Viewing angle control film and display device including the same

Abstract

A viewing angle control film and a display device including the viewing angle control film are disclosed. The viewing angle control film includes a first electrode; a second electrode facing the first electrode and spaced apart from the first electrode; a light conversion layer disposed between the first electrode and the second electrode; and a controller configured to adjust the viewing angle of the light conversion layer by controlling a voltage applied between the first electrode and the second electrode, wherein the light conversion layer includes: a plurality of partition walls disposed to be spaced apart between the first electrode and the second electrode; a plurality of accommodation portions formed between the partition walls and arranged at uniform intervals along the first electrode; and light shielding particles disposed in each of the plurality of accommodation portions, wherein the controller applies a pulsed voltage in a shared mode of operating with a wide viewing angle.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2021 - 0187966, filed on December 27, 2021, the entire contents of which are incorporated herein by reference for all purposes. Technical field

[0003] The present disclosure relates to a viewing - angle control film and a display device including the viewing - angle control film, such as a liquid - crystal display device.

[0004] Related art

[0005] With the development of the information society, there is an increasing demand for display devices for displaying images in various application fields. For display devices, recently, various display devices such as liquid - crystal display devices, light - emitting display devices, organic light - emitting display devices, micro - light - emitting display devices, and quantum - dot light - emitting display devices have been utilized.

[0006] Such display devices are developed to have a wide viewing angle so that a user can view the image of the display device from various angular directions. However, there are cases where the wide viewing angle of the display device may have an adverse effect on the characteristics of the product, and thus a narrow viewing angle may be required for such cases.

[0007] For example, for an automated teller machine (ATM), it is more desirable for the ATM to include a display with a narrow viewing angle because when a user inputs his personal information, it is necessary to prevent others next to the user from identifying the personal information. In addition, when the viewing angle of a display for a vehicle navigation system is wide, during night - time driving of a vehicle, light may be reflected on the windshield of the vehicle, which may have an adverse effect on the safety of the driver. Further, for a computer or a mobile phone, if a user does not want to expose privacy data, then the wide viewing angle of the display device goes against the user's needs.

[0008] Therefore, research on a viewing - angle control film capable of adjusting the viewing angle to suit the required situation has been actively conducted.

[0009] The viewing - angle control film can control the viewing angle of a user by controlling the moving light path to block light from a specific direction and transmit light from a specific direction.

[0010] In such a viewing - angle control film, a user can turn the viewing - angle control on / off, and can block light in a specific direction or transmit light in a specific direction by dispersing and aggregating light - blocking particles according to an electrical signal.

[0011] When the viewing angle control film is driven for a long period of time in the shared mode where the incident light is emitted beyond a predetermined angular range, aggregation of light-shielding particles occurs. When the aggregation of light-shielding particles occurs, due to the reduced responsiveness to the electric signal, the brightness of the light in the side view in the shared mode decreases or dark spots appear, and there is a problem of stain defects when switching to the private mode. Summary of the Invention

[0012] The present disclosure is to solve the above problems, and thus provides the following solutions: The solutions can prevent the decrease in brightness or dark spot defects in the side view even when driven for a long period of time in the shared mode. In addition, for example, the solutions can prevent the occurrence of stain defects when switching to the private mode.

[0013] As a means for solving the above problems, the present disclosure provides an embodiment having the following features.

[0014] The viewing angle control film according to the embodiment includes: a first electrode; a second electrode facing the first electrode and spaced apart from the first electrode; a light conversion layer disposed between the first electrode and the second electrode; and a controller configured to adjust the viewing angle of the light conversion layer by controlling the voltage applied between the first electrode and the second electrode, wherein the light conversion layer includes a plurality of partition walls disposed at intervals between the first electrode and the second electrode; and a plurality of accommodation portions formed between the partition walls and arranged at uniform intervals along the first electrode; light-shielding particles are provided in each of the plurality of accommodation portions, and the controller can apply a pulsed voltage in the shared mode operating at a wide viewing angle.

[0015] The controller applies a pulsed voltage that swings between a second voltage and 0V voltage in the shared mode.

[0016] The controller applies a pulsed voltage that swings between a second voltage having a positive polarity and a third voltage having a negative polarity in the shared mode.

[0017] The magnitude of the absolute value of the second voltage can be greater than the magnitude of the absolute value of the third voltage.

[0018] When switching from the private mode operating at a narrow viewing angle to the shared mode, the controller applies a first voltage greater than the second voltage for a predetermined period of time.

[0019] The controller alternately provides a first pulsed voltage that swings between a second voltage and a third voltage; and a second pulsed voltage that swings between a fourth voltage and a fifth voltage.

[0020] The fourth voltage can be greater than the second voltage.

[0021] The controller provides a first pulse voltage during a first period and a second pulse voltage during a second period that is longer than the first period.

[0022] The second voltage and the fourth voltage may be voltages of positive polarity, and the third voltage and the fifth voltage may be voltages of negative polarity.

[0023] The magnitude of the absolute value of the third voltage may be greater than the magnitude of the absolute value of the fifth voltage.

[0024] The magnitude of the absolute value of the second voltage may be greater than the magnitude of the absolute value of the third voltage, and the magnitude of the absolute value of the fourth voltage may be greater than the magnitude of the absolute value of the fifth voltage.

[0025] When switching from a private mode of operation with a narrow viewing angle to a shared mode, the controller may apply a first voltage greater than the fourth voltage for a predetermined period of time.

