JP3437505B2 - Display panel fixing structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed structure of an image display unit of an irradiation type image display device such as a rear projection display for audio / visual (AV) and a data projector for computer output.

[0002]

2. Description of the Related Art Conventionally, in a color liquid crystal projector using an LCD panel, in order to display a high quality image,
A plurality of LCD panels are used. Color-separated light is applied to the plurality of LCD panels, and the light from the plurality of LCD panels is color-synthesized to display a color image.

As described above, in the conventional method, since alignment to fixing to the movable stage is not required, LCD panels corresponding to respective colors are fixed to the movable stage with screws so that projected images of respective colors are overlapped. In addition, when the movable stage is adjusted to form a color image, a method of fixing the movable stage with an adhesive or the like in the adjusted state has been adopted.

However, since each LCD panel to be color-synthesized is fixed on the movable stage, the alignment is performed not only when the movable stage is not fixed sufficiently but also when the movable stage is firmly fixed. Misalignment may occur.

At present, a small LCD panel having a small optical system has been used for downsizing of a projection apparatus, but on the other hand, a high display resolution has been demanded.
Due to such market demands, the demand for small-sized and high-resolution LCD panels is increasing. However, the size of each pixel is reduced in a small-sized and high-resolution LCD panel, and at present, the size of one pixel of the LCD panel is reduced from several microns to several tens of microns.

As the size of one pixel becomes smaller in this way, the expansion and contraction due to the temperature of the movable stage that fixes the LCD panel and a slight amount of backlash cannot be ignored as misalignment of the LCD panel. Therefore, instead of fixing the LCD panel on the movable stage and adjusting the movable stage for alignment, the LCD panel is directly fixed to an alignment jig different from the projection optical system to position each LCD panel. After the alignment jig is used, a method has been adopted in which the LCD panel is directly fixed to the LCD panel fixing frame on the projection optical system side by means such as solder or adhesive.

In this panel fixing method, a solder fixing portion A is provided on the holding substrate 12 of the LCD panel unit 11,
Between the solder fixing portion and the LCD panel fixing frame 13, the thermal expansion coefficient is small, and the solder material is easily melted by reheating, so that the cream solder 14 or the thread solder whose alignment can be readjusted can be melted. Then fix it. That is, LCD
The solder fixing portion of the panel unit had a structure as shown in FIG. 4 with respect to the panel fixing frame.

In this solder fixing method, it is necessary to melt the solder while performing alignment of each LCD panel, and it is necessary to heat the solder fixing portion while maintaining the alignment state. Heating is preferred.
Further, in order to lower the heating temperature of the solder material to be supplied, it is advantageous to use cream solder rather than thread solder because the solder can be melted faster.

Therefore, when the cream solder is applied to the solder fixing portion and light beam heating is used as the non-contact heating method, the shape of the solder fixing portion of the LCD panel unit is as shown in FIG. It becomes.

[0010]

However, in the conventional example, as can be seen from the cross-sectional view shown in FIG. 4, since the cream solder is heated between the solder fixing portion and the panel fixing frame, it is heated. The flux contained in the sandwiched cream solder evaporates due to the temperature rise during heating. As shown in FIG. 4, when the solder fixing part is plate-shaped, the evaporation of flux facilitates the scattering of the solder to the surroundings, and the display panel and other optical elements are contaminated. Existed.

When the melted solder solidifies, the side surface of the solder fixing portion is wetted by surface tension. Due to this wetting, the solder also wraps around the solder fixing portion, and the fixing strength in the solder fixing portion is increased. However, when the solder fixing portion is plate-shaped, there is a problem that the wetting portion is reduced.

The present invention has been made in view of the above circumstances. A first object of the present invention is to solder the solder fixing portion for fixing the alignment-adjusted LCD panel unit at the time of heating the solder. Is to prevent the scattering of.

A second object of the present invention is to increase the solder strength at the solder fixing portion of the alignment-adjusted LCD panel unit.

[0014]

In order to achieve the above object, in the present invention, a holding substrate for holding a display panel and the holding substrate are provided.
Adhesive between the panel fixing frame that fixes the display panel
In the fixed structure of the display panel to be fixed, it is in the fixed part
At least one of the holding substrate and the panel fixing frame
Having an opening or notch, and the opening or notch
The adhesive is arranged in a circle, including the
To collect.

