CN115718337A - Peep-proof film, manufacturing method thereof and display device - Google Patents
Peep-proof film, manufacturing method thereof and display device Download PDFInfo
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- CN115718337A CN115718337A CN202211280508.2A CN202211280508A CN115718337A CN 115718337 A CN115718337 A CN 115718337A CN 202211280508 A CN202211280508 A CN 202211280508A CN 115718337 A CN115718337 A CN 115718337A
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- 238000000576 coating method Methods 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 13
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- 238000002834 transmittance Methods 0.000 description 24
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- 239000012780 transparent material Substances 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 229920001225 polyester resin Polymers 0.000 description 2
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- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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Abstract
The embodiment of the invention discloses a peep-proof film, a manufacturing method of the peep-proof film and a display device. The peep-proof membrane comprises: a transparent base film; the first light-transmitting layer is arranged on one side of the transparent base film and comprises a plurality of first grooves extending along a first direction; the second light-transmitting layer is arranged on one side, away from the first light-transmitting layer, of the transparent base film and comprises a plurality of second grooves extending along the first direction; the shading part is arranged in the first groove and the second groove; wherein, the vertical projection of the first groove is superposed with the vertical projection of the second groove. According to the embodiment of the invention, the grooves are respectively arranged on the two sides of the transparent base film and are correspondingly arranged, so that the grooves on the two sides can block oblique light rays together, the depth of the groove required by peeping prevention is reduced, and the manufacturing difficulty is reduced. And because the depth of the groove is reduced, the filling material easily enters the groove, and the shading effect of the groove is improved.
Description
Technical Field
The embodiment of the invention relates to a peep-proof film technology, in particular to a peep-proof film, a manufacturing method of the peep-proof film and a display device.
Background
With the continuous development of electronic display technology, flexible screens, curved screens, folding screens and the like are gradually favored by manufacturers of electronic display devices such as mobile phones and tablet computers; meanwhile, in order to increase the privacy and security of the display screen, the peep prevention is also the focus of the current research.
The existing peep-proof film generally adopts an ultrafine shutter structure, and shutter blades are formed in a mode of forming grooves on a light-transmitting film layer and filling light-shielding objects. To obtain a narrow viewing angle, the depth of the groove needs to be deep. But the deeper the depth of the groove, the greater the manufacturing difficulty. Therefore, the current peep-proof film has a larger visual angle and a non-ideal peep-proof effect. Meanwhile, the deeper the groove is, the more difficult the filling material enters the groove, and the poor shading effect of the groove is caused.
Disclosure of Invention
The invention provides a peep-proof film, a manufacturing method of the peep-proof film and a display device, which are used for reducing the visual angle of the peep-proof film and improving the shading effect.
In a first aspect, an embodiment of the present invention provides a privacy film, including:
a transparent base film;
the first light-transmitting layer is arranged on one side of the transparent base film and comprises a plurality of first grooves extending along a first direction;
the second light-transmitting layer is arranged on one side, away from the first light-transmitting layer, of the transparent base film and comprises a plurality of second grooves extending along a first direction;
a light shielding portion disposed within the first groove and the second groove;
wherein a perpendicular projection of the first groove coincides with a perpendicular projection of the second groove, and the first direction is parallel to the surface of the transparent base film.
Optionally, the first light-transmitting layer further includes a plurality of third grooves extending along the second direction, the second light-transmitting layer further includes a plurality of fourth grooves extending along the second direction, the first direction intersects with the second direction, the second direction is parallel to the surface of the transparent base film, and the light shielding portion is further disposed in the third grooves and the fourth grooves.
Optionally, the first direction is perpendicular to the second direction.
Optionally, the intervals of the first groove, the second groove, the third groove and the fourth groove are all equal.
Optionally, the groove cross sections perpendicular to the respective extending directions of the first groove, the second groove, the third groove, or the fourth groove are all isosceles trapezoids, and an upper base of each isosceles trapezoid is closer to the base film than a lower base thereof.
Optionally, the light shielding portion includes black ink.
Optionally, the light shielding portion further includes an elastic material.
