Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
1999-04-27
2003-11-25
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C174S253000, C174S126400
Reexamination Certificate
active
06652342
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a wiring board in which a wiring pattern is formed on a substrate and a gas discharge type display apparatus using such a wiring board.
2. Description of the Related Art
According to a gas discharge type display apparatus such as a plasma display or the like, since a display is performed by a self light emission, an angle of visibility is wide and a display can be easily seen. Such a display apparatus has features that a thin display apparatus can be manufactured and a large screen can be realized and the like. An application of such a display apparatus to a display apparatus of information terminal equipment or a high definition television receiver has been started. The plasma display is mainly classified into a DC driving type and an AC driving type. According to the plasma display of the AC driving type among them, a luminance is high owing to a memory function of a dielectric layer covering electrodes and a life enough to endure an actual use can be obtained due to the formation of a protecting layer or the like. Thus, the plasma display has been put into practical use as a multi-purpose video monitor.
FIG. 6
is a perspective view showing a structure of a plasma display panel which has been put into practical use. To make it easy to see, a front substrate
100
is illustrated in the diagram so as to be away from a back substrate
200
and a discharge space area
300
.
The front substrate
100
has a structure such that display electrodes
600
made of a transparent electrode material such as ITO (Indium Tin Oxide), tin oxide (SnO
2
), or the like, bus electrodes
700
made of a low resistance material, a dielectric layer
800
made of a transparent insulating material, and a protecting layer
900
made of a material such as magnesium oxide (MgO) or the like are formed on a front glass substrate
400
.
The back substrate
200
has a structure such that address electrodes
1000
, barrier ribs
1100
, and a fluorescent layer
1200
are formed on a back glass substrate
500
. Although not shown, a dielectric layer is also formed on the address electrodes
1000
.
By adhering the front substrate
100
and back substrate
200
so that the display electrodes
600
and address electrodes
1000
almost perpendicularly cross, the discharge space area
300
is formed between the front substrate
100
and back substrate
200
.
In the gas discharge type display apparatus, an AC voltage is applied between a pair of display electrodes
600
formed on the front substrate
100
and a voltage is applied between the address electrodes
1000
formed on the back substrate
200
and the display electrodes
600
, thereby generating an address discharge and allowing predetermined discharge cells to generate a main discharge. By ultraviolet rays which are generated by the main discharge, the fluorescent materials
1200
of red, green, and blue separately coated on the discharge cells are allowed to emit light, thereby displaying.
A conventional technique of such a gas discharge type display apparatus has been disclosed in, for example, “Flat Panel Display 1996”, edited by Nikkei Microdevice, pages 208-215, 1995.
A method of forming the bus electrodes
700
provided for the front substrate
100
and the address electrodes
1000
provided for the back substrate
200
will be described further in detail.
FIGS. 4 and 5
show an example of forming the address electrode
1000
onto the back glass substrate
500
. Since the bus electrodes
700
provided for the front substrate
100
are also formed by almost similar steps, its description is omitted here.
First referring now to
FIG. 4
, Cr/Cu/Cr layers (
1000
a
to
1000
c
) serving as an address electrode
1000
and a resist
2500
to form a pattern of the address electrode
1000
are sequentially formed on the back glass substrate
500
so as to be laminated by using a film forming method such as sputtering method, evaporation deposition method, or the like and by using a resist forming method such as rotational coating, laminating, or the like (step (a): film forming step). Subsequently, the resist
2500
is exposed and developed so as to obtain a desired pattern of the address electrode
1000
(steps (b) and (c): photolithographic step). The Cr layer
1000
a
is etched in a desired pattern by using an etchant for Cr (step (d): etching step). Subsequently, the exposed and developed resist
2500
is removed and the resist
2500
is again formed (steps (e) and (f)). Subsequently, referring to
FIG. 5
, by repeating the above processes with respect to each of the Cu layer
1000
b
and Cr layer
1000
c
(steps (g) to (o)), the address electrode
1000
is formed on the back glass substrate
500
.
Although such a process is usually called a photolithograph-etching process, such a process has difficulties that the number of steps is large and costs are high because the resist formation and the like are included. Although the forming method of the Cr/Cu/Cr wirings has been described here, there are similar difficulties so long as a resist is used even if wirings are formed by using another single material. Although a mask to expose and form the resist pattern is necessary to form a resist, according to the gas discharge type display apparatus, since it ordinarily has a large screen, a positional deviation occurs more easily as a position of the mask approaches a periphery and it is difficult to accurately form wirings. It is also difficult to realize a highly accurate position matching itself of the mask. The mask is expensive.
As a wiring forming method in which the resist is made unnecessary, there is a method whereby a photosensitive material (for example, silver material having photosensitivity) is used and the photosensitive material is exposed and developed by a light source such as a mercury lamp or the like, thereby forming wirings.
In this case as well, however, in case of exposing the photosensitive material, a mask on which a desired wiring pattern has been formed is necessary and the difficulties in case of using the mask as mentioned above still remain. That is, there are the difficulties of the positional deviation at the time of formation of the wirings, the positional mismatching of the mask, and the costs of the mask.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an exactly novel process which makes a mask unnecessary. That is, an object of the invention is to provide a gas discharge type display apparatus in which wirings are formed by exactly novel processes without needing a mask.
According to the invention, when wirings are formed by using a photosensitive material, a wiring pattern is directly drawn by a laser and the photosensitive material is exposed by the laser drawing, thereby making the conventional mask unnecessary. That is, according to the invention, to accomplish the above object, a front substrate having a plurality of first electrodes and a back substrate having a plurality of second electrodes are provided, and at least ones of the first and second electrodes are made of a photosensitive material containing silver exposed by using the laser.
As mentioned above, by directly drawing and exposing the photosensitive material with the laser, the conventional exposing process using the mask is unnecessary, so that the difficulties of the positional deviation at the time of the formation of the wirings due to the mask, the positional mismatching of the mask, and the costs of the mask can be solved. Therefore, according to the gas discharge type display apparatus of the invention, there is no positional mismatching of the mask and high positioning precision of the wirings can be easily assured, namely, the wirings can be formed at a desired position as compared with the conventional apparatus, so that uniform discharging characteristics can be obtained on the whole panel surface.
The wirings can be also formed at low costs.
Silver is preferable as a photosensitive material because of a wiring resistance or the like.
REFERENCES:
Ijuin Masahito
Kawai Michifumi
Nishiki Masashi
Satoh Ryohei
Suzuki Shigeaki
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Ramsey Kenneth J.
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