WO2004100203A1

WO2004100203A1 - Device for connecting plasma display panels to a plant for making vacuum and successive filling with ionizable noble gases

Info

Publication number: WO2004100203A1
Application number: PCT/IT2003/000277
Authority: WO
Inventors: Luca Cabrucci
Original assignee: Polo S.R.L.
Priority date: 2003-05-08
Filing date: 2003-05-08
Publication date: 2004-11-18
Also published as: AU2003233185A1

Abstract

A device for automatically connecting a vacuum and gas filling plant to a glazen plasma display panel (P), the panel having a glazen tubular appendix communicating with a chamber inside it. The device comprises: a supporting plane on the panel (P), a tubular body (18) communicating with the vacuum and gas filling plant capable of performing an axial translational motion away from and towards the supporting plane in a direction at right angles thereto and coaxially with the tubular appendix to become engaged in an airtight manner with it, means (9) for centring the tubular appendix with respect to the tubular body comprising a centring element with a substantially V-shaped seating at one of its ends the bisector of the seating being intersected by the axis of the tubular body (18), capable of performing a translational motion away from and towards the tubular appendix in a direction at right angles to its axis to make it become engaged in the V-shaped seating. At the end of the run of the centring element towards the tubular appendix the axis of the latter will likewise come to intersect the bisector of the V-shaped seating. In front of the tubular bod and coaxially with it there is provided a heating unit capable of causing the local melting of the material in proximity of the root of the tubular appendix, the detachment of the appendix and the sealed closure of the chamber.

Description

DEVICE FOR CONNECTING PLASMA DISPLAY PANELS TO A PLANT FOR MAKING VACUUM AND SUCCESSIVE FILLING WITH IONIZABLE NOBLE

GASES DESCRIPTION

Field of the invention

The present invention relates to the field of the production of plasma displays and, more precisely, has as its object a device for connecting plasma display panels to a vacuum plant and for subsequently filling them with ionizable noble gases.

Prior art

As is well known, modern television sets and ultra- flat monitors make use of a plasma display constituted by two paired glass plates with ^' appropriately treated surfaces that delimit a thin chamber within which there is contained an ionizable noble gas, in particular a mixture of neon and xenon. In the plasma display production process a vacuum is first created in the chamber between the two glass plates and the chamber is then filled with the gas mixture through a tubular glass appendix, or tail, that extends at right angles from one of the two glass plates and is situated in a corner of the panel. A typical plasma display is shown in Figure 3a, while Figure 3b shows an enlarged view of the panel portion from which the tail extends.

A typical scheme of a plant for creating a vacuum in the intermediate space of the panel and filling it with gas is shown in Figure 1, while Figure 2 schematically illustrates the trolley used in this plant for the transfer of a certain number of panels to be filled with gas into the furnace and the line. The plant comprises a heating tunnel T through which there are made to pass the trolleys C that move along a ring-shaped circuit and carry the panels P. At the station SI the panels are taken from a feeder belt (not shown) , arranged on the trolley and then, one after the other, manually connected, via the tail, to the plant for creating the vacuum and charging the gas. The temperature in the heating tunnel T is gradually raised to 400°C, while the interior space of the panels is subjected to one or more purges- with nitrogen. When the temperature has reached its steady value, the vacuum is created in the chamber of the panels, after which the temperature is gradually lowered in such a manner as to be close to the environmental temperature at the moment the trolley leaves the tunnel T, When the temperature has reached about 40°C, the inert gas mixture (neon + xenon) is injected into the panel chamber until the internal pressure amounts to about 500 mbar. At the station S3 the glass tail by means of which the panel chamber communicates with the vacuum and gas loading plant is closed at the root by melting the glass, which becomes blocked due to the pressure difference between the inside and the outside. At- the next station S2 the panels are then removed from the trolley C and placed on a return belt (not shown) . While the operations of loading the panels onto the trolley C and removing them therefrom may also be automated using dedicated robots, the operation of connecting the panels to the vacuum and gas loading plant must necessarily be performed by hand and with a great deal of care- to avoid breaking the glass tails at the moment of connecting them in an airtight manner to the respective tubes coming from the vacuum and gas loading plant . The manual connection operation described above causes a significant slowdown of the production process and, even when great care is taken, the glass tail may break on account of its fragility. Object and summery of the invention

The general object of the present invention is that of completely automating a plant for evacuating the plasma display panels and filling them with noble gases.