Optionally, the following are satisfied:
(L 2 +h 2 )tanθ 1 +h s tanθ′+h 1 tanθ 2 ≤a 2 +b 2 -L 1 tanγ 1 ；
wherein L is 2 Is the depth of the second and fourth grooves, h 2 Is the difference between the thickness of the second light-transmitting layer and the depth of the second groove and the fourth groove, h s Is the thickness of the base film, h 1 Is the difference between the thickness of the first light-transmitting layer and the depth of the first and third grooves, a 2 A lower base pitch of the groove section of the second groove, b 2 A lower bottom length of the groove section of the second groove, L 1 Is the depth, γ, of the first and third grooves 1 An imaginary light ray is emitted into the privacy film from the second light-transmitting layer at an inner angle adjacent to the upper bottom in the groove cross section of the first groove, the imaginary light ray is close to a first angle of the second groove cross section perpendicular to the extending direction of a specific second groove and is emitted to a second angle of the first groove cross section perpendicular to the extending direction of the specific first groove, the first angle and the second angle are both adjacent to the upper bottom, and the specific second groove is arranged opposite to the specific first groove,the first angle and the second angle are staggered and correspond to each other, theta 1 Is the incident angle of the imaginary light at the interface formed by the second light-transmitting layer and the base film, theta' is the emergent angle of the imaginary light at the interface formed by the second light-transmitting layer and the base film, and theta 2 The emergent angle of the imaginary light at the interface formed by the base film and the first light-transmitting layer is shown.
In a second aspect, an embodiment of the present invention further provides a method for manufacturing a privacy film, including:
coating light-transmitting materials on two sides of the base film;
forming a plurality of first grooves on the light-transmitting material on one side of the base film through an imprinting process to obtain a first light-transmitting layer, and forming a plurality of second grooves on the light-transmitting material on the other side of the base film to obtain a second light-transmitting layer;
and filling light shielding materials in the first groove and the second groove to form a light shielding part.
In a third aspect, an embodiment of the present invention further provides a display device, including any one of the foregoing peep-proof films.
The peep-proof film in the embodiment of the invention comprises a transparent basal film; the first light-transmitting layer is arranged on one side of the transparent base film and comprises a plurality of first grooves extending along a first direction; the second light-transmitting layer is arranged on one side, away from the first light-transmitting layer, of the transparent base film and comprises a plurality of second grooves extending along the first direction; the shading parts are arranged in the first groove and the second groove; and the vertical projection of the first groove is superposed with the vertical projection of the second groove, and the first direction is parallel to the surface of the transparent base film. Through all setting up the recess in the both sides of transparent base film, and the both sides recess corresponds the setting, can make the recess of both sides block oblique light jointly to reduce the required recess degree of depth of peep-proof, reduce the manufacturing degree of difficulty. And because the depth of the groove is reduced, the filling material easily enters the groove, and the shading effect of the groove is improved.
Drawings
Fig. 1 is a schematic cross-sectional structural view of a peep-proof membrane according to an embodiment of the present invention;
fig. 2 is a top view of a privacy film provided by an embodiment of the present invention;
fig. 3 is a schematic cross-sectional structure view of another privacy film provided in the embodiment of the present invention;
fig. 4 is a schematic cross-sectional view of another privacy film provided in the embodiment of the present invention;
fig. 5 is a schematic cross-sectional view of another privacy film provided in an embodiment of the invention;
fig. 6 is a schematic cross-sectional structure view of a conventional peep-proof membrane according to an embodiment of the present invention;
fig. 7 is a schematic cross-sectional structure view of another privacy film provided in the embodiment of the present invention;
fig. 8 is a schematic flow chart of a method for manufacturing a privacy film according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some structures related to the present invention are shown in the drawings, not all of them.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. It should be noted that the directional terms "upper", "lower", "left", "right", etc. described in the embodiments of the present invention are used in the angle shown in the drawings, and should not be construed as limiting the embodiments of the present invention. In addition, in this context, it will also be understood that when an element is referred to as being "on" or "under" another element, it can be directly formed on "or" under "the other element or be indirectly formed on" or "under" the other element through intervening elements. The terms "first," "second," and the like, are used for descriptive purposes only and are not intended to denote any order, quantity, or importance, but rather are used to distinguish one element from another. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Fig. 1 is a schematic cross-sectional structural view of a peep-proof membrane according to an embodiment of the present invention, referring to fig. 1. The embodiment of the invention provides a peep-proof film, which comprises:
a transparent base film 1;
the first light-transmitting layer 2 is arranged on one side of the transparent base film 1, and the first light-transmitting layer 2 comprises a plurality of first grooves 21 extending along a first direction;
the second light-transmitting layer 3 is arranged on one side, away from the first light-transmitting layer 2, of the transparent base film 1, and the second light-transmitting layer 3 comprises a plurality of second grooves 31 extending along the first direction;
light shielding portions provided in the first groove 21 and the second groove 31;
wherein a perpendicular projection of the first groove 21 coincides with a perpendicular projection of the second groove 31, and the first direction is parallel to the surface of the transparent base film 1.
