Abstract:
A linear groove is formed in a glass sheet along a programmed cut line that is set for the glass sheet, and pressure is applied locally to an end of the groove. The pressure is not applied equally uniformly to the whole groove but applied locally to the end of the groove, where an initial crack is induced by the pressure applied thereto. The initial crack is guided by the groove so that the cracking force is propagated inductively along the groove. Distribution of stress in the glass corresponding to the cracking force thus propagated is concentrated locally to a face intersecting orthogonally to the surface of the glass sheet. The face to which the stress is concentrated intersects substantially orthogonally with the surface of the glass sheet. The glass sheet manufactured in this manner can be utilized effectively as a material of a PDP.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a method and an apparatus for cutting a glass sheet and a method for manufacturing a PDP (plasma display panel), and particularly relates to a method and an apparatus for cutting a glass sheet for obtaining a plurality of glass sheets for the PDP from a single large-size glass sheet, as well as to a method for manufacturing the PDP.  
           [0003]    2. Description of the Related Art  
           [0004]    A glass substrate is used for forming a display screen of a plasma display. Glass substrates of a size corresponding to the PDP screen size can be obtained by dividing a large-size glass sheet into several pieces. A glass sheet cutting apparatus is used for dividing the glass sheet. The glass sheet cutting apparatus comprises a heating device and a cooling device and is constructed such that thermal stress is applied to a sheet glass along a programmed cutting line of the sheet glass to thereby induce a crack in the sheet glass, and the glass sheet is cut along the programmed cutting line along with the progress of the crack. This technique is disclosed in Japanese Patent Laid-Open Publication No. 2000-281375, for example.  
           [0005]    A sheet glass cannot be cut only by a crack induced by thermal stress, since the progress of the crack will stop in the vicinity of the edges of the sheet glass. According to the prior art, the edge of the sheet glass where the progress of the crack has stopped is pressed and held by a suitable presser so that the external pressing force is applied to the sheet glass to cut the same finally.  
           [0006]    However, when the sheet glass is cut by imparting the external pressing force to the sheet glass as is done in the prior art, the sheet will be cut in the warped or deflected state. As the result, the cut surface will be formed obliquely and it is difficult to form the cut surface vertically to the surfaces of the glass substrate. Also, the cut line thus formed will not be straight and it is difficult to form the cut line in a straight line.  
           [0007]    A glass substrate constituting a display is required to have a cut surface vertical to the surfaces of the substrate and, also, the cut line is required to be a single straight line or a single flat plane. With the conventional cutting method, however, these requirements cannot be satisfied.  
         SUMMARY OF THE INVENTION  
         [0008]    An object of the present invention therefore is to provide a method and an apparatus for cutting a glass sheet or PDP substrate having a cut surface vertical to the substrate surfaces, as well as a method for manufacturing a PDP.  
           [0009]    Another object of the invention is to provide a method and an apparatus for cutting a glass sheet or PDP substrate having a cut line formed in a straight line, as well as a method for manufacturing a PDP.  
           [0010]    Followings are the features of the present invention. In the following description, for a better understanding of the invention, the constituent elements are given respective reference numerals of the attached drawings showing an embodiment of the present invention.  
           [0011]    A method for cutting a glass sheet of the present invention comprises the steps of forming a linear groove ( 5 ) in a glass sheet ( 3 ) along a programmed cutting line ( 4 ) that is set for the glass sheet, and applying local pressure to an end of the groove. According to the invention, not the entire groove ( 5 ) is uniformly subjected to equal pressure. Instead, only the end of the groove ( 5 ) is subjected to local pressure so that an initial crack is induced at the end by the pressure applied thereto. Starting from this initial crack, the cracking force is guided by the groove ( 5 ) and inductively propagated along the groove ( 5 ). Distribution of the stress inside the glass corresponding to the cracking force propagated in this manner is concentrated locally at the plane that includes the groove ( 5 ) and is orthogonal to the surface of the glass sheet  3 . The plane to which the stress is concentrated in this manner corresponds to the cut surface due to the physical properties of amorphous glass. The cut surface is substantially orthogonal to the surfaces of the glass sheet. Even if the glass sheet is deflected during a cutting process, it will not affect adversely to the optimization of the cross section of the glass substrate to be cut.  