Therefore, when the flux of the cream solder sandwiched between the solder fixing portion and the solder fixing frame is evaporated due to the presence of the above-mentioned opening or notch, the cream solder flux can be evaporated from the opening or notch. As a result, it is possible to suppress the scattering of the solder to the periphery, and since the solder can be wetted in the opening or the notch, it is possible to increase the solder strength at the solder fixing portion.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) FIG. 1 is an embodiment best showing the features of the present invention. In FIG. 1A showing a cross section, reference numeral 1 is a display element. LCD
Reference numeral 2 is a panel, and 2 is a holding substrate for holding the LCD panel 1. Then, with the LCD panel 1 and the holding substrate 2,
It constitutes an LCD panel unit. The holding substrate 2 is
It has a solder fixing portion indicated by A in FIG. 1, and here, adhesion with solder is required. Therefore, a Fe—Ni alloy having a good solder wettability is used as the material itself of the holding substrate 2.

Although 42 alloy is used as the material of the holding substrate 2 in this embodiment, permalloy is also a suitable material as a metal of the same material. In addition, when the wettability of the holding substrate 2 itself with the solder is not so great, a solder steel plate whose surface has a good bondability with the solder may be used or solder plating may be applied.

Further, reference numeral 3 is a panel fixing frame, and like the solder fixing portion of the holding substrate 2, wettability of solder is required. Therefore, as a material to be used, a material such as permalloy, which is similar to the solder fixing portion, is suitable. Further, as shown in FIG. 1, a round opening (FIG. 2A) is formed in the solder fixing portion, that is, the portion A of the holding substrate 2.

The size of the solder fixing portion is 5 mm × 5 mm.

The holding substrate 2 has a thickness of 0.8 mm, the opening is 2.2 mmφ, and the LCD fixing frame 3 has a thickness of 1.0 mm.
was. The size of the holding substrate 2 is 38 mm × 37 mm (vertical × horizontal).

Further, FIG. 2 shows another example of the shape of the opening in this embodiment. Note that, as shown in FIG. 2, the opening shape is not limited to a circle, and a desired shape such as a triangle (FIG. 2B) or a quadrangle (FIG. 2C) can be used. Further, in this embodiment, an example in which the opening is provided in the solder fixing portion of the holding substrate 2 is shown, but the opening may be provided on the panel fixing frame 3 side or further on both sides. Of course good things. Of course, the number of openings may be one instead of one.

The holding substrate 2 is formed from a steel plate by die pressing. The openings are simultaneously formed by the mold during this press working.

Another method for forming the opening is CO2.
A method using a laser processing machine is also possible.

Reference numeral 4 is solder sandwiched between the solder fixing portion of the holding substrate 2 and the panel fixing frame 3. Before being melted by heating, this is in the form of a paste in which solder balls and flux are mixed as cream solder. The flux improves the wettability of the solder with the metal plate.

The cream solder is generally a solder ball mixed with 10 to 20% of flux. Solder balls have various compositions, but there are combinations such as Sn63% Pb37% and Sn46% Pb46% Bi8%. The solder balls are spherical powders having a grain size of 350-500 mesh. The cream solder used this time had a flux of about 18% mixed in the solder ball of the above composition and a viscosity of 300 Pa.s. It is in the form of paste at about s / 25 ° C. The cream solder in paste form as described above is commercially available from solder makers.

A method of sandwiching the cream solder between the holding substrate 2 and the LCD fixing frame 3 will be described below.

First, a cream solder having a thickness of 0.7 mm is filled in a syringe (a syringe) or a dispenser on the entire surface of the solder fixing portion, and an appropriate amount is applied to the LCD fixing frame. The holding substrate 2 is brought close to the LCD fixing frame 3 by an alignment jig and held so as not to come into contact with the cream solder, and the cream solder is sandwiched.

The alignment of the display is adjusted while the alignment jig is held, and the solder is melted and fixed by heating as it is. Since the gap between the holding substrate and the LCD fixing frame is filled with solder, it can be fixed even if it is separated by about 0.5 mm.