The transparent base film 1 may be a planar film structure made of a transparent material. Alternatively, a suitable material may be selected so that the elastic modulus of the transparent base film 1 is not less than 4000Mpa. Thereby the transparent basement membrane 1 has better flexibility, and is favorable for bending the peep-proof membrane. A first light-transmitting layer 2 and a second light-transmitting layer 3 are provided on both side surfaces of the transparent base film 1, respectively. Hard light-transmitting materials can be selected for the light-transmitting layer, so that the hardness and the wear resistance of the peep-proof film are improved, and meanwhile, the peep-proof film has a certain explosion-proof function due to the fact that the peep-proof film has high hardness and strength. All be equipped with the recess on the euphotic layer that is located 1 both sides of transparent base film, and the recess between the two-layer euphotic layer corresponds the setting. By filling the light-shielding material in the groove, a light-shielding part for shielding light can be formed. The light rays emitted obliquely are shielded by the light shielding parts arranged oppositely in the first light transmitting layer 2 and the second light transmitting layer 3, so that the purpose of shielding the light rays emitted obliquely is achieved. Optionally, the light shield portion comprises black ink. Optionally, the light shielding portion further includes an elastic material. Preferably, the elastic material is a polyurethane material; namely, the light-shielding portion is made of a polyurethane material mixed with black ink. Under the condition that the shading part comprises the elastic material, the deformation amount of the shading part can be improved when the peep-proof film is bent, and the flexibility of the peep-proof film is further improved. The mixture of black ink and polyurethane has better tensile property, so that the maximum deformation of the shading part can be improved. So that the tensile elongation of the light-shielding portion is not less than 200%. The black ink is a light-shielding substance, and by mixing the black ink into an elastic material, a light-shielding portion having elasticity can be obtained. In the embodiment of the invention, the first groove 21 and the second groove 31 which are oppositely arranged block oblique light rays together, so that the single groove depth required by peeping prevention is reduced. The deeper the depth of the groove, the greater the manufacturing difficulty. Therefore, the design of the embodiment can reduce the manufacturing difficulty. And the deeper the groove is, the more difficult the filling material is to fill the groove, so that the shading effect of the groove is poor. Therefore, in this embodiment, the structure that the first groove 21 and the second groove 31 block oblique light together reduces the depth of a single groove, and the filling material easily enters the groove, thereby improving the shading effect of the groove.
Fig. 2 is a top view of a privacy film according to an embodiment of the present invention, referring to fig. 2. In other embodiments, the first light-transmitting layer 2 further comprises a plurality of third grooves 22 extending along the second direction Y, the second light-transmitting layer 3 further comprises a plurality of fourth grooves (not shown in the figure) extending along the second direction Y, the first direction X intersects the second direction Y, the second direction Y is parallel to the surface of the transparent base film 1, and the light-shielding portions are further disposed in the third grooves 22 and the fourth grooves.