           [0012]    It is preferable that the step of applying local pressure as described above further comprises the step of making a crack along the groove ( 5 ) in terms of ensuring the initial induction of stress.  
           [0013]    A method for cutting a glass sheet of the present invention comprises the steps of forming a linear groove ( 5 ) in a glass sheet ( 3 ) along a programmed cutting line that is set for the glass sheet  3 , and arranging an elastic plate  20  at an end of the groove ( 5 ) for dissipating pressure and arranging a pressure absorber ( 15 ) on the rear surface of the glass sheet ( 3 ) opposing the end of the cutting line. When pressure is applied to the glass sheet ( 3 ) for cutting the same, the absorber ( 15 ) helps the dissipation of the pressure to allow the pressure to be dissipated equally along the cutting line, and to promote the concentration of stress of cutting.  
           [0014]    The cutting method of the invention further and effectively comprises an additional step of lifting one of two sections of the glass sheet divided by the groove ( 5 ) with respect to the other one to from a V-shape section together, by using the groove ( 5 ) as the fulcrum. Since the groove ( 5 ) constitutes the junction of the two sections, the stress is concentrated on the groove. This method of bending the glass sheet into a V-shape section by the rotational displacement is adopted following the age-old technique used by glass craftsmen. According to the invention, however, the cutting operation is enabled to be automated and mechanized by locally pressing the programmed cutting line during the bending.  
           [0015]    The glass sheet cutting method of the present invention is particularly effective for manufacturing a constituent element of a plasma display panel. In this case, the glass sheet ( 3 ) is used as a front substrate ( 33 ) or a rear substrate ( 38 ) of a plasma display panel.  
           [0016]    A method for manufacturing a PDP device comprises a first process of producing a plasma display panel  30 , a second process of incorporating the plasma display panel  30  into a module ( 69 ) together with a circuit for driving the plasma display panel ( 30 ), and a third process of electrically connecting an interface ( 72 ) to the module ( 69 ), the interface ( 72 ) for transmitting an image signal after converting the format thereof to the module ( 69 ). In the first process, the method for producing the plasma display panel as described above is performed. By modularizing the PDP device components in this manner, the assembly and repair of the device can be simplified.  
           [0017]    An apparatus for cutting a PDP substrate according to the present invention comprises an elastic plate ( 20 ) arranged at an end of a programmed cutting line ( 4 ) of a glass sheet ( 3 ) for dissipating pressure, a pressure absorber ( 15 ) arranged on the rear surface of the glass sheet ( 3 ) opposing the end of the cutting line, and a pressurizing mechanism ( 12 ) for applying pressure to the elastic plate ( 20 ). The elastic plate ( 20 ) may be formed effectively as a face plate to be in surface contact with the surface of the glass sheet ( 3 ). In this case, the face plate may be formed of a silicon rubber plate. The pressurizing mechanism makes a crack along and over the programmed cutting line ( 4 ). A locally pressing sharp blade ( 12 ) is specifically used as a member of the pressurizing mechanism for locally pressing the plate from over the programmed cutting line ( 4 ).  
           [0018]    It will be effective to add a driving mechanism ( 19 ) for lifting one of two sections of the glass sheet ( 3 ) to be separated from each other by the programmed cutting line ( 4 ), with respect to the other one so as to form a V-shape section. By lifting one of the sections into a V-shape while locally pressing the end of the programmed cutting line ( 4 ), it is ensured that the glass sheet ( 3 ) is cut reliably along the programmed cutting line ( 4 ). By providing the pressurizing mechanism with a pressurizing needle ( 12 ) for transferring pressure to the glass sheet ( 3 ), it is ensured that stress is concentrated on the region of the cutting line.  
