JPH0542648B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to, for example, a projector that projects television images onto a screen, and is suitable for optical modulation using birefringence caused by the electric field of a crystal having an electro-optical effect. Concerning vessels.

BACKGROUND TECHNOLOGY AND PROBLEMS The projector using an optical modulator has a face portion 1 inside a tube body 1, for example, as shown in FIG.
Target 2 is placed opposite f. As shown in FIG. 2, the target 2 is a crystal thin plate having an electro-optic effect, for example, KD ₂ PO ₄ (hereinafter referred to as DKDP).
), or a dielectric mirror film 4 having a multilayer structure, for example, having a high secondary electron emission ratio and reflecting visible light is deposited on one surface of a crystal thin plate 3 made of KH ₂ PO ₄ (hereinafter referred to as KDP). A transparent copper conductive film 5, for example, an In ₂ O ₃ film, is deposited on the other surface, and the transparent conductive film 5 is clamped to a transparent plate 6. Further, this target 2 is arranged so that its transparent substrate 6 side faces the face portion 1f.

Also, inside the tube, there is a mirror film 4 of the target 2.
First and second grid electrodes G1 and G2 are arranged laterally opposite each other.

Then, as shown in FIG. 1, an electron beam b from a cathode K is focused and scanned onto the mirror film 4 of this target 2. 7 and 8 indicate the electromagnetic means for focusing and scanning deflection, respectively.

Visible light from a light source 9 is irradiated from the front of the face portion 1f of the tube body 1 toward the target 2 via a polarizer 10, and the reflected light from the mirror film 4 is transmitted via an analyzer 11 onto a screen 12. to project. On the other hand, a video signal, that is, a video signal to be projected onto the screen 12, is applied between the transparent conductive film 5 and the second grid G2. At this time, an electron beam from the cathode K is scanned with a constant current density Ip over the dielectric mirror film 4 of the target 2, which has a high secondary electron emission ratio δ, and is charged in accordance with the video signal.

The second grid G2 is placed close to the mirror film 4 at a distance of, for example, 40 μm. Moreover, the first grid G1 can be used, for example, to
A potential of 150 V is applied to capture floating secondary electrons generated from the mirror film 4, so that the floating secondary electrons do not cause a change in resolution.

According to this configuration, depending on whether secondary electrons are emitted from the dielectric mirror film 4 or primary electrons are accumulated due to the impact of the electron beam b, that is, the incidence of primary electrons, An electric charge generated in the dielectric mirror film 4 is applied to the dielectric mirror film 4, thereby applying a potential to the dielectric mirror film 4. Since the emission of secondary electrons is suppressed when this potential reaches the same potential as the second grid G2, it is balanced at this potential. That is, at each scanning position of the electron beam b, a charge pattern is generated in accordance with the voltage change due to the video signal applied to the second grid G2, and as a result, a thin crystal plate is generated between the mirror film 4 and the transparent conductive film 5. 3 is given an electric field pattern according to the video signal, and birefringence occurs due to the longitudinal effect according to the video signal.

On the other hand, the polarizer 10 and the analyzer 11 have optical axes that are perpendicular to the light incident on the target 2 from the light source 9 without applying a potential pattern to the thin crystal plate 3 and the light reflected thereby. It is arranged like this.

According to such a configuration, linearly polarized light entering the target 2 through the polarizer 10 is reflected by the dielectric mirror film 4 and passes back and forth through the crystal thin plate 3, so that linearly polarized light is generated in accordance with the video signal there. is modulated by birefringence, thereby causing the analyzer 1
The light passing through the screen 12 is shaded, and an optical image is projected onto the screen 12.

In this way, a projector can be constructed by using a light modulation group, and various proposals have been made for this type of projector. One example is Japanese Patent Publication No. 43-29086.

Generally, in this type of modulator, a thin crystal plate 3
is used after polishing it to a thinner thickness of, for example, 250 μm. This polishing process is performed by temporarily adhering it to a base, and then removing it from the base and adhering it to the transparent substrate 6. However, it is extremely difficult to bond the thinly polished crystal thin plate 3 to the transparent substrate 6 without damaging it, and the workability is extremely low. Distortion caused by shrinkage due to hardening may cause cracks or damage to the thin crystal plate 3, or may cause deformation to reduce flatness, increasing the incidence of defective products. Further, in the above-mentioned modulator, there is a problem that when the thin crystal plate 3 is bonded to the transparent substrate 6, the thickness of the adhesive tends to be uneven.

OBJECTS OF THE INVENTION The present invention provides an optical modulator that avoids the above-mentioned drawbacks, has a low incidence of defective products, is easy to work with, and is highly reliable.

