BACKLIGHT MODULE AND DISPLAY DEVICE

Abstract

A backlight module and a display device are provided, which include a surface light source, an optical film, and a light control film. The light control film has a first reference plane and a plurality of first optical structures provided on the first reference plane. Each of the first optical structures has a first optical surface and a second optical surface, and the first optical surface and the second optical surface respectively form a first interior angle and a second interior angle with the first reference plane, the first interior angle being an acute angle and smaller than the second interior angle. This allows the light beam to be deflected to one side to suppress the light output rate on the other side.

Description

[Technical field]

[0001] This application claims priority to a Chinese patent application bearing application number 202210460207.1, filed on April 28, 2022, and titled "BACKLIGHT MODULE AND DISPLAY DEVICE," the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to optical elements, and in particular to a backlight module and a display device capable of deflecting a light field distribution. [Background technology]

[0003] For example, a vehicle display device in a center console (Center Informative Display: CID) is required to have an extremely wide viewing angle in the horizontal direction so that passengers on both the left and right sides can see the contents displayed on the screen.

[0004] However, the backlight module applied to the center console (Center Informative Display: CID) is difficult to apply to the display in front of the driver's seat (Driver Information Display: DID) or the display in front of the passenger seat (Co-Driver Display: CDD), because the light from the vehicle display device at a large angle may be reflected through the car window and affect driving. Therefore, the conventional backlight module architecture cannot meet the special viewing angle requirements of the vehicle display device. Summary of the Invention

[0005] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS It is therefore an object of the present invention to provide a backlight module in which the light field distribution can be biased to one side.

[0006] The backlight module includes a surface light source, an optical film provided on the light output side of the surface light source, and a light control film. The light control film has a first reference surface and a plurality of first optical structures provided on the first reference surface. The first reference surface is located on the opposite side of the light control film to the optical film, and each of the first optical structures has a first optical surface and a second optical surface, the first optical surface and the second optical surface are arranged along a first direction, the first optical surface and the first reference surface have a first interior angle θ1, and the second optical surface and the first reference surface have a second interior angle θ2, the first interior angle θ1 is an acute angle, and the first interior angle θ1 is smaller than the second interior angle θ2.

[0007] Another technical means of the present invention is that when the light emitted from the surface light source passes through the optical film, its exit angle is within an angle range of δ relative to the forward direction of the backlight module, its transmittance is at least 50%, and after entering the light control film, it is deflected toward a direction away from the first optical surface.

[0008] Another technical means of the present invention is such that, when a light ray leaves the light control film, it is deflected in a direction away from the first optical surface by an angle μ at the first optical surface of the light control film, and the angle μ satisfies the relational expression μ=0.52×θ1+29.7.

[0009] Another technical means of the present invention is that the light output angle δ of the optical film, the first internal angle θ1 of the light control film, and the critical angle θc of the light control film satisfy the relational expression δ+θ1<θc.

[0010] Another technical aspect of the present invention is that the optical film is an optical grating film having a plurality of barrier sections spaced apart along the first direction and a plurality of light-transmitting sections each disposed between adjacent barrier sections, each of the first optical structures extending along a second direction, the first direction being not parallel to the second direction, and each of the barrier sections and each of the light-transmitting sections extending along the second direction.

[0011] Another technical means of the present invention is that the backlight module further includes a prism sheet disposed between the surface light source and the optical film, and the prism sheet has a plurality of strip-shaped microstructures each extending along the first direction.

[0012] Another technical means of the present invention is that the backlight module further includes a prism sheet disposed between the surface light source and the optical film, each of the first optical structures extending along a second direction, the first direction being not parallel to the second direction, and the prism sheet has a plurality of strip-shaped microstructures each extending along the second direction.

[0013] Another technical aspect of the present invention is that the light control film further has a second reference surface opposite to the first reference surface, and a plurality of second optical structures provided on the second reference surface along the first direction, each of the first optical structures extending along the second direction, the first direction being not parallel to the second direction, each of the second optical structures extending along the second direction, each of the second optical structures having a third optical surface and a fourth optical surface, the third optical surface and the second reference surface having a third interior angle θ3, and the fourth optical surface and the second reference surface having a fourth interior angle θ4, the third interior angle θ3 being an acute angle, and the third interior angle θ3 being smaller than the fourth interior angle θ4.

