JPS6178036A - Fluorescent display tube - Google Patents

Abstract

PURPOSE:To reduce a dead space other than a display section by storing a ceramic substrate arranged with the display section on the front face and a drive circuit section on the back face in a vacuum envelope made of glass to form a chip-on-ceramic structure. CONSTITUTION:An anode display section formed with a segment electrode having a phosphor layer is provided on the front face 30A of an anode substrate 30 made of ceramic, an IC chip 11 which is a drive circuit section 5 is arranged on the back face 30B, they are connected via a through hole section 40 provided on the substrate 30, a grid electrode and a filament cathode are arranged on the substrate 30, they are sealed with a lower plate 20 made of glass and a cover glass 10 to form a fluorescent display tube having a three-layer structure of glass-ceramic-glass. Accordingly, wiring from the back face of the substrate 30 to the front face is facilitated by the through hole section, and the display tube having little dead space can be obtained.

Description

[Description of the field to which the invention pertains] The present invention relates to a fluorescent display tube, in which a drive circuit section consisting of a display section and a semiconductor element (pair chip) is formed on a ceramic substrate, and the display section and drive circuit section are formed on a ceramic substrate. Commonly known as "chip on Cerami-C" (hereinafter referred to as COC), the circuit part is provided in the same glass vacuum envelope.
The present invention relates to a fluorescent display tube having a structure called ``.

[Description of conventional technology]

Conventional fluorescent display tubes for this purpose are commonly known as "chip on glass", in which the display section and drive circuit section are integrally formed on a glass substrate, rather than a ceramic substrate.
lass) J (hereinafter referred to as COG) structure.

The first example of a fluorescent display tube with a conventional COG structure is
A structure as shown in the partially cutaway perspective view in the figure and the cutaway plan view of the main part in FIG. 2 is provided.

In the figure, a plurality of wiring films 2, an insulating film 3, a segment electrode 4, and an anode substrate 6 which also serves as a drive circuit section 5 are laminated and deposited on a glass substrate 1, and a 1jX
As input terminals to the pads of the dynamic circuit section 5, a so-called frame electrode group in which a filament cathode 9 is arranged is placed at an appropriate distance from an external lead 7 and a grid 8 integrated with the external lead. Mounting the IC pair chip 11 on the circuit section 5 by bonding method or the like,
The entire board is sealed with low melting point glass in a light-transmitting vacuum-tight container 10, and the terminals of the external lead 7 are connected to -
J1 and has a structure in which a COG fluorescent display tube is driven via an IC chip 11. CoC like this
The fluorescent display tube has a structure in which the display section 12 and the 4D circuit section 5 are arranged on the same plane! Since the electrical connection is made by the wiring film 2 formed by the N1 method or the sputtering method, it has the advantage that the number of external leads 7 can be greatly reduced.

On the other hand, a drawback is that since the display section 12 and the drive circuit 5 are arranged on the same plane, the area occupied by the display section 12 in the entire anode substrate 6 is small.

The display area is the main function of a display tube, and the area other than the display area becomes dead space, and how to reduce this dead space has become a major issue in increasing the commercial value of COG fluorescent display tubes. As a solution to reducing this dead space, there is a method of providing a drive circuit section on the back surface of the anode substrate. An example of this is shown in FIG. 3, in which the drive circuit section 5 is formed on the back surface 6B of the anode substrate. In the circuit section, a method is adopted in which paired chips are attached by bonding, or backcaged (7-rat package, etc.) ICs are attached by soldering or the like. Electrical connections from the six people on the front surface (display side) of the anode substrate to the back surface 6B are made because it is a glass substrate, so it is not possible to form minute through-holes, or because the back surface 6B is outside a vacuum. For example, a method is used in which a lead similar to that of the external drawer lead 7 is bent to the top of the back surface 6B and soldered.

However, in the method shown in FIG. 3, in which the IC is mounted on the back surface 6B of the substrate outside a vacuum, various problems arise in terms of reliability. There is a problem of failure due to Ag migration between soldered pads that occurs in the part where the leads are routed from the front side to the back side of the board, and the cap sealing part when a paired chip is attached to the back side of I# to form a circuit section. This is a problem of defective chip aluminum corrosion caused by defects. Both problems occur when performing high-temperature, high-humidity, and operation tests, and to prevent these problems, it is necessary to select materials with excellent moisture resistance and to ensure a complete padding of the lead joints and the IC sealing area. However, this has the problem of causing an increase in costs. Therefore, in order to obtain a highly reliable drive circuit section, the first step is to
The best method is to form the circuit section in the same vacuum container as the display section as shown in Figure 2.

As mentioned above, in a fluorescent display tube having a conventional CoC structure,
Providing the drive circuit section in the same vacuum container as the display section and making the display section area occupied by the anode substrate as large as possible, reducing the so-called dead space other than the display section, will result in a display tube that is more excellent as a product. This is a necessary condition for this.

