JP3928683B2 - Phosphor layer forming apparatus for plasma display panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus that is used in a manufacturing process of a plasma display panel (hereinafter referred to as PDP) and forms a phosphor layer between ribs of a substrate having a plurality of ribs (partition walls) on the surface.
[0002]
[Prior art]
2. Description of the Related Art Conventional PDP phosphor layer forming apparatuses and methods are known in which phosphor paste is applied to grooves between ribs using a nozzle head having a plurality of nozzles (so-called multi-nozzles).
[0003]
By the way, if the application width of the phosphor paste applied to the groove between the ribs varies, it adversely affects the display characteristics of the PDP. Therefore, in order to obtain a PDP with high display quality, the application width is managed with high accuracy. There is a need to.
Therefore, it is known that the viscosity of the phosphor paste is set to be relatively low and is applied by utilizing the surface tension of the phosphor paste, or the relationship between the nozzle length and the aperture is variously controlled ( For example, refer to JP-A-11-40065 and JP-A-11-73882).
[0004]
[Problems to be solved by the invention]
In such a phosphor layer forming apparatus, a nozzle head having a plurality of nozzles is connected to a container for storing the phosphor paste, and the phosphor paste is nozzled at a predetermined discharge speed by applying a certain pressure to the container. And a constant coating width is maintained.
[0005]
However, the phosphor paste generally has thixotropic properties (the gel turns into a fluid sol when agitated or vibrated, and returns to the gel when left untreated, which is also referred to as thixotropic). Immediately after the start of discharge, the discharge amount is small and gradually increases to reach the set amount. Therefore, there is a problem that the application width of the phosphor paste applied at the start of discharge becomes narrower than other portions.
[0006]
The present invention has been made in consideration of such circumstances, and at the start of the discharge of the phosphor paste, by reducing the moving speed of the nozzle head or temporarily supplementing the shortage of the discharge amount. The present invention provides a phosphor layer forming apparatus for a plasma display panel capable of keeping the coating width constant from the start of discharge.
[0007]
[Means for Solving the Problems]
The present invention is an apparatus for forming a phosphor layer by applying a phosphor paste to a groove formed between a plurality of ribs provided in parallel on a substrate surface, and a mounting table on which a substrate is mounted; A nozzle head having a nozzle for discharging the phosphor paste, a supply unit for supplying the phosphor paste to the nozzle head, a transport unit for relatively moving the nozzle head and the mounting table, and a predetermined groove between the ribs. In contrast, the controller includes a control unit that controls the transport unit and the supply unit so that the phosphor paste is sequentially applied, and the control unit determines whether the nozzle head and the mounting table are relative to each other according to a change in the discharge amount of the phosphor paste from the nozzle. The present invention provides a phosphor layer forming apparatus for a plasma display panel characterized by changing the moving speed.
[0008]
Furthermore, the present invention is an apparatus for forming a phosphor layer by applying a phosphor paste to a groove formed between a plurality of ribs provided in parallel on a substrate surface, and a mounting table on which the substrate is placed A nozzle head having a nozzle for discharging the phosphor paste, a supply unit for supplying the phosphor paste to the nozzle head, a replenishment unit provided in the nozzle head for replenishing the phosphor paste discharged by the nozzle, A conveyance unit that relatively moves the nozzle and the mounting table, and a control unit that controls the supply unit, the replenishment unit, and the conveyance unit so that the phosphor paste is sequentially applied to a predetermined groove between the ribs. The present invention provides a phosphor layer forming apparatus for a plasma display panel.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In this invention, when the control unit changes the relative movement speed between the nozzle head and the mounting table in accordance with the change in the discharge amount of the phosphor paste from the nozzle, the discharge amount gradually increases from the start of the discharge of the phosphor paste. When increasing, the relative movement speed may be increased according to the degree of the increase.
Further, when the nozzle head is provided with a replenishing unit that replenishes the phosphor paste to be supplied to the nozzle, the control unit may control the replenishing unit so that the discharge amount becomes a predetermined value when the phosphor paste discharge of the nozzle is started. Good.
[0010]
Further, in this case, the nozzle head includes a storage chamber for storing the phosphor paste received from the supply unit and supplying the phosphor paste to the nozzle, and the replenishment unit includes a diaphragm constituting a part of the wall surface of the storage chamber, and a diaphragm And an actuator for actuating.