A particular object of the present invention is to provide a device that will connect the panels in an automatic manner to the plant that performs the evacuation, the filling with gas and the sealing of the glass tail by melting.

Another aim of the present invention is to provide an automatic connecting device of the aforementioned type that will realize a perfect alignment of the glass tail with the connection member^' of the vacuum and gas filling plant and thus to avoid it becoming subject to mechanical stresses that could cause it to break. These aims are attained by means of the device for^' connecting plasma display panels to a plant for evacuating them and filling them with noble gases in accordance with the present invention, which comprises a plane to support the panel, a tubular body communicating with the vacuum and gas filling plant capable of performing translational axial motions to and from the supporting plane in a direction at right angles to it and coaxially with the tubular appendix in order to form an airtight joint with it; means for centring the tubular appendix with respect to the tubular body in order to align them coaxially with respect to each other, the means comprising a centring element provided at one of its ends with a substantially V-shaped seating of which the bisector is intersected by the axis of the tubular body and being capable of performing translational motions- to and from the tubular appendix in a direction at right angles to its axis in order to engage it within the V—shaped seating. In this way the axis of the centring element, when the latter has completed its run towards the tubular appendix, will likewise come to intersect the bisector of the V-shaped seating. In front of the tubular body and coaxially with it there is situated a heating unit capable of causing the local melting of the material in proximity of the root of the tubular appendix, its consequent detachment and the sealed closure of said chamber.

Brief description of the drawings Further characteristics and advantages of the device in accordance with the present invention will appear more clearly by the following description of a particular embodiment thereof, which is given by way of example and is not to be considered limitative in any way, the description making reference to the drawings attached hereto, of which:

- Figure 1 shows a schematic layout of a plant for evacuating display plasma panels and filling them with gas ; - Figure 2 ^• shows a schematic side elevation of a panel transport and processing trolley;

Figures 3a and 3b show, respectively, a front elevation and a an enlarged side elevation of a plasma display panel to be filled with inert gas; - Figure 4 shows a top plan view of the panel transport trolley where - for the sake of simplicity - some parts have been removed; - Figure 5 shows an overall front elevation of the connection and centring units provided for each panel;

- Figure 6 shows a side elevation as seen in the direction of the arrow F of Figure 4, partly in section along line VI -VI of Figure 5, of the connection unit of the device in accordance with the present invention;

- Figure 7 shows an enlarged view of a detail of Figure 6 ;

- Figure 8 shows a front elevation, partially as a section, of the panel centring unit;

Figure 9 shows a view of the connection and centring unit of Figure 5 as seen in the direction of the ^' arrow G :

- Figure 10 shows a section through the connection unit along line X-X of Figure 5 ;

- Figure 11 shows a partial side elevation of the actuation device of the connection and centring units as seen in the direction of arrow H of Figure 4.

Description of an embodiment of the invention Referring to the aforesaid drawing, and more particularly to Figure 2, each trolley C is equipped in a conventional manner with a unit 1 for creating the vacuum in the chamber of the panels P, a gas cylinder 2 for the nitrogen needed for purging the panel chamber prior to the evacuation, a gas cylinder 3 for the mixture of noble gases, xenon and neon, to be injected into the chamber of the panels P after the vacuum has been created. The evacuation device 1 and the gas cylinders 2 and 3 are arranged in a lower compartment of the trolley, together with a manifold 4 for the washing and the evacuation and a supply manifold 5 for the noble gases and the various branch lines to the individual panels arranged in herringbone fashion on a plane 6 of the trolley C. In particular, as can also be seen in Figure 6, each panel rests with its back on rollers 7 that are mounted in inclined frames 8, so that the tubular glass appendix d projecting from each panel P will be pointing obliquely upwards .