[Object and structure of the invention]

The present invention aims to provide a fluorescent display tube having a new CoC structure that solves the problems of the more detailed CoC structure described above. The main idea is to create a three-layer fermentation system by installing another positive substrate made of ceramics inside the vacuum envelope formed by sealing the top plate (cover glass) and bottom plate. It is characterized by forming a drive circuit section on the back side by utilizing the through holes provided in the anode substrate.

〔Example〕

The present invention will be explained in detail below using Example 1.

FIG. 4 is a cross-sectional view of essential parts showing an embodiment of a fluorescent display tube having a CoC structure according to the present invention.

In the drawings, the same reference numerals are used for the same members as in Figs. 1 to 3, and their basic roles are no different from the conventional method. In the figure, a drive circuit IC pair chip 11 is mounted on a back surface 30B of a ceramic anode substrate 30. The IC chip 11 is fixed using the Au-8i method or a heat-resistant Guibond material, and is further electrically connected to wiring pads formed on the back surface by ultrasonic bonding using aluminum wires. The wiring pattern for the drive circuit on the back surface 30B is generated at the same time as the wiring pattern on the front surface 30A is formed.
It was formed. - Surface 30A of force field pole substrate 30
The device includes a multi-digit anode display formed by segments with a phosphor layer, and a grid electrode and a filament cathode arranged opposite the anode display. Furthermore, the front surface 30A and the back surface 3 of the anode display section
Electrical connection with 0B is made through the through-hole portion 4 formed on the board.
Connected through 0. Since this through hole portion 40 is a ceramic substrate, it can be easily formed. For example, by designing a pattern in a green sheet state and firing this sheet in a laminated form, a ceramic substrate having a freely patterned through hole portion 40 can be formed. You can get the substrate.

The ceramic anode substrate 30 with the electrodes mounted on both sides of the substrate is fixed to the glass lower plate 20 via the spacer 21. Next, an external lead 7, which serves as a power supply terminal for the fluorescent display tube, is arranged at the end of the LS electrode substrate 30A, and the entire substrate is covered with a translucent glass top plate (cover glass) 10, and its periphery is The portion is hermetically sealed with a sealing material 25 such as low melting point frit glass to form an envelope. Moreover, an external lead 7 electrically connected to the drive circuit section 5, the grid electrode, and the filament cathode is passed through the entire sealing member 25 in an airtight manner, and is a terminal connected to an external material. This is the result.

Although the present invention refers to a segment type implementation array, various modifications can be made to a dot matrix type display tube for displaying graphics etc. without changing the gist of the present invention. .

[Results of effect]

As described above, the COC fluorescent display tube of the present invention is
The device has a three-layer structure of glass-ceramics-glass, and a display section and a drive circuit section are mounted on both sides of a ceramic substrate. With this structure, the dead space seen from the drive circuit section, i.e. the display section, which was conventionally formed on the same surface as the display section, has been moved to the back side of the display section, resulting in a large dead space on the anode substrate. This results in a visual effect of n>e.

7 By using a vertical lamic straightening plate, it is possible to easily extend the line from the surface to the back wall to form a through-hole part, which cannot be achieved with a piggyback COG fluorescent display tube. Is it possible to obtain a display tube with wide application value? It happened.

Most importantly, the drive circuit section is mounted inside a vacuum container, and even the bare chip can maintain high reliability (especially moisture resistance), and the effects obtained from the present invention are extremely simple. .

[Brief explanation of drawings]

Figures 1 and 2 are a partially broken ffT perspective view and a cutaway plan view showing an example of a fluorescent display tube with a conventional COG paulownia structure; Figure 3 is a sectional view showing a conventional CoGJI surface mount; FIG. 4 is a sectional view of a main part showing an embodiment of the COC structure of the present invention. 1...Glass substrate, 2...Wiring coating,
3...Insulating layer, 4...4 segment poles, 5...Drive circuit section, 6...Positive board, 7... External drawer lead, 8...
Grid, f:, stile, 9...filament shade?
, 10... Upper rM plate (cover glass), 11.
...IC pair chip, 12...Display part (
area), 20...Bottom plate (glass plate), 21.
... Spacer, 25 ... Sealing material, 30.
...Ceramics anode-21ii^rg,z
40...Through hole section. \”-

Claims (1)

[Claims] In a vacuum envelope formed by sealing a first translucent glass top plate and a second glass bottom plate, an anode display portion having a phosphor layer on the surface, and the anode A third ceramic anode substrate is provided with a control electrode and a cathode disposed opposite to the display section, and a circuit section made of a semiconductor element for driving the anode display section is mounted on the back surface of the substrate. A fluorescent display tube characterized by having a three-layer structure consisting of ceramic and glass.