[0014] Another technical means of the present invention is that the output angle δ of the optical film, the first interior angle θ1 of the light control film, the third interior angle θ3 and the critical angle θc of the light control film satisfy the relationship δ+(θ1+θ3)<θc.

[0015] Another technical means of the present invention is that the first interior angle θ1 of the first optical structure and the third interior angle θ3 of the second optical structure face the same side of the light control film, the first interior angle θ1 and the third interior angle θ3 are both smaller than 45 degrees, and the second interior angle θ2 and the fourth interior angle θ4 are both greater than 45 degrees.

[0016] Another technical means of the present invention is that the first interior angle θ1 is greater than the third interior angle θ3.

[0017] Another technical means of the present invention is that the surface light source includes a light guide plate and a light bar, the light guide plate has a light input side and a light output side connected to the light input side, the light bar is disposed on the front light input side of the light guide plate, and the light output side faces the optical film.

[0018] Another technical aspect of the present invention is that the light bar has a circuit board extending along the first direction and a plurality of light-emitting members arranged along the first direction.

[0019] Another technical means of the present invention is that the surface light source includes a circuit board parallel to the optical film, and a plurality of light emitting members provided on the circuit board.

[0020] Another technical means of the present invention is that the surface light source further includes a diffusion plate, the diffusion plate having a bottom surface and a top surface opposite to the bottom surface, the bottom surface facing the circuit board, and the top surface facing the optical film.

[0021] Another object of the present invention is to provide a display device including the above backlight module and a display panel provided on the backlight module.

[0022] The present invention has the following technical effects: the barrier part, the light-transmitting part and the first optical structure of the light control film are designed to extend in the same direction, and further match the angle design of the first interior angle, so that the first optical structure of the light control film is an angle-asymmetric microstructure, and when light passes through the light control film, the angle-asymmetric microstructure deflects the light to one side and suppresses the light output rate to the other side. Thus, when the backlight module of the present invention is applied to a display in front of the driver's seat (Driver Information Display: DID) or a display in front of the passenger seat (Co-Driver Display: CDD), the light field distribution is less susceptible to the influence of reflection by the glass of the left / right window, and may be biased to one side. [Brief description of the drawings]

[0023] In order to more completely explain the embodiments and their effects, the following description will be given with reference to the drawings.

[0024] [Figure 1] FIG. 1 is an exploded view of the first preferred embodiment of the backlight module of the present invention, in which the light source is an edge-type light source; [Diagram 2] FIG. 2 is a side view illustrating FIG. 1 from a different angle. [Diagram 3] FIG. 2 is a partially enlarged view showing the configuration of the light control film in the first preferred embodiment. [Figure 4] FIG. 13 is a light field distribution diagram showing the light field distribution when the light control film of the present invention is not used. [Diagram 5] FIG. 2 is a light field distribution diagram illustrating the light field distribution when the microstructure of the light control film and the microstructure of the optical film are perpendicular to each other. [Figure 6] A light field distribution diagram illustrating the light field distribution when the microstructure of the light control film and the microstructure of the optical film are parallel to each other, and the microstructure on the prism sheet and the microstructure of the light control film are perpendicular to each other. [Figure 7]FIG. 2 is an exploded perspective view illustrating that the microstructure of the light control film, the microstructure of the optical film, and the microstructure on the prism sheet are parallel to each other. [Figure 8] FIG. 8 is a light field distribution diagram showing a light field distribution formed by the configuration of FIG. 7. [Figure 9] FIG. 2 is a partial enlarged view of a partial structure of a light control film in the second preferred embodiment of the backlight module of the present invention; [Figure 10] FIG. 10 is a light field distribution diagram showing a light field distribution formed by the configuration of FIG. [Figure 11] FIG. 1 is an exploded perspective view of another configuration of the first preferred embodiment, in which the light source is a direct type light source; [Figure 12] FIG. 11 is an exploded perspective view of the third preferred embodiment of a backlight module of the present invention; [Figure 13] FIG. 13 is a partial enlarged view of a partial structure of a light control film in the third preferred embodiment of the backlight module of the present invention; [Figure 14] FIG. 14 is a light field distribution diagram showing a light field distribution by the configuration of FIG. 13. [Figure 15] 11 is a graph quantifying the light field distribution values ​​of each example. [Figure 16] 11 is a graph illustrating the difference in numerical values ​​of the light field distribution when the light control film is used alone and when the light control film and the optical film are used in combination. [Figure 17] 1 is a graph illustrating light transmittance using an optical film. [Figure 18] 11 is a graph illustrating the difference in numerical values ​​of the light field distribution when the light control film is used alone and when the light control film and the optical film are used in combination. [Figure 19] 11 is a graph illustrating the numerical difference in light field distribution when the light control film has a single-sided microstructure and a double-sided microstructure. [Figure 20] 5 is a schematic diagram illustrating a light deflection range when the backlight module of the present invention is applied to an in-vehicle device; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The scope of the claims and technical contents related to the present invention will become apparent from the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, in which the same components are designated by the same reference numerals.

