JP2730510B2 - Drive circuit integrated type fluorescent display tube optical head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head using a fluorescent display tube, and more particularly to an optical head in which a driving circuit is integrated.

[0002]

2. Description of the Related Art Fluorescent display tubes have been widely used as displays for home electric appliances and the like, and in particular, application to other products such as an optical head of a printer is expected in recent years. Since this fluorescent display tube is inexpensive and can obtain high brightness over the entire visible light range, its application as a color optical writing device such as a color optical head is expected. An optical head using such a fluorescent display tube forms an image on a photosensitive surface with an optical system provided outside the fluorescent display tube, that is, a rod lens array, and emits light from the fluorescent material. By controlling, an arbitrary pattern can be drawn on the photosensitive surface.

In such a fluorescent display tube optical head, a rod lens array as an optical system for forming an image of fluorescent light on a photosensitive surface is provided separately from the fluorescent display tube. For the thickness dimension of the envelope, the rod lens array and the phosphor have to be arranged apart from each other, which causes a problem that the optical head is enlarged by the dimension. In addition, there is a problem that high-precision positioning is required to make the optical axis of the separate rod lens array coincide with the phosphor, and the assembling work becomes extremely complicated.

For this reason, Japanese Patent Application Laid-Open No. Hei 4-310981 proposes a configuration which solves these problems.
FIG. 3 is a cross-sectional view of the structure. The fluorescent display tube constituting the optical head basically has the structure of a triode vacuum tube, and includes a cathode 22 and a grid 23 installed in a vacuum envelope 21. , A phosphor (anode) 24. A rod lens array 25 made of a refractive index distribution type self-focusing glass is integrally formed on a part of the glass surface of the region on which the phosphor 24 is mounted, of the glass surface constituting the vacuum envelope 21. I have. Reference numeral 26 denotes an external connection terminal for making an electrical connection to a circuit 27 connected to the phosphor 24. Therefore, in this configuration, since the rod lens array 25 is formed immediately below the phosphor 24, the phosphor 24
And the rod lens array 25 can be in close contact with each other, so that the above-described dimensions can be reduced and the size can be reduced. Incidentally, reference numeral 29 denotes a photosensitive surface.

On the other hand, in this type of optical head, there has been proposed a configuration in which a driving circuit for driving fluorescent light is integrally housed in a vacuum envelope for the purpose of miniaturizing a fluorescent display tube. I have. For example, in Japanese Patent Application Laid-Open No. 3-40347, as shown in FIG. 4, a fluorescent substance 24, a circuit 27, and a driving circuit 28 are integrally formed on a glass substrate 27 together with a cathode 22 and a grid 23 in a vacuum envelope 21. Has been proposed. However, in the case of this configuration, it is necessary to install an optical system corresponding to the phosphor 24 outside the vacuum envelope.

[0006]

When an optical head which is small and can be miniaturized by making use of the advantages of the conventionally proposed optical head, the following problems arise. Has occurred. That is, when an attempt is made to integrally form a rod lens array 25 having a refractive index distribution type self-focusing function in a part of the vacuum envelope 21 as shown in FIG. 3, soda glass is used as the glass of the material. Can be This is because soda glass is inexpensive and can be reduced in cost, and there is only soda glass as a glass material whose thermal expansion coefficient matches that of the metal material forming the external terminals and frit glass as a sealing material. is there.

On the other hand, since soda glass contains a large amount of alkali metal, it is difficult to form a drive circuit capable of stable operation on a soda glass substrate. For this reason, in the prior art of FIG. 4, a drive circuit 28 and a phosphor 24 are formed on a glass substrate 27 made of non-alkali glass,
The glass substrate 27 is mounted on a glass surface of soda glass constituting the vacuum envelope 21. In this case, since the alkali-free glass has a significantly different coefficient of thermal expansion from soda glass, when the two glasses are bonded to each other, there arises a problem that the glass is cracked in a heat sealing process that forms a vacuum envelope. Therefore, the glass substrate 27 is not fixed to the glass surface of the vacuum envelope 1,
It is inevitable to adopt a configuration of mechanically fixing using the elastic force of the external connection terminal 26.

