graininess can be made inconspicuous.

  In addition, when the same portion of the resin substrate 7 is printed several times and there is some error in the printing position, the position where banding occurs shifts. That is, the positions where banding occurs can be dispersed. This also makes banding inconspicuous.

  As described above, according to the present embodiment, it is possible to expect a stacking error variance due to density division of four primary colors of cyan, magenta, yellow, and black in a pseudo manner.

  From the above, according to the present embodiment, compared to the case where the colored light-transmitting portion is printed by one printing, the graininess becomes stronger without using the receiving layer and the light-based ink. It is possible to prevent the appearance from deteriorating due to the occurrence of banding.

  In the first example of this embodiment, the resolution of the third ink layer 6c and the fourth ink layer 9 is 600 DPI, which is smaller than the resolution of the first and second ink layers. . In this case, the total printing time was about 540 seconds. Therefore, also in the first example of the present embodiment, as shown in FIGS. 5 and 6, it is possible to shorten the printing time as compared with the case where all are printed at the same resolution.

  In the first example described above, the first ink layer and the second ink layer have the same resolution, and the first blue ink layer 4a and the second blue ink layer 4b constituting the blue light-transmitting portion 4 are used. In the above description, the halftone dot ratio is set to the same size, but the resolution and the halftone dot ratio may be set to different sizes as in the second example.

  FIG. 10 shows printing conditions in the second example of the second embodiment. The printing conditions shown in FIG. 9 can be changed as follows. That is, as shown in FIG. 10, for example, the resolution of the second ink layer is changed to 1200 DPI. Further, the halftone dot ratios of the first blue ink layer 4a and the second blue ink layer 4b are changed to C: 60% and 20%, respectively. The dot ratio of the first gray ink layer 5a is C: 20%, M: 20%, Y: 20%, K: 20%, and the dot ratio of the second gray ink layer 5b is C: 10%, M: Change to 10%, Y: 10%, K: 10%.

  As described above, when the colored light-transmitting portions 4 and 5 are constituted by two ink layers, if the total density (halftone dot ratio) of the two ink layers is a desired density (halftone dot percentage), The density (halftone dot ratio) of the two ink layers may be different from each other.

  When the resolution of the two ink layers constituting the colored light-transmitting portions 4 and 5 is changed in this manner, the positions of the dots in the first ink layers 4a and 5a and the second ink layers 4b and 5b The dot position is different.

  Therefore, according to the second example, color dispersion can be achieved as compared with the first example, and graininess and banding can be made less conspicuous compared with the first example.

  In the second example, the resolution of the first ink layer is 1200 DPI, and the resolution of the second to fourth ink layers is 600 DPI, so the printing time is about 410 seconds in total.

  In the first and second examples described above, the case where the colored light transmitting portions 4 and 5 are configured by two ink layers has been described as an example. However, as in the third example, the colored light transmitting portions 4 and 5 are configured. The number of ink layers constituting the can be other numbers.

  11 and 12 show a cross-sectional structure and printing conditions of the instrument panel 1 in the third example of the second embodiment, respectively. As shown in FIG. 11, the blue translucent part 4 is composed of four blue ink layers 4a, 4b, 4c and 4d, and the gray translucent part 5 is composed of three gray ink layers 5a, 5b and 5c. You can also

  In this case, the printing conditions are as follows. The dot ratio of the four blue ink layers 4a, 4b, 4c, and 4d is C: 20%, respectively, and the total dot ratio of the four blue ink layers 4a, 4b, 4c, and 4d is C: 80. %. The three gray ink layers 5a, 5b, and 5c have halftone dot ratios of C: 10%, M: 10%, Y: 10%, and K: 10%, respectively. The total of the dot ratios of 5b and 5c is C: 30%, M: 30%, Y: 30%, and K: 30%. The resolution from the first layer to the fourth layer is the same as in the second example of the present embodiment.

