Operation sheet, switch using operation sheet, and manufacturing method of operation sheet

Abstract

To provide an operation sheet with improved design, functionality and operability, a switch using the operation sheet, and a method for manufacturing the operation sheet.SOLUTION: An operation sheet 11 is used for a switch 1 that energizes by contacting a contact electrode in response to a key input operation, and is an operation sheet 11 on which characters, symbols, patterns, images, etc. that indicate key input are displayed, and which is provided with a display printing layer 13 of characters, symbols, patterns, etc. that indicate key input of the switch, formed by dot printing using ink on one side of a light-transmitting film, and a first solid printing layer 14 formed by solid printing using ink in an area on the same side of the light-transmitting film on which the display printing layer is formed but on which the display printing layer 13 is not formed, or laminated and formed on at least a part of the display printing layer 13 of the light-transmitting film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an operation sheet, a switch using the operation sheet, and a manufacturing method for the operation sheet, and more particularly to an operation sheet used in a thin switch input device in an electronic device, a switch using the operation sheet, and a manufacturing method for the switch. [Background technology]

[0002] 2. Description of the Related Art Sheet-like membrane switches or tact switches are used as thin switch input devices in operation panels of electronic devices and the like. Figure 7 shows an example of a membrane switch disclosed in Patent Document 1, where this membrane switch 50 is composed of an upper operation sheet 51 that is positioned on the front side of the housing of an electronic device, etc., and a lower contact sheet 61 on the back side that fits into the electronic device. In the lower contact sheet 61 on the back side, a flexible film 64 is arranged on a base film 62 via a spacer 63, and contact electrodes 62a and 64a are arranged facing each other on the base film 62 side and the flexible film 64 side, which face each other within a through hole 63a formed in the spacer 63.

[0003] In addition, in the upper operation sheet 51 on the front side, a display layer 54 is attached to the back of the light-transmitting film 52 via a first adhesive layer 53, and a second adhesive layer 55 is applied to the back of this display layer 54. Then, the upper operation sheet 51 is attached to the upper surface of the lower contact sheet 61 by the second adhesive layer 55, thereby forming the membrane switch 50. Therefore, with this membrane switch 50, by pressing (key input operation) the light-transmitting film 52 in accordance with the marking position on the display layer 54 located on the back side of the upper operation sheet 51, the pressing force is transmitted to the lower contact sheet 61 side via the upper operation sheet 51.

[0004] As a result, contact electrode 64a arranged on the flexible film 64 side comes into contact with contact electrode 62a arranged on the base film 62 side, thereby achieving a predetermined switch function (on operation) of the electronic device. It is noted that Patent Document 1 discloses that characters, symbols, patterns, etc., which serve as indicators of key inputs to the membrane switch, are printed on the display layer 54 using an inkjet color printer.

[0005] Patent Document 2 also describes a membrane switch in which a display layer is placed on the back side of the light-transmitting film on the surface, on which characters, symbols, etc. that indicate key input are printed using a color printer. In the example shown in Patent Document 2, the printed markings are made on a display layer that is made of a separate material from the light-transmitting film on the surface, which is similar to the configuration of the membrane switch shown in Figure 7 of Patent Document 1. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-6155 [Patent Document 2] Japanese Utility Model Application Publication No. 5-90762 Summary of the Invention [Problem to be solved by the invention]

[0007] The membrane switches disclosed in Patent Documents 1 and 2 each employ a configuration in which a display layer, which is a separate member from the light-transmitting film and has a printed marking made by a color printer, is attached to the back side of the light-transmitting film that constitutes the operation sheet.

[0008] Inkjet color printers contain cartridges for the primary colors C (cyan), M (magenta), Y (yellow), and K (black), and the ink in each cartridge is ejected as ink droplets from a nozzle according to the desired color. The ink droplets then form dots (points) on the printing surface, and the desired color is reproduced by overlapping these dots during printing. Therefore, inkjet color printers are capable of rendering images and gradations with high precision, and also have the following advantages: (1) The ink in each cartridge is ejected from the nozzle as ink droplets according to the desired color, and the desired color is reproduced by overlapping dots, so there is no need to mix colors in advance, and full-color printing can be performed easily. (2) The ink dries quickly, allowing for fast printing speeds and eliminating the need for long drying times, allowing for continuous printing on paper or film. (3) Because the ink contains only a small amount of solvent, it is easy and safe to work with, and requires almost no preparatory work before or after printing.

[0009] However, the nozzle diameter of inkjet color printers is about 20 μm, and there was a problem that they could not be used with inks containing particles larger than this. For example, inks that enhance design, such as inks containing metallic particles, inks containing pearl particles, inks containing mica particles, and mirror-like inks, as well as inks that enhance functionality, such as inks containing silver particles, inks containing copper particles, inks containing carbon particles, and COS (glass beads) inks, could not be used in inkjet color printers.

[0010] Furthermore, the ink used in inkjet color printers is not heat resistant, which means that post-processing involving high temperatures, such as press working, is not possible. Furthermore, because inkjet color printers use dot printing, the print density (printed layer) is thin, which means that the opacity is poor and the back side of the printed surface can be seen through, which is an issue.

