JPH0261728B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a screen in a rear projection device, and more particularly to a structure of the screen and a structure for attaching the screen to the rear projection device.

[Background of the invention]

Conventionally, rear projection devices have been developed for displaying large television images.

In this system, the television image projected on a cathode ray tube is magnified by a projection lens and projected onto a rear projection screen (rear screen), which is a transmissive type. The enlarged image projected on the projection screen can be observed.

FIG. 1 is a plan view showing a conventional example of a rear projection screen.

In Figure 1, 1 is a rear projection screen, 2
is the first sheet, 3 is the second sheet, 4 is the mounting part,
5 is a lenticular lens, 6 is a black stripe, and 7 is a Fresnel lens.

The rear projection screen 1 has a first lenticular lens 5 and a black stripe 6.
It is formed by laminating two screen members, a sheet 2 and a second sheet 3 provided with a Fresnel lens 7, and the mounting portion 4 at the periphery of the screen is tightly fixed by adhesive, screws, welding, tape, etc. ing.

In the conventional rear projection screen configured in this way, unnecessary residual stress exists, so after the peripheral parts are closely fixed, the first sheet 2 and the second sheet 3 are warped in the direction of separating from each other, and the center The parts may bulge outward. As a result, the first sheet 2 separates from the second sheet 3, spoiling the appearance of the rear projection screen 1 and deteriorating the optical properties of the screen.Furthermore, when the television sound is increased, the two sheets become separated from each other. It had the disadvantage of vibrating and making a rattling sound.

In addition, in order to prevent the central part from bulging due to such warping of the sheet, when manufacturing the rear projection screen, the first sheet 2 and the second sheet 3 are
After superimposing the two, the peripheral part was fixed by applying pressure to the entire surface from the outside, but it was difficult to sufficiently remove residual stress and prevent blisters from occurring in the center, resulting in poor yield. This was a major manufacturing problem.

FIG. 2 is a partial sectional view showing a general example of a rear projection screen.

Recently, a rear projection screen has been developed in which a lenticular lens 5 of a first sheet 2 and a Fresnel lens 7 of a second sheet 3 face each other as shown in FIG.

In such a rear projection screen, if the sharp tip of the Fresnel lens 7 rubs and scratches the surface of the lenticular lens 5 of the first sheet 2 due to vibrations during transportation of the screen, for example, There was a big drawback.

FIG. 3a is a sectional view showing a state in which a rear projection screen is attached in a conventional example. In the same figure, 12 is a screen attachment part.

Conventionally, the rear projection screen 1 was attached to the screen attachment part 12 of the rear projection device with the screen periphery firmly fixed as shown in FIG. When the sheet 3 expands, there is no escape, and the central part of the screen 1 swells, deteriorating its appearance, and the two sheets become separated, deteriorating the optical properties.

In general, rear projection screens are made of acrylic, so they expand and contract rapidly in response to temperature changes. This will be explained using FIG. 3b, taking a 45-inch rear projection device as an example.

FIG. 3b is an explanatory diagram for explaining the degree of expansion of the rear projection screen.

Assuming that the vertical length l of the rear projection screen 1 in FIG. 3a is 700 mm, the elongation Δl of the rear projection screen 1 when the temperature rises by 20° C. is approximately as follows.

Δl=6× ^10-5 ×ΔT×l=6× ^10-5 ×20×
700=0.8mm... According to Figure 3b, the amount of bulge Δd when l=700mm is as follows. However, Δl is Δl=
It is 0.8mm.

l=2Rsinθ...l+Δl=2Rθ...Δd=R(1-cosθ)... From the above equation, when Δd is determined as a function of Δl, the following equation is obtained.

As a result, the amount of bulge of the rear projection screen 1 is approximately 14.5 mm.

On the other hand, the rear projection screen also expands and contracts in response to changes in atmospheric humidity.
If only sheet 2 absorbs water and expands, since the first sheet 2 and second sheet 3 are fixed at their peripheral parts by welding or gluing, the first sheet 2 will have no place to escape, and the central part will expand. The first sheet 2 and the second sheet 3 were bulged outwards and separated from each other, resulting in the same result as described above, which was also a big problem.

Incidentally, a structure has recently been developed in which the screen mounting portion of a rear projection device is curved in advance in an arched manner, and the screen is mounted while being curved in an arched manner.

However, in such a rear projection screen, the periphery is only fixed in a bow shape and the center is free, so if only the first sheet 2 dries and shrinks, the center becomes separated from the second sheet 3. Put it away.
On the other hand, if only the first sheet 2 absorbs water and stretches, it will hit the surface of the second sheet 3, and the central part of the first sheet 2 will have no place to escape, causing it to bulge in any arbitrary place, causing the same big problem as above. was.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to ensure that even if there are temperature and humidity changes around the screen, the two laminated screen members will always be in close contact over the entire surface, and that It is an object of the present invention to provide a screen for a rear projection device, which improves the yield and further prevents scratches between screen members.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention forms the screen members by warping them in advance to give them stress that will cause them to stick together continuously, and also provides a screen mounting part so that the two screen members can freely expand and contract. The screen members are installed so that they can slide up and down and left and right so that they do not get stuck even if they are stretched, and lubricant is applied between the two screen members to prevent them from scratching each other. .

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a side view showing an embodiment of the rear projection screen according to the present invention, and FIG. 5 is a front view thereof. In these figures, parts corresponding to those in FIG. 1 are given the same reference numerals.

