JPS6161355A - Light modulator - Google Patents

Abstract

PURPOSE:To increase mechanical strength and airtightness by accommodating a light modulator used for a projector by combining a metal ring holding a cooling pipe for an assembly having an electro-optical crystal, glass parts at its both ends, and a glass tube body. CONSTITUTION:A projector which projects television picture on a screen is formed by accommodating a light modulator containing an assembly 2 with a crystal having electro-optical effect with a cathode K in a tube body 1 kept in high vacuum. The tube body 1 is formed by bonding a panel formed by bonding glass parts 24, 26 at both ends of a metal ring 25 and a glass tube body 23M with indium alloy. The assembly 20, Peltier effect elements 42A, 42B, and a cooling water passage 21C are arranged within the tube body 1, and a cooling pipe 22 is drawn out from the metal ring 25. Therefore, the tube is sealed in airtightness and its mechanical strength is assured.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention utilizes birefringence caused by an electric field of a crystal that has an electro-optical effect suitable for application to a projector that projects a television image onto a screen, for example. The present invention relates to an optical modulator.

[Conventional technology]

A projector using an optical modulator is, for example, as shown in FIG. The assembly structure (tardatsu) (2) is arranged. As shown in FIG. 3, this structure (2) is coated with a dielectric mirror film (4) having a multilayer structure, for example, which has a high secondary electron emission ratio and reflects visible light, on one surface. A crystal thin plate having an electro-optic effect, with a transparent conductive film (5), e.g., In2O3 film, deposited on the other side, e.g., KD2P04.
(hereinafter referred to as DKDP) or Ni'H2PO4 (hereinafter referred to as KDP) on the transparent conductive film (5) side thereof, a transparent substrate (hereinafter referred to as CaF2) (
6) will be flagged. Further, this structure (2) is arranged so that its transparent substrate (6) side faces the optical window (IW).

In addition, inside the tube (υ) is the mirror film (4) of the structure (2).
side facing first and second grid electrodes G1 and G2;
is placed.

Then, as shown in FIG. 2, the electron beam b from the cathode K is focused and scanned on the mirror film (4) of this structure (2). (7) and (8) indicate the electromagnetic means for focusing and scanning deflection, respectively.

Then, visible light from a light source (9) is irradiated from the front of the tube (1) through the optical window (IW) toward the structure (2) via the polarizer αQ, and the mirror film (4) A video signal, that is, a video signal to be projected onto the screen α, is transmitted between the transparent conductive film (5) and the second grid G2. Apply. At this time, an electron beam from the cathode K is scanned with a constant current density rp over the dielectric mirror film (4) having a high secondary electron emission ratio δ of the structure (2), and the dielectric mirror film (4) having a high secondary electron emission ratio δ is charged in accordance with the video signal.

Note that the second grid G2 is placed close to the mirror film (4) at a distance of, for example, 40 μm.

Further, the first grid G1 is given a potential of, for example, 150V, and captures floating secondary electrons generated from the mirror film (4), and the floating secondary electrons cause resolution degradation. This is to ensure that this does not occur.

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, a corresponding charge is generated. occurs in the dielectric mirror film (4), and this gives a potential to the dielectric mirror film (4).When this potential becomes the same as that of the second grid G2, the emission of secondary electrons is suppressed. Therefore, the potential is balanced at this potential.In other words, at each scanning position of the electron beam b, the second grid G2
A charge pattern is generated in response to a voltage change due to a video signal applied to the crystal thin plate (3), and an electric field corresponding to the video signal is generated between the mirror film (4) and the transparent conductive film (5). When a turn is given, birefringence occurs due to the longitudinal effect depending on the video signal. On the other hand, the polarizer αQ and analyzer C1,) are
) The light source (9) and the crystal assembly structure (2) are arranged so that the optical axis direction thereof is orthogonal to the light incident on the VC and the light reflected from the light source (2) without applying a K potential pattern.

