JP2006068946A - Printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing plate which can minimize a difference in the width of a printing paste printed in stripes in a printing start position and a printing end position, when a striped printing pattern is printed. <P>SOLUTION: This printing plate has the striped printing pattern which gradually diminishes to a regular printing pattern 30 printed on a face substrate 60 from the printing start position to the printing end position XE. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing plate used in a screen printing method.

  2. Description of the Related Art In recent years, various flat-type image display devices have attracted attention as next-generation lightweight and thin display devices that replace cathode ray tubes (hereinafter referred to as CRTs). For example, as a type of field emission display (hereinafter referred to as FED) used as a flat display device, development of a display device (hereinafter referred to as SED) including a surface conduction electron-emitting device as an electron source is being promoted. ing.

  The SED includes a front substrate and a rear substrate that are arranged to face each other at a predetermined interval, and these substrates constitute a vacuum envelope by joining peripheral portions to each other through a rectangular frame-shaped side wall. Yes. Three color phosphor layers are formed on the inner surface of the front substrate, and on the inner surface of the rear substrate, a large number of electron-emitting devices corresponding to each pixel are arranged as an electron source for exciting and emitting the phosphor. . Each electron-emitting device includes an electron-emitting portion and a pair of electrodes that apply a voltage to the electron-emitting portion. A metal back layer is formed on the phosphor layer formed on the front substrate, and a getter layer is further formed thereon.

  An anode voltage is applied to the phosphor screen through a metal back layer, and the electron beam emitted from the electron-emitting device is accelerated by the anode voltage and collides with the phosphor screen, so that the phosphor emits light and an image is displayed. The In this case, the anode voltage applied to the phosphor screen is about 10 kV.

  Further, the gap between the front substrate and the rear substrate cannot be made too large from the viewpoint of resolution, characteristics of the support member, etc., and needs to be set to about 1 to 2 mm. Therefore, in the SED, it is inevitable that a strong electric field is formed in a small gap between the front substrate and the rear substrate, and there is a possibility that discharge (dielectric breakdown) occurs between the two substrates.

  When discharge occurs, a current of 100 A or more may flow instantaneously, which may cause destruction or deterioration of the electron-emitting device and the phosphor screen, and further destruction of the drive circuit. These are collectively referred to as discharge damage. Such a discharge that leads to the occurrence of a defect is not allowed as a product. Therefore, in order to put SED into practical use, it must be configured so that damage due to discharge does not occur for a long period of time. However, it is very difficult to completely suppress the discharge over a long period of time.

  Thus, a technique is disclosed in which the metal back is divided into a plurality of elongated strip-shaped regions so that the influence on the electron-emitting device can be ignored even if discharge occurs (see Patent Document 1).

As a method of dividing the metal back into strips, for example, a striped chemical cut agent (CC agent) is printed in advance on the region to be divided, and Al is vapor-deposited thereon and oxidized at the site of the CC agent. Thus, a method of electrically dividing the Al film into strips is known.
Japanese Patent Laid-Open No. 10-326583

  When the metal back is formed in a strip shape, it is important to make the stripe width uniform in order to make the electrical characteristics of each pixel uniform. That is, when the CC agent described above is used, it is important to form the CC agent with a uniform width. When the printing width of the CC agent is non-uniform, the electrical characteristics of each pixel are non-uniform and display unevenness occurs.

  However, in the screen printing in which the CC agent printing paste is pressed against the screen of the printing plate with a squeegee, the printing paste is reduced in viscosity due to stress caused by the movement of the squeegee or the applied pressure. For this reason, there is a problem that the CC agent that has passed through the printing plate is leaked and spreads beyond the ideal printing area on the printing medium. In particular, as described above, when the striped CC agent is printed, if the CC agent that has passed through the printing plate is spread on the substrate, the CC agent having a non-uniform width is printed, and each pixel is printed. There is a problem in that the electrical characteristics of the display become non-uniform and display unevenness occurs.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a printing plate capable of printing an elongated stripe pattern with a uniform width by screen printing.

