JPH05273405A - Reflection mirror - Google Patents

Abstract

PURPOSE:To obtain a high-accuracy plane reflection mirror which is light in weight, is crack-free and is easy to handle by constituting this reflection mirror of a plastic film mirror, a low sp. gr. structural body contg. many cavities and a substrate having high plane accuracy. CONSTITUTION:The hard plastic film of a polyester system is used for the balance of optical performance and strength as the film material of the film mirror 3. The mirror has the plane substrate 4 consisting of aluminum and has the low sp. gr. structural body 5 which is the low sp. gr. structural body having a prescribed sp. gr. as a whole and consists of the low sp. gr. structural body having the hexagonal cavities 9. The aluminum is used as its material. The three; the substrate 4, the low sp. gr. structural body 5 and the rear surface 6, are integrally adhered and play the role of the structural part of the reflection mirror. The substrate 4 and the rear plate 6 play the role of preventing the infiltration of moisture in an adhesive D used for adhering the three and the deterioration of the strength and accuracy in the structural part of the reflection mirror.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight reflecting mirror, for example, a lightweight reflecting mirror suitable for an optical path bending mirror for a rear projection type projection television.

[0002]

2. Description of the Related Art Conventionally, there are two types of reflecting mirrors: a rear surface mirror used by forming a reflecting surface on the back surface of a transparent substrate and a front surface mirror forming a reflecting surface on the substrate surface.

FIG. 3 shows the points of difference in light reflection between the rear surface mirror and the front surface mirror, and the points of difference in optical performance between the rear surface mirror and the front surface mirror will be described. In the case of a rear surface mirror in which the reflection surface B is formed on the back surface of the glass substrate A, 90% of the reflection of the incident light I occurs on the reflection surface B on the back surface of the glass substrate, but about 4% also occurs on the front surface of the glass substrate. The two reflected lights, i.e., the reflected light I ₁ from the reflecting surface B and the reflected light I ₂ from the surface of the glass substrate are deviated in proportion to the glass thickness H. Therefore, the reflected image is proportional to the glass thickness H. to degrade.

On the other hand, in the case of a front surface mirror which forms a reflection surface B on the surface of the glass substrate A, the reflection of the incident light I does not cause any reflection light other than the reflection light I ₁ on the surface of the glass substrate, and therefore, compared with the rear surface mirror. The reflection image performance of the surface mirror is excellent.

Therefore, conventionally, in the case of an optical device which requires a highly accurate reflection image, after forming the reflection surface B by aluminum vapor deposition on the surface of the mirror glass substrate, the surface of the reflection surface B is protected by a few angstroms of inorganic material. A glass surface mirror having a film attached by vapor deposition is used.

The glass surface mirror is excellent in plane accuracy, durability and optical performance, but on the other hand, it has a drawback that it is heavy and easily broken, so that the weight of the entire set tends to be heavy. For example, 4
In the case of a glass surface mirror for a 3 inch rear projection type projection TV, the size is about 0.3 × 70 × 60 cm ³ ,
It weighs about 5.5 kg, and in order to prevent damage to the reflecting mirror, it is necessary to make the mounting frame and cabinet of the reflecting mirror strong, and the mounting frame and cabinet also become heavy, making the rear projection type projection TV set lightweight. And cost reductions.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lightweight, high-precision flat reflecting mirror in which the above-mentioned drawbacks of the glass surface mirror, which are heavy and easily broken, are improved.

[0008]

In order to achieve the object of the present invention, a reflective surface 2 is formed on the rear surface of a transparent film 1 by vapor deposition of aluminum.
A reflecting mirror is constituted by the film mirror 3 on which the film is formed, the substrate 4 for adhering the film mirror 3, the low specific gravity structure 5 described later, and the back plate 6. FIG. 4 shows the main points of the process for manufacturing the reflecting mirror of the present invention, and the means for realizing the present invention will be described.

First, as the film material of the film mirror 3, a thin plastic film 1 having a thickness of several tens of μm, the surface of which is mirror-finished, is prepared, and as shown in FIG. The reflective surface 2 is formed by aluminum vapor deposition, and the film mirror 3 is created.