           [0019]    The tip end ( 13 ) of the pressurizing needle ( 12 ) is pointed to the programmed cutting line ( 4 ) and is formed sharp so that local stress is concentrated on the linear region of the programmed cutting line ( 4 ). It is particularly effective that the pressurizing needle ( 12 ) applies pressure to the linear region of the glass sheet ( 3 ) through the elastic plate ( 20 ) in terms of realizing both dissipation of pressure and local concentration of stress. The tip end ( 13 ) may be sharp taking the form of a point, a line, or a semispherical surface, or a semicylindrical surface.  
           [0020]    The pressurizing mechanism for applying cutting induction force to a programmed cutting line ( 4 ) set for a glass sheet ( 3 ) is formed by an applying member ( 12 ) mounted on the side of a first surface P 1  of the glass sheet ( 3 ) for applying cutting induction force to the glass sheet ( 3 ) from the side of the first surface P 1  and a support ( 15 ) arranged on the side of a second surface P 2  of the glass sheet ( 3 ) in opposition to the applying member ( 12 ) for elastically supporting the glass sheet ( 3 ) from the side of the second surface P 2 . Cutting force is imparted to the glass sheet ( 3 ) by the local pressure applied by the applying member ( 12 ) while dissipating the pressure on the side of the second surface P 2 , so that the glass sheet ( 3 ) can be cut straight along the programmed cutting line while preventing the glass sheet ( 3 ) from being broken.  
           [0021]    The support is formed of an elastic displacement member ( 15 ) directly joined to the second surface P 2  and a rigid body ( 14 ) supporting the elastic displacement member ( 15 ). The elastic support ( 15 ) is preferably formed from silicon rubber. The tip end ( 13 ) of the applying member ( 12 ) is effectively formed sharp to take a form of a point, a line, a semispherical surface, or a semicylindrical surface.  
           [0022]    The pressurizing mechanism is formed by a first suction member ( 25 ) attached to the second surface P 2  side of one of the sections of the glass sheet ( 14 ) to be divided by the programmed cutting line ( 4 ) so as to adhere by suction to the second surface P 2 , a second suction member ( 23 ) attached to the second surface P 2  side of the other section of the glass sheet ( 3 ) to be divided by the programmed cutting line ( 4 ) so as to adhere by suction to the second surface P 2 , and a driver ( 19 ) for displacing the second suction member ( 23 ) to the direction of the first surface P 1  with respect to the first suction member ( 25 ). The first and second suction members ( 25 ,  23 ) make it possible to cut the glass sheet ( 3 ) stably along the programmed cutting line ( 4 ) while bending the glass sheet ( 3 ). This method of bending the glass sheet into a V-shape for imparting bending stress thereto adopts traditional techniques practiced by glass craftsmen from long ago.  
           [0023]    The cutting apparatus may additionally comprise a streak marking unit ( 2 ) for marking a streak along the programmed cutting line ( 4 ). The applying member ( 12 ) makes a crack at an end of the streak ( 5 ) and the first and second suction members ( 25 ,  23 ) provide final cutting force for cutting the entire of the glass sheet ( 3 ). 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    [0024]FIG. 1 is a front view showing a part of an apparatus for cutting a PDP substrate according to an embodiment of the present invention;  
         [0025]    [0025]FIG. 2 is a front view showing another part of the apparatus for cutting a PDP substrate according to an embodiment of the present invention;  
         [0026]    [0026]FIG. 3 is a front view showing still another part of an apparatus for cutting a PDP substrate according to an embodiment of the present invention;  
         [0027]    [0027]FIG. 4 is plan view showing the cutting position of a glass sheet;  
         [0028]    [0028]FIG. 5 is a plan view showing a position for marking a streak on a glass sheet;  
         [0029]    [0029]FIG. 6 is a plan view showing the cutting position of a glass sheet;  
         [0030]    [0030]FIG. 7 is a perspective view showing a PDP; and  
         [0031]    [0031]FIG. 8 is a circuit diagram showing the modularization of the PDP. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0032]    Preferred embodiments of the present invention will be described specifically with reference to the attached drawings. An apparatus for cutting a glass sheet, particularly an apparatus for cutting a PDP substrate according to the invention comprises a streak marking process, a crack making process, and a cutting process. The streak marking process S 1  is shown in FIG. 1, the crack making process S 2  is shown in FIG. 2, and the cutting process S 3  is shown in FIG. 3.  