  In order to achieve the above object, the printing plate of the present invention has a printing pattern including an elongated opening in a direction in which the squeegee moves, and the width of the opening is lower than the upper side along the moving direction of the squeegee. It is characterized by narrowing.

  In order to achieve the above object, the printing plate of the present invention has a printing pattern in which a plurality of openings elongated in the first direction in which the squeegee moves are arranged in a second direction intersecting the first direction. And the frame holding the screen, the opening is from the upper side to the lower side in the first direction, compared to a regular printing pattern to be printed on the printing medium, The opening is located at the center of the screen along the second direction, and the opening reduction ratio is the largest. The closer to the frame, the opening reduction ratio gradually decreases. It is characterized by being.

  In order to achieve the above object, a printing plate of the present invention is a printing plate for printing an elongated uniform width pattern extending along a moving direction of a squeegee on a printing medium, for forming the pattern. And a width of the opening is narrower on the downstream side than the upstream side along the moving direction.

  According to the present invention, an elongated striped pattern can be printed with a uniform width by screen printing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, an SED manufactured using the printing plate according to the present embodiment will be described.

  FIG. 1 is a schematic perspective view of a display panel of an SED. As shown in FIG. 1, the display panel 50 of the SED is a rectangle that is long in the direction of arrow X, and includes a front substrate 60 and a rear substrate 70 each made of a rectangular glass plate, and these substrates have a certain gap. And are arranged opposite to each other. The distance between the substrates is set to about 1.0 to 2.0 mm. The front substrate 60 and the rear substrate 70 are joined to each other at peripheral edges via a rectangular frame-shaped side wall 81 made of glass, thereby forming a flat vacuum envelope having a vacuum inside.

  As shown in FIG. 2, a phosphor screen 62 that functions as an image display surface is formed on the inner surface of the front substrate 60. The phosphor screen 62 includes a light shielding layer 64 formed in a stripe shape extending long in the direction of the arrow X shown in FIG. 1 and red, green, and red stripes formed between the light shielding layers 64. And blue phosphor layers R, G, and B. The stripe-shaped light shielding layer 64 and the phosphor layers R, G, and B are arranged in parallel to the arrow X direction.

  A metal back layer 66 made of aluminum or the like is formed on the phosphor screen 62. The metal back layer 66 functions as an anode electrode when a predetermined anode voltage is applied during a display operation. Further, a getter layer 68 is formed on the metal back layer 66 to adsorb gas particles in the vacuum envelope that cause ion bombardment to increase the degree of vacuum in the vacuum envelope.

  More specifically, the metal back layer 66 includes an oxidized region 66A formed on the light shielding layer 64 and a non-oxidized region 66B formed on the phosphor layers R, G, and B. The getter layer 68 includes a getter cut region 68A formed on the position corresponding to the light shielding layer 64, that is, the oxidized region 66A, and a position corresponding to the phosphor layers R, G, and B, that is, on the non-oxidized region 66B. The getter region 68B is formed.

  That is, the non-oxidized region 66B of the metal back layer 66 is formed in an elongated stripe shape, extends parallel to each other with a predetermined interval, and is mainly positioned to overlap the phosphor layers R, G, and B. . The oxidized region 66A is formed in a stripe shape, and is formed on the light shielding layer 64 between the non-oxidized regions 66B. It is desirable that the oxidized region 66A does not protrude to the phosphor layers R, G, B side, and a part of the non-oxidized region 66B is also formed on the light shielding layer 64 in order to take a margin. Is preferred.

  In the oxidized region 66A, a chemical cut agent (CC agent) is printed on the light shielding layer 64, and then aluminum is vapor-deposited on the front surface including the non-oxidized region 66B and baked to oxidize only the portion of the CC agent. It is formed by.