Next, a flat plate made of a hard material is prepared as a substrate 4 for adhering the film mirror 3 composed of the plastic film 1 and the reflecting surface 2. The low specific gravity structure 5 is composed of a honeycomb structure having hexagonal cavities 9, a honeycomb structure having a large number of cavities such as a square shape or a corrugated structure, or a foamed structure having a large number of closed cells or open cells. A low specific gravity structure 5 is prepared. Further, the back plate 6 is a flat plate having the same thickness as the substrate 4, and the low specific gravity structure 5 and the back plate 6 are made of the same hard material as the substrate 4.

After the film mirror 3, the substrate 4, the low specific gravity structure 5 and the back plate 6 are prepared, the surfaces 7a and 8a have a highly precise parallelism and each has a highly precise plane. Using a press composed of a lower surface plate 7 and an upper surface plate 8, the four members are integrally pressure-bonded.

Since the mirror surface of the film mirror 3 is adhered in a highly precise plane, as shown in FIG. 4B, the back plate 6, the low specific gravity structure 5 and the substrate are placed on the lower surface plate 7 of the press. 4. Stack the film mirror 3 in this order. At this time, the aluminum mirror-evaporated reflecting surface 2 of the film mirror 3 and the substrate 4 are stacked so as to face each other.

As the adhesive between the film mirror 3 and the substrate 4, a rubber-based adhesive C containing an elastomer, which is a low shrinkage type in which a solid powder filler of a rubber elastic body is highly mixed, is used. Further, the substrate 4, the low specific gravity structure 5, the back plate 6
As the adhesive used for the adhesion of the three parties, a low shrinkage type adhesive D in which a filler of solid powder of the same material as the three parties is highly mixed is used. Then, using the press, the film mirror 3, the substrate 4, the low specific gravity structure 5, and the back plate 6 are lightly pressure-bonded to each other, and the mirror surface of the film mirror 3 in contact with the upper surface plate 8 is a highly precise flat surface. While maintaining the above state, the adhesive C and the adhesive D are solidified to manufacture a reflecting mirror surface.

[0014]

The film mirror 3 consisting of the plastic film 1 and the reflecting surface 2 shown in FIG. 4 (1) is a kind of rear surface mirror because the reflecting surface 2 is formed on the rear surface side of the transparent film 1, and it is a reflection mirror formed by aluminum vapor deposition. Film 1 as well as surface 2a
Reflection also occurs on the surface a, and the reflection image is deteriorated in proportion to the film thickness. However, since the film thickness is as thin as several tens of μm, the film mirror 3 has an optical advantage suitable for rear projection type projection television applications in which the reflection image is less deteriorated in principle.

Moreover, as shown in FIG. 4B, when the film mirror 3, the substrate 4, the low specific gravity structure 5 and the back plate 6 are integrally bonded, the reflecting surface 2 vapor-deposited with aluminum is bonded to the bonding surface. Since the film mirror 3 is adhered with the plastic film 1 on the front side, the plastic film 1
Can also function as a protective film for the reflecting surface 2 by vapor deposition of aluminum.

The low specific gravity structure 5 is a honeycomb structure having hexagonal cavities 9 or a honeycomb structure having a large number of cavities such as a square shape and a corrugated shape, or a foamed structure having a large number of closed cells and continuous cells. , Low specific gravity substance. On the other hand, substrate 4
The back plate 6 is a hard strength body having no cavity inside.
Therefore, if the low specific gravity structure 5, the substrate 4, and the back plate 6 are integrally bonded, a structure that is lightweight but highly rigid can be configured and bonded integrally with the film mirror 3. After that, the three members as a whole serve as the structural portion of the reflecting mirror of the present invention.