         [0033]    In the streak marking process S 1  as shown in FIG. 1, a suction unit  1  and a streak marking unit  2  are used. The suction unit  1  extends long along a programmed cutting line of a glass substrate  3  and adheres by suction to a first surface P 1  of the glass substrate  3  to hold the glass substrate  3  by suction. As shown in FIG. 4, a programmed cutting line  4  is set virtually in the suction unit  1 . The streak marking unit  2  is capable of marking a straight cut guiding streak (or groove)  5  corresponding with the programmed cutting line  4  that is assumingly drawn on one surface of the glass substrate  3 . The streak marking unit  2  is provide with a moving mechanism (not shown) for moving a diamond cutter along the programmed cutting line  4 . The diamond cutter may be substituted by a nozzle for blowing a harsh jet of steel sand against the glass surface.  
         [0034]    In the crack making process S 2 , a pressurizing mechanism  6  is used as shown in FIG. 2. The pressurizing mechanism  6  comprises a pressurizer  7  and a pressure receiver  8 . The pressurizer  7  is constituted by an air cylinder  9 , an abutting unit  11  supported by the air cylinder  9  and abutting against the first surface of the glass sheet  3 , and a locally pressing sharp blade  12  constructed to move toward the glass sheet  3  by receiving thrust from the air cylinder  9  and accommodated inside the abutting unit  11 . The locally pressing sharp blade  12  is formed of a thin stainless plate. The stainless plate is formed from stainless steel. When the air cylinder  9  moves towards the glass sheet  3 , the abutting unit  11  comes into contact with the glass sheet  3  elastically and not with impact. The abutting unit  11  is formed as a cylindrical body of rubber itself. Alternatively, it is constructed so as to receive biasing force from a coil spring and be thereby pushed out with the advancing position restricted by the coil spring. The abutting unit  11  is formed in the shape of a closed-end cylinder, the bottom of which is effectively formed as an upper elastic plate (e.g. silicon plate)  20  that is brought into surface contact with and joined with the surface of the glass sheet  3 .  
         [0035]    The thickness of the stainless plate is preferably in the range of 0.3 mm to 0.5 mm. The tip end (lower end) of the stainless plate is formed into a sharp point or a sharp line  13 . This sharp point or sharp line is preferably formed in a rounded (semispherical or semicylindrical) shape. The pressure receiver  8  comprises a backing plate  14  and a lower elastic plate (pressure dissipating plate)  15 . The lower elastic plate  15  is arranged between the backing plate  14  and the second surface P 2  of the glass substrate  3 . The pressurizer  7  and the pressure receiver  8  are arranged on the opposite sides, respectively, across the glass substrate  3 . The lower elastic plate  15  is preferably formed from silicon rubber having an appropriate hardness. The appropriate hardness value is preferably around  70  according to the JIS standard relating to rubber.  
         [0036]    As shown in FIG. 5, the pressurizing mechanism  6  is arranged at a position or positions corresponding to one end site or the opposite end sites (opposite ends) of a cut guiding streak  5 . The sharp line  13  of the locally pressing sharp blade  12  positionally corresponds to a point P in the end region of the cut guiding streak  5 . The point P may be enlarged to a short line segment. An initial crack is generated in the point region or short line segment region positionally corresponding to the point P in the end region of the programmed cutting line  4  in the glass substrate  3  squeezed between the locally pressing sharp blade  12  and the backing plate  14 .  