At the time of assembly, while the image displayed on the LCD panel unit is projected by the projection optical system and the LCD panels for each color are projected, the alignment adjustment between the three LCD panels is performed and the state is maintained. To do. next,
In order to heat the cream solder sandwiched between the solder fixing portion of the holding substrate 2 and the panel fixing frame 3 while the alignment adjustment is being performed, the solder fixing portion of the holding substrate 2 and the solder fixing portion of the holding substrate 2 are heated by the light beam heating device. A light beam is applied to the panel fixing frame 3.

The intensity of the light beam used was about 15 to 20 W. Since more than twice this power can be taken out from the light beam device, we adjusted the irradiation intensity and irradiation time according to the shape of the solder fixing part to set the optimum solder melting conditions.

It is important to heat only the solder fixing portion in the irradiation range of the light beam. In this embodiment, the irradiation of the light beam is about 5 mmΦ around the opening of the solder fixing portion.
Also, the irradiation angle of the light beam depends on the configuration of the alignment jig, and the equipment used this time had an inclination of about 45 degrees.

By irradiating the light beam, during 10 s,
The temperature of the solder fixing portion of the holding substrate 2 can rise to about 250 ° C. As the temperature rises due to the irradiation of the light beam, the flux contained in the cream solder partially evaporates,
In addition, part of the liquid becomes liquid. The liquid and evaporate of the flux are also released from the opening of the solder fixing portion of the holding substrate 2. Further, there is an effect of improving the wettability of the solder by the flux, and at the same time, the solder balls can be melted and the solder fixing portion of the holding substrate 2 and the panel fixing frame 3 can be fixed to each other.

(Second Embodiment) Here, the configuration will be described with reference to FIG. 1 used in the first embodiment. In FIG. 1, reference numeral 1 in (a) shown in cross section is an LCD panel which is a display element, and 2 is a holding substrate which holds the LCD panel 1. The LCD panel 1 and the holding substrate 2 are L
It constitutes a CD panel unit. In the holding substrate 2, the portion A shown in FIG. 1 is the solder fixing portion, and the adhesiveness with the solder is required. Therefore, a Fe—Ni alloy having a good solder wettability is used as the material itself of the holding substrate 2. Note that 42 alloy was used in this embodiment. Permalloy is also a suitable material as a metal of the same material. In addition, when the holding substrate 2 itself does not have much solder wettability, a solder steel plate having a good surface for joining with solder may be used or solder plating may be applied.

Further, reference numeral 3 is a panel fixing frame, and like the solder fixing portion of the holding substrate 2, wettability of solder is required. Therefore, as the material to be used, the same material as the holding substrate 2 such as permalloy is suitable. Further, A of the holding substrate 2
As shown in FIG. 3, the notch is formed in the portion. It should be noted that FIG. 3 also shows a cutout portion having another shape in this embodiment. Further, in this embodiment, the notch is provided in the solder fixing portion of the holding substrate 2, but the notch may be provided on the panel fixing frame 3 side or on both sides.

Reference numeral 4 is solder sandwiched between the solder fixing portion of the holding substrate 2 and the panel fixing frame 3. Before being melted by heating, this is a paste in which solder balls and flux are mixed as cream solder.

Here again, while projecting the image displayed on the LCD panel unit by the projection optical system, the LC for each color is displayed.
While projecting the D panel, alignment adjustment is performed and this state is maintained. Next, with the alignment adjusted, the light beam heating device fixes the solder of the holding substrate 2 in order to heat the cream solder sandwiched between the solder fixing portion of the holding substrate 2 and the panel fixing frame 3. The part and the panel fixing frame 3 are irradiated with a light beam. By the irradiation of this light beam, the temperature of the solder fixing portion of the holding substrate 2 can be raised to about 250 ° C. within 10 seconds. The flux contained in the cream solder partially evaporates due to the rise in temperature due to the irradiation of the light beam, and part of the flux becomes liquid. The liquid and evaporated material of the flux is also released from the cutout portion of the solder fixing portion of the holding substrate 2. Furthermore, there is an effect of improving the wettability of the solder by the flux, and at the same time, the solder balls can be melted and the solder fixing portion of the holding substrate 2 and the panel fixing frame 3 can be fixed to each other.