  On the inner surface of the rear substrate 70, a number of surface conduction electron-emitting elements 72 that emit electron beams are provided as electron sources for exciting and emitting the phosphor layers R, G, and B of the phosphor screen 62. ing. These electron-emitting devices 72 are arranged in a plurality of columns and a plurality of rows corresponding to each pixel. Each electron-emitting device 72 includes an electron emitting portion (not shown) and a pair of device electrodes for applying a voltage to the electron emitting portion. In addition, on the inner surface of the back substrate 70, a large number of wirings 82 for supplying a voltage to the electron-emitting devices 72 are provided in a matrix shape, and end portions thereof are drawn out of the display panel 50.

  The side wall 81 that functions as a bonding member is sealed to the peripheral edge of the front substrate 60 and the peripheral edge of the back substrate 70 by, for example, a sealing material 83 such as low melting glass or low melting metal, and these substrates are bonded to each other. is doing.

  The display panel 50 includes a plurality of rectangular plate-like spacers 74 disposed between the front substrate 60 and the rear substrate 70. The spacers 74 are arranged in a stripe shape, abut against the inner surfaces of the front substrate 60 and the rear substrate 70 so as not to interfere with each electron-emitting device 72 and the phosphor layers R, G, B, and act on these substrates. The atmospheric pressure load is supported, and the distance between the substrates is maintained at a predetermined value. The shape of the spacer is not limited to this, and may be a number of columnar spacers, for example.

  When displaying an image, the electron-emitting device 72 is driven through the wiring 82 to emit an electron beam from an arbitrary electron-emitting device, and an anode voltage is applied to the phosphor screen 62 through the metal back layer 66. The electron beam emitted from the electron emitter 72 is accelerated by the anode voltage and collides with the phosphor layers R, G, and B of the phosphor screen 62. Thereby, the corresponding phosphor layers R, G, and B are excited to emit light and display an image.

  As described above, in the metal back layer 66, the adjacent non-oxidized regions 66B are electrically divided by the plurality of oxidized regions 66A. Therefore, even when a discharge occurs between the front substrate 60 and the rear substrate 70, the discharge current at that time can be sufficiently reduced. Therefore, damage due to discharge of the phosphor layers R, G, B and the electron-emitting device 72 can be suppressed.

  The oxidized region 66B means a region oxidized in the layer thickness direction from one surface of the metal back layer 66 to the other surface, and the non-oxidized region 66A does not mean that there is no oxidation at all. Only the surface layer of the metal back layer 66 means a naturally oxidized region.

  Next, the printing plate of the present invention will be described.

  FIG. 3 is a schematic diagram of a printing plate according to the present invention, and FIG. 4 is a schematic diagram for explaining the printing plate shown in FIG. 3 in more detail.

  As shown in FIG. 3, the printing plate 10 includes a rectangular frame 11 and a screen 12 stretched inside the frame 11 with a certain tension.

  The frame 11 has a rectangular shape that is long in the arrow X direction. The arrow X direction shown in FIG. 3 corresponds to the arrow X direction shown in FIG.

  The screen 12 is formed by forming a printing pattern having a plurality of stripe-shaped openings extending in the arrow X direction on a mesh material formed by knitting metal wires such as stainless steel in a mesh shape. This print pattern is formed by removing the photosensitive resin fixed to the entire surface of the screen 12 in a desired pattern. In the present embodiment, the print pattern formed on the screen 12 is a print pattern for forming the oxidized region 66A shown in FIG. 2 and is formed at a position corresponding to the light shielding layer 64.

  More specifically, the screen 12 includes a pattern 21 formed at a position close to the frame body 11 in an arrow Y direction orthogonal to the arrow X direction, a pattern 22 formed at a central position in the arrow Y direction, and an arrow Y And a pattern 23 formed at a position between the pattern 21 and the pattern 22 in the direction.

  The lengths of the patterns 21-23 in the arrow Y direction, that is, the stripe widths, respectively, are shown in FIG. 4 along the arrow X1 direction from one end side XS toward the other end side XE. It is getting narrower gradually. The arrow X1 direction is a moving direction in which the squeegee moves while being pressed against the screen 12 when the printing plate 10 is used in the screen printing apparatus, which will be described in detail later. That is, one end side XS is a printing start position, and the other end side XE is a printing end position.

