Plasma display device

Abstract: A plasma display device is provided with one substrate having a plurality of electrode drawing-out portions extending up to a side end thereof for applying an AC voltage to X side electrodes each independently, a second substrate having a plurality of electrode terminal portions formed independently on its electrode-disposed surface, the plural electrode terminal portions being electrically connected respectively to the plural electrode drawing-out portions by a connector portion. The connection of each of the X and Y electrodes with an external power source can thus be made on only the Y side electrode-disposed surface of the second substrate. Besides, the shape of the substrates is simplified. In addition, said connector means comprises a spacer member (8) having a plurality of through-holes for enabling communication between said electrode connector terminals (4) and corresponding electrodes (2) of said second substrate (1), said through-holes being filled with electrically conductive material (9) for electrically connecting said electrode connector terminals (4) to said electrodes (2) of said second substrate (1).

Description: The invention relates to a plasma display device suitable for use as a computer terminal display device or a destination display device comprising a first transparent substrate having a plurality of linear electrodes arranged thereon in parallel in a first direction; a second transparent substrate having a plurality of linear electrodes arranged thereon in parallel in a second direction orthogonal to said first direction; said first and second substrates being hermetically sealed together to form a discharge space therebetween with said electrodes intersecting to form a display matrix; a discharge gas sealed within said discharge space for emitting a visible plasma discharge when a predetermined driving voltage is applied between intersecting electrodes; a plurality of electrode connector terminals arranged along peripheral edge portions of said first substrate for connection to an a.c. driving voltage; connector means for electrically connecting said plurality of electrodes arranged on said second substrate to respective ones of said electrode connector terminals; and means for providing a.c. driving voltage to said plurality of electrodes on said first substrate. Such a plasma display device is known from the U.S. patent US-A-4,039,882. Further, H.A. Whitaker describes in "IBM Technical Disclosure Bulletin", Vol. 15, no. 9, February 1973, page 2774, a gas discharge panel with built-in cavity. This panel being provided with two step surfaces, one carrying a plurality of electrodes and another one being sealed to a transparent substrate. In a plasma display device, a plurality of linear electrodes are arranged in parallel and closely spaced on each of a pair of insulating plates formed by a transparent, hard material such as, for example, glass, both insulating plates being opposed to each other so that the linear electrodes cross perpendicularly in the form of a matrix through a thin discharge space, the outer peripheral portion being sealed hermetically and the interior being evacuated and filled with an inert gas such as neon. An AC voltage is applied between selected ones of the linear electrodes to cause gas discharge between the intersecting points of the electrodes, thereby forming a predetermined luminous display pattern. Fig. 1 is a sectional view showing a conventional plasma display device, in which the numeral 1 denotes a front glass as a display surface of a conventional plasma display device; numeral 2 represents a row of long, thin, strip-like front electrodes arranged on an inner surface of the front glass 1; numeral 6 denotes a rear glass disposed in opposed relation to the front glass 1 at a predetermined spacing; numeral 5 represents a row of long, thin, strip-like rear electrodes arranged on an inner surface of the rear glass 6 so as to form a matrix together with the front electrode row 2; numeral 7 denotes a sealing glass provided along the outer periphery of the front glass 1 and that of the rear glass 6 to seal the display portion formed by both electrode rows hermetically from the exterior; numeral 13 denotes a flexible printed circuit (hereinafter referred to as "FPC") soldered to each of the front electrode row 2 of the front glass 1 and that of the rear electrode row 5 to connect the display portion electrically to an external drive unit; and numeral 14 denotes a driving IC which receives an external display signal and causes corresponding display cells to emit light. The arrangement of such a conventional plasma display device will now be described. The front glass 1 serves as the display surface of the display device, and supports the front electrode row 2 comprising image or character information displaying electrodes. The end portion of glass 1 has the electrodes of the front electrode row 2 drawn out to the exterior. The rear glass 6 supports the rear electrode row 5 spaced apart from the front electrode row 2 in the form of a matrix. The end portion of glass 6 has the electrodes of the rear electrode row drawn out to the exterior. The front and rear glass plates are sealed hermetically by the sealing glass 7. The thus-sealed space between both glass plates is filled with an inert gas such as neon. The electrode end portions of the front and rear glass plates 1, 6 are drawn out of the sealing glass 7 and exposed, then connected to the FPC 13 by soldering or the like for conduction with an external power source. Further, the driving IC 14 for selecting an intersecting point of matrix electrodes in the plasma display device, is mounted on the FPC 