         [0037]    In the cutting process S 3  as shown in FIG. 3, a cutting force imparting (bending force imparting) unit  16  is used. The cutting force imparting unit  16  comprises a driven-side cutting force imparting unit  17  and a non-driven-side cutting force imparting unit  18 . The driven-side cutting force imparting unit  17  comprises a driving mechanism  19  and a suction unit  21 . The driven-side and non-driven-side cutting force imparting units  17  and  18  are arranged on the side of the second surface P 2  of the glass sheet  3 . The driven-side cutting force imparting unit  17  is arranged on the opposite side of the non-driven-side cutting force imparting unit  18  with respect to the cut guiding streak  5  corresponding with the programmed cutting line  4 .  
         [0038]    The suction unit  21  comprises a driven-side main body  22  moved toward and away from the surface of the glass sheet  3  by receiving drive force from the drive mechanism  19 , and a driven-side suction member  23  supported by the driven-side main body  22  to move substantially integrally with the driven-side main body  22  and adhering by suction to the second surface P 2  of the glass sheet  3 . The non-driven-side cutting force imparting unit  18  comprises a non-driven-side main body  24  fixed to the glass substrate  3  and a non-driven side suction member  25  supported by the non-driven-side main body  24  to move substantially integrally with the non-driven-side main body  24  and adhering by suction to the second surface P 2  of the glass substrate  3 . The driven-side cutting force imparting unit  17  is arranged substantially in mirror symmetry with the non-driven-side cutting force imparting unit  18  with respect to the plane including the cut guiding streak  5  and orthogonal to the surface of the glass substrate  3 .  
         [0039]    Process S 1   
         [0040]    As shown in FIG. 1, the suction unit  1  operates to adhere by suction to the first surface P 1  of the glass substrate  3 , and the streak marking unit  2  operates to form a cut guiding streak  5  in the first surface P 1  of the glass substrate  3 . The streak marking unit  2  is moved along the programmed cutting line  4 . The programmed cutting line  4  is, as shown in FIG. 4, formed in the vicinity of one edge of one panel of three panels to be formed from the glass substrate  3 . Alternatively, as shown in FIG. 5, the line  4  is formed in the vicinity of one edge of one panel of two panels to be formed from the glass substrate  3 .  
         [0041]    Process S 2 :  
         [0042]    As shown in FIG. 2, the pressurizing mechanism  6  operates to bring the upper elastic plate  20  in contact with the first surface P 1  of the glass sheet  3 , and the locally pressing sharp blade  12  presses the glass plate  3  through the upper elastic plate  20 , and the sharp line  13  of the locally pressing sharp blade  12  locally applies pressure to the point region or short line segment region of the cut guiding streak  5 . The local pressure is dissipated uniformly through the upper elastic plate  20  to the local periphery of the local point or to the local sides of the local short line segment. The pressure generated by the downward movement of the locally pressing sharp blade  12  is attenuated and further dissipated within the lower elastic plate  15 .  
         [0043]    The locally pressing sharp blade  12  presses the first surface P 1  of the glass sheet  3  with an appropriate pressure. The pressure is transmitted to the backing plate  14  via the glass substrate  3 , and the glass sheet  3  is squeezed between the sharp line of the locally pressing sharp blade  12  and the surface of the rigid backing plate  14 , whereas the lower elastic plate  15  present between the glass sheet  3  and the backing plate  14  effectively prevents excessive stress from being applied to the local site in the glass sheet  3 , namely the end region of the cut guiding streak  5 . The sharp line  13  of the locally pressing sharp blade  12  matches the end region of the cut guiding streak to cause proper stress to be generated in the glass sheet  3  through the end region. This proper stress enables the glass sheet  3  to be cut along the cut guiding streak  5 .  