  More specifically, the patterns 21 to 23 are changed from one end side XS to the other end side XE with respect to a regular print pattern 30 (shown by a broken line in FIG. 4) printed on the substrate. On the other hand, the stripe width is reduced. The regular print pattern 30 is an ideal print pattern that is desired to be printed on the printing medium, and has a uniform width along the arrow X direction as shown in FIG. The regular print pattern 30 in the present embodiment is formed at a position corresponding to the light shielding layer 64 shown in FIG. 2, and the printing paste (CC agent) printed on the front substrate 60 through the opening is formed by the light shielding layer. The overall size is slightly smaller than the light shielding layer 64 so as not to protrude from 64.

  More specifically, the width of the opening of the pattern 21 located at the end of the screen 12 is such that the width D1 on the other end side XE of the print end position is 1 / P times the width DY of the regular print pattern 30. In this way, it is formed so as to be gradually reduced from one end side XS to the other end side XE. Further, the width of the opening of the pattern 23 is from one end side XS so that the width D2 on the other end side XE of the printing end position is 1 / Q times the width DY of the regular print pattern 30. It is formed so as to be gradually reduced toward the other end side XE. Further, the width of the opening of the pattern 22 located at the center of the screen 12 is such that the width D3 on the other end side XE of the printing end position is 1 / R times the width DY of the regular print pattern 30. It is formed so as to be gradually reduced from one end side XS toward the other end side XE. These P, Q, and R are numerical values larger than 1, and a relationship of P> Q> R is established between them.

  Thus, the screen 12 has a plurality of tapered openings parallel to each other at the position corresponding to the regular print pattern 30 and narrowing from one end side XS to the other end side XE. Are arranged side by side. Among these openings, the opening of the pattern 22 arranged in the center in the arrow Y direction has a small reduction rate toward the other end XE, and the reduction rate increases as the frame body 11 is approached in the arrow Y direction. Go. That is, as in the present embodiment, when the regular print patterns 30 each have a uniform stripe width, the stripe width on the other end side XE of the central pattern 22 is the largest, It gradually becomes narrower as it approaches the frame 11.

  Next, a method for forming the oxidized region 66A shown in FIG. 2 using the printing plate 10 shown in FIG. 4 will be described with reference to FIG.

  As shown in FIG. 5, the screen printing apparatus that can be used in the present embodiment includes a squeegee S that is moved in the direction of the arrow X1 while pressing the screen 12 of the printing plate 10 against the front substrate 60 that is the printing medium. It includes a mounting table 91 on which the front substrate 60 is mounted, and a support body 92 that fixes and supports the printing plate 10 disposed to face the mounted front substrate 60 at a predetermined position.

  The front substrate 60 is positioned and arranged on the mounting table 91 so that the striped light shielding layer 64 extending in the arrow X direction and the arrow X1 that is the moving direction of the squeegee S are parallel to each other. The printing plate 10 is aligned at a position corresponding to the front substrate 60 and fixed to the support 92. That is, the printing plate 10 is aligned so that the opening of the printing pattern formed on the screen 12 of the printing plate 10 corresponds to the light shielding layer 64. A CC agent (for example, a silica-based paste) is supplied as a printing paste from the side of the screen 12 where the squeegee S comes into contact to the upper side in the moving direction of the squeegee S of the stripe-shaped printing pattern. The supplied CC agent is pushed out to the surface side of the front substrate 10 through the pattern 21-23 by the squeegee S moved in the direction of the arrow X1, and is printed on the light shielding layer 64 with a uniform width.

Thus, since the CC agent supplied to the screen 12 passes through the screen 12 and is printed on the front substrate 60 along with the movement of the squeegee S, it is moved on the screen at the same time.
The CC agent on the screen 12 is rotated by the squeegee S. In other words, the CC agent receives shear stress from the squeegee S. For this reason, the viscosity of the CC agent decreases as the shear stress from the squeegee S increases. The printing paste with reduced viscosity is printed on the front substrate 60 after being printed on the front substrate 60, and spreads more than the printing pattern of the printing paste with higher viscosity. For this reason, the printed CC agent has a wider stripe width at the print end position than the stripe width at the print start position, and the CC agent having a non-uniform width is printed.

