Board panel

Abstract

The present invention is transportable economically in a flat state, and easy to attach and detach, and can provide a curved surface simply while maintaining decoration and strength without craftsmanship and absorb sound. Slits are provided on a rectangular board panel comprising two or more layers of a hard material and a soft material. Two or more layers comprising a hard material and a soft material are laminated on a rectangular board panel, and slits having a length of ½ to ¾ of the vertical side are provided thereto. The use of slits makes formation of curved surfaces easy. Since there is no need to reinforce the outside to maintain the strength thereof, the board panel can be removed easily. Even if an external pressure is applied to the board panel, the flexibility of the hard material divided by the slits and the elastic characteristic of the soft material cause the pressure to be dispersed and absorbed, and sound to be absorbed.

Claims

1. A board panel comprising: a rectangular top of three or more stacked layers, wherein at least two layers are a hard material and at least one layer is a soft elastic pressure absorbing and sound absorbing material; a front face layer and a back face layer are layers of a hard material in which slits are provided in parallel with a vertical side of said rectangular top; said slits have a length of ½ to ¾ of said vertical side, and one end thereof touches the horizontal side of said rectangular top; and said slits include one type in which one end thereof touches an upper horizontal side of said rectangular top, forming upper slits, and another type in which one end thereof touches a lower horizontal side of said rectangular top, forming lower slits, said slits have a depth that do not penetrate through the board panel, wherein said slits provided on the front face layer alternate between slits touching the upper horizontal side and slits touching the lower horizontal side of said rectangular top, said slits provided on the back face layer alternate between slits touching the upper horizontal side and slits touching the lower horizontal side of said rectangular top, and wherein said front face layer and said back face layer alternate between slits touching the upper horizontal side and the lower horizontal side.

2. The board panel as set forth in claim 1 wherein said slits are spaced 5 mm or more on the straight line connecting the middle points of said vertical sides while said slits are spaced 40 mm or less on said horizontal sides.

3. The board panel as set forth in claim 1 wherein said front face layer is a wood layer and said vertical side is in the direction of wood grain of the wood.

4. A board panel comprising: a rectangular top with three or more stacked layers of a hard material and a soft elastic pressure absorbing and sound absorbing material; wherein a first hard material layer is on a front face, a soft elastic pressure and sound absorbing material layer touches said first hard material layer; and a second hard material layer is more toward a rear face side than said middle soft elastic pressure absorbing and sound absorbing material layer; layers other than said first hard material layer and the second hard material layer are soft elastic pressure absorbing and sound absorbing material layers; slits are formed in parallel with a vertical side of said rectangle on said front face of said first hard material layer of said board panel, forming front face-side slits; said front face-side slits have a length of ½ to ¾ of a length of said vertical side, and one end thereof touches a horizontal side of said rectangle while a depth thereof reaches said middle soft elastic pressure absorbing and sound absorbing material layer but does not reach said second hard material layer; said two or more front face-side slits include a type in which one end thereof touches the upper horizontal side of said rectangular top, forming upper front face slits and another type in which one end thereof touches the lower horizontal side of said rectangular top, forming lower front face slits; two or more slits that are in parallel with the vertical side of said rectangular top are provided on the rear face-side of said board panel, forming rear face-side slits; said rear face-side slits have a length of ½ to ¾ of that of said vertical side, and one end thereof touches the horizontal side of said rectangular top while the depth thereof goes through said second hard material layer but does not reach said first hard material layer; said two or more rear face-side slits include the type in which one end thereof touches the upper horizontal side of said rectangle, forming upper rear face slits, and the other type in which one end thereof touches the lower horizontal side of said rectangular top, forming lower rear face slits; and said upper slits and lower slits are arranged alternately on said front face-side, said upper slits and lower slits are arranged alternately on said rear face-side, said front face-side slits and said rear face-side slits are arranged alternately, and said front face-side slits and said rear face-side slits have a depth that do not penetrate through the board panel.

5. The board panel as set forth in claim 4 wherein said front face-side slits and said rear face side-slits are spaced 5 mm or more on the straight line connecting the middle points of said vertical sides, and said front face side-slits and said rear face side-slits are spaced 40 mm or less on said horizontal side.