[0011] Furthermore, as mentioned above, the membrane switches disclosed in Patent Documents 1 and 2 employ a configuration in which a display layer made of a separate material from the light-transmitting film is attached to the back side of the light-transmitting film that constitutes the operation sheet, which requires many work processes, including alignment when attaching each adhesive layer, which increases costs. Furthermore, the upper operation sheet described in Patent Document 1 includes a first adhesive layer and a second adhesive layer, which not only increases the overall thickness of the upper operation sheet but also impairs the flexibility of the portion that is pressed, resulting in problems such as a poor operational feel as a membrane switch.

[0012] The present inventors have conducted extensive research into an operation sheet with excellent design and functionality, which utilizes the advantage of inkjet color printers, such as the ability to accurately print images and gradations, and which uses inks that enhance design and functionality. They have also conducted extensive research into switches that offer a good operational feel. As a result, we discovered that by directly forming an image or a gradation or other shaded image using an inkjet color printer on the back of the light-transmitting film that serves as the operation panel, and then printing inks that enhance the design and inks that enhance the functionality using silk screen printing, we can improve the design, functionality, and operability of the operation sheet, and have completed this invention.

[0013] The present invention is intended to solve the above-mentioned problems of conventional operation sheets, and aims to provide an operation sheet with improved design, functionality, and operability, a switch using the operation sheet, and a method for manufacturing the operation sheet. [Means for solving the problem]

[0014] The operation sheet of the first embodiment of the present invention, which has been made to solve the above-mentioned problems, is an operation sheet on which characters, symbols, patterns or images etc. that serve as indicators of key input are displayed, and which is used for a switch that energizes by contacting a contact electrode in response to a key input operation, and is characterized by comprising: a display printing layer of characters, symbols or patterns etc. that serve as indicators of key input of the switch, formed by dot printing using ink on one side of a light-transmitting film; and a first solid printing layer formed by solid printing using ink, formed in an area on the same side of the light-transmitting film on which the display printing layer is formed but on which the display printing layer is not formed, or laminated and formed on at least a part of the display printing layer of the light-transmitting film.

[0015] In addition, an operation sheet of a second embodiment according to the present invention is an operation sheet on which letters, symbols, patterns, etc. that indicate key input are displayed, and which is used in a switch that energizes by contacting a contact electrode in response to a key input operation, and is characterized by comprising: a light-transmitting heat-resistant layer formed by solid printing using ink on one side of a light-transmitting film; a display printing layer on the light-transmitting heat-resistant layer by dot printing using ink, the display printing layer being letters, symbols, patterns, images, etc. that indicate key input of the switch; and a first solid printing layer formed by solid printing using ink in an area on the same side as the display printing layer of the light-transmitting heat-resistant layer on which the display printing layer is formed, where the display printing layer is not formed, or which is laminated and formed on at least a part of the display printing layer of the light-transmitting heat-resistant layer.

[0016] In this way, the display print layer is formed by dot printing using ink on one side of the light-transmitting film or on a light-transmitting heat-resistant layer formed by solid printing on one side of the light-transmitting film, allowing for highly accurate depiction of images, gradations, and other shades. Furthermore, because the ink from each cartridge is ejected as ink droplets from the nozzles according to the desired color and the desired color is reproduced by overlapping dots, there is no need for pre-mixing, making full-color printing easy. Furthermore, the ink dries quickly, allowing for fast printing speeds and eliminating the need for long drying times, allowing for continuous printing on paper or film. The ink uses a small amount of solvent, making the process easy and safe.

[0017] In addition, a first solid print layer formed by solid printing using ink is formed in an area where no display print layer is formed on the same surface of the light-transmitting film as the display print layer formed on it, or the first solid print layer is formed by being laminated on at least a part of the display print layer of the light-transmitting film. For example, by forming a first solid print layer in an area where the display print layer is not formed using an ink containing metallic particles, pearl particles, mica particles, etc., the design effect of the area where the display print layer is not formed can be enhanced. Also, when a first solid print layer is laminated by solid printing, for example, white ink on at least a part of the display print layer of the light-transmitting film, the back side of the display print layer can be made concealing, thereby solving the problem of the back side of the printed surface being visible through the display print layer.

[0018] Preferably, the ink for the display printing layer contains particles with a particle size of 20 μm or less, and the ink for the first solid printing layer contains particles with a particle size of more than 20 μm. The nozzle diameter of the inkjet color printer used to print the display printing layer is about 20 μm, and ink containing particles with a diameter larger than this cannot be used. On the other hand, since the first solid print layer is printed by silk screen printing, even ink containing particles with a particle size of more than 20 μm can be suitably used.

[0019] Furthermore, the ink used for printing the light-transmitting heat-resistant layer in the operation sheet of the second embodiment according to the present invention is preferably a medium ink. Medium ink does not contain pigments, which are the key coloring elements, and silkscreen printing using this medium ink can form a colorless, transparent print layer. Therefore, the display printed by an inkjet color printer can be clearly seen through the medium ink print layer and the light-transmitting film. Furthermore, the colorless and transparent printing layer can function as a heat-resistant layer, and can contribute to suppressing discoloration, deterioration, etc. caused by heat applied to the display printing layer when embossing the operation sheet described below.

[0020] The ink of the first solid print layer preferably contains any of metallic particles, pearl particles, mica particles, silver particles, copper particles, carbon particles, and glass beads. In this way, by forming the first solid print layer using a specific particle-containing ink that contains metallic particles, pearl particles, mica particles, silver particles, copper particles, carbon particles, or glass beads, it is possible to improve design and functionality.