[0026] The light field distribution diagram disclosed in the present invention is based on the luminance height in the 360-degree direction of the light-emitting surface as viewed from the forward direction of the backlight module (perpendicular to the light-emitting plane), so the light field distribution diagram is circular, and the peripheral scale of the circle is an angle. The scale shown on each inner concentric circle represents the tilt angle between the observation direction and the forward direction of the backlight module.

[0027] Next, terms such as "about", "approximately", "approximate" or "substantially" used in the present specification include not only clearly stated numerical values ​​and numerical ranges, but also allowable deviation ranges that can be understood by a person having ordinary knowledge in the technical field to which the invention belongs, and among them, this deviation range can be determined by an error that occurs during measurement, and this error is due to, for example, limitations of both the measurement system and the process conditions. In addition, "about" can represent within one or more standard deviations of the above numerical values, for example, within ±5%, ±3%, or ±1%. Terms such as "about", "approximately", "approximately", or "substantially" used in the present specification can select an allowable deviation range or standard deviation depending on optical properties, etching properties, mechanical properties, or other properties, and do not apply all properties such as the above optical properties, etching properties, mechanical properties, and other properties to only one standard deviation.

[0028] 1 and 2 show a first preferred embodiment of the backlight module of the present invention, which includes a surface light source 2, a prism sheet 3, an optical film 4 and a light control film 5. A display panel (not shown) is installed in the light output direction of the light control film 5, that is, a display device.

[0029] The optical film 4 is defined as having a first direction X and a second direction Y not parallel to the first direction X, and in this embodiment, the second direction Y is perpendicular to the first direction X, but the present invention is not limited thereto. In this embodiment, the optical film 4 is an optical grating film, and has a plurality of barrier portions 41 spaced apart along the first direction X and a plurality of light-transmitting portions 42 each disposed between adjacent barrier portions 41, and each barrier portion 41 and each light-transmitting portion 42 extends along the second direction Y. In other embodiments, the optical film 4 may be a light-transmitting film having a prism structure or a spectroscopic structure instead of an optical grating film, and is therefore not limited to the description of this embodiment.