However, in such a fixed structure,
It is impossible to reliably prevent the glass substrate 27 from being moved with respect to the vacuum envelope due to external vibration, external shock, or the like. For this reason, as shown in FIG. When the configuration shown in FIG. 4 is applied as it is to the one integrally formed, the relative position between the phosphor and the rod lens array cannot be maintained with high accuracy, and the reliability of the optical head is reduced. It may not function as a head.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fluorescent display tube optical head capable of achieving miniaturization by incorporating a drive circuit therein, miniaturizing the lens array by integrating the lens array, and obtaining high reliability. Is to do.

[0010]

An optical head according to the present invention is provided with a phosphor contained in a glass vacuum envelope and a driving circuit for driving the phosphor on a glass base. A microlens array corresponding to the phosphor is formed on the base to form a drive circuit board, and the drive circuit board is held in close contact with the inner glass surface of the vacuum envelope.

In this case, there is provided an external connection terminal having an elastic force which penetrates the inside and outside of the vacuum envelope, and the drive circuit board is pressed and held on the inner surface of the glass by the elastic force generated at the inner end of the external connection terminal. In addition, it is preferable that electrical connection to a drive circuit, a phosphor, and the like be made by the external connection terminal. Also,
The microlens array can be formed by etching the back surface of the base in a hemispherical shape and embedding substances having different refractive indexes in the hemispherical portion. For example, the vacuum envelope is formed of solder glass, and the drive circuit board is formed of non-alkali glass.

[0012]

The optical head can be miniaturized by integrally forming the drive circuit and the phosphor on the drive circuit board, and the microlens array is integrally formed on the glass base of the drive circuit board. The displacement between the phosphor and the lens can be prevented, the reliability as an optical head is improved, and the optical head can be downsized. In addition, since the drive circuit board is held by the vacuum envelope with elastic force, the glass is not broken even by heat history.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a first embodiment of the present invention. The inside of the vacuum envelope 1 is held in a vacuum state by a case 2 and a cover 3 made of soda glass. A drive circuit board 4 on which a drive circuit and a phosphor (anode) to be described later are integrally mounted is mounted on a glass bottom surface 1a on the bottom surface of the case 2 constituting the bottom portion of the vacuum envelope 1. The distal end of the external connection terminal 5 penetrating the envelope 1 is electrically connected. A filament-shaped cathode 6 is provided at a position above the drive circuit board 4 inside the vacuum envelope 1,
A grid 7 is provided, and the configurations of the cathode 6 and the grid 7 are the same as the conventional configuration.

The drive circuit board 4 has a base 8 made of a non-alkali glass substrate, and a thin film transistor is formed on the surface thereof to form a drive circuit 9. A metal thin film such as aluminum is formed on the base 8 in a mesh shape.
Alternatively, a pixel electrode 10 formed of a transparent electrode represented by ITO is formed, and a phosphor 11 is formed corresponding to the pixel electrode 10.

A microlens array 12 is formed on the base 8 of the drive circuit board 4 corresponding to the position of the phosphor 11. The microlens array 12 has a structure in which a spherical region having a different refractive index is formed in a part of the base 8 in the thickness direction. Here, base 8
After the drive circuit 9 and the phosphor 11 are formed on the front surface of the base 8, a portion corresponding to the phosphor on the back surface of the base 8 is etched in a hemispherical shape. It is formed by embedding transparent substances having different refractive indexes.

Then, the drive circuit board 4 is placed on the glass bottom surface 1a of the vacuum envelope 1 in a close contact state, and the inner end of the external connection terminal 5 is bent to give an elastic force. The inner end is elastically contacted with the exposed surface of the drive circuit 9 or the like from above. Thereby, the drive circuit board 4
Is pressed onto the glass bottom surface 1a by the elastic force of the external connection terminal 5, and is held by the pressing force. At the same time, the drive circuit 4 is electrically connected to the external connection terminal 5.

Therefore, according to this configuration, the phosphor 11 is provided on the surface of the drive circuit board 4 held in the vacuum envelope 1.
In addition, since the drive circuit 9 is formed integrally, miniaturization of the optical head can be realized. The drive circuit board 4 constituting the drive circuit 9 has a base 8 on which a microlens array 12 is formed integrally, and the light generated by the phosphor 11 is transmitted to the vacuum envelope 1 by the microlens array 12. Since the image can be formed at the outer position, there is no need to provide a separate lens array, and the optical head can be made compact.