Summary of the Invention The present invention comprises a thin crystal plate having an electro-optic effect on which a transparent conductive film is adhered, and a transparent substrate to which the thin crystal plate is bonded with a transparent adhesive. A dam made of conductive adhesive having a uniform height and setting the distance between the transparent substrate and the crystal thin plate is provided at the peripheral edge where the thin plate is bonded. Further, a conductive pattern is applied extending from below the dam of the transparent substrate to the outside of the dam, and a transparent adhesive injection groove is provided across the dam. Then, an adhesive is filled between the transparent substrate and the thin crystal plate surrounded by the dam to bond the thin crystal plate to the transparent substrate.

Embodiment An example of the present invention will be described with reference to FIG. 3 and subsequent figures. FIG. 3 is a block diagram of an example of a projector using a modulator according to the present invention, and FIG. 4 is a schematic cross-sectional view of the optical modulator. In FIGS. 3 and 4, parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals, and redundant explanation will be omitted. In the figure, 22 indicates a modulator, ie, a target, according to the present invention.
In order to facilitate understanding of the present invention, the manufacturing process will be explained in order with reference to FIG. 5 and subsequent figures.

A transparent substrate 26 is prepared as shown in a plan view in FIG. 5A and as shown in a side view in FIG. 5B. This transparent substrate 26 clamps a thin crystal plate having an electro-optical effect to suppress the piezo effect, and attaches, for example, a Peltier element to cool the thin crystal plate to a temperature near the Curie point during operation of the modulator. It is provided with the following objectives, and is required to have characteristics that meet these objectives, as well as characteristics such as high light transmittance for visible light and high thermal conductivity. Furthermore, this transparent substrate 26
is desired to have a refractive index close to that of the crystal thin plate. This transparent substrate 26 is composed of, for example, a CaF ₂ substrate having a thickness of 5 mm, a width of 56 mm, and a length of 66 mm. One main surface 26a of this substrate 26
As shown in FIG. 4, a thin crystal plate 23 having an electro-optical effect is bonded to the thin crystal plate 23. Now, the area where this thin crystal plate 23 is placed is surrounded by a chain line a as shown in FIG. , the main surface 26 of the substrate 26
Two or more grooves 28A and 28B are formed in the area a so as to extend from within the area a to the outer periphery.
These grooves 28A and 28B may be arranged near diagonal positions of area a.

Then, as shown in a plan view in FIG. 6A and a side view in FIG. 6B, a conductive pattern 29 is formed on the main surface 26a of the substrate 26. This conductive pattern 29
can be formed by, for example, an Al vapor-deposited film with a thickness of about 0.3 μm. Further, the conductive pattern 29 extends from the inside of the area a to the outer periphery along each side of the substrate 26, for example, and is formed such that the portions along each side are separated from each other by the cutouts 30. be done.

As shown in the plan view in FIG. 7A and in the side view in FIG. The dam 31 is formed with a uniform height at each part.

As shown in FIG. 8A a plan view, FIG. 8B a side view, and FIG. 8C a sectional view taken along line C-C in FIG. A crystal plate 33 having an electro-optic effect is mounted. This crystal plate 33 is made of, for example, DKDP, KDP, etc., and has a thickness sufficiently larger than that of the crystal thin plate 23 finally obtained, for example, 3 mm, a width of 30 mm, and a length of 40 mm.
Form a rectangle of mm. The main surface 33a of this crystal plate 33 on the side to be bonded to the dam 31 is finished as a smooth surface, and a transparent conductive film 25 with a thickness of, for example, 1500 Å, such as indium oxide or
An ITO (complex oxide of In and Sn) film is deposited. In this case, the transparent conductive film 25 includes at least a portion thereof,
Desirably, it is electrically connected to the dam by directly bonding it to the dam using a conductive adhesive over almost its entire circumference.

In this way, the crystal plate 33 and the substrate 26 are set at a uniform interval regulated by the height of the dam 31 interposed between the crystal plate 33 and the substrate 26.
A space 34 surrounded by a dam 31 is formed between the dam 6 and the dam 31. In this case, the above-mentioned grooves 28A and 28B are arranged so as to extend from the space 34 to the outside of the space 34 across the bottom of the dam 31. Then, a syringe is inserted into one of the grooves 28A to inject and fill the space 34 with the transparent adhesive 27. In this case, the other groove 28B acts as a hole through which air escapes from within the space 34, and therefore these grooves 28A and 28B
As described above, it is preferable to provide the position at the diagonal point of the space 34.

After filling the space 34 with the adhesive 27 in this way, the space 34 formed by both grooves 28A and 28B is
The communication hole 4 with the outside is sealed.

After the crystal plate 33 is bonded to the transparent substrate 26 using the dam and the transparent adhesive 27 in this manner, the crystal plate 33 is in this state shown in FIG. 8B by machining, for example. and until the required thickness t, for example, t = 250 μm, shown by the chain line b in C, is reached.
Polish and make it thin.