Because the first groove 21 and the second groove 31 are provided, light passing through the privacy film can be partially blocked when having a first direction X component, so that the privacy film has privacy performance in a specific direction. On the basis of the above, a third groove 22 and a fourth groove which are oppositely arranged can be added, and the third groove 22 and the fourth groove can be used for blocking part of the light rays with the second direction Y component. Therefore, the first direction X and the second direction Y can be freely arranged as required, and the required peep-proof angle can be obtained. The embodiment of the invention can enable the shading film to have shading effect under more viewing angles.
With continued reference to fig. 2, further, the first direction X is perpendicular to the second direction Y.
Wherein, first recess 21 and second recess 31 can block the light that has first direction X weight, and third recess 22 and fourth recess can block the light that has second direction Y weight, can set up first direction X and second direction Y into mutually perpendicular to furthest blocks the light under each slant observation visual angle, realize 360 degrees peep-proofings, further improve the peep-proof effect.
Further, the intervals of the first groove 21, the second groove 31, the third groove 22 and the fourth groove are all equal.
Wherein, because the size of recess interval is influencing the peep-proof angle of peep-proof membrane, can set up first recess 21, second recess 31, third recess 22 and fourth recess into impartial interval, make the peep-proof effect homogeneous phase of each department of peep-proof membrane. The display device has the advantage that each position of a display device picture attached with the peep-proof film has a consistent peep-proof effect at the same viewing angle.
Furthermore, the groove cross sections perpendicular to the respective extending directions of the first groove 21, the second groove 31, the third groove 22 or the fourth groove are all isosceles trapezoids, and the upper base of each isosceles trapezoid is closer to the base film than the lower base thereof.
Wherein, the upper bottom of the trapezoid is a short side, and the lower bottom is a long side. The cross sections of the first groove 21, the second groove 31, the third groove 22 and the fourth groove may be isosceles trapezoids. The isosceles trapezoid is easy to form and low in process difficulty. And further, the yield of the peep-proof film can be improved, and the manufacturing cost is reduced.
Fig. 3 is a schematic cross-sectional structure view of another privacy film provided in the embodiment of the present invention, and fig. 4 is a schematic cross-sectional structure view of another privacy film provided in the embodiment of the present invention, see fig. 3 and fig. 4. Further, the peep-proof film meets the following requirements:
(L 2 +h 2 )tanθ 1 +h s tanθ′+h 1 tanθ 2 ≤a 2 +b 2 -L 1 tanγ 1 ；
wherein L is 2 Depth of the second groove 31 and the fourth groove, h 2 Is the difference between the thickness of the second light-transmitting layer 3 and the depth of the second recess 31 and the fourth recess，h s Thickness h of the transparent base film 1 1 Is the difference between the thickness of the first light-transmitting layer 2 and the depth of the first recess 21 and the third recess 22, a 2 The distance between lower bottoms of the groove cross-section of the second groove 31, b 2 Is the lower base length, L, of the groove cross section of the second groove 31 1 Is the depth, γ, of the first recess 21 and the third recess 22 1 In the groove cross section of the first groove 21, the inner angle adjacent to the upper bottom, the imaginary light rays are emitted into the peep-proof film from the second light-transmitting layer 3, the imaginary light rays are close to the first angle of the cross section of the second groove 31 vertical to the extending direction of the specific second groove 31 and are emitted to the second angle of the cross section of the first groove 21 vertical to the extending direction of the specific first groove 21, the first angle and the second angle are adjacent to the upper bottom, the specific second groove 31 is opposite to the specific first groove 21, the first angle and the second angle are staggered and correspond, and theta is theta 1 Is an incident angle of an imaginary light ray at an interface formed by the second light-transmitting layer 3 and the base film, theta' is an emergent angle of the imaginary light ray at the interface formed by the second light-transmitting layer 3 and the base film, and theta 2 Is the exit angle of an imaginary ray at the interface formed by the base film and the first light-transmitting layer 2.