[0030] 2 and 3, the light control film 5 has a first reference surface 51 facing away from the optical film 4, and a plurality of first optical structures 52 arranged on the first reference surface 51 along a first direction X. Each first optical structure 52 extends along a second direction Y, that is, the barrier portion 41 and the light-transmitting portion 42 of the optical film 4 are arranged parallel to the first optical structure 52 of the light control film 5. Each first optical structure 52 has a first optical surface 521 and a second optical surface 522. In this embodiment, the first optical surface 521, the second optical surface 522 and the first reference surface 51 together form a triangle, so that each first optical structure 52 has a triangular cross section, but in other embodiments, each first optical structure 52 does not have a triangular cross section, and one or two of the first optical surface 521 and the second optical surface 522 can be designed as a compound slope, so that the description of this embodiment is not limited. 3, the first optical surface 521 and the second optical surface 522 are arranged along a first direction X, the first optical surface 521 and the first reference surface 51 have a first interior angle θ1, and the second optical surface 522 and the first reference surface 51 have a second interior angle θ2, the first interior angle θ1 is an acute angle, and the first interior angle θ1 is smaller than the second interior angle θ2. In a first preferred embodiment of the present invention, the first interior angle θ1 is 20°, and the second interior angle θ2 is 80°, so that each first optical structure 52 is a triangular cross section in which the angles between the first interior angle θ1 and the second interior angle θ2 are asymmetric.

[0031] The backlight module disclosed in this embodiment first uses the optical film 4 to change the light field distribution of the surface light source 2 to a single direction, and then uses the first optical structure 52 of the light control film 5, which has the same stretching direction as the barrier part 41 of the optical film 4, to adjust the light field distribution in a single direction. The first optical structure 52 of the light control film 5 has an asymmetric microstructure in which the first interior angle θ1 is smaller than the second interior angle θ2, so that when the light passes through the light control film 5, the microstructure with the asymmetric angle effectively deflects and guides the light to a specific side and emits it, while effectively suppressing the light output efficiency of the other side. In this way, when the backlight module is applied to a display in front of the driver's seat (Driver Information Display, DID) or a display in front of the passenger seat (Co-Driver Display, CDD), the light field distribution is less susceptible to the influence of reflection by the glass of the left / right window and may be biased to one side.

[0032] As shown in FIG. 4, this is a light field distribution diagram without using the light control film 5 of the present invention, and it can be seen that the dark color area is located in the middle, and no polarization effect is generated. In addition, as shown in FIG. 5, even if the light control film 5 of the present invention is used, the stretching direction of the first optical structure 52 of the light control film 5 and the stretching direction of the barrier part 41 and the light-transmitting part 42 of the optical film 4 are perpendicular to each other, so the polarization effect still cannot be generated, and large noise occurs on both sides. Therefore, as shown in FIG. 1, in the present invention, when the light control film 5 and the optical film 4 need to be used at the same time, and the stretching direction of the first optical structure 52 of the light control film 5 and the stretching direction of the barrier part 41 and the light-transmitting part 42 of the optical film 4 must be parallel to each other, the dark color area is shifted from the center, as shown in FIG. 6, and the desired polarization effect is generated.

[0033] In addition, the prism sheet 3 is interposed between the surface light source 2 and the optical film 4, and helps the convergence of the light field distribution of the surface light source 2, so that the light can enter the optical film 4 above the prism sheet 3 more intensively, and the loss of energy or brightness of the light can be avoided. In addition, the prism sheet 3 has a plurality of strip-shaped microstructures 31, and the strip-shaped microstructures 31 are stretched along the first direction X as shown in FIG. 1, and the light field distribution thereof can generate a good polarization effect as shown in FIG. 6. The strip-shaped microstructures 31 may be stretched along the second direction Y as shown in FIG. 7, and the light field distribution thereof can also generate a good polarization effect as shown in FIG. 8. As can be seen by comparing FIG. 6 and FIG. 8, the stretching direction of the strip-shaped microstructures 31 of the prism sheet 3 does not affect the polarization effect.

[0034] FIG. 9 shows a second preferred embodiment of the backlight module of the present invention, which is different from the first preferred embodiment in that the first interior angle of the light control film 5 is less than 45 degrees and the second interior angle is a right angle. In FIG. 9, the first interior angle θ1 is 10° and the second interior angle θ2 is 90°, so that each first optical structure 52 has a right-angled triangular cross section. However, the second interior angle θ2 may be an acute angle, which improves the problem that the film mold is difficult to release when designed with a right angle. As can be seen from the light field distribution diagram of FIG. 10, the polarization effect can be generated as well, and the light-colored stripe area on the left side is obviously reduced compared with FIG. 6, which means that the loss of energy or brightness can be effectively reduced and a better light output offset effect can be generated.