         [0044]    Process S 3 :  
         [0045]    As shown in FIG. 3, the drive mechanism  19  of the driven-side cutting force imparting unit  17  operates to lift the driven-side main body  22  so that one of the left and right sections of the glass sheet  3  divided by the cut guiding streak  5  is thereby pushed up in the direction from the second surface P 2  to the first surface P 1  under appropriate pressure. The other of the left and right sections of the glass sheet  3  is held by suction by means of the non-driven-side suction member  25  of the non-driven-side cutting force imparting unit  18 . Relative rotational movement is generated between the left and right sections around the line including the cut guiding streak  5  and the above-mentioned initial cracks formed in the form of line segments in the end regions of the cut guiding streak  5 . This relative rotational movement causes the stress to be concentrated on the initial cracks. The stress thus concentrated causes shear stress to be produced in the initial cracks and the initial cracks are initially cut off in a shearing way. The cutting force is guided to the cut guiding streak  5  by the inductive property due to the crystallinity of glass and transmitted from one end to the other end of the cut guiding streak  5 . The glass sheet  3  is cut off by the line corresponding to the programmed cutting line  4 .  
         [0046]    In the cutting process, the sharp line  13  directly applies pressure to the cut guiding streak  5  inducing the cutting force, while the rear side position corresponding to the site receiving the pressure is supported elastically by the lower elastic plate  15 . The pressure applied to the rear side is dissipated all over by the variability of the internal stress possessed by the lower elastic plate  15  itself. One point or one line segment in the lower elastic plate  15  serves as a fulcrum or fulcrum line when the glass sheet left and right sections divided by the programmed cutting line  4  are bent relative to each other, and this fulcrum line also constitutes a symmetry reference line for cutting off the glass sheet  3  into the left and right sections. The glass sheet  3  thus can be cut off with the cut surface formed flat along a straight line. It is preferable that, during the cutting process, either one or both of the driven-side suction member  23  and the non-driven-side suction member  25  is or are displaced to the side of the first surface P 1  of the glass sheet  3 . The cut guiding streak  5  and the cracks at the ends thereof both initially guide the cutting force as stress in the glass that is an amorphous material.  
         [0047]    [0047]FIG. 7 shows a plasma display panel  30  as an example that is assembled by incorporating a glass substrate produced by the method described above. The plasma display panel  30  comprises a front frame board  31  and a rear frame board  32 . The front frame board  31  is formed of a first transparent glass substrate  33  manufactured by the PDP substrate cutting method of the invention, a transparent dielectric layer  34  joined to the rear side of the first transparent glass substrate  33 , and a surface protective layer  35  joined to the rear side of the transparent dielectric layer  34 . A scanning electrode  36  and a sustaining electrode  37  are arranged between the first transparent glass substrate  33  and the transparent dielectric layer  34 . The scanning electrode  36  and the sustaining electrode  37  are disposed parallel with each other. The scanning electrode  36  and the sustaining electrode  37  are respectively constituted by a transparent electrode and a bus electrode. The transparent dielectric layer  34  covers the scanning and sustaining electrodes  36  and  37 .  
         [0048]    The rear frame board  32  is formed of a second transparent glass substrate  38  manufactured by the PDP substrate cutting method of the invention, a white dielectric layer  39  joined to the front side of the second transparent glass substrate  38 , and a plurality of partitions  41  joined to the front side of the white dielectric layer  39 . The partitions  41  define display cells. A data electrode  42  is arranged between the second transparent glass substrate  38  and the white dielectric layer  39 . The data electrode  42  intersects orthogonally with the scanning electrode  36  and the sustaining electrode  37 . The white dielectric layer  39  covers the data electrode  42 . A phosphor layer  43  is formed on the side faces of the partitions  41  and on the front surface of the white dielectric layer  39  for converting ultraviolet rays generated by the discharge of discharge gas into visible light. The phosphor layer  43  is color coded with three primary colors of R, G, and B for each cell.  