6. The board panel as set forth in claim 5 wherein said first hard material layer and said second hard material layer are wood layers, and said vertical sides thereof is in the direction of wood grain.

7. The board panel as set forth in claim 5 wherein said second hard material layer is the rear face layer.

8. The board panel as set forth in claim 5 further comprising a face between the front face and the rear face of said board panel wherein it does not contain any of said front face side-slits and said rear face side-slits between the tip of said front face side-slits and the tip of said rear face side-slits.

9. The board panel as set forth in claim 1 wherein the soft material layer is layer of foam material.

10. The board panel of claim 9 wherein the soft material is made of foam material with open cells.

11. The board panel of claim 10 wherein the soft material is a melamine foam.

12. The board panel of claim 10 wherein the soft material is polyurethane foam.

13. The board panel of claim 1 wherein the weighted sound absorption coefficient is at least 0.80.

14. The board panel of claim 10 where the open area formed by the slits range between 15% and 40% of surface area.

15. The board panel of claim 10 where tensile strength of the board panel is more than 75 kPa.

16. The board panel of claim 10 with density of the foam material is more than 90 kg/m3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view illustrating an example of the board panel of the present invention.

(2) FIG. 2 is a diagram illustrating the side view of the board panel.

(3) FIG. 3 is a plan view illustrating the board panel.

(4) FIG. 4 is a bottom view of the board panel.

(5) FIG. 5 is a diagram showing one half of the board panel.

(6) FIG. 6 is a cross-sectional view of the board panel.

(7) FIG. 7 is a diagram illustrating an example of the state in which a curved surface is formed.

(8) FIG. 8 is an illustrative example of sound energy wave traveling into/through board panel with closed cell foam.

(9) FIG. 9 is an illustrative example of sound energy wave traveling into/through board panel with open cell foam.

(10) FIG. 10 is an illustrative example of sound wave traveling into/through board panel in straight configuration.

(11) FIG. 11 is an illustrative example of sound wave traveling into/through board panel in concave configuration.

(12) FIG. 12 is an illustrative example of sound wave traveling into/through board panel in convex configuration.

(13) FIG. 13 is an illustrative example of a cross sectional view of the board panel with open cell foam, mineral wool insulation and base wall or ceiling.

(14) FIG. 14 is an illustrative example of a cross-sectional view of the board panel with open cell foam, mineral wool, air cavity, and base wall or ceiling.

(15) FIG. 15 is an illustrative example of sound absorption, sound reflection and transmitted sound.

(16) FIG. 16 is an illustrative example of sound diffusion.

(17) FIG. 17 is an illustrative example of open area of a board panel and width of the slits.

(18) FIG. 18 is the dimension of the reverberation room used for acoustic testings.

(19) FIG. 19A shows the overview of first set up of the board panel specimen tested and 19B shows the result of the testing.

(20) FIG. 20A shows the overview of second set up of the board panel specimen tested and 20B shows the result of the testing.

WORKING EXAMPLES

(21) The present invention is described herein with reference to working examples.

Working Example 1

(22) FIG. 1 is a perspective view illustrating an example of the board panel of the present invention.

(23) As illustrated in FIG. 2, in board panel 1, front face hard material layer 2, rear face hard layer 3 and soft material layer 4 are adhered and laminated. Front face hard material layer 2 and rear face hard layer 3 are made of plywood, and soft material layer 4 is made of a synthetic resin (PE 30).

(24) FIG. 3 is a plan view of the board panel. FIG. 4 is a bottom face view of the board panel.

(25) The plywood that constitutes hard material layer 2 and rear face hard layer 3 has wood grain in the vertical direction of FIGS. 3 and 4. Furthermore, in the external rectangle of FIGS. 3 and 4, the side drawn vertically in the figure is the vertical side, and the side drawn horizontally is the horizontal side.

