a preferred embodiment of the present invention will be described with reference to the accompanying drawings in detail . fig1 is a schematic cross - sectional view showing a first embodiment of a plasma - addressed display panel of the present invention . as shown in fig1 this plasma - addressed display panel has a laminated structure where a dielectric sheet 3 of glass , etc . is interposed between a display cell 1 and a plasma cell 2 . the display cell 1 includes an upper side transparent substrate of glass or the like , with a plurality of parallel signal electrodes 5 of transparent electrically conducting film being formed in columns at the inner surface of the transparent substrate 4 . this transparent substrate 4 is adhered to the upper surface of the dielectric sheet 3 with a prescribed gap therebetween using sealing members 6 to form a cell . the cell is then filled up with an electro - optical substance such as a liquid crystal . on the other hand , the plasma cell 2 is constituted by an insulating substrate 8 of the same glass . discharge electrodes 9 extending in a direction that is orthogonal with respect to the direction of the signal electrodes 5 are formed at the primary inner surface of the insulating substrate 8 . each pair of these discharge electrodes 9 acts as an anode a and a cathode k that generate a plasma discharge . barrier ribs 10 are then formed so as to block out each pair of discharge electrodes 9 . the top surfaces of the barrier ribs 10 come into contact with the lower side surface of the dielectric sheet 3 so that the ribs act as spacers . the insulating substrate 8 is bonded to the lower surface of the dielectric sheet 3 using a glass flit 11 to form a cell that is sealed air - tight . individual discharge channels 12 are formed as a result by dividing up this cell using barrier ribs 10 . each discharge channel 12 includes the pair of an anode a and a cathode k . the air - tight cell is filled up with an ionizable gas selected from , for example , helium , neon , argon , or a compound thereof . the present invention is characterized in that the discharge electrodes 9 are electrically conducting material embedded in grooves 13 formed into the surface of the insulating substrate 8 in rows . in the embodiment shown in fig1 the electrically conducting material completely fills the grooves 13 so that the surfaces of the discharge electrodes 9 are flush with the surface of the insulating substrate 8 . this invention , however , is not restricted in this respect , and the surface of the discharge electrodes 9 may be sunken below the surface of the insulating substrate 8 . it also becomes more difficult for the plasma particle sputtering to have any undesired influence when this sunken electrode structure is adopted . the manufacturing method for this plasma - addressed display panel will now be described with reference to fig1 . first , rows of grooves 13 are formed at the surface of an insulating substrate 8 . this process is carried out by either sandblasting or etching using a photoresist as a mask . next , discharge electrodes 9 are manufactured by carrying out a heating process and a sintering process on the electrically conductive material after filling the grooves 13 with the electrically conductive material . this process may be carded out using , for example , screen printing techniques employing conductive paste or using blade techniques . in other words , a blade moved over the grooved surface pushes the conductive paste into the grooves . further , the plasma cell 2 is assembled by bonding the lower surface of the dielectric sheet 3 onto the insulating substrate 8 with a gap therebetween to form a cell and sealing an ionizable gas into the cell . finally , the display cell 1 is assembled by bonding the transparent substrate 4 provided with column - arranged , stripe - shaped signal electrodes 5 in advance onto the upper surface of the dielectric sheet 3 to form a cell and sealing an electro - optical substance such as a liquid crystal into the cell . fig2 is a cross - sectional view showing the essential pans of a second embodiment of the plasma - addressed display panel of the present invention . here , only the plasma cell 2 is shown and the display cell to be overlaid thereon is omitted . the second embodiment has basically the same structure as the first embodiment , with corresponding portions bearing the corresponding reference numerals for ease of understanding . the point of difference is that the discharge electrodes 9 formed at the grooves 13 are sunken . i . e . the surface of the discharge electrodes 9 is deeper than the surface of the insulation substrate 8 . in this case , the discharge paths of the discharges occurring between the cathodes k and the anodes a within the discharge channel 12 are arced or parabolic . this presents no problem with regards to the operating characteristics even if the surfaces of the discharge electrodes 9 are sunk within the grooves 13 . fig3 is a cross - sectional view showing the essential parts of a third embodiment of the plasma - addressed display panel of the present invention . only the insulating substrate 8 is illustrated for ease of understanding . the basic structure is the same as for the other embodiments shown in fig1 and fig2 and corresponding portions are given the corresponding reference numerals . the point of difference is that only the lower pan of the groove 13 is restrictedly filled with the electrically conducting material forming the discharge electrodes . this has the benefits of lessening the undesired influence of the sputtering and lengthening the service life of the panel . more specifically , the amount of the electrically conducting material sputtered that flies out of the groove 13 is small even with sputtering by ions , etc . included in the plasma particles . accordingly , deterioration in the insulation between the anodes a and the cathodes k and the deterioration of the transmissivity of the insulating substrate 8 are suppressed thereby resulting in prolonging the service life of the panel . plasma discharges are also possible even if the discharge electrodes are formed restricted to the bottom part of the groove 13 because the discharge paths of a medium such as the ions and the electrons are parabolic . finally , a detailed description of the method of manufacturing the embedded discharge electrodes that are characteristic of the present invention is given with reference to fig4 . first , a glass substrate 21 is prepared in step ( a ). a photosensitive film ( photoresist ) 22 having a thickness of about 100 μm is coated or pasted onto the glass substrate 21 . next , the step advances to step ( b ) where the photosensitive film 22 is exposed to ultra - violet light ( uv ) using a mask 23 drawn with the desired stripe pattern . after this , the photosensitive film 22 is developed using a weak alkali solution and the unnecessary portions are removed . then , the step advances to step ( c ) where grooves are formed in the glass substrate 21 by sandblasting , etc . in particular , a high - pressure jet of particles such as sic of a particle diameter of a few μm to several tens of μm is directed to the surface of the glass substrate 21 through a patterned film 22 . unnecessary parts of the film 22 are then removed using acetone , etc . after the sandblasting . proceeding to step ( d ), the paste 25 of electrically conductive material is filled into the grooves 26 using a blade 24 . screen printing techniques may also be employed in place of the method using the blade . finally , in step ( e ), the discharge electrodes 27 are produced by carrying out a heating process at a temperature of about 580 ° c . and sintering the paste . the discharge electrode structure as shown in fig1 is obtained from the above processes . the depressed or concaved type of discharge electrode structure shown in fig2 and fig3 can be obtained in place of the completely filled - up type of discharge electrode structure shown in fig1 by selecting the paste filling - up method ( blade method , screen printing method , etc .) and adjusting the paste viscosity . the embedded discharge electrodes made using the processes shown in fig4 have the following advantages . firstly , the photolithography for the photosensitive film determines the accuracy of the patterning for the stripes . a finely detailed stripe pattern can therefore be more accurately made than when direct screen printing is applied . secondly , a groove of a depth of greater than 100 μm can be dug using sandblasting techniques . as a result , the discharge electrodes may therefore be made thicker so that the electrical resistance thereof can be lowered . thirdly , adherence is made strong because the discharge electrodes are embedded into the insulating substrate . fourthly , substrate warping caused by differences in the thermal expansion coefficients of the insulating substrate and the electrically conductive material can be reduced . for example , it is preferable to have adhesive strength with respect to the bottom surface of the groove weak while maintaining adhesive strength with respect to the discharge electrodes only at the side walls of the grooves . specifically , a friction reducing micro particle layer is formed as a foundation at the bottom of the groove before filling up with the paste . as described above , according to the present invention , the discharge electrodes within the plasma cell are constituted by an electrically conductive paste , which are embedded into grooves dug in rows in the surface of the insulating substrate . alternatively , this electrically conducting material is sunk down within the grooves . this kind of discharge electrode structure is obtained by filling up grooves with electrically conductive material such as a paste and then carrying out a heating process after stripe - shaped grooves have been formed at the surface of the insulating substrate using sandblasting . a finely detailed discharge electrode stripe pattern can therefore be accurately made . further , because the film thickness of the discharge electrodes can easily be made large , the electrical resistance becomes small resulting in making the discharge characteristics stable accordingly . discharge electrodes that are strongly adhered to the insulating substrate can be made and panel reliability can be made high . moreover , it becomes harder for sputtering to exert any negative influence on the panel and the service life of the panel is , thus , prolonged . warping of the insulating substrate due to differences in thermal expansion coefficients is also reduced . in fig6 is an embodiment of the invention in which the electrodes 9 which include the anodes a and the cathodes k are in grooves 13 , as in the previous embodiment . the barrier ribs 10 are on the anodes a and extend to the dielectric layer 3 , however . the cathodes k do not have the barrier ribs formed on top . the ribs 10 are narrow enough to expose the anodes a on one , and preferably on both sides of the ribs 10 , so that the anodes a are exposed to the discharge chambers . a further embodiment is shown in fig7 wherein the barrier ribs 10 are on both the anodes a and the cathodes k of the discharge electrodes 9 . as in the embodiment of fig6 the ribs 10 are narrow enough , or conversely , the electrodes are wide enough to extend from beneath the ribs 10 and be exposed to the discharge chambers . although other modifications and changes may be suggested by those skilled in the art , it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art .