[0021] It is also desirable that the keypad has a second solid print layer laminated on a display print layer containing characters, symbols, patterns or images that indicate key input, or laminated on the first solid print layer, and that the second solid print layer is a heat-resistant layer containing glass beads formed from ink containing glass beads. In this way, since a heat-resistant layer is formed, processing involving high heat such as press processing can be carried out.

[0022] In particular, the operation sheet has an embossment that gives a clicking sensation to the key input operation, and the second solid print layer is formed in the area where the embossment is formed. Since a heat-resistant layer, which is a second solid print layer, is formed, embossing can be performed without affecting the display print layer.

[0023] It is also preferable to use the operation sheet to configure a switch, and it can be suitably used for, for example, a membrane switch or a tact switch.

[0024] In addition, the manufacturing method of an operation sheet of a first embodiment of the present invention, which has been made to solve the above-mentioned problems, is a manufacturing method of an operation sheet used for a switch that energizes by contacting contact electrodes in response to key input operation, and is characterized by having a display printing process in which a display printing layer such as letters, symbols, patterns or images that indicate key input of the switch is formed on one side of a light-transmitting film of the operation sheet by a color printing means using an inkjet method, and a first solid printing layer forming process in which a solid printing layer is formed by a silk screen printing means in an area on the side of the light-transmitting film on which the display printing layer is formed where the display printing layer is not formed, or in at least a part of the area of ​​the display printing layer of the light-transmitting film.

[0025] In addition, a manufacturing method for an operation sheet of a second embodiment according to the present invention is a manufacturing method for an operation sheet used for a switch that energizes by contacting contact electrodes in response to key input operation, and is characterized by having: a light-transmitting heat-resistant layer printing process for forming a light-transmitting heat-resistant layer on one side of a light-transmitting film in the operation sheet by silk screen printing means; a display printing process for forming a display printing layer on the light-transmitting heat-resistant layer by inkjet color printing means, the display printing layer including letters, symbols, patterns or images that indicate key input of the switch; and a first solid printing layer forming process for forming a solid printing layer by silk screen printing means in an area on the side of the light-transmitting heat-resistant layer on which the display printing layer is formed where the display printing layer is not formed, or in at least a part of the display printing layer of the light-transmitting heat-resistant layer.

[0026] In this way, the display print layer is formed by dot printing using ink on one side of the light-transmitting film or on a light-transmitting heat-resistant layer formed by solid printing on one side of the light-transmitting film, allowing for highly accurate depiction of images, gradations, and other shades. Furthermore, because the ink from each cartridge is ejected as ink droplets from the nozzles according to the desired color and the desired color is reproduced by overlapping dots, there is no need for pre-mixing, making full-color printing easy. Furthermore, the ink dries quickly, allowing for fast printing speeds and eliminating the need for long drying times, allowing for continuous printing on paper or film. The ink uses a small amount of solvent, making the process easy and safe.

[0027] In addition, a first solid print layer formed by solid printing is formed in an area where no display print layer is formed on the same surface of the light-transmitting film as the display print layer formed on it, or the first solid print layer is laminated and formed on at least a part of the display print layer of the light-transmitting film. For example, by forming a first solid print layer in an area where the display print layer is not formed using an ink containing metallic particles, pearl particles, mica particles, etc., the design effect of the area where the display print layer is not formed can be enhanced. Also, when a first solid print layer is laminated by solid printing, for example, white ink on at least a part of the display print layer of the light-transmitting film, the back side of the display print layer can be concealed, solving the problem of the back side of the printed surface being visible through the film.

[0028] Preferably, the ink for the display printing layer contains particles with a particle size of 20 μm or less, and the ink for the first solid printing layer contains particles with a particle size of more than 20 μm. The nozzle diameter of the inkjet color printer used to print the display printing layer is about 20 μm, and ink containing particles with a diameter larger than this cannot be used. On the other hand, since the first solid print layer is printed by silk screen printing, even ink containing particles with a particle size of more than 20 μm can be suitably used.

[0029] Furthermore, following the first solid print layer forming step, the method may include a heat-resistant layer forming step in which a second solid print layer, a heat-resistant layer, is formed on the display print layer or on the first solid print layer by silk screen printing using ink containing glass beads; an embossing step in which the heat-resistant layer side is brought into contact with a heated press mold to form an embossment on the operation sheet that conforms to the press mold; and an upper contact forming step in which, following the embossing step, an upper contact is formed on the heat-resistant layer that comes into contact with the contact electrode of the lower contact sheet and conducts electricity. A second solid print may be performed on the display print layer by silk screen printing using ink containing glass beads. In this case, it is preferable to use an ink having opacity such as white ink containing glass beads as the ink for the second solid print.

[0030] In this way, a heat-resistant layer is formed by silk screen printing using ink containing glass beads on the display printing layer or the first solid printing layer, so that when forming an embossment on the operation sheet, even if the operation sheet is brought into contact with a heated press mold, discoloration, deterioration, etc. of the display printing layer of the light-transmitting film can be suppressed. Furthermore, since the upper contact point is formed on the heat-resistant layer of the operation sheet, the overall thickness of the operation sheet can be reduced, the flexibility of the part where pressure is applied is maintained, and the operation feel can be improved. [Effects of the Invention]