According to the embodiment of the invention, when various parameters of the peep-proof film are designed, the propagation path of light in the peep-proof film is fully considered, so that various parameters of the peep-proof film are determined according to the propagation path of the light, and the peep-proof effect of the peep-proof film is further improved. In addition to the above parameters, the parameters of the peep-proof membrane further include a lower bottom spacing a of the groove section of the first groove 21 1 The length b of the lower bottom of the groove cross section of the first groove 21 1 Refractive index n of first light-transmitting layer 2 1 Refractive index n of second light-transmitting layer 3 2 Refractive index n of transparent base film 1 s ，γ 2 Is the inner angle of the groove section of the second groove 31 adjacent to the upper base. Refractive index n of second light-transmitting layer 3 2 . Fig. 5 is a schematic cross-sectional structure view of another privacy film provided in an embodiment of the present invention, referring to fig. 5. There may be numerous paths of light in the privacy film, and representative three light rays are selected for discussion, namely, the first light ray m1, the second light ray m2 and the third light ray m 3. S1 is a light shielding part, and S2 is a part between two light shielding partsA light-transmitting portion is formed. First light ray m1 enters between the bottom of light-blocking portion S1 and the top of light-transmitting portion S2 in second light-transmitting layer 3, and strikes the rightmost end of the top of light-transmitting portion S2 in first light-transmitting layer 2 corresponding to light-transmitting portion S2 in second light-transmitting layer 3. The second light ray m2 enters between the lower bottom of the light shielding portion S1 and the upper bottom of the light transmitting portion S2 in the second light-transmitting layer 3, and strikes the rightmost end of the upper bottom of the right-side adjacent light shielding portion S1 in the first light-transmitting layer 2. Third light ray m3 enters between the lower bottom of light-shielding portion S1 and the upper bottom of light-transmitting portion S2 in second light-transmitting layer 3, and strikes the leftmost end of the lower bottom of light-shielding portion S1 separated by one light-shielding portion in first light-transmitting layer 2.
When the light incident angle is smaller than the first light m1, the light can penetrate through the peep-proof film. At this time, the peep-proof film is transparent at the front view angle.
When the light incident angle is between the first light m1 and the second light m2, the light is absorbed by the light shielding portion S1. This is shown as side-looking opaque to the viewing mask.
When the light incident angle is between the second light m2 and the third light m3, the light incident angle is significantly larger than the lower bottom angle of the light shielding portion S1, and the light will not intersect with the interface between the light shielding portion S1 and the light transmitting portion S2 and will not be absorbed, so the light will exit in the area S2. This appears as a large viewing angle light leakage of the privacy film, which needs to be eliminated.
When the light incident angle is larger than the third light m3, it is not necessary to consider, because the light is absorbed by the light shielding portion S1 inevitably at this time.
In order to prevent light leakage at a large viewing angle, parameters such as positions and shapes of the light shielding portion S1 and the light transmitting portion S2 should be adjusted to avoid light emission when the light incident angle is between the second light m2 and the third light m 3. N is obtained from the law of refraction 1 sinθ 1 ＝n s sinθ'，n s sinθ'＝n 2 sinθ 2 ，
The condition that the imaginary ray is absorbed by the light shielding portion S1 is that the lateral displacement X2 of the imaginary ray is equal to or less than the first displacement a' + the second displacement b 1 '. Large visual angle preventing leakageThe light is constrained such that an imaginary ray intersects the groove cross-section. The embodiment of the invention can set the interval of the shading parts according to the actual requirement while ensuring that the peep-proof film does not leak light at a large visual angle. The peep-proof performance of the peep-proof film is ensured.
Optionally, the light transmission angle of the peep-proof film can be adjusted by adjusting various parameters of the peep-proof film. Setting the interface between the second light-transmitting layer 3 and the transparent base film 1 as a first interface, setting the interface between the transparent base film 1 and the first light-transmitting layer 2 as a second interface, and setting the incident angle of light at the first interface as theta 3 Angle of refraction theta 4 Angle of refraction at the second interface is θ 5 Then the transmission angle is 2 x theta 3 Or 2 θ 4 。
N is obtained from the law of refraction 1 sinθ 4 ＝n s sinθ 4 ，n s sinθ 4 ＝n 2 sinθ 5 . The constraint condition that the light is not absorbed by the light shielding portion S1 is that the lateral displacement of the light is a or less 1 . The light transmission angle satisfies the following conditions:
through adjusting parameter in the above-mentioned formula, can adjust the printing opacity angle size of peep-proof membrane, and then can freely design the peep-proof membrane according to actual need, satisfy different in-service use demands.
