GROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Korean Application No. 2001-48309, fried on Aug. 10, 2001 in the Korean Patent Office the entire disclosures of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a vacuum fluorescent display and, more particularly, to a built-in chip vacuum fluorescent display which is mounted with driver chips within a vacuum tube.

BACKGROUND OF THE INVENTION

Generally, vacuum fluorescent displays (VFDs) may be classified into various formats depending upon the structure, the display area, the display content, and the manner of driving. Particularly in view of the display area, the VFDs can be classified into a usual type, a front luminescent type, and a dual layer type. In view of the display content, the VFDs can be classified into a number display type, a character display type, and a graphic display type.

The graphic display type VFD has phosphors patterned in a dot matrix type corresponding to the picture signal information, and driver chips for selectively driving the grid electrodes. For example, assume that the graphic display type VFD with a dot matrix of 128×128 is driven in a fourfold or eightfold manner. When only the phosphors (the anode electrodes) are driven while omitting the drivers for driving the grids, the number of anode electrodes interconnected via the same wiring line amounts to 512 with the fourfold driving manner, and to 1024 with the eightfold driving manner. Accordingly, even with the use of a 128 bit driver, four driver chips should be provided with the fourfold drive type VFD, and eight driver chips with the eightfold drive type VFD.

The driver chips are mounted on a glass placed at the inside or outside of a vacuum tube outlining the VFD by way of a mounting technique called chip on glass (COG) or chip in glass (CIG). For example, such a structure is disclosed in U.S. Pat. No. 5,739,634.

When the mounting of the driver chips is made by way of the COG or CIG technique, the driver chips, the phosphors and the anode electrodes are provided at the same substrate. Therefore, it becomes necessary for an additional space for mounting the driver chips to be provided as compared to the VFD wherein the driver chips are not mounted within the vacuum tube. For this reason, the size of the vacuum tube becomes needlessly enlarged to accommodate the increase in area unnecessary for the display purposes.

Such a problem becomes serious in the graphic display type VFD mounted with large numbers of driver chips within the limited effective area.

In the case of a graphic display type VFD with a dot matrix of 128×128, when four or eight driver chips are mounted in accordance with the CIG technique, the non-effective area for mounting the driver chips at the inside of the vacuum tube is at best in the range of 15˜25 mm from the periphery of the effective area. Consequently, as the area for mounting the driver chips is extremely limited, it becomes difficult to design the structure of the VFD in a suitable manner.

SUMMARY OF THE INVENTION

In accordance with the present invention a built-in chip vacuum fluorescent display is provided which can be effectively mounted with a plurality of driver chips within a vacuum tube.

According to one aspect of the present invention, the built-in chip vacuum fluorescent display includes a vacuum tube having a transparent top substrate, a bottom substrate facing the top substrate with driver chip wirings while being spaced apart from the top substrate with a predetermined distance, and a side glass disposed between the top and the bottom substrates while interconnecting the top and the bottom substrates. A plurality of driver chips are mounted at the bottom substrate within the vacuum tube while being electrically connected to the driver chip wirings. At least one subsidiary substrate is provided at the space between the top and the bottom substrates within the vacuum tube while having wirings electrically connected to the driver chip wirings. Cathodes are provided between the subsidiary substrate and the top substrate within the vacuum tube to emit thermal electrons. Anodes with phosphors are patterned at the subsidiary substrate while being electrically connected to the wirings.

According to another aspect of the present invention, the built-in chip vacuum fluorescent display includes a vacuum tube having a transparent top substrate with first wirings, a bottom substrate facing the top substrate with driver chip wirings while being spaced apart from the top substrate with a predetermined distance, and a side glass disposed between the top and the bottom substrates while interconnecting the top and the bottom substrates. A plurality of driver chips are mounted at the bottom substrate within the vacuum tube while being electrically connected to the driver chip wirings. At least one subsidiary substrate is provided at the space between the top and the bottom substrates within the vacuum tube while having second wirings electrically connected to the driver chip wirings. Cathodes are provided between the subsidiary substrate and the top substrate within the vacuum tube to emit thermal electrons. First anodes with phosphors are patterned at the top substrate while being electrically connected to the first wirings. Second anodes with phosphors are patterned at the subsidiary substrate while being electrically connected to the second wirings.