[0031] According to the present invention, it is possible to obtain an operation sheet with improved design, functionality and operability, a switch using the operation sheet, and a method for manufacturing the operation sheet. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a longitudinal sectional view showing a layer structure corresponding to one embossed portion in a state in which the operation sheet according to the first embodiment of the present invention is used in a membrane switch. FIG. [Figure 2]10 is a perspective view showing a modified example of printing on the operation sheet of the membrane switch according to the embodiment of the present invention; FIG. [Figure 3] 1. FIG. 4 is a longitudinal cross-sectional view showing a manufacturing process of the operation sheet of the first embodiment in the membrane switch shown in FIG. [Figure 4] 10 is a longitudinal cross-sectional view showing a final manufacturing process of the membrane switch in which the operation sheet of the first embodiment is attached to the lower contact sheet. FIG. [Figure 5] 5A to 5C are vertical cross-sectional views illustrating a manufacturing process of the operation sheet according to the second embodiment of the present invention. [Figure 6] 10 is a longitudinal cross-sectional view showing the final manufacturing process of the membrane switch in which the operation sheet of the second embodiment is attached to the lower contact sheet. FIG. [Figure 7] FIG. 1 is a longitudinal sectional view showing an example of a conventional membrane switch. DETAILED DESCRIPTION OF THE INVENTION

[0033] An operation sheet and a manufacturing method thereof according to the present invention will be described with reference to the drawings, taking an operation sheet for a membrane switch and a manufacturing method thereof as an example. An example in which the operation sheet according to the first embodiment of the present invention is used is shown in FIGS. As shown in Fig. 1, the membrane switch 1 is composed of an operation sheet 11 that is placed on the front side of the housing of an electronic device, etc., and a lower contact sheet 21 on the back side that fits inside the electronic device. In this embodiment, an embossment 11a that gives a clicking sensation when operating keys is applied to the operation sheet 11. This type of membrane switch 1, which is mounted on a general electronic device, is formed with multiple embossments 11a arranged along the surface direction of the operation sheet 11, but Figure 1 shows the layer structure corresponding to one embossment 11a.

[0034] The operation sheet 11 that forms the front side of the membrane switch 1 is constructed by laminating, in order from its top surface to its back side, a light-transmitting film 12, a display printing layer 13, a solid printing layer (first solid printing layer) 14, a heat-resistant layer 15, and an upper contact 16. The light-transmitting film 12 can be made of a flexible resin material such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polyimide, with PET being particularly suitable.

[0035] On the back surface of the light-transmitting film 12, a display print layer 13 containing characters, symbols, patterns, images, etc. that serve as indicators for key input of the membrane switch is formed directly on the light-transmitting film 12. As will be explained later, this display print layer 13 is printed by inkjet color printing means. In this way, an inkjet color printing means is used to print the display print layer 13, and since the diameter of the ink ejection nozzles of the color printing means is generally about 20 μm, the display print layer is formed by dot printing using ink containing particles with a particle size of 20 μm or less. This display print layer 13 is formed on one side of the light-transmitting film 12 by dot printing using an inkjet color printing means using ink containing particles with a particle size of 20 μm or less, so images, gradations, and other shades can be drawn with high precision.

[0036] In addition, a solid print layer 14 is formed by silkscreen printing on the back surface of the display print layer 13. This solid print layer 14 acts as a light reflective layer that prevents light from passing through the display print layer 13 to the back surface side. This solid print layer 14 is generally made of white (ivory) material, but by using ink in which pigments such as black or silver or metallic particles are dispersed in a solvent, it can act as a reflective layer with a variety of different background colors.

[0037] This solid print layer 14 is formed by silk screen printing, and therefore ink containing particles with a particle size of more than 20 μm can be used. For example, the ink for the first solid print layer 14 may contain, in addition to the metallic particles described above, pearl particles, mica particles, silver particles, copper particles, carbon particles, or glass beads. By using these inks, the solid print layer 14 not only functions as a light reflective layer that blocks light from passing through the display print layer 13 to the back side, but also enhances the design.

[0038] The heat-resistant layer 15, which is a second solid printing layer formed on the back side of the solid printing layer 14, reduces the degree to which heat from the heated press mold applied to the display printing layer 13 when embossing 11a on the upper operation sheet 11. The heat-resistant layer 15 is used mainly to prevent the display print layer 13 from being damaged by heat, since the display print layer 13 obtained by inkjet printing is weak against heat. A specific example of the heat-resistant layer 15 will be described later, but preferably, COS ink containing glass beads is used, and this is formed as a solid print layer by silk screen printing.

[0039] The heat-resistant layer 15 made of COS ink (ink containing glass beads) not only provides a heat-shielding effect to the display printing layer 13, but also contributes to improving the adhesion of the carbon material when forming the upper contact 16 using carbon ink (carbon printing) on ​​the back surface of this heat-resistant layer 15. Therefore, the heat-resistant layer 15 made of COS ink can avoid the problem of the upper contact 16, which is formed by carbon printing, peeling off from the heat-resistant layer 15 even in membrane switches that do not have an embossment 11a, thereby contributing to improving the durability of the upper contact 16. The upper contact 16 is formed at the center inner bottom of the back side of the embossment 11a in a state of being in close contact with the back surface of the heat-resistant layer 15. In this way, since the upper contact 16 is formed on the heat-resistant layer 15 of the operation sheet 11, the overall thickness of the operation sheet can be reduced, the flexibility of the part where pressing is performed is maintained, and the operation feel as a membrane switch can be improved.