Alternatively, the first and second light transmitting layers 2, 3 may be made of the same material, such that the refractive index n of the first light transmitting layer 2 is 1 Refractive index n with respect to the second light-transmitting layer 3 2 Same, i.e. n 1 ＝n 2 . And the first light-transmitting layer 2 and the second light-transmitting layer 3 may be provided symmetrically with respect to the transparent base film 1, and the light-shielding portion in the first light-transmitting layer 2 and the second light-transmitting layer 3 may also be provided symmetrically with respect to the transparent base film 1. The depth of the groove for accommodating the light shielding portion may be 90% of the thickness of the first light-transmitting layer 2 and the second light-transmitting layer 3, or may be the same as the thickness of the first light-transmitting layer 2 and the second light-transmitting layer 3. The material of the transparent base film 1 may be a polyester resin (PET) material. The refractive index of the transparent base film 1 may be in1.60-1.69. Alternatively, the refractive index of the transparent base film 1 may be 1.65. The refractive indices of the first light-transmitting layer 2 and the second light-transmitting layer 3 may be 1.60, i.e. n1= n2=1.60. In the groove cross section of the grooves in the first and second light transmitting layers 2, 3, the internal angle adjacent to the top may be 95 °, i.e. γ 1 ＝γ 2 ＝95°。
Hereinafter, the transmittance of the privacy film in the related art and the transmittance of the privacy film in the present embodiment are compared, so that the transmittances of the two are quantitatively compared.
Fig. 6 is a schematic cross-sectional structural view of a conventional privacy film according to an embodiment of the present invention, referring to fig. 6. The traditional peep-proof film structure comprises light absorption ink and a light transmission part, wherein the shaded part of a left oblique line is the light absorption ink, and the shaded part of a right oblique line is the light transmission part. Setting the depth of the groove to be C 1 The transparent length is a, the ink length is b, and the refractive index and the incidence angle are set as the graph.
The relationship between the angles of refraction can be found according to the law of refraction:
the transmittance calculation is divided into 2 parts, namely the transmission attenuation caused by the reflection of the material and the reduction of the light-passing area caused by the peep-proof structure. Let TT (θ) = η (θ) · TT (θ) when the total transmittance is TT (θ), the transmittance of the material itself is TT (θ), and the transmittance of the privacy film light transmission ratio structure is η (θ).
For tt (θ), it can be calculated by fresnel formula. The s-wave and p-wave components of the incident light are assumed to be equal.
First, n is calculated 0 To n s (calculation of different film layers, e.g. t, is indicated by subscripts 0s Denotes from n 0 The medium is incident on n s Transmittance of medium) transmission coefficients of s-wave and p-wave (the following formula is a primary formula of fresnel formula):
the luminous flux transmission for the corresponding s-and p-waves is (s and p in the last position of the subscript indicate the calculation of s-and p-waves, respectively):
Here, natural light incidence is used, and the ratio of s-wave to p-wave of natural light is 1:1, total transmittance of
Can obtain T in the same way s1s 、T 10p 、T s1s 、T 10p (calculation of different film layers, e.g. T, is indicated by subscript s1s Denotes from n S The medium is incident on n 1 S-wave transmittance of the medium), and finally multiplying the S-wave transmittance and the p-wave transmittance respectively to obtain the total transmittance of the S-wave and the p-wave (when each film layer is required to be calculated, the ratio of the S-wave to the p-wave cannot be ensured, and the total transmittance T cannot be calculated by using T).
Combining the law of refraction allows all angles to be represented by theta to be converted into a function containing only theta.
Then, η (θ) is calculated. η (θ) is essentially the transmittance ratio, which is the ratio of the light-transmitting portion to the entire structure period. One period of the traditional peep-proof film structure is a + b, and the light-passing part is a-delta x, so that
Is provided with
(1) When theta is less than or equal to 90-gamma, delta x is less than or equal to 0,
(2) when theta is more than 90 degrees and gamma and less than or equal to theta Cut-off ，0＜Δx≤a，
(3) When theta > theta Cut-off ，Δx＞a，η(θ)＝0。
Wherein, theta Cut-off Is the cut-off angle.