(26) As illustrated in FIG. 3, equally-spaced upper slits 5a, 5b, . . . and the equally spaced lower slits 6a, 6b, . . . are provided alternately. The space of slits (referred to as “v”) of the area in which both upper slits and lower slits exist is 6 mm, and the space of slits (referred to as “w”) of the area in which only upper slits exist and the area in which only upper slits exist is 12 mm.

(27) As illustrated in FIG. 2, the front face is provided with slits at different locations from those of the rear face of board panel 1, and slits in FIG. 3 are provided at different locations from those in FIG. 4. Slits of the board panel do not overlap with each other in the thickness direction, and the overall strength of the board panel can be reinforced.

(28) FIG. 5 is a diagram illustrating a half of the board panel. It shows only one half of the inner part in FIG. 1. FIG. 6 is a cross-sectional view of the board panel. It shows the side view thereof in FIG. 5, and the cross-sectional view cut out in the center section in FIG. 1.

(29) As illustrated in FIGS. 2 and 6, board panel 1 has slits having a depth which does not reach the center thereof, and has middle plane 7 which does not have slits between the front face and rear face. Middle plane 7 enhances the strength of the board panel. Moreover, the middle plane is shown with one-dotted line in FIG. 6; however, this does not mean that there is an article in reality. Middle plane 7 is a part of soft material layer 4.

(30) FIG. 7 is a diagram showing an example of a state in which a curved surface is formed. Figure (a) illustrates the flat state. By the use of slits, curved surfaces having the shapes as illustrated in Figures (b) and (c) can be formed. The middle plane section has no slit but deforms along the curved surface because it is a soft material.

(31) FIG. 8 shows an example of a board panel with the soft material layer having closed cell formation. The magnified section of the soft material shows an example of how a sound energy wave may travel once it enters the board panel through the soft material with closed cell formation. On the other hand, FIG. 9 shows an example of a board panel with the soft material layer having open cell formation. The magnified section of the soft material shows an example of how a sound energy wave may travel once it enters the board panel.

(32) FIG. 10 shows an example of a board panel set up as a straight board panel. The drawing also shows how a sound energy wave may be stopped by the board panel's outer surface, how a sound energy wave may enter the board panel through a slit, and how the sound energy wave may travel through the soft material layer of a board panel. FIGS. 11 and 12 show a similar example of a board panel and its relationship with the sound energy wave which the board panel is bent so it is concave in FIG. 11 and convex in FIG. 12 relative to the direction of the traveling sound energy wave.

(33) FIG. 13 is an illustrative example of a cross sectional view of the board panel in straight configuration with open cell foam, and mineral wool insulation placed between the board panel and the wall or the ceiling. FIG. 14 shows a similar set up to FIG. 13 but it includes a layer of air cavity between the base wall or ceiling and the mineral wool insulation.

(34) FIG. 15 is an illustrative example of sound absorption, sound reflection and transmitted sound energy wave where the board panel is in a flat straight configuration. FIG. 16 shows how sound energy wave may be diffused by a board panel.

(35) FIG. 17 shows how the surface area of the board may be covered with slits and shows how the width and the frequency or the interval of the slits result in different amount of area to be considered an open area or in other words, area covered with slits. The board panel tends to weaken with increasing open area although the acoustic property of absorbing sound increases with the amount of open area. An ideal ratio of open area to the entire surface area so the acoustic quality is good while maintaining strength is between 15% to 45%.

(36) FIG. 18 is the dimension of the reverberation room used for acoustic testing. All numbers are in meters and the numbers on the four corners are the height of the room at each of the corners.

(37) FIGS. 19A and 20A shows the overview of the tested specimen and 19B and 20B shows the result of the testing.

INDUSTRIAL APPLICABILITY

(38) Since the present invention is a board panel which can provide a curved surface simply while maintaining decoration and strength, and one type of standardized board panel can be used to form curved surfaces of various shapes, it can expect utilization by furniture manufacturers, construction companies, and so on.

(39) Acoustic Property—Sound Absorption

(40) The board panel was tested for sound absorption. The testing was conducted in accordance with DIN EN ISO 354 standard. The curved board was tested in two different set up.