[0040] On the other hand, the lower contact sheet 21 that forms the back side of the membrane switch 1 is composed of, as shown in Figure 1, a base film 22, a circuit pattern 23 formed on the base film 22, and a resist printing layer 24 for circuit protection that covers most of the circuit pattern except for necessary parts of the circuit pattern 23, laminated in this order from the back side to the top side. A first double-sided adhesive tape 25 is patterned and adhered to the upper surface of the resist printing layer 24, and a second double-sided adhesive tape 26 is adhered to the back side of the base film 22 so as to cover the entire back surface of the base film 22.

[0041] The circuit pattern 23 formed on the base film 22 is formed by silk printing using silver ink, and the circuit pattern 23 has a first contact electrode 23a and a second contact electrode 23b formed facing each other in the surface direction. In addition, the resist printing layer 24 is formed by silk printing using insulating ink, and the upper surfaces of the first contact electrode 23a and the second contact electrode 23b are avoided by the resist printing, leaving the first and second contact electrodes 23a, 23b exposed.

[0042] Therefore, by placing the operation sheet 11 on the lower contact sheet 21, the two are bonded together with the first double-sided adhesive tape 25 to form the membrane switch 1. At this time, the upper contact 16 on the operation sheet 11 side is positioned directly above the gap between the first contact electrode 23a and the second contact electrode 23b formed on the circuit pattern 23. Then, the membrane switch 1 can be attached to the housing surface of the electronic device using the second double-sided adhesive tape 26 attached to the back surface of the lower contact sheet 21.

[0043] With this membrane switch 1, pressing (key input) the embossed portion 11a of the operation sheet 11 causes the operation sheet 11 to bend, and the first lower contact 23a and the second lower contact 23b are brought into conduction with a click action via the upper contact 16. This allows electricity to flow through the circuit pattern 23 formed on the lower contact sheet 21.

[0044] In the above embodiment, the solid print layer 14 is formed on the display print layer 13 of the light-transmitting film 12 of the operation sheet 11, but the solid print layer 14 may be formed as needed, and it is not necessary to form the solid print layer 14 over the entire display print layer 13. In other words, the solid print layer 14 may be formed in a partial area of ​​the display print layer 13 where the solid print layer 14 is required. 2, a solid print layer 14 may be formed by solid printing using ink containing ink-containing particles having a particle size exceeding 20 μm in an area 11B on the same surface of the operation sheet 11 as the display print layer 13, where the display print layer is not formed. The solid print layer 14 in this area 11B can enhance the design. Furthermore, the ink used for solid printing in area 11A where the display printing layer is formed and the ink used for solid printing in area 11B where the display printing layer is not formed do not necessarily have to be the same ink, and different inks may be used taking into consideration design and functionality.

[0045] Next, FIGS. 3 and 4 illustrate the manufacturing process of the membrane switch 1, and in particular, FIGS. 3(A) to 3(E) show the lamination process of the operation sheet 11. FIG. First, Figure 3(A) shows the display printing process in which a display printing layer 13 such as letters, symbols, or patterns that serve as indicators for key input operations is printed on the back of a light-transmitting film 12 (preferably the PET film already described). For this purpose, a color printing means using an inkjet method is used to print directly onto the light-transmitting film 12 in a non-contact state.

[0046] FIG. 3(A) shows a schematic diagram of an inkjet head He, which is arranged so that ink droplets of at least cyan, magenta, yellow, and black are ejected toward the back surface of the light-transmitting film 12 by individual drive. The inkjet head He moves along a carriage (not shown) in the direction of the arrow, and the light-transmitting film 12 is scanned and fed line by line in a direction perpendicular to the surface of Figure 3(A), thereby forming a display printing layer 13 on the back of the light-transmitting film 12, which contains characters, symbols, patterns, images, etc. that serve as indicators for key input operations.

[0047] In color printing using this inkjet method, printing is performed on the light-transmitting film 12 by a collection of dots made of ink of at least the colors cyan, magenta, yellow, and black, as described above. In this case, an example of ink that is particularly suitable when a PET film is used as the light-transmitting film 12 that is the printing substrate will be given below. Manufacturer / Distributor: Mimaki Engineering Co., Ltd. Product Name: LUS-120 Product Numbers: LUS12-K-BA-3 (Black), LUS12-C-BA-3 (Cyan), LUS12-W-BA-3 (White), LUS12-Y-BA-3 (Yellow), LUS-12-M-BA-3 (Magenta). These inks contain acrylic acid ester (monomer), titanium oxide (pigment), and vinyl compound (photopolymerization initiator) in their ink composition, which is preferable in terms of high coating strength and quick drying. In this case, the display print layer 13 is formed to a thickness of 30 μm to 40 μm.

[0048] FIG. 3(B) shows a solid printing step in which a solid print layer 14 is further applied to the back surface of the display print layer 13. As already explained, this solid print layer 14 functions as a light reflective layer that prevents light from passing through to the back side through the display print layer 13. Therefore, the solid print layer 14 is laminated at least on the area on the back side of the display print layer where concealment is required. The background color of the display print layer 13 can be selected by selecting the printing material, and this solid print layer 13 is preferably applied to the back side of the display print layer 13 by silk screen printing.

[0049] 3(B) shows a squeegee Sq used in silk screen printing moving in the direction of the arrow. During silk screen printing, the squeegee Sq presses ink on a screen (not shown) placed on the back surface of the display printing layer 13 against the display printing layer 13 while moving in the direction of the arrow, thereby performing printing. The thickness of the solid print layer 14 at this time is preferably 12 to 30 μm. The thickness of the film printed by moving the squeegee Sq in the direction of the arrow is about 4 to 10 μm, and since it is generally applied three times, the thickness of the solid print layer 14 is 12 to 30 μm.