  However, the printing plate 10 according to the present invention includes the screen 12 in which the printing pattern is reduced from the upper side toward the lower side along the moving direction of the squeegee S. Therefore, by adjusting the numerical values of P, Q, and R related to the reduction ratio of the pattern 21-23 formed on the screen 12, the squeegee S made of the printing paste whose viscosity has changed is moved in the lower side of the moving direction. The difference in stripe width between the printing pattern and the printing pattern on the upper side in the moving direction of the squeegee S can be substantially eliminated. Therefore, a CC agent having a uniform width can be printed.

  The decrease in the viscosity of the printing paste varies depending on the material of the printing paste, the angle / pressure of the squeegee S in contact with the screen 12, the moving speed of the squeegee S, and the like. For this reason, a sample printing medium is prepared and trial printing is performed, and P, Q, and R related to the reduction ratio of the pattern 21-23 are adjusted based on the difference in width of the printed paste of the printed stripes, Alternatively, by adjusting the material of the printing paste, the angle / pressure of the squeegee S in contact with the screen 12 or the moving speed of the squeegee S, the difference in stripe width can be minimized, and stripe printing having a uniform width is possible. Can be executed. As a printing plate used for the trial printing, a conventional printing plate described below can be used.

  Hereinafter, the result in the trial printing using the conventional printing plate will be considered.

  Here, the silica-based paste used as the printing paste has a property that the viscosity decreases as the rotational speed increases, as shown in FIG. In particular, the viscosity is greatly reduced when the rotational speed is 0-15 rpm. As described above with reference to FIG. 5, this rotational speed corresponds to the shear stress that the CC agent receives when being pushed out from the opening of the screen 12 by the squeegee S, and is determined by the squeegee S of the CC agent. Increases as the moving length of the squeegee increases, and increases as the moving speed of the squeegee S increases.

  Furthermore, a printing plate on which about 800 stripe openings having a stripe length of 800 mm and a stripe width of 200 μm were formed was prepared, and a silica-based paste was screen-printed on a sample substrate. The distance between the printing plate and the printing medium at this time is 5 mm, the pressure from the squeegee S is 200 MPa, and the moving speed of the squeegee is 20 mm / sec. The results are shown in FIGS. Note that XX shown in FIGS. 7 and 8 is a numerical value representing a position in the long side direction of the printing medium, where XX = 0 indicates a printing start position and XX = 800 indicates a printing end position. YY is a numerical value representing the position of the printing medium in the short side direction, YY = 0 indicates the center position in the short side direction, and YY = 250 is a frame body 250 mm away from YY = 0. The position closest to is shown.

  FIG. 7 shows the stripe widths at XX and YY positions measured at intervals of 50 mm, respectively, and FIG. 8 is a graph of the results of FIG.

  As shown in FIGS. 7 and 8, the stripe width increases as XX increases. That is, the stripe width on the lower side in the moving direction of the squeegee is wider than that on the upper side in the moving direction. In addition, the stripe width increases as YY increases. That is, the stripe width of the print pattern printed near the edge of the screen, that is, the frame on which the screen is stretched, is wider than the print pattern printed at the center of the screen.

  Specifically, the pattern printed at the center is 16 μm wider at the print end position of XX = 800 than the stripe width at the print start position of XX = 0, as indicated by YY = 0 in FIG. It has become. Further, as shown by YY = 250 in FIG. 8, the pattern printed at the extreme end is approximately 21 μm wider at the print end position of XX = 800 than the stripe width at the print start position of XX = 0. It has become. Further, in the pattern printed between the center pattern and the end pattern, the pattern indicated by YY = 200, 150 in FIG. 8 has a stripe width wider by 19 μm at the print end position, and YY = 100 in FIG. , 50, the stripe width at the printing end position is 17 μm wider. Based on this result, by determining the numerical values of P, Q, and R described above, it is possible to execute stripe printing having a constant stripe width in the moving direction of the squeegee.