[0035] 1 and 2, in a first preferred embodiment, the surface light source 2 is an edge type, and includes a light guide plate 21, a diffusion film 22, and a light bar 23. The light guide plate 21 has a light input side 211 and a light output side 212 connected to the light input side 211, the diffusion film 22 is provided on the light output side 212 of the light guide plate 21, and the light bar 23 is provided on the light input side 211 of the light guide plate 21, and the light output side 212 faces the optical film 4. The light bar 23 has a circuit board 231 (not shown in FIG. 2) and a plurality of light emitting members 232, the circuit board 231 extends along a first direction X, and the plurality of light emitting members 232 are arranged along the first direction X. Therefore, the extension direction of the circuit board 231 and the arrangement direction of the plurality of light emitting members 232 are different from the extension directions of the barrier portion 41 of the optical film 4 and the first optical structure 52 of the light control film 5, and are perpendicular to each other in this embodiment. In this way, the light is effectively biased and guided to a specific side and emitted, while effectively suppressing the light emission efficiency on the other side; if the extension direction of the circuit board 231 and the arrangement direction of the multiple light-emitting members 232 are the same as the extension directions of the barrier portion 41 of the optical film 4 and the first optical structure 52 of the light control film 5, the light emission phenomenon on the other side still occurs and cannot be suppressed.

[0036] 11, in practice, the surface light source 2 is a direct type, and includes a circuit board 231 parallel to the optical film 4, and a plurality of light emitting members 232 and a diffusion plate 24 provided on the circuit board 231. The diffusion plate 24 has a bottom surface 241 and a top surface 242 opposite to the bottom surface 241, with the bottom surface 241 facing the circuit board 231 and the top surface 242 facing the optical film 4. In the present invention, the surface light source 2 can be either an edge type or a direct type.

[0037] 12 shows a third preferred embodiment of the backlight module of the present invention, which includes a surface light source 2, a prism sheet 3, an optical film 4 and a light control film 5. The difference from the first preferred embodiment is that the light control film 5 further includes a second optical structure 54 arranged along the first direction X toward the optical film 4. Each of the first optical structures 52 and each of the second optical structures 54 extend along the second direction Y.

[0038] 13, in more detail, the light control film 5 further has a second reference surface 53 facing the first reference surface 51 and toward the optical film 4, and a plurality of second optical structures 54 provided on the second reference surface 53 along the first direction X. Each first optical structure 52 has a first optical surface 521 and a second optical surface 522, the first optical surface 521 and the first reference surface 51 have a first interior angle θ1, and the second optical surface 522 and the first reference surface 51 have a second interior angle θ2, the first interior angle θ1 is an acute angle, and the first interior angle θ1 is smaller than the second interior angle θ2. Each second optical structure 54 has a third optical surface 541 and a fourth optical surface 542, the third optical surface 541 and the second reference surface 53 have a third interior angle θ3, and the fourth optical surface 542 and the second reference surface 53 have a fourth interior angle θ4, the third interior angle θ3 is an acute angle, and the third interior angle θ3 is smaller than the fourth interior angle θ4. The first interior angle θ1 of the first optical structure 52 and the third interior angle θ3 of the second optical structure 54 face the same side of the light control film 5. The first interior angle θ1 and the third interior angle θ3 are both smaller than 45 degrees, the second interior angle θ2 and the fourth interior angle θ4 are both larger than 45 degrees, the first interior angle θ1 is larger than the third interior angle θ3, the fourth interior angle θ4 is larger than the second interior angle θ2, and the fourth interior angle θ4 is a right angle. In this embodiment, the first interior angle θ1 is 20°, the second interior angle θ2 is 80°, the third interior angle θ3 is 10°, and the fourth interior angle θ4 is 90°. As can be seen from the light field distribution diagram of FIG. 14, the same polarization effect can be generated, and compared with FIG. 6, the dark color range is further shifted from the positive center, generating a greater light output shift effect. In short, in order to fine-tune the light field deflection effect, this embodiment can carry out angle fine-tuning changes to meet different usage situations or customer requirements for the light field deflection effect of the first optical structure 52 on only one side by designing the second optical structure 54 on the second reference surface 53 of the light control film 5. In addition, the first optical structure 52 and the second optical structure 54 are protruding structures, but in actual implementation, a recessed structure may be adopted, and the light field deflection effect is basically the same or similar, so it is not limited to the description of this embodiment.