[0050] A wide variety of printing materials are available for the solid print layer 14, depending on the color and whether or not it has gloss. For example, white ink or black ink can be used as the ink for the solid print layer 14, and ink containing metallic particles, pearl particles, mica particles, silver particles, copper particles, carbon particles, or glass beads can also be used. For example, examples of white ink and black ink include (1) color: white, manufactured and sold by: Teikoku Ink Mfg. Co., Ltd., product name: EG Ink, product number: 611 White, and (2) color: black, manufactured and sold by: Teikoku Ink Mfg. Co., Ltd., product name: EG Ink, product number: 911 Black.

[0051] FIG. 3(C) shows a heat-resistant layer forming step in which a heat-resistant layer 15 is further formed on the back surface of the solid print layer 14. In this heat-resistant layer forming process, as described above, a COS ink containing glass beads can be suitably used, and this COS ink is applied by silk screen printing to the back surface of the solid print layer 14. Note that Figure 3(C) also shows the movement of the squeegee Sq used in silk screen printing in the direction of the arrow, and the printing operation is the same as the example explained based on Figure 3(B).

[0052] The glass beads contained in the COS ink have an average particle size of about 27 to 35 μm, and these glass beads have heat resistance, scratch resistance, and the ability to prevent blocking (a phenomenon in which stacked printed items stick to each other due to the tackiness of the ink, a cause of manufacturing defects).The thickness of this heat-resistant layer 15 is preferably 20 to 30 μm.

[0053] A preferred example of COS ink that can be used as the printing material for the heat-resistant layer 15 is manufactured and sold by Teikoku Ink Mfg. Co., Ltd., product name: COS Matte Clear (C), product number: COS-200 Matte Clear (C).

[0054] FIG. 3(D) shows an example of an embossing step that follows the heat-resistant layer forming step. In this embossing process, a press die 18 heated to 80 to 100°C is used, and the heat-resistant layer 15 formed in the previous process is brought into contact with the heated press die 18 to form an embossment 11a along the press die 18 in the semi-finished operation sheet 11. In this embodiment, the embossment 11a is formed in a truncated cone shape along the outer shape of the press die 18, but by changing the outer shape of the press die 18, for example, the embossment 11a can be formed in a dome shape.

[0055] FIG. 3(E) shows the upper contact film formation step that follows the embossing step described above. As already explained, this upper contact film formation process involves forming upper contacts 16 by silkscreen printing using carbon ink on the heat-resistant layer 15 at the center inner bottom of the back side of the embossment 11a. Note that Fig. 3(E) also shows how the squeegee Sq used in silkscreen printing moves in the direction of the arrow, and the printing operation is the same as the example explained based on Fig. 3(B).

[0056] The above describes the manufacturing process of the operation sheet 11 having the embossment 11a, but in the case of a model in which the embossment 11a is not required, the embossing formation process shown in Figure 3 (D) can be omitted to obtain an operation sheet 11 without the embossment.

[0057] FIG. 4 shows in vertical cross section the final manufacturing process of the membrane switch, in which the operation sheet 11 is mounted on the lower contact sheet 21. In this final manufacturing process, as already explained based on Figure 1, the first double-sided adhesive tape 25 is attached to the upper surface of the lower contact sheet 21, and the operation sheet 11 is placed on top of the lower contact sheet 21, so that the two are bonded together by the first double-sided adhesive tape 25, thereby forming the membrane switch 1. As already explained, this membrane switch 1 can be attached to the surface of the housing of an electronic device by using the second double-sided adhesive tape 26 attached to the back surface of the lower contact sheet 21.

[0058] Next, FIGS. 5 and 6 show a manufacturing process of an operation sheet according to a second embodiment of the present invention, and an example in which the operation sheet according to the second embodiment is attached to a lower contact sheet to form the membrane switch 1. 5 and 6, the parts corresponding to the operation sheet 11 and the lower contact sheet 21 of the first embodiment already described are denoted by the same reference numerals, and therefore detailed description thereof will be omitted as appropriate.

[0059] The operation sheet 11 of this second embodiment is specifically designed to reduce the degree to which heat from a heated press mold is applied to the display printing layer 13 when embossing 11a on the operation sheet 11. As already explained, in the operation sheet 11 of the first embodiment, a heat-resistant layer 15 is applied and measures are taken to reduce the degree to which heat from the press mold 18 is applied to the display printing layer 13 when the embossment 11a is formed on the operation sheet 11. In the illustrated example, the heat-resistant layer 15 is shown in contact with a heated convex press mold 18, but in reality, there is also a concave upper mold that contacts the upper side of the light-transmitting film 12 opposite the press mold 18 shown in the figure.

[0060] For this reason, the applicant has verified that heat from the upper mold is applied to the display print layer 13 through the light-transmitting film 12, causing damage to the display print layer 13 due to heat. Therefore, the configuration of the operation sheet 11 of the second embodiment is based on the above-mentioned verification results, and is characterized in that a light-transmitting heat-resistant layer 17 is further arranged between the light-transmitting film 12 and the display printing layer 13 in the operation sheet 11 of the first embodiment.