[0011]
The plasma display panel (PDP) according to the present invention is such that a discharge is locally generated between two opposing substrates to excite and emit light from a phosphor layer partitioned on the substrate. This is composed of a pair of substrate assemblies 50 and 50a as shown in FIG. 1 (for one pixel), for example.
[0012]
In the substrate assembly 50a, a pair of sustain electrodes X and Y for generating surface discharge along the substrate surface are arranged on the inner surface of the front glass substrate 11 for each line. The sustain electrodes X and Y are each composed of a wide straight strip-like transparent electrode 41 made of an ITO thin film and a narrow straight strip-like bus electrode 42 made of a metal thin film.
[0013]
The bus electrode 42 is an auxiliary electrode for ensuring proper conductivity. A dielectric layer 17 is provided so as to cover the sustain electrodes X and Y, and a protective film 18 is deposited on the surface of the dielectric layer 17. Both the dielectric layer 17 and the protective film 18 are translucent.
[0014]
Next, in the substrate assembly 50, the address electrodes A are arranged on the inner surface of the glass substrate 21 on the back side so as to be orthogonal to the sustain electrodes X and Y. Between each address electrode A, a strip-like (linear in the figure) partition wall, that is, a rib r is provided.
[0015]
In the substrate assembly 50, an elongated groove-shaped discharge space 30 communicated in the address electrode direction by adjacent ribs r is partitioned for each subpixel (unit light emitting region) EU in the line direction, and the gap size of the discharge space 30 is defined. The
Note that the partition wall is provided with a protrusion for narrowing the space between the partition walls at a portion corresponding to the non-discharge portion (reverse slit) between the pair of sustain electrodes, or at the bottom of the inter-partition groove groove at the site. A low barrier can be attached, and in the present invention, these shapes are included and defined as a band shape.
[0016]
In the elongated groove, phosphor layers 28 of three colors R, G, and B for color display are provided so as to cover the wall surface on the back side including the upper portion of the address electrode A and the side surface of the rib r. It is done.
[0017]
The rib r is made of low-melting glass and is opaque to ultraviolet rays. As a method for forming the ribs r, for example, a process of providing an etching mask by photolithography on a solid film-like low melting point glass layer and patterning by sandblasting is used.
[0018]
The sustain electrode pair 12 corresponds to one line of the matrix display, and one address electrode A corresponds to one column. Three columns correspond to one pixel (pixel) EG. That is, one pixel EG includes three subpixels EU of R, G, and B arranged in the line direction.
[0019]
By the opposing discharge between the address electrode A and the sustain electrode Y, the wall charge accumulation state in the dielectric layer 17 is controlled. When a sustain pulse is alternately applied to the sustain electrodes X and Y, a surface discharge (main discharge) is generated in the subpixel EU in which a predetermined amount of wall charges exist.
[0020]
The phosphor layer 28 is excited locally by ultraviolet rays generated by surface discharge and emits visible light of a predetermined color. Of this visible light, the light transmitted through the glass substrate 11 becomes display light. Since the arrangement pattern of the ribs r is a so-called stripe pattern, the portion corresponding to each column in the discharge space 30 is continuous in the column direction across all the lines. The light emission colors of the subpixels EU in each column are the same.
[0021]
In manufacturing such a PDP, the phosphor layer 28 is formed after providing the address electrodes A and the ribs r on the substrate 21 as shown in FIG.
[0022]
Further, the phosphor paste is obtained by dissolving a powdery phosphor and a synthetic resin in a solvent, and the content of the phosphor in the phosphor paste is suitably 60 to 10% by weight.
[0023]
The fluorescent substance contained in the phosphor paste differs depending on the emission color. Specifically, Y ₂ O ₃ : Eu, YVO ₄ : Eu, (Y, Gd) BO ₃ : Eu, Y ₂ O ₃ S: Eu, γ-Zn ₃ (PO ₄ ) ₂ : Mn, (Zn, Cd) S: Ag (above red), Zn ₂ GeO ₂ : Mn, BaAl ₁₂ O ₁₉ : Mn, Zn ₂ SiO ₄ : Mn, LaPO ₄ : Tb , ZnS: (Cu, Al) , ZnS: (Au, Cu, Al), (Zn, Cd) S: (Cu, Al), Zn 2 SiO 4: (Mn, As), Y 3 Al 5 O 12: Ce, Gd ₂ O ₂ S: Tb, Y ₃ Al ₅ O ₁₂ : Tb, ZnO: Zn (more green), Sr ₅ (PO ₄ ) ₃ Cl: Eu, BaMgAl ₁₄ O ₂₃ : Eu, BaMgAl ₁₆ O ₂₇ : _{Eu, BaMgAl 10 O 17: Eu} , ZnS: Ag, Y 2 SiO 3: Ce ( or blue) and the like It is raised.