The front and back surfaces of each of the above three members are not flat in terms of manufacturing cost, and thus the surface accuracy is not good. Therefore, in order to integrally bond the film mirror 3, the substrate 4, the low specific gravity structure 5, and the back plate 6 to each other, these four members are stacked on the lower surface plate 7 and are attached to the upper surface plate 8 and the lower surface plate 7. When lightly pressure-bonded while maintaining parallelism, the film mirror 3 is in direct contact with the upper surface plate 8 having a highly accurate flat surface, so that the flat surface of the film mirror 3 is highly accurate due to the surface 8a of the upper surface plate 8. Although it is shaped into a flat surface (flatness) and becomes a highly accurate flat surface, the gaps formed between the four are not uniform. When this gap is enlarged, it is inevitable that the size of the gap varies like the gaps δ ₁ and δ ₂ shown in FIG. Therefore, when the four members are to be bonded together, fluctuations in the amounts of the adhesive C and the adhesive D existing in the gaps between the four members are inevitable, like the gaps δ ₁ and δ ₂ shown in FIG. ..

On the other hand, when the adhesive undergoes a solidification reaction, it necessarily shrinks, regardless of the degree, and a shrinkage stress acts on the adhesive surface. The shrinkage stress generated by the adhesive C and the adhesive D existing in the gaps of the four members varies depending on the size of the gaps δ ₁ , δ _{2 and the} like of the four members, and the four members each have different degrees. , It causes swells and warps depending on the fluctuations of the four gaps and the contraction stress.

In the present invention, in order to prevent this deformation, when the four members are integrally bonded, as the adhesive C between the film mirror 3 and the substrate 4, a filler containing a solid powder of a rubber elastic body is highly compounded and has a low shrinkage. A type of rubber-based adhesive containing an elastomer is used. Further, as the adhesive between the substrate 4, the low specific gravity structure 5 and the back plate 6, a low shrinkage type adhesive D in which a filler made of solid powder of the same material as the three is highly mixed is used. .. Since the fine powder solids that do not shrink even when the adhesives C and D undergo a solidification reaction occupy most of the volume of the adhesives C and D, the shrinkage rate of the adhesives C and D is small.

As described above, the shrinkage ratios of the adhesives C and D existing in the gaps of the four members are small, and therefore, due to the variation of the gaps δ ₁ and δ ₂ between the four members and the shrinkage of the adhesive CD. It is possible to reduce the shrinkage stress and the fluctuation of the shrinkage stress, and it is possible to prevent the film mirror 3 from visibly waviness and warp even after the four members are integrally bonded and the reflecting mirror of the present invention is completed.

As described above, the low shrinkage type adhesives C and D are used to adhere the film mirror 3, the substrate 4, the low specific gravity structure 5 and the back plate 6 to each other, as shown in FIG. 4 (2). In addition, the surface of the film mirror 3 is pressure-bonded by using the surface plates 7 and 8 having a highly accurate flat surface (flatness), and the adhesive C is formed while shaping the flat surface of the film mirror 3 into a highly accurate flat surface (flatness). , D can be solidified, so that the plane of the film mirror 3 can be made into a highly precise plane, and even after the four members are integrally bonded and the reflecting mirror is completed, the highly precise plane of the film mirror 3 is It is possible to substantially prevent deterioration due to fluctuations in the gaps δ ₁ , δ _{2 and the} like and contraction of the adhesives C and D.

Further, since the adhesive D, which is the structural part of the reflecting mirror and which integrates the three members, is highly mixed with the powder filler made of the same material as the three members, the coefficient of thermal expansion of the adhesive D is reduced. It is close to the coefficient of thermal expansion of the three. Therefore, even when the environmental temperature changes after the reflecting mirror is completed, it is possible to prevent warping or twisting due to the difference in the coefficient of thermal expansion between the three members and the adhesive D from occurring in the structural portion of the reflecting mirror.

Further, as the adhesive between the film mirror 3 and the substrate 4, a rubber-based adhesive C containing an elastomer, in which a solid powder filler of a rubber elastic material is highly mixed, is used.
Since the adhesive C is a rubber elastic body, the film mirror 3 and the substrate 4 are adhered to each other but not firmly bound to each other. Therefore, when the film mirror 3 and the three-body integrated structure undergo thermal expansion displacement, the adhesive C is a rubber elastic body on the adhesive surface 2a on the film mirror 3 side and the adhesive surface 4a on the substrate 4 side. , Film mirror 3 and substrate 4
It is possible to follow both different thermal expansion displacements. in this way,
Since the structure composed of the film mirror 3 and the above-mentioned three members can be freely thermally expanded without being affected by each other, so to speak, even when the environmental temperature changes, the structure between the film mirror 3 and the structure of the above-mentioned three members integrated. It is possible to prevent warpage and torsional deformation due to the difference in thermal expansion, and it is possible to maintain good planar accuracy of the reflecting surface 2.