[0061] (A) to (F) shown in FIG. 5 show the laminating process of the operation sheet 11 of the second embodiment. First, Figure 5(A) shows the printing process of the light-transmitting heat-resistant layer 17, in which the light-transmitting heat-resistant layer 17 is formed on the back surface of the light-transmitting film 12 (preferably the PET film already described) by silk screen printing means. Medium ink is used as the printing ink in the printing process of this light-transmitting heat-resistant layer 17. As mentioned above, this medium ink does not contain pigments that are the elements of color, and by silkscreen printing using this medium ink, a colorless and transparent light-transmitting layer can be formed.

[0062] Therefore, the display printing layer 13 formed on the light-transmitting heat-resistant layer 17 in a subsequent process using an inkjet color printer can be clearly seen through the medium ink printing layer (light-transmitting heat-resistant layer 17) and the light-transmitting film 12. Furthermore, the colorless and transparent printing layer can function as a heat-resistant layer, and when the operation sheet 11 is embossed in a later process, discoloration, deterioration, etc. due to heat applied to the display printing layer 13 through the light-transmitting film 12 can be effectively suppressed.

[0063] 5(A) shows the state in which the squeegee Sq used in silk screen printing moves in the direction of the arrow. As already explained in the manufacturing process of the operation sheet shown in FIG. 3, this is because the ink on the screen (not shown) placed on the back surface of the light-transmitting film 12 is pressed against the light-transmitting film 12 while moving in the direction of the arrow, thereby performing printing. The thickness of the silk screen printing using medium ink is preferably 4 to 10 μm. Preferred examples of the medium ink include Teikoku Ink Mfg. Co., Ltd., product name: Medium, product number: MIX-HF000, and Teikoku Ink Mfg. Co., Ltd., product name: Victoria, product number: MIX-HF001.

[0064] FIG. 5(B) shows a display printing step of printing a display print layer 13 such as characters, symbols, or patterns that serve as indicators for key input operations on the back surface of the light-transmitting heat-resistant layer 17. For this purpose, inkjet color printing is used to perform printing in a non-contact state on the light-transmitting heat-resistant layer 17. This display printing process is the same as the display printing process shown in Fig. 3(A) already described, and therefore its description will be omitted.

[0065] 5(C) shows a solid printing process in which a solid printing layer 14 is further applied to the back surface of the display printing layer 13. This solid printing layer 14 functions as a light reflective layer that prevents light from passing through the display printing layer 13 to the back surface side. This solid printing step is the same as the solid printing step shown in FIG. 3(B) already described, and therefore its description will be omitted. 5(D) shows a heat-resistant layer forming step in which a heat-resistant layer 15 is further formed on the back surface of the solid print layer 14. In this heat-resistant layer forming step, a COS ink containing glass beads is formed by silk screen printing. This heat-resistant layer forming step is the same as the heat-resistant layer forming step shown in FIG. 3(C) already described, and therefore its description will be omitted.

[0066] Figure 5(E) shows an example of an embossing process following the heat-resistant layer forming process, in which the semi-finished operation sheet 11 is brought into contact with a heated press die 18 to form an embossment 11a along the press die 18. This embossing step is the same as the embossing step shown in FIG. 3(D) already described, and therefore its description will be omitted. Figure 5(F) shows the upper contact film formation process that is carried out following the emboss formation process described above. In this upper contact film formation process, an upper contact 16 is formed on the heat-resistant layer 15 at the central inner bottom of the back side of the embossment 11a by silkscreen printing using carbon ink. This upper contact film forming step is the same as the upper contact film forming step shown in FIG. 3(E) already described, and therefore its description will be omitted.

[0067] According to the operation sheet 11 of the second embodiment obtained by the manufacturing process described above, the display printing layer 13, which indicates key input, receives heat-shielding effects from the heat-resistant layer 15 containing glass beads on the one hand and the light-transmitting heat-resistant layer 17 made of medium ink on the other hand, thereby significantly reducing the degree of damage caused by heat during embossing. This makes it possible to provide an operation sheet having a display print layer 13 that takes advantage of the characteristics of inkjet color printing means, which can draw images and gradations with high precision.

[0068] FIG. 6 is a vertical cross-sectional view showing the final manufacturing process of the membrane switch, in which the operation sheet 11 obtained by the manufacturing process shown in FIG. 5 is mounted on the lower contact sheet 21. In this final manufacturing process, as already explained based on Figure 1, the first double-sided adhesive tape 25 is attached to the upper surface of the lower contact sheet 21, and the operation sheet 11 is placed on top of the lower contact sheet 21, so that the two are bonded together by the first double-sided adhesive tape 25, thereby forming the membrane switch 1. The membrane switch 1 can be attached to the surface of the housing of an electronic device by using the second double-sided adhesive tape 26 attached to the back surface of the lower contact sheet 21.

[0069] As described above, according to the operation sheet and its manufacturing method of the present invention, letters, symbols, patterns, images, etc. that serve as indicators for key input of the membrane switch can be printed by inkjet printing means on the back of the light-transmitting film that constitutes the operation sheet, or on the back of the light-transmitting heat-resistant layer formed on the light-transmitting film, thereby realizing markings similar to high-resolution photographic printing. Then, by forming a solid print layer using ink containing metallic particles, pearl particles, mica particles, etc. in the area on the back of the operation sheet where the display print layer is not formed, the design effect of the area where the display print layer is not formed can be enhanced. Also, since the solid print layer is laminated on at least a part of the display print layer of the light-transmitting film, the back side of the display print layer can be concealed, and the back side of the printed surface can be prevented from being seen through.