  As described above, the number of ink layers constituting the blue light-transmitting portion 4 and the gray light-transmitting portion 5 is increased, and the dot ratio of each ink layer constituting the blue light-transmitting portion 4 and the gray light-transmitting portion 5 is further reduced. You can also In addition, when increasing the ink layer which comprises the blue translucent part 4 and the gray translucent part 5, in order to suppress the frequency | count of printing to the minimum, it is preferable to make the frequency | count of printing of a black opaque part into an upper limit.

  Next, other features of the first and second embodiments will be described below.

  When the colored light-transmitting portions 4 and 5 are printed with only a low-resolution ink layer, the number of dots in the printed region is small, and thus color unevenness may occur.

  In contrast, in the first and second embodiments, the blue ink layer 4a and the gray ink layer 5a (the first layer in the second embodiment) are printed with high resolution. For this reason, according to the first and second embodiments, many dots are dispersed in the printed region, and the occurrence of color unevenness is suppressed.

  Furthermore, from the viewpoint of making the uneven glossiness inconspicuous, the blue light-transmitting portion 4 and the gray light-transmitting portion 5 are interposed via a transparent substrate such as the transparent resin substrate 7 as in the first and second embodiments. It is effective for the driver to be visually recognized. That is, it is effective to perform printing by the inkjet method using UV ink on the back surface 7b, not the front surface (display surface) 7a of the resin substrate 7.

  There may be a difference in the thickness of the ink layer depending on the color of the ink. Therefore, when the ink layer is formed on the main surface 7a of the resin substrate 7 and the thickness of the ink layer is different, when the ink layer is viewed without the resin substrate 7, the ink surface Due to irregular reflection, it appears that there is uneven gloss. Therefore, as in the first and second embodiments, printing on the back surface 7b of the resin substrate 7 and making the ink layer visible through the resin substrate 7 can make gloss unevenness inconspicuous. it can.

(Other embodiments)
(1) In each of the above-described embodiments, the case where printing is performed on the back surface 7b of the resin substrate 7 has been described as an example. However, the main surface (display side) 7a of the resin substrate 7 is applied by an inkjet method using UV ink. It can also be printed.

  In this case, the ink layer formed on the main surface 7a of the resin substrate 7 is overcoated with a radical polymerization type UV clear to which acrylic beads, urethane beads, silicone beads and the like having an average particle diameter of 10 to 30 μm are added.

Thereby, the regular thickness nonuniformity of an inkjet ink layer can be relieved. As a result, uneven gloss due to uneven thickness of the ink layer can be made inconspicuous.
(2) In each of the above-described embodiments, the case where the first ink layers 4a, 5a, and 6a in contact with the resin substrate 7 have high resolution has been described as an example, but the first ink layer 4a, 5a and 6a may not have high resolution. Even when the first ink layer 4a, 5a, 6a is set to low resolution and the second or third ink layer is set to high resolution, the same effects as those of the above-described embodiments can be obtained.
(3) In each of the above-described embodiments, the case of changing the appropriate amount of ink when printing each ink layer has been described as an example. However, it is also possible to print all with the same appropriate amount of liquid.
(4) In each of the above-described embodiments, the case where the escape (trapping) 10 is provided for the second and subsequent black ink layers 6b and 6c has been described as an example, but the second and subsequent black ink layers 6b, 6c, etc., without providing relief, as in the comparative example shown in FIGS. 5 and 6, the end portions of the first black ink layer 6a and the second and subsequent black ink layers 6b, 6c, etc. Boundary) can be aligned. Even in this way, the object of the present invention can be achieved.
(5) According to each of the above-described embodiments, even if an ink receiving layer is not provided on the resin substrate 7 or a light-based ink is used as the ink, the appearance is deteriorated due to the occurrence of graininess or banding. However, a method of providing an ink receiving layer or a method using a light-based ink can be used in combination.
(6) In each of the above-described embodiments, for example, in printing the black opaque portion 6, printing is performed a plurality of times on the same portion of the resin substrate 7, and the ink layers 6a, 6b, 6c, and 9 are stacked. Explained that printing time can be shortened. However, the printing time can be shortened not only when printing the same portion a plurality of times and laminating the ink layers, but also when printing as follows.