According to such a configuration, the structure (
2) The linearly polarized light entering the dielectric mirror film (4) is reflected by the dielectric mirror film (4) and passes back and forth through the crystal thin plate (3), where it is modulated by the birefringence generated in response to the video signal. The light passing through CL, ) will be shaded, and an optical image will be projected onto the screen (2).

In this way, if a projector can be constructed by using an optical modulator, this type of projector
This is where many proposals are being made. One example is Japanese Patent Publication No. 43-29086.

[Problem that the invention seeks to solve]

Since the electro-optic crystal in this type of optical modulator is used in a state where it is cooled to about -50 DEG C., which is near its Curie point, a cooling means is provided for this optical modulator. Therefore, as mentioned above, in an optical modulator that obtains two turns of charge according to a signal by electron beam scanning, the assembled structure having the electro-optic crystal and the cooling means for cooling it are also maintained at a high degree of vacuum. It will be placed in a vacuum-sealed tube.

Therefore, this vacuum-sealed tube accommodates the assembled structure of these crystals having an electro-optical effect and the accompanying cooling means, and also supplies a cooling medium such as cooling water to the cooling means. It is necessary to derive a cooling medium introduction and outlet section 74 for taking out and circulating the cooling water, and also to adopt a structure in which this outlet section is reliably sealed without hindering vacuum containment. be.

Furthermore, in practice, if there is a defect in the electro-optic crystal after the tube has been assembled, the sealed tube must be able to be disassembled so that it can be replaced and other parts reused. There is. Furthermore, when this electro-optic crystal is heated to a temperature of more than 100 degrees Celsius, its characteristics deteriorate, so when sealing the tube, it is necessary to take care not to involve high-temperature heating.

The present invention makes it possible to solve the above-mentioned problems in this type of optical modulator.

[Means for solving problems]

In the present invention, an assembled structure having an electro-optic crystal and a cooling means for cooling the assembled structure are housed in a vacuum-sealed tube.
It consists of a tube body made of a glass tube and a panel section joined to the front part of the tube body. And this no (
The channel portion is an optical window portion, for example, when applied to a projector as described above, it is a glass window having a parallelism of approximately the thickness above the wavelength λ of the light from the external light source that illuminates the optical modulator. an optical window section consisting of an optical window section 1, a metal ring section extending rearwardly from the optical window section and a metal ring section extending rearwardly through the respective tubes for introducing and discharging the cooling medium to the cooling means described above in the so-called skirt section; It is composed of a ring-shaped glass part that extends rearward and is joined to the tube body that extends from the glass tube body mentioned above, and this glass part and the glass tube body are connected to each other. is indium I
It is fused by low-temperature heating using an n-alloy.

The cooling means does not reduce the degree of vacuum inside the vacuum tube and is made of thermally conductive material, for example, oxygen-free copper, and the pipes for introducing and discharging a cooling medium, such as cooling water, to the cooling means are, for example, Constructed of stainless steel, i.e. metal.

[For production]

According to the above-described structure of the present invention, in particular, the cooling medium introduction pipe and outlet nozzle in the cooling means of the tunnel part of the vacuum-sealed tube body, that is, the penetration part of the metal nosape, are formed by the metal ring part. The airtight sealing between each of the introduction and extraction pipes and the metal ring in the penetration part can be reliably performed because the metal rings are joined together.

In addition, since the joint part of this panel part with the glass tube main body is constituted by a glass part, the joint between these panel parts and the main body is a glass-to-glass joint, so this joint is made using a low-temperature material such as an In alloy. The bonding can be carried out by fusion bonding, and since such a bonding mode has been adopted, when the structure of the present invention is used, the electro-optic crystal can be reliably bonded at a high degree of vacuum without being thermally inhibited. It can be sealed. Furthermore, according to the configuration of the present invention,
If there is a crystal defect in the electro-optic crystal and it is a defective product, parts can be replaced without disturbing the electro-optic crystal at the joint between the panel and the glass tube body. Since this In alloy joint can be disassembled, parts can be easily replaced and recycled.