[0039] Referring to the graph in FIG. 15, each light field distribution value is quantified. Here, the circle dotted line represents the comparative example using only the optical film 4, the dashed line represents the first preferred embodiment, the line with alternating long and short dashed lines represents the second preferred embodiment, and the solid line represents the third preferred embodiment. As can be seen from FIG. 15, compared with the comparative example, the third preferred embodiment can most effectively suppress the amount of emitted light at a viewing angle of -30° to -15°, and by shifting the amount of emitted light to a viewing angle of 15° to 30°, the light output rate on one side can be effectively suppressed, resulting in a polarization effect. In addition, the angle of each internal angle of the light control film 5 can be adjusted to adjust the light deflection range according to different application environments and obtain the optimal polarization effect.

[0040] Returning to the first preferred embodiment of the backlight module of the present invention, mainly due to the design of the light control film 5, the light entering the light control film 5 is deflected toward the direction away from the first optical surface 521 when it leaves the light control film 5, so that the light is deflected to one side and the light output rate of the other side is suppressed, and the backlight module can be applied to the usage environment requiring anisotropic light field. However, when there is no optical film 4 and only the light control film 5, as shown in Figure 16, the horizontal viewing angle distribution still generates obvious stray light in the viewing angle range of ±60 to ±90 degrees, which is mainly because when the incident light with a large angle enters the light control film 5, total reflection is likely to occur, and thus a large angle stray light is generated when it leaves the light control film 5. In order to eliminate the large angle stray light caused by total reflection, the first preferred embodiment of the backlight module of the present invention needs to design an optical film 4 between the light control film 5 and the surface light source 2 to cut off the light rays that are easily totally reflected in the light control film 5 (i.e., the light rays whose incident angle is larger than the critical angle θc of the light control film 5) before entering the light control film 5. In FIG. 16, the circle dotted line represents a comparative example using only the light control film 5, and the dashed line represents the first preferred embodiment. Therefore, as shown in FIG. 16, only when the light control film 5 and the optical film 4 are combined, the light rays can be deflected to one side and the light output rate of the other side can be suppressed, and the occurrence of the large angle stray light can be avoided, and the light energy or brightness in the viewing angle range of ±60 to ±90 degrees can be significantly reduced.

[0041] More specifically, the light output angle δ of the optical film 4, the first internal angle θ1 of the light control film 5, and the critical angle θc of the light control film 5 must satisfy the relational expression δ+θ1<θc.

[0042] 17, when the light emitted by the surface light source 2 passes through the optical film 4, its exit angle is within the angle range of δ relative to the forward direction of the backlight module, and its transmittance is at least 50%, that is, the viewing angle in the figure is about -17° to -18°, +24° to +25°, and in order to bias the negative viewing angle light, this embodiment designs the value of δ to be 17. The material of the light control film 5 is polycarbonate (PC), and its critical angle θc is 39, so the angle value of the first interior angle θ1 of the light control film 5 is designed to be less than 22, and satisfies the above-mentioned relationship δ+θ1<θc. In the first preferred embodiment of the present invention, the first interior angle θ1 is 20°, which is smaller than 22. In this embodiment, the light control film 5 is made of a PC material, but other materials such as Optically Clear Adhesives (OCA), Polyethylene terephthalate (PET), Poly(methyl methacrylate) PMMA, etc. may also be used, and the critical angle θc is different for each material, so it is not limited to the description of this embodiment.