  That is, the printing plate according to the present invention has a print pattern that is reduced with respect to the regular print pattern 30 printed on the front substrate 60 toward the print end position XE. With this configuration, the viscosity of the printing paste decreases due to the shear stress from the squeegee S, and the printing paste printed on the front substrate 60 is dripped, and the phosphor layers R, G, and B from the light shielding layer 64 of the front substrate 60 It is possible to improve the problem that the print paste protrudes. Thereby, since the non-oxidized region 66B is formed in a region including at least the phosphor layers R, G, and B, a sufficient anode voltage can be supplied to the phosphor layers R, G, and B. Incidentally, when the printing paste protrudes from the light shielding layer 64 and the oxidized region 66A is formed on the phosphor layers R, G, B, the anode voltage applied to the phosphor layers R, G, B becomes insufficient. There is a problem that display unevenness occurs due to variations in the value of the applied anode voltage between the pixels.

  In the present embodiment, since the oxidized region 66A and the non-oxidized region 66B are formed in the metal back layer 66 using the printing plate 10, the silica-based paste has been described as an example of the printing paste. However, the present invention can be applied to a printing plate used for striped screen printing, and can be used to form the getter cut layer 68A on the getter layer 68 shown in FIG.

  Also, the values such as P, Q, and R relating to the reduction ratio of the opening of the pattern 21-23 formed on the screen 12 shown in FIG. 4 are printed using the conventional printing plate shown in FIGS. By calculating based on the spread of the width of the printing paste, it is possible to realize screen printing more easily and with high accuracy even in stripe-like printing with a fine width as in the present embodiment. Further, by forming the opening of the print pattern in a tapered shape like the pattern 21-23 shown in FIG. 4, the adjusted print pattern can be formed on the screen more easily.

Schematic which shows an example of the display panel which is one embodiment of this invention. FIG. 2 is a schematic cross-sectional view of the display panel shown in FIG. 1. Schematic which shows an example of the printing plate which is one embodiment of this invention. Schematic for demonstrating in more detail about the printing plate shown in FIG. Schematic of the screen printing apparatus for demonstrating the screen printing using the printing plate shown to FIG. The table | surface for demonstrating the property of the printing paste used in the printing plate shown to FIG. The table | surface which shows the change of stripe width at the time of printing the printing paste which has the property shown in FIG. 6 using the printing plate in which the printing pattern which has a fixed stripe width is formed. The table | surface which shows the result shown in FIG.

Explanation of symbols

10 ... printing plate,
11 ... Frame,
12 ... Screen,
21-23 ... Print pattern,
30: Regular printing pattern,
X1 ... direction of squeegee movement,
50 ... Display panel,
60 ... front substrate,
R, G, B ... phosphor layer,
64 ... light shielding layer,
66. Metal back layer,
66A ... oxidation region,
66B: non-oxidized region.

Claims (4)

Having a printed pattern including an elongated opening in the direction in which the squeegee moves;
The printing plate according to claim 1, wherein the width of the opening is narrower on the lower side than on the upper side along the moving direction of the squeegee. A screen on which a printing pattern in which a plurality of openings elongated in a first direction in which a squeegee moves is arranged in a second direction intersecting the first direction is formed;
A frame for holding the screen;
The opening is gradually reduced from the upper side to the lower side in the first direction as compared to a regular print pattern to be printed on the printing medium.
The reduction rate of the opening located at the center of the screen along the second direction is the largest, and the reduction rate of the opening gradually decreases as the frame is approached. Edition. A printing plate for printing an elongated uniform width pattern extending along a moving direction of a squeegee on a printing medium,
Having an elongated opening for passing a printing paste for forming the pattern;
A printing plate, wherein the width of the opening is narrower on the downstream side than the upstream side along the moving direction.   The printing plate according to claim 3, wherein the opening is tapered.

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