The effects of the present invention will become clearer from the following description of specific embodiments of the optical modulator according to the present invention.

〔Example〕

An example of an optical modulator that can be applied to the projector described in FIGS. 2 and 3 will be described with reference to FIG. 1. The arrow in the figure shows the crystal assembly structure as a whole having a crystal thin plate (3) made of DKDP (or KDP) having an electro-optic effect, ■ indicates the cooling means attached to this, and @ indicates these. The tubular body to be contained and sealed is shown as a whole.

The crystal assembly structure (e) consists of nine crystal thin plates (3) suspended on a transparent substrate (6) made of, for example, CaF2, as explained in FIG. The transparent substrate (6) side of the crystal thin plate (3), or the crystal thin plate (3) of the transparent substrate (6)
The transparent conductive film explained in FIG. 3 is formed on the side (not shown), and the dielectric explained in FIG. A mirror film is deposited. And this crystal thin plate (3
), a second grid electrode G2 and a first grid electrode G are sequentially arranged to form an electron beam emitting source, that is, a cando, which is provided on the neck side (not shown) of the tube body (c).
The thin crystal plates (3) are arranged to face each other.

A first plate body made of oxygen-free copper is placed in contact with the front surface of the transparent substrate (6) opposite to the side where the crystal thin plate (3) is placed. For the plate @η,
A through hole with an internal shape is bored in the center of the thin crystal plate (3) facing the effective operating area and surrounding it along its periphery. The levers are brought into contact with the arranged crystal thin plate (3) in areas other than the operating area that forms the potential pattern according to the projected image.The transparent substrate (6) of this first plate (0)
) on the side opposite to the side that comes into contact with the first plate 61).
A first stage Peltier effect element group (42A) is provided in which a plurality of Bertier effect elements are arranged around a central hole of the hole. Although the Bertier effect elements of this element group (42A) are electrically connected to each other in series, they are thermally arranged in parallel, with each cooling (endothermic) side facing the first plate under vacuum. Apply grease to create a tight thermal bond. Furthermore, a second plate (G) made of oxygen-free copper is similarly brought into contact with the heat generating side of each of the Vertier effect elements of the first stage Peltier effect element group (42A).

Also in the center of this second plate 03 is a central hole, which faces the effective working area of the crystal thin plate (3) and has an internal shape corresponding to the contour of this working area. Vacuum grease is also interposed between the second plate 03 and each Bertier effect element, so that the two are thermally closely coupled. Furthermore, the first stage Peltier effect element group (
42A), a second stage Peltier effect element group (42B) in which a plurality of Bertier effect elements are similarly arranged and housed around the center hole of the plate 0→ will be established. In this Peltier effect element group (42B) as well, the Bertier effect elements are electrically connected in series and thermally arranged in parallel with each other, such that the endothermic side of each Bertier effect element is connected to the second plate. The body 01 is tightly and thermally bonded to the body 01 using vacuum grease.

In addition, these first and second stage Peltier effect element groups (42A) and (42B) are, for example, connected to each other in series, and two common terminals are led out of the pipe body (goods). .

And the second stage Peltier effect element group (42B) I7c of this structure (7) is thermally coupled as a cooling means?
η is provided. This cooling means e]) has a plate (21A) made of oxygen-free copper, for example, which also has good thermal conductivity, and this is thermally connected to the second stage Peltier effect element group (42B) described above. They are arranged in close contact, for example through vacuum grease as well. This plate (21A) is similarly provided with a central hole at its center in a portion facing the effective operating area of the thin crystal plate (3), and a similar hole with a U-shaped cross section is provided along almost the entire circumference. For example, a shell (21B) made of oxygen-free copper is arranged in a C-shape, and a cooling medium water channel (21C) is formed between the shell (21B) and the plate (21A). Then, cooling medium, for example, cooling water introduction and outlet pipes (A) are welded to both ends of this water channel (21C) through the shell (21B) (in the figure, one pipe (
only financial assets) are shown. ).