FIG. 5 shows an optical system in which a reflective liquid crystal panel (liquid crystal display device) using a semiconductor device having the characteristic structure of the present invention is applied to a project type display device. Here, at least three liquid crystal panels for three colors are provided, blue light is separated by a high reflection mirror and a blue reflection dichroic mirror, and further, a red reflection dichroic mirror and a green / blue reflection dichroic mirror. The red and green are separated by and the liquid crystal panels are projected.

That is, reference numeral 71 is a light source such as a halogen lamp, 72 is a condenser lens for narrowing down a light source image, and 73 and 75.
Is a planar convex Fresnel lens, and 74 is a color separation optical element that decomposes into R, G, and B, and a dichroic mirror, a diffraction grating, and the like are effective.

Reference numeral 76 denotes R, G, and B separated lights.
Mirrors for guiding the three panels of G and B, 77 is a field lens for illuminating the condensed beam to the reflection type liquid crystal panel by parallel light, and 78 is a reflection type liquid crystal element. is there. Further, reference numeral 80 is a projection lens, and 8
Reference numeral 1 denotes a screen, which is normally composed of two Fresnel lenses for converting the projected light into parallel light and a lenticular lens for displaying a wide viewing angle vertically and horizontally, thereby obtaining a clear and high-contrast bright image. You can In the configuration of FIG. 15, only one color panel is displayed, but between the color separation optical element 74 and the narrowed portion 79,
It is divided into three colors, and three panels are arranged.

Then, a voltage is applied to the liquid crystal layer of the liquid crystal element, and the light specularly reflected by each pixel passes through the squeezed portion indicated by reference numeral 79 and is projected on the screen. On the other hand, when a voltage is not applied and the liquid crystal layer is a scatterer, the light incident on the reflective liquid crystal element is isotropically scattered, and the scattered light is at an angle that looks into the aperture of the diaphragm. Other than that, it is not necessary for the projection lens. This displays black.

As can be understood from the above optical system, since a polarizing plate is unnecessary and the signal light enters the projection lens with a high reflectance from the entire surface of the pixel electrode, a display which is 2-3 times brighter than the conventional one can be obtained. realizable. Moreover, antireflection measures are taken on the surface and interface of the counter substrate, so that the noise light component is extremely small and high contrast display can be realized. Further, since the panel size can be reduced, all optical elements (lenses, mirrors, etc.) are downsized, and low cost and light weight are achieved. Also, the color unevenness, brightness unevenness, and fluctuation of the light source are
By inserting an integrator (fly-eye lens type rod type) between the light source and the optical system, on the screen,
I was able to solve it.

[0042]

As described above, according to the present invention,
When fixing the alignment by solder fixing, it was possible to reduce the scattering of the solder in the solder fixing portion and further increase the fixing strength of the solder fixing portion.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is also an example showing the shape of another opening in the above embodiment.

FIG. 3 shows an example of a notch shape showing a second embodiment of the present invention.

FIG. 4 shows a configuration diagram of a conventional example.

FIG. 5 shows an example of a display panel used in the present invention.

[Explanation of symbols]

1,11 LCD panel 2,12 panel holding substrate Part A Solder fixing part 3,13 panel fixing frame 4,14 solder

Continuation of the front page (56) Reference JP-A-10-232447 (JP, A) JP-A-10-142466 (JP, A) JP-A-9-138389 (JP, A) JP-A-11-84196 (JP , A) JP-A-8-18214 (JP, A) JP-A-8-23141 (JP, A) JP-A-7-74461 (JP, A) JP-A-60-249410 (JP, A) 58-147191 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/1333 G02F 1/13 505 G09F 9/00-9/46

Claims (3)

(57) [Claims] 1. A display panel fixing structure in which a holding substrate for holding a display panel and a panel fixing frame for fixing the display panel are fixed by an adhesive, the holding substrate and the panel fixing frame in a fixing portion. Has an opening or notch in at least one of the
A structure for fixing a display panel , wherein the adhesive is arranged in a circle including the parts . 2. The display panel fixing structure according to claim 1, wherein the adhesive is solder. 3. The display panel fixing structure according to claim 2, wherein the holding substrate and the panel fixing frame are fixed with the solder after alignment.