The drive circuit board 4 is made of non-alkali glass and the vacuum envelope 1 is made of soda glass. The drive circuit board 4 is made of the vacuum envelope 1 by the elastic force of the external connection terminals 5. Since it is pressed and held by the glass bottom surface 1a, the base 8 and the glass bottom surface 1a are not cracked by the heat sealing process of the vacuum envelope 1. The drive circuit board 4 is connected to the external connection terminals 5.
Is simply pressed and held on the glass bottom surface 1a, so that the microlens array 12 is formed integrally with the drive circuit substrate 4 even when the position of the drive circuit substrate 4 is changed with respect to the glass bottom surface 1a. There is no displacement between the phosphor 11 and the microlens array 12,
The reliability of the optical head is not reduced.

Further, since the microlens array 12 is located inside the glass bottom surface 1a of the vacuum envelope 1, the image forming position by the microlens array 12 is set at a position along the outer surface of the glass bottom surface 1a. It is also possible to set, so that the photosensitive operation can be performed while the photosensitive surface 13 is in close contact with the outer surface of the glass bottom surface 1a, and the optical head can be further downsized.

Here, in the present invention, as shown in FIG. 2, a grid 7A may be formed on a part of the surface of the drive circuit board 4. Also in this case, the phosphor 11 and the drive circuit 9 are mounted on the surface of the glass base 8 constituting the drive circuit board 4,
Further, by forming the microlens array 12 on the base 8 at a position corresponding to the phosphor 11, it is needless to say that the same effect as in the first embodiment can be obtained.

In the above embodiment, the present invention is applied to an optical head for performing optical drawing on a photosensitive surface. However, the present invention is also applicable to a case where the present invention is simply used as a fluorescent display tube. Needless to say, it can be applied to.

[0022]

As described above, according to the present invention, a phosphor and its driving circuit are mounted on a glass base, and a microlens array is formed on the base corresponding to the phosphor to drive. Since the circuit board is configured and this drive circuit board is held in close contact with the inner glass surface of the vacuum envelope,
The optical head can be miniaturized, and the displacement between the phosphor and the lens can be prevented, the reliability as the optical head is improved, and the optical head can be downsized.

Further, the driving circuit board is pressed and held on the inner surface of the glass by the elastic force generated at the inner end of the external connection terminal penetrating the vacuum envelope in and out, and the external connection terminal is used to drive the driving circuit and the phosphor. By making the electrical connection described above, the glass does not crack even by heat history.

Further, by constituting the drive circuit board with non-alkali glass, stable operation of the drive circuit becomes possible.
In addition, by forming the vacuum envelope with solder glass, cost reduction can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of an optical head according to the present invention.

FIG. 2 is a sectional view of a modification of the optical head of the present invention.

FIG. 3 is a cross-sectional view of an example of a conventional optical head.

FIG. 4 is a cross-sectional view of another example of the conventional optical head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum envelope 4 Drive circuit board 5 External connection terminal 6 Cathode 7 Grid 8 Base 9 Drive circuit 10 Pixel electrode 11 Phosphor 12 Micro lens array

Claims (4)

(57) [Claims] 1. A phosphor inside a vacuum envelope made of glass,
In a fluorescent display tube optical head in which a grid and a cathode electrode are provided and light generated by the phosphor is imaged by a lens, the phosphor and a driving circuit for driving the phosphor are mounted on a glass base. And a microlens array corresponding to the phosphor is formed on the base to form a drive circuit board, and the drive circuit board is held in close contact with the inner glass surface of the vacuum envelope. An optical head integrated with a driving circuit. 2. An external connection terminal having an elastic force penetrating the vacuum envelope into and out of the vacuum envelope, wherein the drive circuit board is pressed and held on an inner surface of the glass by an elastic force generated at an inner end of the external connection terminal. 2. The fluorescent display tube optical head integrated with a drive circuit according to claim 1, wherein the external connection terminal makes an electrical connection to a drive circuit, a phosphor, or the like. 3. The fluorescent display tube integrated with a driving circuit according to claim 1, wherein the microlens array is formed by etching the back surface of the base in a hemispherical shape and embedding substances having different refractive indexes in the hemispherical portion. Light head. 4. The vacuum envelope is formed of solder glass,
4. The optical head according to claim 2, wherein the drive circuit board is formed of non-alkali glass.