13. A high voltage is applied between the thus-selected front and rear electrodes, so that the encapsulated gas discharges to emit light and the corresponding points on the panel become luminous to effect a display pattern. In the above construction of the conventional plasma display device, the surface of the electrode end portions which serve as connections and which are drawn out and exposed to the exterior for connection with the driving IC 14 are disposed in the direction opposite to the display surface, that is, in opposed relation thereto. Further, since the electrodes constitute a matrix, it is necessary that such electrode end portions be drawn out in two directions. This causes restrictions in the electrical connection of many terminals. Also in sealing both front and rear glass plates hermetically, serious problems are involved such as three-dimensional portions, e.g. corner portions, being present in the connection of both glass plates. Further, since the electrode end portions serving as connecting portions extend out from both the front and rear glass plates, the shape of the display portion (panel portion) is restricted. The spacing between the hermetically-sealed front and rear glass plates is determined by the thickness of spacers (ribs) 15 each interposed between adjacent electrodes of the front electrode row 2 or the rear electrode row 5 as shown in Fig. 2. The ribs 15, which are generally black, are provided to prevent the emission of light by discharge of gas at an intersecting point between the matrix electrodes from spreading to the other portions. By the abutment of the ribs 15 with the front and rear glass plates 1, 6 there is determined the spacing between both glass plates. The thickness of spacers 15 is determined by the amount of luminance emitted by discharge, the kind of gas sealed, etc. Usually, such spacing is set at 100 µm or so. In order to obtain a rib thickness of about 100 µm, the present inventors repeated printing on a glass plate suing a black glass paste and a screen having a mesh size of 127 µm (No. 200 mesh). The film thickness obtained by a single printing-drying-calcining cycle was about 20 µm ± 5 µm. By repeating this cycle five times there could be obtained a thickness of about 100 µm. Fig. 3 is a normalized graph of a scattered thickness state of the resulting film at the end of each printing-drying-calcining cycle. As shown therein, the scatter in film thickness is about ± 15 µm at a resulting film thickness of about 100 µm. This scatter is caused by various factors, including the mesh mark in printing, non-registration in overlap printing and variations in the viscosity of paste. Consequently, the spacing between both glass plates varies with scattering in the thickness of the ribs 15. Thus, the scatter in thickness varies device by device, and even in a single plasma display device, there occurs difference in rib thickness at some particular points, so that the said spacing is not uniform. Since the luminance amount of the light emitted depends on the spacing between both glass plates, the emitted light luminance distribution in the conventional display device is non-uniform. The present invention shall overcome the above-mentioned problems. It is the first object of the present invention to provide a display device wherein the connection between the electrodes in the display portion and a power source for an external drive system, etc. can be done on a single surface. It is the second object of the present invention to provide a plasma display device capable of effecting a hermetic seal between an internal space formed by both glass plates and the exterior in a superior and easy manner. It is the third object of the present invention to provide a plasma display device wherein there are few restrictions on the shape of a display portion or the whole of the display device and which therefore has a lightly reliable display portion. It is the fourth object of the present invention to provide a plasma display device wherein the spacing between electrode rows which form a matrix is made constant to give a uniform emitted luminance distribution characteristic. It is the fifth object of the present invention to provide a plasma display device which can be easily produced and reduced in size and cost, while permitting easy production of its components and affording high reliability. According to the invention, a plasma display device as defined above (preamble of claim 1) is characterized in that said connector means comprises a spacer member having a plurality of through-holes for enabling communication between said electrode connector terminals and corresponding electrodes of said second substrate, said through-holes being filled with electrically conductive material for electrically connecting said electrode connector terminals to said electrodes of said second substrate. Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Fig. 1 is a sectional perspective view showing a conventional prior art plasma display device; Fig. 2 is a sectional side view of the device of Fig. 1. Fig. 3 is a diagram showing how the rib thickness as the resulting film thickness scatters with repetition of printing; Figs. 4(a), (b), (c) and (d) are fragmentary views showing a plasma display device; Figs. 5(a) and (b) are fragmentary views showing a plasma display device according to an embodiment of the present invention. In Fig. 4, the numeral 1 denotes a front glass serving as a display surface of the display device; numeral 2 denotes a row of long, thin strip-like front electrodes arranged on one side of the front glass 1; numeral 3 denotes a row of metallic leads for interconnecting the electrodes of the front electrode row 2 with an external power source; numeral 4 denotes a connecting electrode row for bringing out the metallic lead row 3; numeral 6 denotes a rear glass opposed to the front glass 1 and separated by a predetermined spacing; numeral 5 denotes a rear electrode row disposed in the form of a long strip on one side of the rear glass 6 to form a matrix together with the front electrode row 2; and numeral 7 denotes a sealing glass provided along the outer periphery of the front glass 1 and that of the rear glass 6 to seal a display portion formed by both electrode rows hermetically from the exterior. In Fig. 5, the numeral 8 denotes a glass plate having through holes of the same pitch as the interelectrode pitch of the front electrode row, the glass plate 8 serving to determine the spacing between the front glass 1 and the rear glass 6 and maintain the insulation between both electrode rows. The through holes are located at the intersection points between the front and rear row electrodes. Numeral 9 denotes an electrically conductive material inserted into the holes of the glass plate 8 to allow electrical conduction between the upper and lower surfaces of the glass plate 8. The arrangement of Fig. 4 will now be described. The front electrode row 2 is drawn out to the exterior of the front glass 1 by connecting the metallic lead row 3 to the front electrode row 2 for specifying a display position (a discharge position). Then, the front electrodes, like the rear electrode row 5, are drawn out onto the rear glass 6 by connecting the metallic leads 3 independently for each terminal to the connecting electrode row 4 formed on the rear glass 6, whereby the transmission and reception of external signals are performed on only the rear glass 6. Where the front glass 1 and the rear glass 6 are to be sealed hermetically, the sealing glass 7 is applied to only the vicinity of the outer peripheral end portion on the rear glass 6 to effect the sealing. The glass plate 8 provided on the front glass 1 as shown in Fig. 5 and having through holes of the same pitch as that of the front electrode row 2 and also having the electrically conductive material 9 inserted in those through holes is sandwiched between the front glass 1 and the rear glass 6 under registration of the three of front electrode row 2, electrically conductive material 9 and connecting electrode row 4 to make electrical connection between the front electrode row 2 and the connecting electrode row 4, while the front electrodes are insulated from one another and the connecting electrodes also insulated likewise, and the front electrode row 2 is drawn out onto the rear glass 6. The glass plate 8 serves as a spacer between the front glass 1 and the rear glass 6 to maintain the spacing between the front and rear electrode rows 2, 5. Although in the above embodiment the metallic leads are drawn out of the sealing glass and connected to the connecting electrode row, this connection may be made inside the sealing glass. Although in the above embodiment an electrically conductive material is charged into the through holes formed in the glass plate, a predetermined thickness of material may be formed on the connecting electrodes to form electrically conductive connections. Further, although in the above embodiment the front electrode row is drawn out onto the rear glass, the rear electrode row may be equivalently drawn out to the front glass side. Thus, according to the above embodiment of the present invention all the connecting terminals of the display electrodes to the external power supply are gathered on the same side, and the sealing of glass can be done on one surface in a simplified shape, so there can be obtained a plasma display device easy to manufacture and high in both productivity and reliability.

Claims: A plasma display device, comprising: a first transparent substrate (6) having a plurality of linear electrodes (5) arranged thereon in parallel in a first direction; a second transparent substrate (1) having a plurality of linear electrodes (2) arranged thereon in parallel in a second direction orthogonal to said first direction; said first and second substrates (6, 1) being hermetically sealed together to form a discharge space therebetween with said electrodes (5, 2) intersecting to form a display matrix; a discharge gas sealed within said discharge space for emitting a visible plasma discharge when a predetermined driving voltage is applied between intersecting electrodes (5, 2); a plurality of electrode connector terminals (4) arranged along peripheral edge portions of said first substrate (6) for connection to an a.c. driving voltage; connector means for electrically connecting said plurality of electrodes (2) arranged on said second substrate (1) to respective ones of said electrode connector terminals (4); and means for providing a.c. driving voltage to said plurality of electrodes (5) on said first substrate (6); characterized in that said connector means comprises a spacer member (8) having a plurality of through-holes for enabling communication between said electrode connector terminals (4) and corresponding electrodes (2) of said second substrate (1), said through-holes being filled with electrically conductive material (9) for electrically connecting said electrode connector terminals (4) to said electrodes (2) of said second substrate (1).

Inventors: ARIMOTO HIRONOBU, ENDO TAKAFUMI, ITO HIROSHI, ARIMOTO, HIRONOBU, ENDO, TAKAFUMI, ITO, HIROSHI, ARIMOTO, HIRONOBU, C/O MITSUBISHI DENKI K. K., ENDO, TAKAFUMI, C/O MITSUBISHI DENKI K. K., ITO, HIROSHI, C/O MITSUBISHI DENKI K. K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1990
Main classification: H01J17
IPC codes: H01J17