In accordance with the present invention, for each panel there is provided a unit for connecting the tubular appendix to the evacuation and gas filling plant and a unit for centring the tubular appendix d with respect to the connection unit. The two units are jointly illustrated as a front elevation in Figure 5, where the reference number 9 indicates the centring and guide unit of the connection, while the principal motion and guide unit of the connection is indicated by the reference number 10. Figure 6, on the other hand, shows the centring unit 9 as a side elevation and partial section and partially also the connection unit 10.

As shown in Figure 5, 9 and 10, the unit 10 for connecting the tubular glass appendix and_. the evacuation and gas filling plant comprises a supporting upright member 11 that is fixed to the plane 6 of the trolley C and from which a guide column 12 extends obliquely upwards. A runner 13 mounted on the guide column '12 by means of a sliding fit carries a box-shaped arm 14 that extends sideways and is made up. of a bottom plate 14a with two stiffener ribs 14b and a side piece 14c.

A second supporting upright 15 rises from the plane 6 of the trolley C by the side of the first supporting upright 11. As can be seen also in Figure 6, a guide column 16 that points obliquely upwards and is parallel to the guide column 12 extends from the support 15 and on it there is mounted by means of a sliding fit a runner 17 made integral with the box-shaped arm 16 by means of the bottom plate 14a. Likewise integral with the arm 16 is a tubular hood 18 of which the axis is inclined with respect to the horizontal by an angle equal to the positioning angle of the tubular glass appendix d. Following a sliding motion of the unit 10 along the guide columns 12 and 16 to bring it closer to the panel P, the tubular glass appendix d, after appropriate centring (as will be seen further on) , becomes engaged in an airtight manner inside the tubular hood 18.

The tubular hood communicates with the vacuum and gas filling plant by means of a duct 19 that extends along the box-shaped arm 14 and is connected to the closed end of the hood 18. Air tightness between the glass tail d and the tubular hood 18 is assured by a gasket 20 placed between them.

Around the tubular hood 18 and in line with the airtight gasket 20 there is provided a chamber 42 in which there circulates a liquid for cooling the gasket fed and discharged by means of appropriate tubes 43 and 44 carried on the arm 14.

In front of the tubular hood and integral with it there is arranged an electric resistance furnace 41 that is toroidal in shape and coaxial with the hood; this furnace makes it possible to melt the glass of the tail d in proximity of the tail root at the end of the evacuation and gas filling operation, thus obtaining a hermetic closure of the chamber of the panel d. Figure 6 shows the tail d closed and already broken off, i.e. as it appears at the end of the filling operation. In particular, the furnace 41 (shown in schematic form in Figure 6) is sustained by a small disk 45 connected to the bottom plate 14a of the arm 14 by means of studs 46 that form a sliding fit with through holes 47 of the bottom plate 14a.

The small furnace 41 can therefore float with respect to the tubular hood 18, thus making it possible for the furnace to be moved towards the bottom plate 14a after the hood 18 has completed its engagement run. Following this motion, a sleeve 48 (see Figure 7) , integral with the disk 45 and coaxial with the gasket 20, comes to exert an axial pressure on the gasket 20, deforming it in such a manner as to create the necessary airtight seal around the tail d, as shown in Figure 6. At first there exists a certain clearance between the gasket 20 and the side walls of its housing in order to facilitate the insertion of the tail d, but this is annulled by the compression of the gasket brought about by the sleeve 48. The initial clearance permits the tail d to be centred in the vertical direction with respect to the tubular hood 18.