[0043] Referring to FIG. 18, in this embodiment, when the light ray leaves the light control film 5, it is deflected in the direction away from the first optical surface 521 of the light control film 5 by an angle μ, and the angle μ satisfies the relational expression μ=0.52×θ1+29.7×. When the first interior angle θ1 is 20°, the deflection angle μ is about 40° (0.52×20°+29.7=40.1°). That is, in the figure, when the light control film 5 and the optical film 4 are not combined, 50% of the energy or brightness of the light ray is at a viewing angle of about -52°, whereas when the light control film 5 and the optical film 4 are combined, 50% of the energy or brightness of the light ray is at a viewing angle of about -10°, and the difference between the two is 42°, which is quite close to the calculation result of the above relational expression. In another embodiment, when the first interior angle θ1 is 10°, the deflection angle μ is about 35° (0.52×10°+29.7=34.9°), and when the first interior angle θ1 is 40°, the deflection angle μ is about 50° (0.52×40°+29.7=50.5°), so the above relational expression can effectively represent the relationship between the deflection angle μ and the first interior angle θ1. In Fig. 18, the dotted circle line represents a comparative example using only the light control film 5, and the dashed line represents the first preferred embodiment.

[0044] When the light control film 5 adopts a double-sided microstructure similar to the third preferred embodiment of the backlight module of the present invention, the output angle δ of the optical film 4, the first interior angle θ1, the third interior angle θ3 and the critical angle θc of the light control film 5 must satisfy the relationship δ+(θ1+θ3)<θc. 19, when the first interior angle θ1 of the single-sided microstructure is 20°, 50% of the energy or brightness of the light is at a viewing angle of about -10° (shown by the dashed line in the figure), and when the first interior angle θ1 of the double-sided microstructure is 10° and the third interior angle θ3 is 10°, 50% of the energy or brightness of the light is also at a viewing angle of about -10° (shown by the dashed line in the figure). Compared with this, both the single-sided microstructure of the first preferred embodiment and the double-sided microstructure of the third preferred embodiment can similarly deflect the light to one side, suppress the light output rate of the other side, and avoid the generation of stray light at a large angle. However, the double-sided microstructure of the third preferred embodiment can further reduce the steep rise of the energy or brightness at viewing angles of -30° to -60° and +70° to +90°.

[0045] With the above design, when the backlight module of the present invention is applied to an in-vehicle device, as shown in (a) of FIG. 20, the image of the in-vehicle instrument panel 91 located on the driver's side can be projected to the positions of the driver's seat and the passenger seat without being reflected by the window on the driver's seat; or, as shown in (b) of FIG. 20, the image of the display 92 located on the passenger seat side can be projected to the positions of the driver's seat and the passenger seat without being reflected by the window on the passenger seat, thereby reducing interference caused by image reflection.

[0046] As described above, the backlight module of the present invention can deflect light rays to one side and suppress the light output rate on the other side by combining an optical film and a light control film, and can be applied to usage environments requiring an anisotropic light field.

[0047] The above is merely a preferred embodiment of the present invention, and does not limit the scope of the present invention; that is, simple equivalent changes and modifications made based on the claims and the contents of the specification of the present invention are all within the patentable scope of the present invention. Symbol Description

[0048] 2 surface light source 21 Light guide plate 211 Light receiving side 212 Idemitsu side 22 Diffusion film 23 Light Bar 231 Circuit Board 232 Illuminating materials 24 Diffuser 241 Bottom 242 Top surface 3 Prism sheet 31 Strip-like microstructure 4 Optical film pieces 41 Barrier section 42 Translucent part 5. Light Control Film 51 First Reference Plane 52 First Optical Structure 521 First Optical Surface 522 Second Optical Surface 53 Second Reference Plane 54 Second Optical Structure 541 Third Optical Surface 542 The Fourth Optical Surface 91 Automotive Instrument Panel 92 Display X First Direction Y Second Direction θ1 First interior angle θ2 Second interior angle θ3 Third interior angle θ4 Fourth interior angle

Claims

1. A surface light source; an optical film provided on a light output side of the surface light source; a light control film having a first reference surface and a plurality of first optical structures provided on the first reference surface; The first reference surface is located on the opposite side of the light control film to the optical film, each of the first optical structures has a first optical surface and a second optical surface, the first optical surface and the second optical surface are arranged along a first direction, the first optical surface and the first reference surface have a first interior angle θ1, and the second optical surface and the first reference surface have a second interior angle θ2, the first interior angle is an acute angle θ1, and the first interior angle θ1 is smaller than the second interior angle θ2. Backlight module.