[0070] In the above embodiment, an operation sheet for a membrane switch has been described as an example, but the operation sheet according to the present invention is not limited to an operation sheet for a membrane switch. For example, it can also be suitably used for a so-called tactile switch operation sheet, in which a tactile switch is mounted on a substrate, an operation sheet is placed on its surface (top surface), and pressing the operation sheet presses the tactile switch placed below the operation sheet. [Explanation of symbols]

[0071] 1 membrane switch 11 Operation sheet 11a Emboss 12 Light-transmitting film 13 Display printing layer 14 Solid printing layer (first solid printing layer) 15 Heat-resistant layer (second solid printing layer) 16 Upper Contact 17 Light-transparent heat-resistant layer 18 Press mold 21 Lower contact sheet 22 Base film 23 Circuit Pattern 23a 1st grounding electrode 23b 2nd contact electrode 24 Resist printing layer 25 First double-sided adhesive tape 26 Second double-sided adhesive tape He inkjet head Sq Squeegee

Claims

1. An operation sheet on which characters, symbols, patterns, etc. are displayed as indicators of key input, and which is used for a switch that energizes by contacting a contact electrode in response to a key input operation, A display print layer of characters, symbols, patterns, images, etc., which are formed by dot printing using ink on one side of the light-transmitting film and serve as an indicator of key input of the switch; a first solid print layer formed by solid printing using ink, the first solid print layer being formed in an area on the same surface of the light-transmitting film as the surface on which the display print layer is formed, where the display print layer is not formed, or being laminated and formed on at least a part of the display print layer of the light-transmitting film; An operation sheet comprising:

2. An operation sheet on which characters, symbols, patterns, etc. are displayed as indicators of key input, and which is used for a switch that energizes by contacting a contact electrode in response to a key input operation, a light-transmitting heat-resistant layer formed by solid printing using ink on one surface of the light-transmitting film; a display print layer formed on the light-transmitting heat-resistant layer by dot printing using ink, the display print layer including characters, symbols, patterns, images, etc., which serve as indicators for key input of the switch; a first solid print layer formed by solid printing using ink, the first solid print layer being formed in an area on the same surface as the surface on which the display print layer of the light-transmitting heat-resistant layer is formed, where the display print layer is not formed, or being laminated and formed on at least a part of the display print layer of the light-transmitting heat-resistant layer; An operation sheet comprising:

3. 3. The operation sheet according to claim 2, wherein the ink for the light-transmitting heat-resistant layer is a medium ink.

4. the ink of the display print layer is an ink containing particles having a particle size of 20 μm or less, 3. The operation sheet according to claim 1, wherein the first solid print layer is an ink containing particles having a particle size of more than 20 [mu]m.

5. 3. The operation sheet according to claim 1, wherein the ink of the first solid print layer contains any one of metallic particles, pearl particles, mica particles, silver particles, copper particles, carbon particles, and glass beads.

6. a second solid print layer formed on the display print layer for characters, symbols, patterns, images, etc., which serve as an indicator of key input, or formed on the first solid print layer; 3. The operation sheet according to claim 1, wherein the second solid print layer is a heat-resistant layer containing glass beads formed from ink containing glass beads.

7. The operation sheet according to claim 6, characterized in that an embossment is formed on the operation sheet to give a clicking sensation to the key input operation, and the second solid print layer is formed in the area where the embossment is formed.

8. A switch constructed using the operation sheet according to any one of claims 1 to 7.

9. A method for manufacturing an operation sheet used for a switch that energizes by contacting a contact electrode in response to a key input operation, comprising: a display printing step of forming a display printing layer such as characters, symbols, patterns, or images serving as indicators of key input of the switch on one side of the light-transmitting film of the operation sheet by a color printing means using an inkjet method; a first solid print layer forming step of forming a solid print layer by silk screen printing means in an area on the side of the light-transmitting film on which the display print layer is formed, where the display print layer is not formed, or in at least a part of the display print layer of the light-transmitting film; A method for manufacturing an operation sheet, comprising:

10. A method for manufacturing an operation sheet used for a switch that energizes by contacting a contact electrode in response to a key input operation, comprising: a printing step of forming a light-transmitting heat-resistant layer on one surface of the light-transmitting film of the operation sheet by silk screen printing means; a display printing step of forming a display printing layer such as characters, symbols, patterns, or images that serve as indicators for key input of the switch on the light-transmitting heat-resistant layer by a color printing means using an inkjet method; a first solid print layer forming step of forming a solid print layer by silk screen printing in an area where the display print layer is not formed on the surface of the light-transmitting heat-resistant layer on which the display print layer is formed, or in at least a part of the display print layer of the light-transmitting heat-resistant layer; A method for manufacturing an operation sheet, comprising:

11. the ink of the display print layer is an ink containing particles having a particle size of 20 μm or less, 11. The method for manufacturing an operation sheet according to claim 9, wherein the first solid print layer is an ink containing particles having a particle size of more than 20 [mu]m.

12. Following the first solid print layer forming step, a heat-resistant layer forming step of forming a heat-resistant layer, which is a second solid print layer, on the display print layer or the first solid print layer by silk screen printing using an ink containing glass beads; an embossing step of bringing the heat-resistant layer side into contact with a heated press die to form an embossment on the operation sheet along the press die; an upper contact forming step of forming an upper contact on the heat-resistant layer, the upper contact being in contact with the contact electrode of the lower contact sheet to conduct electricity, following the embossing step; The method for manufacturing an operation sheet according to claim 9 or 10, further comprising:

Images