In the above configuration, the dam 31 is
The same or the same type of adhesive as the transparent adhesive 27 filled in the space 34 surrounded by Thermal distortion and generation of shear force due to the temperature difference between the operating state, that is, the cooling state, and room temperature or the curing temperature of the adhesive is avoided. As the adhesive for the dam 31 and the transparent adhesive 27, an epoxy adhesive or an acrylic adhesive may be used.

In the adhesive constituting the dam 31, a filler of uniform dimensions, for example, glass fiber of a uniform diameter, is added to regulate the height, that is, the distance between the crystal plate 33 and the transparent substrate 26, and conductivity is added. for
Mix with conductive powder such as Ag. Further, the glass used as the filler may be a glass having a low glass transition point such that it has a low Young's modulus in a cooled state during operation of the modulator, for example, a glass whose glass transition point is 40° C. or less, for example, 25° C.

Incidentally, in some cases, this conductive powder can also be used by itself to obtain the above-mentioned filler effect. This dam 31 can be formed in a predetermined pattern, for example, in the shape of a rectangular frame, by screen printing, for example, and has a height of, for example, 3.
~5 μm, width 4 mm, inner spacing on the short side 26 mm, and inner spacing on the long side 36 mm.

According to this configuration, the transparent conductive film 25 on the crystal thin plate 23 having an electro-optic effect is electrically connected to the conductive pattern 29 on the transparent substrate 26 via the conductive dam 31. Therefore, this conductive pattern 29 can be used as a connection terminal for, for example, an external lead to the transparent conductive film 25.

In this case, when dividing the conductive pattern 29 into a plurality of parts as described above, pair patterns, for example, patterns facing each other, are set and the conductivity between each pair of patterns is measured. In other words, it is possible to judge whether the contact between the external terminal and the transparent conductive film 25 and the adhesion of the crystal plate 33 are good or bad.

In addition, if there is a possibility that the transparent adhesive 27 filled in the space 34 may react with the conductive pattern, the dam 3
A separation dam can be provided inside the area surrounded by 1 to separate the two.

Effects of the Invention According to the above-described configuration of the present invention, the thin crystal plate 23 having an electro-optical effect is bonded to the transparent substrate 26 with the transparent adhesive 27 having a thickness regulated by the dam 31, so that the crystal thin plate 23 having an electro-optic effect is bonded to the transparent substrate 26 with the transparent adhesive 27 having a thickness regulated by the dam 31. The thin plate 23 has an even thickness and is therefore reliably and firmly bonded with an appropriate amount of adhesive. Furthermore, since the external terminals of the transparent conductive film 25 are led out through the conductive dam 31 from the substrate 26 side, which has a wider area than the crystal thin plate 23, that is, from the conductive pattern 29 which can have a wide area, for example, external leads for this can be easily and reliably connected.

Furthermore, according to the configuration of the present invention, the thin crystal plate 23 can be obtained by bonding the crystal plate 33 onto the thick transparent substrate 26 and then polishing it to a desired thickness.
It becomes easier to handle, avoids problems such as damage and deformation, drastically reduces the incidence of defective products, and improves reliability.
It can bring many benefits.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a projector using a conventional optical modulator, FIG. 2 is a schematic sectional view of the optical modulator, FIG. 3 is a block diagram of an example of a projector according to the present invention, and FIG. 4 is a block diagram of a projector using a conventional optical modulator. The schematic cross-sectional views of the optical modulator and FIGS. 5 to 8 are manufacturing process diagrams of the optical modulator according to the present invention. 1 is a tube, 9 is a light source, 10 is a polarizer, 11 is an analyzer, 12 is a screen, 22 is a target, 2
3 is a crystal thin plate, 24 is a dielectric mirror film, 25 is a transparent conductive film, 26 is a transparent substrate, 27 is a transparent insulating adhesive, 29 is a conductive pattern, and 31 is a dam made of conductive adhesive.

Claims (1)

[Claims] 1 Comprising a crystal thin plate having an electro-optical effect on which a transparent conductive film is adhered, and a transparent substrate to which the crystal thin plate is adhered with a transparent adhesive, and the crystal thin plate is attached to the transparent substrate. A dam made of a conductive adhesive having a uniform height and setting a distance between the transparent substrate and the crystal thin plate is provided on the peripheral edge to be bonded, and a conductive pattern extends from below the dam to outside the dam. A transparent adhesive injection groove is provided across the dam, and an adhesive is filled between the transparent substrate and the crystal thin plate surrounded by the dam to form the transparent substrate. An optical modulator comprising the above-mentioned thin crystal plate bonded to the substrate.