(41) In the first set up, the board panel was formed into a curved surface in front of a cavity of 160-290 mm with 100-150 mm of mineral wool insulation. The wooden board was curved to form a radius of 200 mm. The wooden board of the board panel tested had slots width of 1.6 mm before curving and two wooden board sandwiched a polyurethane foam. The total thickness of the board panel was 19 mm and the total area tested were 12 m.sup.2.

(42) In the second set up, the board panel was formed into a curved surface in front of a cavity of 300-340 mm with 150 mm of mineral wool insulation. The wooden board was curved to form a radius of 600 mm. The wooden board of the board panel tested has slots width of 1.6 mm before curving and two wooden board sandwiched a polyurethane foam. The total thickness of the board panel was 19 mm and the total area tested were 12 m.sup.2.

(43) The temperature in the reverberation room was approx. 22° C.; the air humidity was approx. 45%. The atmospheric air pressure was approx. 1007 hPa. The test specimens were inserted into a frame laying on the floor of the reverberation room.

(44) The following test and measuring equipment were used:

(45) Hand-held sound level meter type Norsonic Nor 140 (channel 1)

(46) Hand-held sound level meter type Norsonic Nor 140 (channel 2)

(47) Microphone type Norsonic Nor 1225 (channel 1)

(48) Microphone type Norsonic Nor 1225 (channel 2)

(49) Microphone preamplifier type Norsonic Nor 1209 (channel 1)

(50) Microphone preamplifier type Norsonic Nor 1209 (channel 2)

(51) Power amplifier type Norsonic Nor 280

(52) Dodecahedron loudspeaker type Norsonic Nor 276

(53) Acoustic calibrator type Norsonic Nor 1251

(54) The following standards were applied for testing and assessing the measurement results. /1/ DIN EN ISO 354, Edition December 2003 “Akustik; Messung der Schallabsorption in Hall-räumen”—Acoustics—Measurement of sound absorption in a reverberation room /2/ ISO 9613, Part 1, Edition June 1993 “Acoustics—Attenuation of sound during propagation outdoors—Calculation of the absorption of sound by the atmosphere” /3/ DIN EN ISO 11654, Edition July 1997 “Akustik; Schallabsorber für die Anwendung in Gebäuden—Bewertung der Schallabsorption”—Acoustics—Sound absorbers for use in buildings—Rating of sound absorption
Test Results

(55) TABLE-US-00001 TABLE 1 Absorption coefficient α.sub.s Third- First Set Up at radius First Set Up at radius octave 200 mm in front of a 200 mm in front of a center cavity of 160-290 mm cavity of 160-290 mm frequency with 100-150 mm mineral with 100-150 mm mineral octave center wool insulation wool insulation frequency in third- Averaging in in third- Averaging in [Hz] octaves octaves octaves octaves 100 0.56 0.69 0.61 0.76 125 0.67 0.75 160 0.82 0.93 200 0.88 0.78 0.83 0.72 250 0.74 0.67 315 0.73 0.65 400 0.78 0.76 0.64 0.69 500 0.75 0.70 630 0.73 0.72 800 0.71 0.73 0.74 0.74 1000 0.74 0.73 1250 0.74 0.76 1600 0.75 0.80 0.79 0.82 2000 0.80 0.80 2500 0.86 0.86 3150 0.87 0.75 0.90 0.79 4000 0.78 0.80 5000 0.60 0.66 Average reverberation times T [s] Second set up (radius First set up with radius 600 mm) in front of a Third- 200 mm in front of a cavity of 300-340 mm octaves cavity of 160-290 mm with 150 mm mineral center with 100-150 mm mineral wool insulation on frequency empty wool insulation average 100 8.54 3.07 2.91 125 8.73 2.73 2.54 160 8.90 2.38 2.17 200 7.84 2.19 2.28 250 7.30 2.41 2.58 315 7.17 2.43 2.63 400 7.98 2.39 2.74 500 7.80 2.44 2.57 630 6.95 2.39 2.43 800 6.20 2.34 2.30 1000 5.78 2.23 2.25 1250 5.53 2.19 2.15 1600 4.93 2.06 2.01 2000 4.57 1.93 1.93 2500 4.19 1.78 1.78 3150 3.77 1.68 1.66 4000 3.10 1.61 1.61 5000 2.56 1.59 1.57
Table 2

(56) The test was performed in accordance with DIN EN ISO 354 (December 2003). The airborne sound excitation in the reverberation room was generated by a Dodekaeder as omnidirectional transmitter, which was set up in at least 2 different positions. The spatial averaging of the sound pressure level between 100 Hz and 5.000 Hz was performed with fixed microphone positions.