On the other hand, the tube body (A) has a bottom that is lower than the glass tube body (2).
3A) and a panel part (23
P).

The tunnel part (23P) includes an optical window (IW), a ring-shaped front glass part (c) extending rearward from the periphery thereof, and a glass plate made of, for example, Kovar (Co-N1-Fe), which is joined to the rear end and extends further rearward. Metal ring part (c) made of alloy)
and a ring-shaped rear glass part that is further joined to the rear end■
Toyoshi becomes.

Structure (a) having an electro-optic crystal inside this tube body
The arrangement of the accompanying cooling means 01) and the steps for manufacturing the tube body (c) are first carried out using the metal IA”) ring part (a).
A front glass part (c) and a rear glass part (c) made of, for example, borosilicate glass are bonded and sealed to each end of the glass using a metal and glass adhesive called copal seal. . The cooling means 01) is attached to the nonel part (23P) formed by joining and combining the three parts in this way, with the assembly structure (1) of the electro-optic crystal (3) not yet attached. . Finally, the cooling medium inlet pipe and outlet pipe of means Q]) are inserted into the corresponding through holes (25a) bored in the metal ring, respectively.
The inner circumference of these through holes (25a) and the circumferential surface of each metal pie f) are sealed airtightly by brazing with silver solder or the like, or by bath-welding them by metal welding. And at the front end of the front glass part (c) of this panel (23P),
The optical window (IW), ie, the glass plate, is hermetically sealed by sandwiching an In ring (incorporated) and fitting a ring-shaped retainer (c) around its outer periphery and pressurizing it. In this way, the optical window part (IW) is sealed to the glass part (c), but this optical window part (1, W), that is, its glass plate, can be replaced by attaching and detaching the retainer (c). can be done easily.

On the other hand, on the opening end surface (26a) of the rear glass part (c),
Gold (Au), for example, is deposited to a thickness of 0.2 to 0.4 μm by vapor deposition, or chromium (Cr) is deposited, for example, as a base, and Au is deposited, for example, on this. This vapor deposition treatment is carried out after or before the sealing of the metal ring (25) and the glass parts (24) and (26), or on the metal ring part (25) of the metal introduction and derivation hole f (22). It can be carried out at any step such as before or after sealing.

And the cooling means (23P) attached to the panel part (23P)
2]), an assembled structure (
Attach 1). In this way, the assembled structure (
7) and cooling means? The panel section (
The open end surface (23a) of the tube main body (23M) is sealed to the end surface (26m) of the tube body (23P). In this case, as described above for the open end surface (23M) of the tube main body (23M), for example, gold Au is vapor-deposited to a thickness of 0.2 to 0.4 μm or Cr is used as an underlayer. A metal layer having a two-layer structure with a gold vapor deposited layer formed thereon is deposited on each end face (2
6a) and (23Ma), for example,
Wire-shaped or ring-shaped In alloy, e.g. 90 weight 31
%In-10w%Ag alloy is interposed between both end faces (26a) and (23Ma) and heated and pressurized for bonding and sealing. This joining is performed while the crystal structure (4) is being cooled by the cooling means 01). That is, for example, cooling water is circulated in the water channel (21C) through both ports of the cooling means Q, and the assembly structure (A) having the electro-optic crystal is assembled.
While cooling the In alloy 4, heat it at a temperature above the melting point of the In alloy 4, for example, 23.7°C in a vacuum atmosphere of 1O-5 Torr.
Welding is carried out by heating the material to a temperature of 100 m/m and pressurizing it with a load of, for example, 100 to 500 m/i. In this way, the open end (26 m) of each glass part and the open face (23 Ma) of the tube body (23 M) are firmly joined by mutual diffusion between the In alloy and Au, resulting in an airtight seal. . In this case, an annular metal retainer (2) made of stainless steel, for example, is fitted around the In alloy (a), and pressure welding is performed thereon. In addition, the tensile strength in the case of such joining was 112 bales.