According to still another aspect of the present invention, the built-in chip vacuum fluorescent display includes a vacuum tube having a pair of main substrates facing each other while being spaced apart from each other with a predetermined distance, and a side glass disposed between the main substrates while interconnecting the main substrates. A subsidiary substrate is provided between the main substrates. Anodes are patterned at the subsidiary substrates with phosphors. The phosphors emit light upon landing of thermal electrons emitted from cathodes. A grid controls the thermal electrons landing on the phosphors. A plurality of driver chips are mounted at one of the main substrates within the vacuum tube to selectively drive either the anode or the anode and the grid.

The driver chip wirings and the wirings are electrically connected to each other by way of bonding wires.

The driver chips have output terminals electrically connected to the driver chip wirings by way of bonding wires.

The phosphors are patterned in a dot matrix type for display graphic images.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or the similar components, wherein:

FIG. 1

is a cross sectional view of a built-in chip vacuum fluorescent display according to a first embodiment of the present invention; and

FIG. 2

is a cross sectional view of a built-in chip vacuum fluorescent display according to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1

is a cross sectional view of a built-in chip vacuum fluorescent display according to a first embodiment of the present invention.

As shown in

FIG. 1

, the built-in chip vacuum fluorescent display includes transparent top substrate

10

, bottom substrate

12

facing top substrate

10

while being spaced apart from each other, and side glass

14

disposed between substrates

10

and

12

while interconnecting them to thereby form vacuum tube

13

.

Top and bottom substrates

10

and

12

become main substrates for forming vacuum tube

13

. In vacuum tube

13

, at least one subsidiary substrate

16

is placed over bottom substrate

12

with a size smaller than that of top and bottom substrates

10

and

12

while being supported by thin glass plate-based spacer

18

. Subsidiary substrate

16

is spaced apart from bottom substrate

12

with a distance of 1˜3 mm.

A predetermined pattern of anode wirings

20

is formed on subsidiary substrate

16

together with insulating layer

22

for preventing needless communication between anode wirings

20

.

Phosphors

26

are formed on insulating layer

22

while being patterned in a dot matrix type in correspondence with the pattern of anode wirings

20

. Phosphors

26

are arranged within through-holes

22

a

of insulating layer

22

such that they form anodes for the vacuum fluorescent display together with dot layer

24

electrically interconnecting anode wirings

20

and phosphors

26

.

Carbonate-coated filaments

28

for cathodes are mounted between phosphors

26

and top substrate

10

while being supported by supports (not shown). Furthermore, mesh grid

30

is provided between phosphors

26

and filaments

28

to control the thermal electrons emitted from filaments

28

.

The supports for supporting filaments

28

may be fixed to any one of subsidiary substrate

16

and bottom substrate

12

. It is preferable that mesh grid

30

be fixed to the top of subsidiary substrate

16

.

A plurality of driver chips

32

are provided on bottom substrate

12

within vacuum tube

13

to selectively drive either phosphors

26

or phosphors

26

and mesh grid

30

in correspondence with the picture signal information.

Driver chips

32

are provided with input and output terminals (not shown) electrically connected to driver chip wirings

34

provided on bottom substrate

12

to receive the required driving voltages from the outside of vacuum tube

13

. The electrical connection of driver chips

32

to driver chip wirings

34

is made by way of bonding wires

36

.

Anode wirings

20

are also electrically connected to driver chip wirings

34

such that the electrical signals due to the driving of driver chips

32

are substantially applied to phosphors

26

via dot layer

24

. The electrical connection of anode wirings

20

to driver chip wirings

34

is also made by way of bonding wires

36

′.

The electrical connection of driver chips

32

to driver chip wirings

34

as well as the electrical connection of anode wirings

20

to driver chip wirings

34

may be made by way of metal bumps in addition to bonding wires

36

and

36

′.