(57) Using the method of interrupted noise, the reverberation time in the reverberation room was determined with and without absorptive material in accordance with DIN EN ISO 354 for at least 12 different combinations of loud-speaker and microphone positions. The sound absorption coefficient α.sub.s is thus calculated in accordance with:

(58) $\begin{array}{cc}{\alpha }_s=55.3.Math.\frac{V}{S}.Math.\left(\frac{1}{c_2{T}_2}-\frac{1}{c_1{T}_1}\right)-4.Math.\frac{V}{S}\left(m_2-m_1\right)\mathrm{Cf}.\mathrm{DIN}\mathrm{EN}\mathrm{ISO}354,\mathrm{section}8\mathrm{where}\text{:}T1\text{:}\mathrm{Reverberation}\mathrm{time}\mathrm{in}\mathrm{the}\mathrm{reverberation}\mathrm{room}\left[s\right]T2\text{:}\mathrm{Reverberation}\mathrm{time}\mathrm{in}\mathrm{the}\mathrm{reverberation}\mathrm{room}\text{.Math.}\mathrm{following}\mathrm{installation}\mathrm{of}\mathrm{the}\mathrm{test}\mathrm{specimen}\left[s\right]V\text{:}\mathrm{Volume}\mathrm{of}\mathrm{the}\mathrm{empty}\mathrm{reverberation}\mathrm{room}\left[m^3\right]S\text{:}\mathrm{Surface}\mathrm{of}\mathrm{the}\mathrm{test}\mathrm{specimen}\left[m^2\right]c_1\mathrm{Sound}\mathrm{velocity}\mathrm{in}\mathrm{air}\mathrm{during}\mathrm{measurement}\mathrm{of}\text{.Math.}{T}_1\left[m\text{/}s\right]c_2\mathrm{Sound}\mathrm{velocity}\mathrm{in}\mathrm{air}\mathrm{during}\mathrm{measurement}\mathrm{of}{T}_2\left[m\text{/}s\right]m_1\mathrm{Air}\mathrm{absorption}\mathrm{coefficient},\mathrm{calculated}\mathrm{according}\mathrm{to}\text{.Math.}\mathrm{ISO}9613\text{-}1,\mathrm{during}\mathrm{measurement}\mathrm{of}{T}_1.\text{.Math.}{m}_2\mathrm{Air}\mathrm{absorption}\mathrm{coefficient},\mathrm{calculated}\mathrm{according}\mathrm{to}\mathrm{ISO}9613\text{-}1,\mathrm{during}\mathrm{measurement}\mathrm{of}{T}_2.& \mathrm{Equation}\left(1\right)\end{array}$

(59) Air absorption occurs through the friction and resonance effects of the air molecules. This portion of sound absorption does not depend on the test specimen, but exclusively on temperature, air humidity and atmospheric air pressure. If differences result between the reference measurements in the empty reverberation room and a measurement of the test specimens, the difference of the respective portion of air absorption is mathematically corrected (cf. Equation 1). The calculation of the air absorption coefficient is performed following the procedure in ISO 9613, Part 1, June 1993 (/2/).

(60) Air absorption is relevant beginning at a frequency of approx. 1000 Hz and increases towards higher frequencies. The portion of air absorption, and therefore any correction that may have been considered, ranges, where the differences in the above-mentioned parameters are not too great, from approx. +/−0.01 to +/−0.1 points.

(61) The determination of the weighted sound absorption coefficient α.sub.w derived from the frequency-dependent values of the sound absorption coefficient α.sub.s, serves as a simplified statement of an individual value.