If the glass tail d is to become engaged with the tubular hood 18, it is essential that they should be axially aligned. It is also necessary for this alignment to be as accurate as possible in order to avoid all mechanical stressing of the glass tail d, which, given its fragility, could easily break. For this purpose there is provided the centring unit 9 shown in detail in Figure 8. Referring to this figure, but also to Figures 5 and 6, the centring unit 9 comprises a fork-shaped element 21 extending parallel to the plane in which there rests the panel P in the position of the root of the glass tail d. The active end 21a of the fork-shaped element 21 is provided with a substantially V-shaped seating 21b to engage the root of the tail d. The fork-shaped element 21 is integral with a slide 22 capable of moving parallel to the plane in which there rests the panel P to bring it towards and away from the root of the glass tail. The motion of the slide 22 takes place with respect to the upright member 15 and, more particularly, along an inclined face 15a of said member, i.e. the face from which there extends the orthogonal guide column 16. The guide column 16 passes through a slot-shaped opening 23 provided in the slide 22 to permit the slide to move in the direction at right angles to the column 16.

The tubular hood 19 is positioned in such a way that its axis intersects the bisector of the V-shaped seating 21b of the fork-shaped element 21 at a certain height. The motion that brings the fork-shaped element 21 towards the root of the tail d assures that the latter will be positioned in such a way that its axis will intersect the bisector of the V-shaped seating 21b at the same height, so that at the end of the centring operation, i.e. at the end of the run of the fork-shaped element 21, the tail d and the tubular hood 18 will be aligned.

From the slide 22 there also extends in a sideways direction an arm 24 that carries at its free end a stem 25 terminating with a roller 26 elastically loaded to keep it in contact -with the lower edge of the panel P and therefore to sustain the panel when, after the centring of the glass tail, the fork-shaped element 21 is lowered. In particular, as can be seen in Figure 8, the arm 24 is rigidly connected to the slide 22 and hinged at 51 with a bracket 49 extending from the frame 8 that supports the panel P. The free end of the bracket 49 terminates with a sleeve 50 in which there is engaged the stem 25 that carries the roller 26 at its end. During the phase of centring the tail d, in which the fork-shaped element 21 moves upwards, the roller 26 is lowered and is therefore no longer in contact with the panel P, which, at this point, is supported by the fork-shaped element 21. When the latter is lowered, the roller resumes contact with the panel P to sustain it. A further roller support (not shown in the figure) of the fixed type is provided at the same height as the roller 26 in proximity of the other side of the panel P . Each centring unit 9 and evacuation and filling unit 10 of a panel P is operated simultaneously with the homologous units of the other panels P arranged on a trolley C. To this end, as can be seen in Figure 4, there is provided a transmission shaft 27 for operating the centring units 9 that extends above the plane 6 of the trolley C, parallel with it and passing through the supporting uprights 15. At each upright member 15 the transmission shaft 27 is provided with an axial cross notch 28 (Figures 5 and 6) in which there is a arranged a cam 29 with a substantially circular profile that is in contact with the end of the slide 22. Clearly an alternating motion of the bar 27 in the axial direction will cause a motion of the slide 22, and therefore also of the fork-shaped element 21 integral with it, along the face 15a towards and away from the glass tail d. With a view to controlling the motion of the transmission bar 21, there is provided a lever 30 (Figures 4 and 11) that is coplanar with it and is attached to the plane 6 of the trolley by means of a fulcrum; said lever is connected to the shaft 27 at one of its ends, while the other lever end is connected to a pair of toggle rods 31a, 31b hinged on the stem 32 of an actuator 33 extending within the trolley C.

With a view to assuring the simultaneous motion of each connecting unit present on the trolley C, there is similarly provided a transmission shaft 34 that extends above the plane 6 of the trolley C parallel to the transmission shaft 27 and passes the supporting uprights 11 of each connecting unit 11. A pair of arms 35 (Figure 1) connected to the runner 13 sliding along the guide column 12 extends from the transmission shaft 34 at each supporting upright .11. In this case, once again, an alternating axial motion of the shaft 34 (arrows B2) will have as its counterpart a sliding of the connecting unit 10 along the guide columns 12 and 16 sufficient to make the tubular hood 18 engage with the glass tail d or become detached therefrom.