In operation, when voltage is applied to driver chip wirings

34

via lead pins (not shown), driving signals are output from driver chips

32

via the output terminals such that either phosphors

26

or the phosphors and mesh grid

30

are selectively driven in correspondence with the picture signal information. The driving signals from driver chips

32

are transmitted to either phosphors

26

or the phosphors and mesh grid

30

via bonding wires

36

, driver chip wirings

34

, bonding wires

36

′ and anode wirings

20

. Consequently, phosphors

26

turn on/off to thereby display the desired graphic images.

FIG. 2

is a cross sectional view of a dual layer type built-in chip vacuum fluorescent display according to a second embodiment of the present invention.

In vacuum tube

13

, at least one subsidiary substrate

16

is placed over bottom substrate

12

while being supported by spacer

18

. Subsidiary substrate

16

is spaced apart from bottom substrate

12

with a distance of 1˜3 mm. Second wirings

40

, insulating layer

22

, dot layer

24

and phosphors

26

of a dot matrix type are formed on subsidiary substrate

16

. First wirings

42

based on aluminum Al or indium tin oxide (ITO) are formed on top substrate

10

facing subsidiary substrate

16

, and phosphors

26

′ are formed at first wirings

42

with a predetermined pattern.

A plurality of filaments

28

for cathodes are mounted between first and second wirings

42

and

40

. First mesh grid

30

′ is provided between first wirings

42

and filaments

28

, and second mesh grid

30

is provided between second wirings

40

and filaments

28

. First mesh grid

30

′ is standing with the side of top substrate

10

, and second mesh grid

30

with the side of subsidiary substrate

16

.

A plurality of driver chips

32

are provided on bottom substrate

12

within vacuum tube

13

. Driver chips

32

are provided with input and output terminals (not shown) electrically connected to driver chip wirings

34

provided on bottom substrate

12

by way of bonding wires

36

.

First and second wirings

42

and

40

are also electrically connected to driver chip wirings

34

. In this embodiment, the electrical connection of first wirings

42

to driver chip wirings

34

is made by way of pin members

38

, and the electrical connection of second wirings

40

to driver chip wirings

34

is made by way of bonding wires

36

′.

In operation, when voltage is applied to driver chip wirings

34

via lead pins (not shown), driving signals are output from driver chips

32

via the output terminals such that either phosphors

26

or phosphors

26

and mesh grid

30

are selectively driven in correspondence with the picture signal information. The driving signals from driver chips

32

are transmitted to phosphors

26

or to phosphors

26

and mesh grid

30

via bonding wires

36

, driver chip wirings

34

, bonding wires

36

′ and first wirings

42

. In addition, the driving signals from driver chips

32

are transmitted to phosphors

26

′ or to phosphors

26

′ and mesh grid

30

′ via pin members

38

and second wirings

40

. Consequently, phosphors

26

and

26

′ turn on/off to thereby display the desired graphic images.

The above structure may be applied for use in the front luminescent type vacuum fluorescent display in addition to the usual type vacuum fluorescent display and the dual layer type vacuum fluorescent display.

In the front luminescent type vacuum fluorescent display, anodes for forming a predetermined display pattern by way of the light emission of the phosphors are formed at the inner surface of the top substrate, and driver chips for selectively driving the anodes and the grids are formed at the inner surface of the bottom substrate.

As described above, in the inventive built-in chip vacuum fluorescent display, the anodes for displaying information by way of light emission of the phosphors are formed at the subsidiary substrate or at the subsidiary substrate and the top substrate. In this way, the driver chips for driving the anodes or for driving the anodes and the grids can be mounted at the bottom substrate intercepted by the subsidiary substrate with no anodes, and hence, most internal area of the bottom substrate can be utilized as the driver chip mounting space.

In the above structure, sufficient chip mounting space is easily obtained irrespective of the number of driver chips. With the sufficient chip mounting space, the number of driver chips can be arbitrarily increased, and the signals applied to the built-in drivers of the respective driver chips can be rapidly controlled in a separate manner.

While the present invention has been described in detail with reference to the embodiments set forth herein, those skilled in the art will appreciate that various modifications and substitutions can be made thereto without departing from the spirit and scope of the present invention as set forth in the appended claims.