[0024]
In addition, any resin known in the art can be used as the synthetic resin contained in the phosphor paste. Specific examples include ethyl cellulose, nitrocellulose, acrylic resin, polyvinyl alcohol, and the like, and may further contain a photosensitive resin. On the other hand, examples of the solvent include alcohols, terpineol, butyl carbitol acetate (BCA), butyl carbitol, toluene, and butyl acetate.
[0025]
In the nozzle head that discharges the phosphor paste, the nozzle inner diameter is set to be smaller than the rib interval, but the nozzle tip is not inserted between the ribs, so the outer diameter of the tip is rib It may be larger than the interval. For example, when the rib interval is 250 to 300 μm, the nozzle preferably has an inner diameter of about 200 to 250 μm and an outer diameter of about 400 to 450 μm. In addition, a nozzle head in which a plurality of (for example, 50 to 150) nozzles are arranged in a line at a pitch that is an integral multiple of the rib pitch can be used.
[0026]
The present invention will be described in detail below based on the embodiments shown in the drawings. This does not limit the invention.
FIG. 2 is an explanatory view showing the structure of the embodiment of the present invention. In this embodiment, the phosphor layer 28 is formed on the substrate 21 having the address electrodes A and the ribs r shown in FIG. An apparatus for applying to the grooves between the ribs r will be described.
[0027]
In FIG. 2, the manipulator 1 is supported by the shaft 2 in the directions indicated by the arrows Y1, Y2 (Y) while the manipulator 1 moves up and down in the directions indicated by the arrows Z1, Z2 (Z-axis direction) while holding the shaft 2 horizontally. A Y-axis moving device 4 that slides in the axial direction), X-axis moving devices 5a and 5b that reciprocate the Z-axis moving devices 3a and 3b vertically (X-axis direction) with respect to the paper surface, and a substrate 21 are placed. The mounting table 7 is provided. The nozzle head 51 is fixed to the handle 6 of the Y-axis moving device 4.
[0028]
A storage tank 52 for storing the phosphor paste is connected to a pressurized tank 56 via tubes 53 and 54 and an electromagnetic valve 55. A compressed air source (for example, an air compressor) 57 is connected to a pressurized tank 56 via a pressure regulator 61, an electromagnetic valve 62, and tubes 58, 59, 60, and a phosphor stored in the pressurized tank 56 from the storage tank 52. The paste is pressurized. The pressurized tank 56 is connected to the nozzle head 51 via an electromagnetic valve 63 and tubes 64 and 65.
[0029]
3 is a front view of the nozzle head 51, and FIG. 4 is a cross-sectional view taken along the line AA in FIG.
In these drawings, the main body 80 includes therein a storage chamber 81 that stores the phosphor paste supplied from the tube 65, and 107 nozzles that project downward from the bottom surface of the main body 80 in communication with the storage chamber 81. N1 to N107 are arranged in a line at a pitch Pn.
Here, the nozzles N1 to N107 have a length of 15 mm, an outer diameter of 400 μm, and an inner diameter of 200 μm.
[0030]
Further, on the back surface of the main body 84, as shown in FIG. 4, three replenishing portions 84 for replenishing the phosphor paste discharged from the nozzles N <b> 1 to N <b> 107 are provided in the accommodation chamber 81. Here, the replenishing portion 84 includes a diaphragm 101 that constitutes a part of the wall surface of the storage chamber 81, an actuator 102 that reciprocates the diaphragm 101 in the direction of the arrow, and a housing 100.
The actuator 102 can be a motor type or an air cylinder type.
[0031]
FIG. 8 is a block diagram illustrating a control unit of the apparatus shown in FIG. The control unit 103 incorporating the microcomputer receives an output from the keyboard 104 for inputting various conditions, and drives the pressure regulator 61, the electromagnetic valves 55, 62, 63, and the X-axis moving devices 5a, 5b. 105, the Y-axis motor 106 that drives the Y-axis moving device 4, the Z-axis motor 107 that drives the Z-axis moving devices 3a and 3b, and the actuator 102 are controlled, and input conditions from the keyboard 104 are displayed on the CRT 108.