Further, since the substrate 4 made of a hard material is interposed between the film mirror 3 and the low specific gravity structure 5,
It is possible to maintain the surface of the film mirror 3 as a highly accurate plane without affecting the film mirror 3 by the influence of cavities or bubbles in the low specific gravity structure 5 despite the temperature and humidity fluctuations over a long period of time.

[0025]

EXAMPLES An example of the present invention will be given below for further explanation. FIG. 1 is a structural diagram showing a configuration of a reflecting mirror according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a film, and as the film material of the film mirror 3, a polyester-based hard plastic film is used in view of the balance between optical performance and strength.

Reference numeral 2 is a reflecting surface formed by aluminum vapor deposition on the back surface of the plastic film. The plastic film 1 functions as a protective film for the reflecting surface 2 by vapor deposition of aluminum.

The film mirror 3 composed of 1 and 2 is also a kind of rear surface mirror because the reflective surface 2 is formed on the rear surface of the transparent film 1. For this reason, reflection occurs not only on the aluminum-deposited reflecting surface 2a but also on the film surface 1a, and the optical performance of the reflected image deteriorates. As described above, the thinner the plastic film 1 is, the less the deterioration of the optical performance of the reflected image can be. Therefore, in terms of optical performance, the thinner the plastic film 1, the more desirable.

However, the film mirror 3 consisting of 1 and 2
It is necessary to apply a little tension to the film mirror 3 in order to maintain the plane accuracy of the film mirror 3 when bonding the film onto the substrate 4, and when the thickness of the plastic film 1 is less than 20 μm and too thin, the film mirror 3 is distorted. As it occurs, it cannot be made too thin. 30 from the balance of optical performance and strength
To 200 μm is in a practical range and 30 to 70 μm is preferable in terms of optical performance. In this embodiment, a film having a uniform thickness of 40 ± 5 μm was used.

Reference numeral 4 is a 0.5 mm thick aluminum flat substrate. 5 is a low specific gravity structure having a specific gravity of 0.05 as a whole, and is composed of a low specific gravity structure having a hexagonal cavity 9. The material of the low specific gravity structure 5 has a thickness of 200 ± 10.
Aluminum with a uniform thickness of μm is used. Reference numeral 6 denotes a back plate stretched on the back of the low specific gravity structure 5, which is made of aluminum of the same material and the same thickness as the substrate 4.

The substrate 4, the low specific gravity structure 5 and the back plate 6 are integrally bonded and serve as a structural portion of the reflecting mirror. Further, the substrate 4 and the back plate 6 also have a role of preventing humidity from penetrating into the adhesive D used for the adhesion of the three members and deteriorating the strength and accuracy of the structural portion of the reflecting mirror.

When adhering the four members, the back plate 6 is first placed on the lower surface plate 7 as shown in FIG. 4 (2). Next, the low specific gravity structure 5 having the adhesive D attached to one surface 5a is placed thereon. Furthermore, the one surface 5b where the low specific gravity structure 5 remains
Adhesive D is attached to and the substrate 4 is placed thereon. Then, after the adhesive C is attached to the entire surface 4a of the substrate 4, the plastic film 1 is caused to function as a protective film for the reflection surface 2 by aluminum vapor deposition, so as shown in FIG.
The film mirror 3 is placed on the substrate 4 with the aluminum-deposited surface 2a of the plastic film 1 as the adhesive surface. At this time, the film mirrors 3 are overlapped with a slight tension applied in order to maintain the plane accuracy. Next, press the upper platen 8
And lightly crimp the lower surface plate 7 while maintaining the parallelism. Since the film mirror 3 that is in direct contact with the upper surface plate 8 is in direct contact with the upper surface plate 8 having a highly accurate flat surface to apply pressure, the flat surface of the film mirror 3 is higher than the surface 8 a of the upper surface plate 8. It is shaped into an accurate plane (flatness) and becomes a highly accurate plane.
While maintaining this state, the adhesives C and D are solidified to bond the four members together.