         [0049]    The front frame board  31  and the rear frame board  32  are assembled fixedly with a gap defined therebetween. The width of the gap is designed to be about 100 μm. The side peripheries of the front and rear frame boards  31  and  32  are tightly sealed with a seal material, so that the gap forms a sealed space. The sealed space is filled with helium, neon, xenon, or mixture gas including any of these. The rear frame board  32  is provided with a vent tube (not shown) passing through the second transparent glass substrate  38  and opening into the sealed space. The outside end opening of the vent tube is connected to a gas discharging and filling apparatus (not shown), so that gas such as air or the like is sucked and discharged through the opening, and then the above-mentioned gas is injected into the above-mentioned sealed space. After the injection, the opening is chipped on by heating means so that the open end is closed to hermetically enclose the injected gas within the sealed space.  
         [0050]    It is important that the side peripheries  44  of the first and second transparent glass substrates  33  and  38  of the plasma display panel  30 , where such hermetical seal is required, are formed as a flat face, not as a curved face, intersecting orthogonally to the first surface P 1  described above. In this regard, the side periphery  44  is formed to be an orthogonal plane by the PDP substrate cutting method according to the present invention. The side periphery  44  thus formed is coated with a fusing material.  
         [0051]    [0051]FIG. 8 shows a plasma display device  50  including a plasma display panel  30  assembled as described with reference to FIG. 7. The plasma display device  50  is modularized. The modularized plasma display device  50  comprises an analog interface  51 , and a plasma display panel module  52 .  
         [0052]    The analog interface  51  comprises a Y/C separator circuit  53  having a chroma decoder, an A/D converter circuit  54 , an image format converting circuit  55 , a synchronous signal control circuit  57  having a PLL circuit  56 , a reverse y converter circuit  58 , a system control circuit  59 , and a PLE control circuit  61 . The analog interface  51  converts a received analog video signal (an analog RGB signal  62  and an analog video signal  63 ) into a digital video signal  64  and outputs this digital video signal  64  to the plasma display panel module  52 . More specifically, an analog video signal  63  transmitted by a TV tuner is decomposed into luminance signals of colors R, G, and B by the Y/C separator circuit  53 , and then converted into a digital video signal  64  by the A/D converter circuit  54 . If the pixel constitution of the plasma display panel module  52  is different from that of the analog video signal  63 , the digital video signal  64  is converted into an appropriate image format by the image format converting circuit  55 .  
         [0053]    The analog video signal  63  does not include a sampling clock or data clock signal for A/D conversion. The PLL circuit  56  included in the synchronous signal control circuit  57  generates a sampling clock  65  and a data clock signal  66  with reference to a horizontal synchronizing signal supplied thereto at the same time with the analog video signal  63 . The sampling clock  65  and the data clock signal  66  are outputted from the analog interface  51  and received by the plasma display panel module  52 . The PLE control circuit  61  increases the display luminance if the average luminance level is not more than a predetermined value, and decrease the display luminance if the average luminance level is not less than the predetermined value. The system control circuit  59  generates various types of control signal  67 . The control signal  67  is outputted by the analog interface  51  and received by the plasma display panel module  52 .  
         [0054]    The plasma display panel module  52  comprises a digital signal processing/controlling circuit  68 , a panel part  69 , and a module power source circuit  71  having a built-in DC/DC converter. The panel part  69  includes the plasma display panel  30  described above. The digital signal processing/controlling circuit  68  comprises an input interface signal processing circuit  72 , a frame memory  73 , a memory control circuit  74 , and a driver control circuit  75 . The average luminance level of the digital video signal  64  inputted to the input interface signal processing circuit  72  from the analog interface  51  is calculated by an input signal average luminance level calculating circuit (now shown) provided in the input interface signal processing circuit  72  and outputted as data of an appropriate number of bits (e.g. 5 bits). PLE control data  76  set by the analog interface  51  in correspondence with the average luminance level is inputted to a luminance level control circuit (not shown) in the input interface signal processing circuit  72 .  