[0032]
In such a configuration, the red phosphor paste is first applied to the grooves between the ribs r of the substrate 21 shown in FIG. In this embodiment, a substrate for a 42-inch PDP (panel size 980 mm × 580 mm) is used as the substrate 21, and 2569 ribs r (FIG. 1) are previously provided in parallel at a pitch Pr on the surface, thereby 2568. A groove of a book is formed.
Here, the rib pitch Pr is set to (1.08 / 3) mm, and the relationship between the nozzle pitch Pn and the rib pitch Pr is Pn = 6Pr.
[0033]
Therefore, the substrate 21 shown in FIG. 2 is placed on the placing table 7 so that the longitudinal direction of the ribs r is perpendicular to the paper surface. As shown in FIG. 6, the phosphor paste application region S of the substrate 21 is divided into four small regions S1 to S4 with the boundary line L as a boundary so that one small region has 6 × 10 7 grooves. The coating process is started from the small area S1.
[0034]
The X-axis moving devices 5a and 5b, the Y-axis moving device 4, and the Z-axis moving devices 3a and 3b are driven to align the nozzles N1 to N107 and the rib r and adjust the gap between the nozzles N1 to N107 and the rib r. Do it. A part of the red phosphor paste previously stored in the storage tank 52 is supplied to the pressurized tank 56 by the operation of the valve 55, and then the air pressure is supplied from the compressed air source 57 via the pressure regulator 61 and the electromagnetic valve 62. Is applied to the pressurized tank 56. Therefore, when the electromagnetic valve 63 is opened, the phosphor paste is supplied to the nozzle head 51, and the nozzles N1 to N107 start discharging the phosphor paste to a predetermined groove between the ribs r as shown in FIG.
[0035]
At the same time, after the nozzle head 51 is advanced from the front end to the rear end of the rib r by the X-axis moving devices 5a and 5b, the electromagnetic valve 63 is closed and the discharge of the nozzles N1 to N107 is stopped. Thereby, the phosphor paste is applied to the 107 grooves with the pitch Pn, that is, the pitch 6Pr over the entire length. This completes the process indicated by the arrow (1) in FIG.
[0036]
Next, the Y-axis moving device 4 moves the nozzle head 51 by 3 Pr in the Y2 direction (FIG. 2). Next, while opening the electromagnetic valve 63 and discharging the phosphor paste from the nozzles N1 to N107, the nozzle head 51 is retracted from the rear end to the front end of the rib r by the X-axis moving devices 5a and 5b. Is closed to stop the discharge of the nozzles N1 to N107. This completes the process indicated by the arrow (2) in FIG.
[0037]
By repeating the application process as indicated by arrows (3) to (8) in FIG. 6, the red phosphor paste is applied to all the grooves in which the red phosphor layer is to be formed. Next, the phosphor pastes for green and blue are applied in the same manner using apparatuses similar to those in FIG. 2, and the application work of the three color phosphor pastes on the substrate 21 is completed.
[0038]
In this way, the application work is performed, but since the phosphor paste has thixotropy, the discharge amount at the start of discharge becomes smaller than the set value, and as a result, the width of the phosphor paste applied to each groove is A phenomenon occurs in which the thickness gradually increases from the beginning. The present invention takes the following two countermeasures against this phenomenon.
[0039]
(1) Speed control of the nozzle head immediately after the start of discharge FIG. 9A shows the on / off state of the electromagnetic valve 63 (FIG. 2) for turning on / off the discharge of the phosphor paste, and FIG. These are time charts showing speed changes of the X-axis moving devices 5a and 5b.
As shown in FIG. 9A, the control unit 103 turns on the electromagnetic valve 63 and starts the X-axis motor 105 at the same time as the discharge of the phosphor paste starts, and the speeds of the X-axis moving devices 5a and 5b are curved. Control is performed so as to rise along (a), (b), or (c) and eventually reach a steady speed V.
[0040]
That is, the moving speed of the nozzle head 51 is controlled according to the change in the discharge amount immediately after the start of discharge. Therefore, the phenomenon that the application width of the phosphor paste becomes narrow at the start end is eliminated, and the phosphor paste is applied with a constant width from the start end to the end.