The front and back surfaces of each of the three members that serve as the structural portion of the reflecting mirror of the present invention, that is, the surfaces 4a and 4b of the substrate 4, the surfaces 5a and 5b of the low specific gravity structure 5, and the surface 6a of the back plate 6, 6
Since the surface of b is not particularly finished, the surface accuracy is not good. Therefore, when the four members are stacked and lightly pressed while maintaining parallelism between the upper surface plate 7 and the lower surface plate 8, the gaps formed between the four members are not uniform, and δ ₁ shown in FIG. , Δ ₂ , it is unavoidable that the size of the gap fluctuates. Therefore, fluctuations in the amounts of the adhesives C and D existing in the gaps between the four are unavoidable.

On the other hand, when the adhesive undergoes a solidification reaction, the adhesive always shrinks, regardless of the extent, and the adhesive between the bonding surfaces generates shrinkage stress. Therefore, each of the four parties, to a different extent,
Deformation occurs due to swells and warps according to the variation in the size of the gaps δ ₁ , δ ₂ etc. between the four members and the amount of shrinkage stress of the adhesive.

In order to prevent this deformation, as the adhesive C between the film mirror 3 and the substrate 4, a low shrinkage type elastomer in which a filler of a solid powder of a rubber elastic body is highly compounded at a volume ratio of 70 to 90% is used. A compounded rubber type adhesive C is used. Further, as a bonding agent between the substrate 4, the low specific gravity structure 5 and the back plate 6, a filler made of solid aluminum powder of the same material as the substrate is used in a volume ratio of 50 to 70.
%, And a low shrinkage type adhesive D with a high blending ratio was used. Adhesives C and D are both highly mixed with a fine powder solid filler,
Since the shrinkage rate is small, the variation in the gap between the four members and the shrinkage stress due to the shrinkage of the adhesives C and D and the shrinking stress are small, and even after the four members are integrally bonded and the reflecting mirror is completed, The highly accurate flat surface of the film mirror 3 shaped by the surface 8a of the upper surface plate 8 deteriorates due to fluctuations in the gaps δ ₁ , δ _{2 and the} like between the four members and contraction of the adhesives C and D. Can be prevented.

As described above, it is possible to realize a reflecting mirror body having a high rigidity and a highly accurate surface which is hard to be deformed despite being lightweight.

FIG. 5 is a cross-sectional view of an essential part of a rear projection type projection television set in which the flat reflecting mirror according to the present invention composed of the above 1 to 6, C and D is installed.
Is a cathode ray tube, 11 is a projection lens, 12 is 1 to 6, C,
A flat reflecting mirror 13 according to the present invention composed of D is a screen, and a light beam (arrow) projected from the cathode ray tube 10 is magnified by the projection lens 11 and then reflected by the flat reflecting mirror 12 to be projected on the screen 13. Is projected on.

When used in a projection television set, since the earthquake resistance of the flat reflecting mirror 12 against the acoustic vibration from the speaker 14 is also important, as shown in FIG. 1, the low specific gravity structure 5 has a multi-layer (two layers) cavity. The structure has good seismic resistance against acoustic vibration.

When used in a projection television set, since it is important to take measures against thermal expansion due to temperature rise and temperature unevenness of the flat reflecting mirror 12 due to heat radiation from the cathode ray tube 10, an elastomer compound is used as an adhesive between the film mirror 3 and the substrate 4. The rubber adhesive C is used. Environmental temperature rises,
When the film mirror 3 and the above-mentioned three-body integrated structure undergo thermal expansion displacement, the adhesive C on the adhesive surface 2a on the film mirror 3 side and the adhesive surface 4a of the substrate 4 is a rubber elastic body, so The substrate 4 can be deformed by following different thermal expansions. Therefore, although the film mirror 3 and the substrate 4 are adhered to each other, they are not firmly bound to each other, so that the film mirror 3 and the above-mentioned three-body structure are, so to speak, mutually opposed even when the environmental temperature rises. The film mirror 3 can be expanded freely without being affected.
Therefore, the three-body structure does not cause warping or twisting, and the plane accuracy of the reflecting surface 2 can be maintained well.