(62) For this, following the procedure in DIN EN ISO 11654 /3/, the third-octave values of the sound absorption coefficient α.sub.s are converted into octave values α.sub.pi, the so-called “practical sound absorption coefficient.” The reference curve in frequency range 250 Hz is defined up to 4 kHz and is in each case moved in steps of 0.05 until the sum of the most unfavorable deviation is smaller than or equals 0.10.

(63) When the practical sound absorption coefficient α.sub.pi exceeds the value of the moved reference curve in an octave center frequency by 0.25 or more, then, supplemental to the α.sub.w value, one or more shape indicators need to be stated in parentheses. The following designations are used:

(64) L: when a value is exceeded by 0.25 or more at f=250 Hz

(65) M: when a value is exceeded by 0.25 or more at f=500 Hz or 1.000 Hz

(66) H: when a value is exceeded by 0.25 or more at f=2.000 Hz or 4.000 Hz.

(67) With the classification system given in DIN EN ISO 11654, the single number quantities of the weighted sound absorption coefficient α.sub.w is divided into sound absorption classes, which are presented in the following table:

(68) TABLE-US-00002 Sound absorption class α.sub.w value A 0.90; 0.95; 1.00 B 0.80; 0.85 C 0.60; 0.65; 0.70; 0.75 D 0.30; 0.35; 0.40; 0.45; 0.50; 0.55 E 0.25; 0.20; 0.15 Unclassified 0.10; 0.05; 0.00

(69) The measurements were taken in a reverberation room as shown in FIG. 13 with 6.31 m×5.94 m×5.79 m×6.41 m and height of the room ranging 4.86 m to 5.95 m at the four corners with a volume of 200 m.sup.3 and surface area of 207 m.sup.2. Four diffusers were suspended from the ceiling to obtain a sound field that is as diffuse as possible.

(70) In summary, the first set up of the board panel with 19 mm thickness formed from two plywood boards sandwiching a layer of polyurethane with an open area surface area of 16% with 1.6 mm wide slots (without bending/curving of the board panel) tested for acoustic property with the board panel bent to form a 200 mm radius and placed in front of a cavity of 160-290 mm thickness with 100-150 mm of mineral wool insulation (more mineral wool where the cavity was larger), resulted in a weighted sound coefficient of 0.80 and “B” classification. FIG. 19A shows the overview of the tested specimen and 19B shows the result of the testing.

(71) Acoustically Effective Surface:

(72) Height (individual): 3.00 m

(73) Width (individual): 4.00 m

(74) Specimens in reverberation room: 1 pc.

(75) Area of the test specimen: 12.00 m2

(76) Volume: 200 m3

(77) Total surface: 207 m2

(78) Test method: Method using interrupted noise according to DIN EN ISO 354:2003

(79) Test signal: Pink Noise

(80) Receive filter: third octave

(81) Setup of specimen in reverberation room: type E-290

(82) in accordance with DIN EN ISO 354, no. B.4

(83) empty/with specimen

(84) Temperature: 21.4/22.0° C.

(85) Air humidity: 49.5/45.5%

(86) Air pressure: 100.6/100.8 kPa

(87) Speed of sound: 344.18 m/s

(88) ISO 9613

(89) TABLE-US-00003 Averaging in octaves: f in Hz α.sub.s 125 0.69 250 0.78 500 0.76 1000 0.73 2000 0.80 4000 0.75

(90) The second setup of the board panel with 19 mm thickness formed from two plywood boards sandwiching a layer of polyurethane with an open area surface area of 16% with 1.6 mm wide slots (without bending/curving of the board panel) tested for acoustic property with the board panel bent to form a 600 mm radius and placed in front of a cavity of 300-340 mm thickness with average of 150 mm of mineral wool insulation, resulted in a weighted sound coefficient of 0.75 and “C” classification. FIG. 20A shows the overview of the tested specimen and 20B shows the result of the testing.

(91) TABLE-US-00004 Averaging in octaves: f in Hz α.sub.s 125 0.76 250 0.72 500 0.69 1000 0.74 2000 0.82 4000 0.79

(92) As the result of the tests show, the board panel as described here show superior acoustic property of absorbing sound in addition to all other properties and qualities of the board panel.