In addition, the alloy composition of In alloy ring 4 is, for example, 5
2wt% In-balance Sn alloy (melting point = 118°C) or 50% In-balance Sn (MP = 125°C)
), 97 weight i% In-balance Ag (MP = 143°C
) etc. can be used.

In this way, the tube main body (23M) with the a4' neck section (23P) bonded and sealed at the front has, for example, the cathode of the electron beam emitting source explained in FIG. 2 at the rear end of the neck section. The tube is inserted and heated and evacuated to maintain a vacuum inside the tube.

Further, in FIG. 1, 0 indicates a terminal lead-out part, and this terminal lead-out part (3) is connected to a glass part, for example, a panel part (2).
3P) is provided in advance on the rear glass part (c). This terminal lead-out part 0 is a trap (for example, in a glass part), which is penetrated and sealed with a glass capillary tube 02, and a plurality of terminal pins (to) are implanted at the outer end of this glass capillary tube 0, insulated from each other. The stems (b), which are arranged vertically and penetratingly, are sealed and removed.

The terminal bins 03 are made of, for example, metal capillary tubes that are hermetically sealed.Although not shown, two selected terminal bins are provided with the aforementioned Bertier effect element group (42A).
The connection terminals (42B) and (42B) are connected, respectively.

Although not shown in the figure, for example, a thermistor or thermocouple as a temperature detection element is provided on the transparent substrate (6), and each terminal thereof, for example, the end of each metal wire of the thermocouple made of copper-constantan (Nl-Cu alloy). The terminal lead-out part 01) is led out in an airtight manner from the other pair of terminals (to).

〔Effect of the invention〕

As described above, in the present invention, before the assembly structure (7) having an electro-optic crystal is installed, the introduction pipe and the outlet pipe 76 (a) of the cooling medium of the cooling means (goods) to the pipe body are installed. Due to the number of penetrations and the use of the metal ring part (7) in this mounting part, the penetration part of the metal ring (A) is not a metal-to-metal joint. Because of this, the seal can be firmly and effectively airtight.

In addition, since the electro-optic crystal is attached before the metal ring part (a) and the glass parts (c) and (c) sealed to the front and rear parts of the metal ring part (a), the electro-optic crystal is Without any consideration, the bond can be fused under heat to provide sufficient bond strength and hermeticity. Furthermore, although the connection between the nonel part (23P) and the tube main body (23M) is performed after the electro-optic crystal assembly structure (7) is attached, is the attachment done by cooling means? Since this can be carried out in a cooled state by η, it is possible to avoid disturbing the electro-optic crystal due to heating during bonding. Therefore, the incidence of defective products is drastically reduced.

Again? By joining the flannel portion (23P) and the main body (23M) with heat and pressure using an In alloy, the joint can be reliably and firmly established. Furthermore, since this bonding was performed using an In alloy, by heating and melting this again, the panel portion (23F) and the main body (23M) can be separated again, making it possible to replace or reuse defective parts.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main parts of an example of an optical modulator according to the present invention, FIG. 2 is a schematic diagram of an example of a conventional optical modulator, and FIG. 3 is a diagram of the main parts thereof. . (G)...Pipe body, (23M)...Pipe body, (23
P)...lignnel part, (c)...metal ring part, (c)...front and rear glass part, (IW)...
・Optical window part, 4... Assembly structure having electro-optic crystal, 4... In alloy, (Foundation)... Cooling means, vessel...
The introduction pipe and outlet pipe for the cooling medium. Figure 1

Claims (1)

[Claims] An assembled structure having an electro-optic crystal and a cooling means for cooling the assembled structure are housed in a vacuum-sealed tube, and the tube has a tube main body made of a glass tube, a panel part joined to the front part of the tube main body, the panel part having an optical window part and a metal ring part penetrating and holding each pipe for introducing and leading out the cooling medium to the cooling means;
An optical modulator comprising a glass portion joined to the tube body, the glass portion and the tube body being fused and sealed with an In alloy.