Further, the substrate 4, the low specific gravity structure 5, the back plate 6
Aluminium metal having good thermal conductivity is used together as the material of the three members, and an aluminum powder solid of the same material as the above three members is highly compounded as an inorganic filler of the adhesive D between the three members for adhesion. The thermal conductivity of the agent D is improved, and a large temperature difference is prevented from occurring between the three parties and the adhesive agent D in spite of the temperature rise and temperature unevenness in the projection television set 15.

Further, the three materials are made the same, the thermal expansion coefficients are made the same, and further, aluminum powder solid of the same material as the three is used as a filler of the adhesive D used for the adhesion of the three. It is used in a high blending ratio to bring the coefficient of thermal expansion of the adhesive D close to that of the above three. Therefore, even when the temperature inside the set 15 rises, warpage and twist deformation due to the difference in the coefficient of thermal expansion between the three members and the adhesive D are prevented from occurring, and no visible deformation such as warpage occurs. Therefore, the plane accuracy of the plane reflecting mirror 12 can be maintained well.

Although the flat reflecting mirror is applied to the rear projection type projection television set in this embodiment, it goes without saying that it may be applied to other purposes. Further, although the reflecting mirror is a plane reflecting mirror, it goes without saying that it may be applied to any curved reflecting mirror.

In this embodiment, the substrate 4 and the low specific gravity structure 5,
Aluminum was used as the material of the back plate 6 in consideration of the balance between strength, lightness and cost, but metal or metal foil such as stainless steel or titanium may be used depending on requirements such as accuracy, strength, weight and cost. Needless to say, other materials such as resin-impregnated paper, cloth, and plastic may be used.

When a metal foil is used, compared with a hexagonal cavity,
It is easier to make a hollow shape such as a square shape or a corrugated shape. In the case of plastic, it is easy to make a foam structure. In this example,
As the low specific gravity structure 5, a low specific gravity structure having a honeycomb-shaped hexagonal cavity 9 was used as shown in FIG. 2, but the low specific gravity structure 5 is required to have rigidity strength, seismic resistance against acoustic vibration, and manufacturing. Needless to say, a hollow structure having a large number of cavities of various shapes such as a square shape and a corrugated shape or a low specific gravity structure having independent cells or continuous cells may be used depending on the cost.

In this embodiment, the back plate 6 is stretched on the back of the low specific gravity structure 5. However, when the strength is not so required, the back plate 6 may not be used.

In the present embodiment, considering the balance of strength, lightness and cost, the specific gravity of the low specific gravity structure 5 as a whole is set to 0.05. It is possible to mold a low specific gravity structure having a specific gravity of 0.01 to 0.8, and when a plastic foam is used as the low specific gravity structure, 0.01 to 0.5 is possible. It goes without saying that the specific gravity of the low specific gravity structure 5 may be set according to the accuracy, strength and weight balance required for the reflecting mirror.

In this embodiment, the film mirror 3 and the substrate 4
An elastomer-containing rubber-based adhesive C in which a filler of a rubber elastic solid powder is highly blended is used as an adhesive between
As the adhesive between the substrate 4 or the back plate 6 and the low specific gravity structure 5, a low shrinkage type adhesive D in which an inorganic powder filler of the same material as the substrate 4 is highly mixed is used, but it is required for the reflecting mirror. It goes without saying that other types of adhesives may be used depending on the requirements of plane accuracy, strength, weight, cost and the like.

In this embodiment, an adhesive is used as a means for fixing the substrate 4 and the low specific gravity structure 5 to each other. However, depending on the shapes of the substrate 4 and the low specific gravity structure 5, other fixing means such as screws may be used. May be used.