The first sheet 2 and the second sheet 3 in this embodiment
The structure of is similar to that shown in FIG.

As shown in FIGS. 2 and 4, the first sheet 2 (having a black stripe 6 on the exit surface and a lenticular lens 5 on the entrance surface) provided on the observer side is placed on the image source side. It is formed by greatly warping it in advance, and the second
The sheet 3 (with a Fresnel lens 7 provided on the exit surface) is pre-formed so as to be warped less than the first sheet 2 toward the image source side, and the first sheet 2 and second sheet 3 thus formed are They are stacked so that they are in close contact with each other over the entire surface, and double-sided adhesive tape is inserted only on the upper and lower edges or the left and right edges as the mounting portion 4, and the adhesive is fixed by applying force in the direction of the arrow.

When the two screen members are overlapped in this way, stress is constantly exerted in the center of the first sheet 2 and the second sheet 3 in the direction of making them come into close contact with each other, so that the two screen members are always placed over the entire surface. They will be in close contact. Furthermore, as shown in FIG. 5a, only the upper and lower edges (or left and right edges) of the mounting portion 4 are adhered with double-sided adhesive tape, so even if only the first sheet 2 of the screen 1 absorbs water and stretches. The second sheet 3 can also slide on the attachment part 4 and extend freely without being caught by the second sheet 3, so that the center part of the first sheet 2 does not bulge. The same effect can be obtained even if the adhesive tape of the device part 4 is wrapped around the edge of the sheet as shown in FIG. 5b. If the first sheet is warped vertically (or left and right) in a cylindrical shape, and the second sheet is warped vertically (or left and right) in a cylindrical or spherical shape, environmental resistance will be improved.

By the way, in order to mold the first sheet 2 and second sheet 3 by pre-warping them, if the material is acrylic, you can easily anneal them by leaving them warped in a room with an internal temperature of about 60°C. Can be done.

In this embodiment, the surface of the lenticular lens 5 of the first sheet 2 is coated in advance with a very thin lubricating oil (for example, silicone oil) having a thickness of several μm. In this way, the surface of the lenticular lens 5 of the first sheet 2 and the pointed tip of the Fresnel lens 7 of the second sheet 3 will touch smoothly, so even if they rub against each other, it will not be possible due to friction. There will be almost no scratches.

FIG. 6 is a cross-sectional view showing a rear projection device equipped with a screen according to the present invention.

In FIG. 6, 8 is a rear projection device, 9 is a cathode ray tube, 10 is a projection lens, 11 is a mirror, and 12
is the screen mounting part.

As shown in FIG. 6, a television image projected on a cathode ray tube 9 is enlarged by a projection lens 10, reflected by a mirror 11, and projected onto a rear projection screen 1 according to the present invention. An observer can observe the transmitted light of the enlarged image projected onto the rear projection screen 1 from an observation position on the opposite side of the projection lens 9.

Next, the mounting structure of the rear projection screen 1 in section A of FIG. 6 will be explained using FIG. 7.

FIGS. 7a and 7b are enlarged views of section A in FIG. 6, respectively.

In FIGS. 7a and 7b, 13 is a spring, 14 is a foamed plastic tape material, and 15 is a gap.

As shown in FIG. 7a, a gap 15 is provided in the upper part of the screen attachment part 12, and the screen 1 is further held down by a spring 13 and attached so that the screen 1 can slide on the attachment part 12.

Also, in FIG. 7b, like in a, screen 1
Foamed plastic tape material with rubber elasticity 1
4 and attach it, screen 1 is the mounting part 1
2 to be able to skate.

In this embodiment, the left and right mounting portions of the screen 1 have a similar structure.

With the structure described above, even if the rear projection screen 1 were to stretch due to an increase in temperature or humidity, the extension could escape to the mounting part 12 of the screen 1, so the central part of the rear projection screen 1 would not swell. It disappears.

〔Effect of the invention〕

As explained above, according to the present invention, since the two laminated screen members are always in close contact with each other over the entire surface, the appearance of the screen as a whole may be spoiled, vibrations may be generated due to sound, etc. Since the optical properties are not deteriorated and assembly is easy, the manufacturing yield is improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a conventional example of a rear projection screen, FIG. 2 is a partial sectional view showing a general example of a rear projection screen, and FIG. Third
FIG. 4 is a side view showing an embodiment of the present invention, FIG. A sectional view showing the attached rear projection device, FIG. 7 is an enlarged view of part A in FIG. 6,
It is. DESCRIPTION OF SYMBOLS 1... Rear projection screen, 2... First sheet, 3... Second sheet, 4... Mounting part, 8... Rear projection device, 12... Screen mounting part.

Claims (1)

[Claims] 1. In a rear projection device for enlarging and projecting an optical image from a video source onto a plastic screen from the back side thereof, a first member, which is the exit side member of the screen, has a lenticular lens on its entrance surface and a black stripe on its exit surface. and a second sheet, which is an entrance side member of the screen and has a Fresnel lens on its exit surface, constitute at least the screen, and the first sheet is closer to the image source side than the second sheet. The first and second sheets are configured in advance so that they are warped more than the second sheet, and the two sheets are stacked so that they are in close contact with each other over the entire surface, and the screen is installed so that the two sheets can expand and contract independently of each other. A screen for a rear projection device, characterized in that the lenticular lens surface provided on the entrance surface of the first sheet is coated in advance with extremely thin silicone oil having a thickness of several μm. .