With a view to producing the alternating motion of the shaft 34, one end of the latter is connected to a shaft 36 (Figures 4 and 11) , substantially coplanar with the transmission shaft 34 and at right angles thereto. The shaft 36 is connected by means of a sliding joint to a guide 37 parallel to the transmission shaft 34 and is connected to a pair of toggle rods 38a, 38b hinged on the stem 39 of an actuator 49 extending within the trolley 39, so that a motion of the toggle bars 38a, 38b produce a translation of the shaft 36 and a corresponding motion of the operating shaft 34. The movements controlled by the actuators 33 and 40 are synchronized in such a way that the various centring units 10 are operated before the respective connecting units 10, which begin their run towards the glass tails d only after the latter have been axially aligned with the tubular hood 18.

Claims

1. A device for automatically connecting a vacuum and gas filling plant to a glass plasma display panel (P) , said panel having a glazen tubular appendix (d) communicating with a chamber inside it, characterized in that it comprises a supporting plane (8) of said panel (P) , a tubular body (18) communicating with said vacuum and gas filling plant capable of performing an axial translational motion away from and towards said supporting plane in a direction at right angles thereto and coaxially with said tubular appendix to .become engaged in an airtight manner with it, means (9) for centring said tubular appendix with respect to said tubular body comprising a centring element (21) with a substantially V- shaped seating (21b) at one of its ends (21a) , the bisector of the seating being intersected by the axis of said tubular body, capable of performing a translational motion away from and towards said tubular appendix in a direction at right angles to its axis to make it become engaged in said V-shaped seating, so that at the end of the run of said centring element towards said tubular appendix the axis of the latter will likewise come to intersect the bisector of said V-shaped seating, in front of said tubular body and coaxially^' with it there being provided a heating unit (41) capable of causing the local melting of the material in proximity of the root of the tubular appendix, the detachment of the appendix and the sealed closure of said chamber.

2. A device in accordance with claim 1, wherein said tubular body (18) is slidably mounted on a first guide

(16) at right angles to said supporting plane (P) , said guide extending from a first support ^" (15) fixed with respect to said plane along which said centring element (21) is slidingly mounted.

3. A device in accordance with claim 1 or 2 , wherein said tubular body (18) has substantially the form of a hood connected at its closed end to a duct (19) arriving from said plant and provided on its inside with a sealing gasket .

4. A device in accordance with any one of the preceding claims, wherein from said tubular body (18) there extends in a sideways direction an arm (14) slidably mounted on a second guide (12) parallel to said first guide (16) fixed with respect to said supporting plane and by the side of said support (15) , said duct (19) being arranged along said arm.

5. A device in accordance with any one of the preceding claims, wherein said arm (14) is connected to a sliding runner (13) , said runner being connected, with the help of connecting rod means (35) , to a first transmission shaft (34) slidably mounted on said second support (11) and capable of performing an .alternating axial motion.

6. A device in accordance with any one of the preceding claims, wherein said centring element (21) is connected to a slide (22) capable of moving along said first support (15) , said slide being controlled, through appropriate cam means (29) , by a second transmission shaft (7) mounted by means of a sliding fit on said first support (15) and capable of performing alternating axial motions.

7. A device in accordance with any one of the preceding claims, wherein said first and said second transmission shaft (34, 27) are connected to respective actuating means (40, 33) capable of causing them to perform the alternating axial motion.

8. A device in accordance with any one of the preceding claims, wherein from said centring element (21) there extends an arm (24) hinged on said supporting plane (8) at some intermediate point along its length and carrying at its opposite end a supporting element (26) on which there rests the lower corner of said panel (P) .

9. A device in accordance with any one of the preceding claims, wherein said supporting plane (P) is inclined in such a way that said tubular appendix (d) comes to point upwards .

10. A device in accordance with any one of the preceding claims, wherein said sealing gasket (20) is mounted with a radial clearance inside said tubular body (18) , a plunger

(48) extending from said heating unit (41) in a coaxial relationship with said tubular body (18) , said plunger being capable of compressing said gasket (20) during the motion that brings the tubular body (18) towards said supporting plane (8) to realize an airtight joint between said tubular body (18) and said tubular appendix (d) .