Further, in this embodiment, the low specific gravity structure 5 has a structure having no front and back skins, but as shown in FIG. 6, a low specific gravity structure having front and back skins 18 and 19 is used. A sandwich-like low specific gravity structure may be used. In this case, the film mirror 3 may be directly adhered to one surface of the low specific gravity structure 5 without the substrate 4.

In this embodiment, the substrate 4 and the low specific gravity structure 5,
The same good heat conductive aluminum metal is used as the material of the back plate 6, but as the material of the substrate 4, the low specific gravity structure 5, and the back plate 6 depending on the requirements such as the use and cost of the reflecting mirror, It goes without saying that metals such as aluminum, stainless steel and titanium, metal foils, resin-impregnated papers, cloths, plastics and plastic foams may be used in the same or different combinations.

[0050]

The effect of the low specific gravity structure reflecting mirror according to the present invention shown in FIG. 1 will be described below.

In the present invention, since the reflecting mirror is composed of a plastic film mirror, a low specific gravity structure containing a large number of cavities, and a substrate having a highly precise plane accuracy, it is heavy and easily cracked, so care should be taken when handling. It is possible to realize a light-weight, high-precision flat reflecting mirror that is easy to handle and does not break, improving the drawbacks of glass surface mirrors. Also, since the reflecting mirror itself is made lighter and less prone to cracking, the need for a sturdy mounting frame or cabinet required to prevent damage to the reflecting mirror is reduced, and the mounting frame 16 or the mounting wall 17 of the reflecting mirror can be made lighter. It is possible to reduce the weight of the entire cabinet that houses the reflector.

[Brief description of drawings]

FIG. 1 is a structural cross-sectional view showing a configuration of a flat reflecting mirror according to an embodiment of the present invention.

FIG. 2 is a plan view showing an AA cross section of a flat reflecting mirror according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a difference between a back surface mirror and a front surface mirror.

FIG. 4 is an explanatory diagram of a manufacturing process of a flat reflecting mirror according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view of essential parts of a rear projection type projection television set according to an embodiment of the present invention.

FIG. 6 is a view showing a low specific gravity structure according to another embodiment of the present invention.

[Explanation of symbols]

 A ... Glass substrate, B ... Reflective surface, C ... Adhesive C, D ... Adhesive D, 1 ... Plastic film, 2 ... Reflective surface by aluminum vapor deposition, 3 ... Film mirror, 4 ... Substrate, 5 ... Low specific gravity structure , 6 ... back plate, 7 ... lower surface plate, 8 ... upper surface plate, 9 ... hexagonal cavity, 10 ... cathode ray tube, 11 ... projection lens, 12 ... plane reflecting mirror, 13 ... screen, 14 ... speaker, 15 ... TV set Inside, 16 ... Mounting frame, 17 ... Mounting wall, 18, 19 ... Epidermis.

Claims (8)

[Claims] 1. A reflecting mirror comprising at least a film mirror and a low specific gravity structure having a large number of cavities such as hexagon, quadrangle, corrugation, etc. and foams. 2. A reflecting mirror comprising at least a film mirror, a substrate, and a low specific gravity structure having a large number of cavities such as hexagons, quadrangles, and corrugations, and a large number of foams. 3. The reflecting mirror according to claim 2, wherein the substrate and the low specific gravity structure are made of a material having the same or substantially the same coefficient of thermal expansion. 4. The reflecting mirror according to claim 3, wherein the substrate and the low specific gravity structure are made of aluminum metal or plastic. 5. The reflecting mirror according to any one of claims 2 to 4, wherein a solid powder made of the same material as the substrate or the low specific gravity structure is mixed as a bonding means between the substrate and the low specific gravity structure. A reflecting mirror characterized by using the above adhesive. 6. The reflecting mirror according to claim 1, wherein any one of a film mirror and a low specific gravity structure, a film mirror and a substrate, and a substrate and a low specific gravity structure. A reflecting mirror characterized by using a rubber-based adhesive compounded with an elastomer as an adhesive agent at one or more locations. 7. A reflecting mirror characterized in that a plastic film is used as a film material in the reflecting mirror according to any one of claims 1 to 6. 8. A rear projection type projection television, comprising the reflecting mirror according to any one of claims 1 to 7.