  For example, in the printing of the black opaque part 6, in the black opaque part 6, a part (contour part) near the boundary with the light transmitting parts 3, 4, 5 and a part (inside) away from the boundary are separately provided. Print on. In the black non-transparent portion 6, printing is performed at a high resolution at a portion near the boundary with the light transmitting portions 3, 4, and 5, and printing is performed at a low resolution at a portion away from the boundary.

As a result, in the black non-transparent portion 6, the portion near the boundary with the translucent portions 3, 4, and 5 and the portion away from the boundary are printed separately, and both portions have the same height. The printing time can be shortened as compared with the case of printing at the resolution.
(7) In each of the above-described embodiments, the case where the instrument panel 1 of a vehicle instrument is manufactured has been described as an example. However, in the manufacture of a display panel having a light-impermeable portion and a colored light-transmitting portion in other fields, The present invention can be applied.

  For example, in the field of home appliances, a non-light-transmitting portion and a colored light-transmitting portion are also formed on a display panel that transmits light from a light-emitting diode such as a touch panel. Therefore, the present invention can be applied to the manufacture of such a display panel.

It is a front view of the display board in 1st Embodiment of this invention. FIG. 2 is a cross-sectional view taken along line A-A ′ of the display board in FIG. 1. (A), (b) is an enlarged view of the blue translucent part 4 and the gray translucent part 5 in FIG. It is a graph which shows the printing conditions of each ink layer which comprises the black opaque part 6, the blue transparent part 4, and the gray transparent part 5 in the 1st example of 1st Embodiment. It is sectional drawing of the instrument panel 1 which the present inventors examined. It is a graph which shows the printing conditions of each ink layer which comprises the black opaque part 6, the blue transparent part 4, and the gray transparent part 5 of the instrument panel 1 which the present inventors examined. It is a table | surface which shows the printing conditions of each ink layer which comprises the black opaque part 6, the blue transparent part 4, and the gray transparent part 5 in the 2nd example of 1st Embodiment. It is sectional drawing of the display board in the 1st example of 2nd Embodiment. It is a graph which shows the printing conditions of each ink layer which comprises the black opaque part 6, the blue transparent part 4, and the gray transparent part 5 in the 1st example of 2nd Embodiment. It is a graph which shows the printing conditions of each ink layer which comprises the black opaque part 6, the blue transparent part 4, and the gray transparent part 5 in the 2nd example of 2nd Embodiment. It is sectional drawing of the display board in the 3rd example of 2nd Embodiment. It is a graph which shows the printing conditions of each ink layer which comprises the black opaque part 6, the blue transparent part 4, and the gray transparent part 5 in the 3rd example of 2nd Embodiment.

Explanation of symbols

1 ... instrument panel, 2 ... light source,
3 ... transparent translucent part, 4 ... blue translucent part, 5 ... gray translucent part, 6 ... black impervious part,
7 ... Resin substrate, 8 ... Surface matte layer, 9 ... White ink layer,
10 ... Escape (trapping), 11 ... Opening,
4a, 4b, 4c, 4d ... blue ink layer,
5a, 5b, 5c ... Gray ink layer 6a, 6b, 6c, 6d ... Black ink layer.

Claims (2)

Using a printing method in which an ultraviolet curable ink is attached to the surface (7a) of the translucent resin substrate (7) by an inkjet method, and then the ink is irradiated with ultraviolet rays to cure the ink. A display board obtained by printing an image on the resin substrate (7),
  A display board, wherein the surface of the image is overcoated with an ultraviolet curable clear. The display panel according to claim 1, wherein the ultraviolet curable clear is a radical polymerization type to which at least one of acrylic beads, urethane beads, and silicone beads having an average particle diameter of 10 to 30 μm is added.

Images