In summary, the final transmittance is calculated.
The above is the transmittance of the light flux of a single wavelength. If the transmittance of the light intensity in the visible light wave band needs to be calculated, the transmittance of all wavelengths with the interval of 5nm between 380 nm and 780nm needs to be calculated, and the Y value is calculated, only the conversion of tt (theta) can be carried out, and eta (theta) is kept unchanged. This is not described in detail herein.
The transmittance of the privacy film provided by the embodiment of the invention is calculated as follows.
Fig. 7 is a schematic cross-sectional structure view of another privacy film provided in the embodiment of the present invention, referring to fig. 7. The peep-proof film structure comprises light absorption ink and a light transmission part, wherein the light absorption ink is arranged on the shaded part of the left oblique line, and the light transmission part is arranged on the part of the right oblique line. Setting the whole thickness as C 2 The thickness of the intermediate substrate is C 2 ' transparent length is a, ink length is b, refractive index and angle of incidence are set as shown.
Because the upper and lower refractive indexes are the same, theta is easily obtained 1 ＝θ 3 、θ＝θ’，Also according to the law of refraction, the relationship between angles is listed:
the transmittance TT (theta) is calculated into 2 parts as the traditional peep-proof film, the transmittance TT (theta) of the material and the light-passing area ratio eta (theta) caused by the peep-proof structure, and the TT (theta) = eta (theta) · TT (theta).
The calculation of tt (θ) is the same as for the conventional privacy film.
Like the traditional peep-proof film,
but the new privacy film is equivalent to a γ =90 ° rectangular channel, Δ x has no contribution of the ink structure, and is divided into 2 segments:
when theta is less than or equal to theta Cut-off ，Δx≤a，
C' 2 tanθ 2 +(C 2 -C′ 2 ) tan theta = a, theta = theta Cut-off 。
Followed by simplification of tan θ 2 Note q = C' 2 tanθ 2 +(C 2 -C′ 2 )tanθ，n 1s ＝n 1 /n s ，
By calculation
Are small, and therefore the capsule
Apply taylor expansion and take the first 2 items for simplification:
it can be seen that equation q = a is a 6 th order unitary equation for sin θ, and the analytical solution is too cumbersome, and only comparison with the conventional peep-proof membrane is made here. Recording the peep-proof cut-off angle of the traditional peep-proof film as theta old The peep-proof cut-off angle of the novel peep-proof film is theta new . Collectively referred to as θ Cut-off 。
Gamma is generally very close to 90 deg., cot gamma is very small; generally theta is close to 45 DEG and smaller than 45 DEG, tan theta new Close to 1 but less than 1 and is,
the influence is small. It can thus be seen that if the privacy structures are the same: a is a 1 ＝a 2 、C 1 ＝C 2 (1) when n 1s When < 1, theta new ＜θ old ，C 2 ' the greater the theta new The smaller; (2) When n is 1s At > 1, typically θ new ＞θ old . When theta > theta Cut-off ，Δx＞a，η(θ)＝0。
In summary, the final transmittance is calculated:
the same TT (θ) is the transmittance of the single wavelength light flux. After evaluating the above results, it can be found that even though the angle γ ≈ 89 ° of the conventional privacy film reaches the top of the process, the effect of γ does not exist for the new privacy film, and it is naturally γ =90 °. Compared with the traditional peep-proof film with the general gamma =80 degrees, the peep-proof film has great advantages.
Fig. 8 is a schematic flow chart of a method for manufacturing a privacy film according to an embodiment of the present invention, and fig. 8 is a schematic flow chart. The embodiment of the invention also provides a manufacturing method of the peep-proof film, which comprises the following steps:
s1: the transparent material is coated on both sides of the base film.
S2: through an imprinting process, a plurality of first grooves are formed in a light-transmitting material on one side of a base film to obtain a first light-transmitting layer, and a plurality of second grooves are formed in a light-transmitting material on the other side of the base film to obtain a second light-transmitting layer.