Note that the speed change curves (A), (B), or (C) in (b) of FIG. 9 are stored and set in the control unit 103 in advance, so that the keyboard 104 depends on the thixotropy of the phosphor paste. One of them can be selected by operating.
[0041]
(2) Replenishment of phosphor paste immediately after the start of discharge FIG. 10 (a) shows the on / off state of the electromagnetic valve 63 (FIG. 2) for turning on / off the discharge of the phosphor paste, and FIG. It is a time chart which shows the operation state of 102.
[0042]
When the controller 103 turns on the electromagnetic valve 63 and starts discharging the phosphor paste as shown in FIG. 10A, the diaphragm 101 is pushed most into the storage chamber 81 from the state of FIG. Then, the actuator 102 is continuously operated over time T1. As a result, the volume of the storage chamber 81 is gradually reduced, and the supply amount of the phosphor paste to the nozzles N1 to N107 is increased corresponding to the reduced volume. Therefore, the phenomenon that the application width of the phosphor paste becomes narrow at the beginning is eliminated.
Further, as shown in FIG. 10, the control unit 103 operates the actuator 102 in the reverse direction for the time T2 when the electromagnetic valve 63 is turned off to return the diaphragm 101 to the state shown in FIG. This is because when the bulb 63 is turned off, that is, when the application of the phosphor paste is completed, the phosphor paste from the nozzles N1 to N107 is pulled back to the storage chamber 81 to prevent unnecessary dripping.
In this way, the phosphor paste is applied with a constant width from the start to the end.
[0043]
It should be noted that the time T1 and T2 required from the start to the completion of the operation of the actuator 102, that is, the operation speed, is set by operating the keyboard 104 with an optimum value determined from the degree of thixotropy of the phosphor paste and other conditions. can do.
About said countermeasure (1) and (2), you may select and use any suitable one and may use together.
[0044]
【The invention's effect】
According to this invention, since the shortage of the discharge amount at the start of the discharge of the phosphor paste is resolved, the phosphor paste can be applied with a constant width from the start end to the end.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a main part of a PDP according to the present invention.
FIG. 2 is a configuration explanatory view showing an embodiment of the present invention.
FIG. 3 is a front view of a nozzle head according to the present invention.
4 is a cross-sectional view taken along the line AA in FIG. 3;
FIG. 5 is an explanatory view showing a phosphor paste application state of the present invention.
FIG. 6 is a plan view of a substrate according to the present invention.
7 is an enlarged side view of a portion B in FIG. 6. FIG.
FIG. 8 is a block diagram showing a control unit of the present invention.
FIG. 9 is a time chart showing a change in nozzle head speed according to the present invention.
FIG. 10 is a time chart showing the operation of the actuator of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Manipulator 2 Shaft 3a Z-axis movement apparatus 3b Z-axis movement apparatus 4 Y-axis movement apparatus 5a X-axis movement apparatus 5b X-axis movement apparatus 6 Handle 7 Mounting stand 51 Nozzle head 52 Storage tank 53 Tube 54 Tube 55 Electromagnetic valve 56 Pressurization Tank 57 Compressed air source 58 Tube 59 Tube 60 Tube 61 Pressure regulator 62 Electromagnetic valve 63 Electromagnetic valve 64 Tube 65 Tube 80 Main body 81 Storage chamber 84 Replenishment part 100 Housing 101 Diaphragm 102 Actuator N1 Nozzle N2 Nozzle N3 Nozzle N106 Nozzle N107 Nozzle

Claims (1)

An apparatus for forming a phosphor layer by applying a phosphor paste to a groove formed between a plurality of ribs provided on the surface of a substrate, and placing a substrate on which the substrate is placed, and discharging the phosphor paste A nozzle head having a nozzle for performing the operation, a supply unit for supplying the phosphor paste to the nozzle head, a replenishment unit provided in the nozzle head for replenishing the phosphor paste discharged from the nozzle, and the nozzle and the mounting table. And a control unit for controlling the supply unit, the replenishment unit, and the transport unit so that the phosphor paste is sequentially applied to a predetermined groove between the ribs. A phosphor layer forming apparatus for a plasma display panel , wherein the replenishment unit is operated in a direction to increase the discharge amount for a predetermined time after the start of discharge.

Images