2. When the light emitted from the surface light source passes through the optical film, the exit angle of the light is within an angle range of δ relative to the forward direction of the backlight module, and the transmittance of the light is at least 50%. After entering the light control film, the light is deflected in a direction away from the first optical surface. The backlight module according to claim 1 .

3. When a light ray leaves the light control film, it is deflected at the first optical surface of the light control film by an angular amount μ in a direction away from the first optical surface, and the angular amount μ satisfies the relationship μ = 0.52 × θ1 + 29.7; The backlight module according to claim 2 .

4. The output angle δ of the optical film, the first internal angle θ1 of the light control film, and the critical angle θc of the light control film satisfy the relational expression δ+θ1<θc; The backlight module according to claim 2 .

5. The optical film is an optical grating film and has a plurality of barrier sections spaced apart along the first direction and a plurality of light-transmitting sections each spaced apart between adjacent barrier sections, each of the first optical structures extending along a second direction, the first direction being non-parallel to the second direction, and each of the barrier sections and each of the light-transmitting sections extending along the second direction. The backlight module according to claim 1 .

6. The optical film further includes a prism sheet disposed between the surface light source and the optical film, the prism sheet having a plurality of strip-shaped microstructures each extending along the first direction. The backlight module according to claim 1 .

7. The optical film further includes a prism sheet disposed between the surface light source and the optical film, wherein each of the first optical structures extends along a second direction, the first direction is not parallel to the second direction, and the prism sheet has a plurality of strip-shaped microstructures each extending along the second direction. The backlight module according to claim 1 .

8. The light control film further has a second reference surface opposite to the first reference surface, and a plurality of second optical structures provided on the second reference surface along the first direction, each of the first optical structures extending along the second direction, the first direction being not parallel to the second direction, each of the second optical structures extending along the second direction, each of the second optical structures having a third optical surface and a fourth optical surface, the third optical surface and the second reference surface having a third interior angle θ3, and the fourth optical surface and the second reference surface having a fourth interior angle θ4, the third interior angle θ3 being an acute angle, and the third interior angle θ3 being smaller than the fourth interior angle θ4; The backlight module according to claim 1 .

9. The output angle δ of the optical film, the first interior angle θ1 of the light control film, the third interior angle θ3 of the light control film, and the critical angle θc of the light control film satisfy the relational expression δ+(θ1+θ3)<θc; The backlight module according to claim 8.

10. A first interior angle θ1 of the first optical structure and a third interior angle θ3 of the second optical structure face the same side of the light control film, the first interior angle θ1 and the third interior angle θ3 are both smaller than 45 degrees, and the second interior angle θ2 and the fourth interior angle θ4 are both greater than 45 degrees; The backlight module according to claim 8.

11. The first interior angle θ1 is greater than the third interior angle θ3. The backlight module according to claim 8.

12. The surface light source includes a light guide plate and a light bar, the light guide plate has a light input side and a light output side connected to the light input side, the light bar is disposed on the front light input side of the light guide plate, and the light output side faces the optical film; The backlight module according to any one of claims 1 to 11.

13. The light bar includes a circuit board and a plurality of light emitting members, the circuit board extends along the first direction, and the plurality of light emitting members are arranged along the first direction. The backlight module according to claim 12.

14. The surface light source includes a circuit board parallel to the optical film and a plurality of light emitting members provided on the circuit board. The backlight module according to any one of claims 1 to 11.

15. The surface light source further includes a diffusion plate, the diffusion plate having a bottom surface and a top surface opposite to the bottom surface, the bottom surface facing the circuit board, and the top surface facing the optical film. The backlight module according to claim 14.

16. A display device comprising: a backlight module according to any one of claims 1 to 15; and a display panel provided on the backlight module. Display device.

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