S3: and filling light shielding materials in the first groove and the second groove to form a light shielding part.
The transparent material is easy to form through a process of coating and then stamping, so that the yield of the product is improved, and the production cost is reduced.
The embodiment of the invention also provides a display device which comprises any one of the peep-proof films.
The display device provided by the embodiment of the invention comprises the peep-proof film provided by the embodiment of the invention, and has corresponding characteristics and beneficial effects.
It is to be noted that the foregoing description is only exemplary of the invention and that the principles of the technology may be employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in some detail by the above embodiments, the invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the invention, and the scope of the invention is determined by the scope of the appended claims.
Claims (10)
1. A privacy film, comprising:
a transparent base film;
the first light-transmitting layer is arranged on one side of the transparent base film and comprises a plurality of first grooves extending along a first direction;
the second light-transmitting layer is arranged on one side, away from the first light-transmitting layer, of the transparent base film and comprises a plurality of second grooves extending along a first direction;
a light shielding portion disposed within the first groove and the second groove;
wherein a perpendicular projection of the first groove coincides with a perpendicular projection of the second groove, and the first direction is parallel to the surface of the transparent base film.
2. The privacy film of claim 1, wherein the first light transmitting layer further comprises a plurality of third grooves extending in a second direction, the second light transmitting layer further comprises a plurality of fourth grooves extending in a second direction, the first direction intersects the second direction, the second direction is parallel to the surface of the transparent base film, and the light blocking portions are further disposed within the third and fourth grooves.
3. The privacy film of claim 2, wherein the first direction is perpendicular to the second direction.
4. The privacy film of claim 3, wherein the first groove, the second groove, the third groove, and the fourth groove are all equally spaced.
5. The privacy film of claim 4, wherein the groove cross-section perpendicular to the direction in which each of the first groove, the second groove, the third groove, or the fourth groove extends is an isosceles trapezoid, the upper base of the isosceles trapezoid being closer to the base film than the lower base.
6. The privacy film of claim 1, wherein the light blocking portion comprises black ink.
7. The privacy film of claim 6, wherein the light blocking portion further comprises an elastic material.
8. The privacy film of claim 5, wherein the following is satisfied:
(L 2 +h 2 )tanθ 1 +h s tanθ′+h 1 tanθ 2 ≤a 2 +b 2 -L 1 tanγ 1 ；
wherein L is 2 Is the depth of the second and fourth grooves, h 2 Is the difference between the thickness of the second light-transmitting layer and the depth of the second groove and the fourth groove, h s Is the thickness of the base film, h 1 Is the difference between the thickness of the first light-transmitting layer and the depth of the first groove and the third groove, a 2 A lower base pitch of the groove section of the second groove, b 2 A lower bottom length of the groove section of the second groove, L 1 Is the depth of the first and third grooves, γ 1 In the groove cross section of the first groove, an inner angle adjacent to the upper bottom, an imaginary light ray is emitted into the peep-proof film from the second light-transmitting layer, the imaginary light ray is close to a first angle of the second groove cross section vertical to the extension direction of the specific second groove and is emitted to a second angle of the first groove cross section vertical to the extension direction of the specific first groove, the first angle and the second angle are both adjacent to the upper bottom, the specific second groove is arranged opposite to the specific first groove, the first angle and the second angle are staggered and correspond to each other, and theta is 1 Is the incident angle of the imaginary light at the interface formed by the second light-transmitting layer and the base film, theta' is the emergent angle of the imaginary light at the interface formed by the second light-transmitting layer and the base film, and theta 2 The emergent angle of the imaginary light ray at the interface formed by the base film and the first light-transmitting layer is provided.
9. A method of making a privacy film, comprising:
coating light-transmitting materials on two sides of the base film;
forming a plurality of first grooves on the light-transmitting material on one side of the base film through an imprinting process to obtain a first light-transmitting layer, and forming a plurality of second grooves on the light-transmitting material on the other side of the base film to obtain a second light-transmitting layer;
and filling a light shielding material in the first groove and the second groove to form a light shielding part.
10. A display device comprising the privacy film of any one of claims 1-8.
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