         [0055]    The digital signal processing/controlling circuit  68  processes the above-mentioned signal in the input interface signal processing circuit  72  and transmits the processed control signal  77  to the panel part  69 . At the same time as the transmission of the processed control signal  77 , the memory control circuit  74  and the driver control circuit  75  generate a memory control signal  78  and a driver control signal  79 , respectively, and transmit these signals to the panel part  69 .  
         [0056]    The panel part  69  comprises the plasma display panel  30 , a scanning driver  81  (mounted integrally in the panel part  69 ) for driving the scanning electrode  36  (see FIG. 7), and a data driver  82  (mounted integrally in the panel part  69 ) for driving the data electrode  42  (see FIG. 7). The panel part  69  further comprises a high-voltage pulse circuit  83  for supplying pulsed voltage to the plasma display panel  30 , scanning driver  81 , and data driver  82 . The high-voltage pulse circuit  83  is arranged and packaged at a plurality of positions of the panel part  69  as a part of the panel part  69 .  
         [0057]    The plasma display panel  30  has 1365×768 pixels arrayed in 1365×768 grid. In the plasma display panel  30 , the scanning driver  81  controls the scanning electrode  36  and the data driver  82  controls the data electrode  42 , so that control is performed to turn on or not to turn on a predetermined number of pixels from among the above-mentioned number of pixels, and prescribed display is thereby performed.  
         [0058]    A logic power supply (not shown) supplies logic power to the digital signal processing/controlling circuit  68  and the panel part  69  through a power input terminal  84 . The module power source circuit  71  is supplied with DC power from a display power supply (not shown) through another power input terminal  85  and supplies the DC power to the panel part  69  after changing the voltage thereof to a predetermined voltage.  
         [0059]    The plasma display panel  30 , the scanning driver  81 , the data driver  82 , and the high-voltage pulse circuit  83  are arranged and packaged, together with a power collecting circuit  86 , on a single substrate constituting the main body of the panel part  69 . In the panel part  69 , the main body, the plasma display panel  30 , the scanning driver  81 , the data driver  82 , the high-voltage pulse circuit  83 , and the power collecting circuit  86  are constructed integrally. The digital signal processing/controlling circuit  68  is separated from the panel part  69  and formed mechanically independently from the panel part  69 .  
         [0060]    The module power source circuit  71  is separated from the digital signal processing/controlling circuit  68  and the panel part  69  and formed mechanically independently therefrom. The digital signal processing/controlling circuit  68 , the panel part  69 , and the module power source circuit  71  are assembled as a single module. The plasma display panel module  52  constitutes the single module thus assembled. The analog interface  51  is separated from the plasma display panel module  52  and is formed mechanically independently therefrom. The plasma display panel module  52  is electrically connected to the analog interface  51  by electric wiring for transmitting the control signal  67 , the digital video signal  64 , the sampling clock  65 , the data clock signal  66 , the PLE control data  76 , and other signals.  
         [0061]    The analog interface  51  and the plasma display panel module  52  are, after being formed separately, incorporated and fixedly supported in the housing of the plasma display device to build up the plasma display device  50 . In the plasma display device  50  modularized in this manner, the analog interface  51  and the plasma display panel module  52  can be manufactured separately from other equipment components. Therefore, if the plasma display device  50  breaks down, the plasma display device  50  with failure can be replaced with a new plasma display device  50  while leaving the plasma display panel module  52  as it is, so that the repair of the plasma display device  50  can be simplified and the time required for the repair can be shortened.  
         [0062]    With the method and the apparatus for cutting a PDP substrate and the method for manufacturing a PDP device according to the present invention, it is possible to produce a glass substrate having a cut surface that is highly vertical to the substrate surface and hence to ensure good quality for the PDP devices produced using the glass substrate.