[0026] A display device according to an embodiment includes a display panel that includes pixels disposed in the display panel and is configured to display an image; and a viewing angle control film, wherein the viewing angle control film is disposed on the display panel and operates in a private mode or a shared model. In the private mode, light emitted from the display panel is controlled to be emitted only within a predetermined angular range; in the shared mode, light emitted from the display panel is controlled to be emitted beyond the predetermined angular range.

[0027] A viewing angle control film and a display device including the viewing angle control film according to an embodiment of the present disclosure may reduce or prevent a decrease in the brightness of light in a side view or the occurrence of dark spot defects even when driven for a long period of time in the shared mode, and at the same time prevent the occurrence of stain defects when switching to the private mode. Description of the Drawings

[0028] Figure 1 is a perspective view showing the viewing angle control film.

[0029] Figure 2 is a waveform diagram showing the drive voltage of the viewing angle control film.

[0030] Figure 3 is Figure 1 a part of the figure for describing the light path in the private mode.

[0031] Figure 4 is Figure 1 a part of the figure for describing the light path in the shared mode.

[0032] Figure 5 is a diagram showing the state of the light-shielding particles in the accommodating portion.

[0033] Figure 6It is a waveform diagram showing the drive voltage of the viewing angle control film according to the first embodiment of the present disclosure.

[0034] Figure 7 It is a waveform diagram showing the drive voltage of the viewing angle control film according to the second embodiment of the present disclosure.

[0035] Figure 8 It is a diagram showing the state in which the light-shielding particles are dispersed in the accommodation portion in the third mode.

[0036] Figure 9 It is a diagram showing the state in which the light-shielding particles are clumped in the accommodation portion in the third mode.

[0037] Figure 10 It is a waveform diagram showing the drive voltage of the viewing angle control film according to the third embodiment of the present disclosure.

[0038] Figure 11 It is a diagram showing the state of the light-shielding particles in the accommodation portion according to the third embodiment.

[0039] Figure 12 It is a graph comparing the brightness changes of the side viewing angles according to the first embodiment, the second embodiment, and the third embodiment.

[0040] Figure 13 It is a cross-sectional view of the display device according to the embodiment. Detailed Embodiments

[0041] The shapes, sizes, ratios, angles, numbers, etc. shown in the drawings for describing various embodiments of the present disclosure are merely examples, and the present disclosure is not limited thereto. Throughout the specification, the same or similar reference numerals generally denote the same or similar elements. In addition, in the following description of the present disclosure, detailed descriptions of known related arts may be omitted to avoid unnecessarily obscuring the subject matter of the present disclosure. Terms such as "comprising", "having", "including", etc. used herein generally intend to allow the addition of other elements, unless these terms are used together with the term "only". Any reference to the singular may include the plural unless otherwise explicitly stated.

[0042] Even if not explicitly stated, elements are construed to include a normal error range.

[0043] When using terms such as "on", "above", "under", and "near" to describe the positional relationship between two parts, one or more parts may be positioned between these two parts, unless the terms are used with the terms "immediately" or "directly".

[0044] Although terms such as "first", "second", etc. are used to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another. Thus, the first element mentioned below may be the second element in the technical concept of the present disclosure.

[0045] Throughout the specification, the same or similar reference numerals generally denote the same or similar elements.

[0046] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The names of the elements used in the following description may be selected in consideration of the ease of preparing the specification, and thus the names of the elements may be different from the names of the elements used in actual products.

[0047] Figure 1 is a perspective view showing the viewing angle control film. Figure 2 is a waveform diagram showing the drive voltage of the viewing angle control film. Figure 3 is Figure 1 a part of the diagram for describing the light path in the private mode. Figure 4 is Figure 1 a part of the diagram for describing the light path in the shared mode.

[0048] The viewing angle control film 10 includes a first film 100, a second film 200, a light conversion layer 500, and adhesive layers 310 and 320.

[0049] The viewing angle control film 10 can be coupled to a display panel to form a display device, and the display device controls the light emitted from the display panel (not shown) according to the operation mode. For example, the viewing angle control film 10 can be coupled to the light-emitting side of the display panel such that the light emitted from the display panel is emitted only within a predetermined angle range and the light outside the predetermined angle range is blocked, thereby controlling the light emitted from the display panel. In addition, the viewing angle control film 10 can allow the light emitted from the display panel to be emitted beyond the predetermined angle range.

[0050] Hereinafter, making the light emitted from the display panel be emitted only within a predetermined angle range is referred to as the private mode (or narrow viewing angle mode), and making the light emitted from the display be emitted beyond the predetermined angle range is referred to as the shared mode (or wide viewing angle mode). The viewing angle control film 10 can be driven to switch to the private mode or the shared mode.

[0051] The viewing angle control film 10 includes a first film 100, a first adhesive layer 310 provided on the first film 100, a light conversion layer 500 provided on the first adhesive layer 310, a second adhesive layer 320 provided on the light conversion layer 500, a second film 200 provided on the second adhesive layer 320, and a controller 700 configured to adjust the amplitude of the electric field applied to the light conversion layer 500.

[0052] The first film 100 may be disposed at the lowermost side of the viewing angle control film 10. When the viewing angle control film 10 is coupled to a display panel (not shown), the first film 100 may be the part coupled to the display panel. The first film 100 may be coupled to the display panel by a transparent adhesive or the like.

[0053] The first film 100 includes a first base film 110 and a first electrode 120. The first electrode 120 may be disposed on the upper surface of the first base film 110. The first electrode 120 may include a transparent conductive material. For example, the first electrode 120 may include at least one metal among chromium (Cr), nickel (Ni), copper (Cu), aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), titanium (Ti), and their alloys. The first electrode 120 is used to form an electric field in the viewing angle control film 10. The first electrode 120 is connected to the power supply unit S, and thus may contribute to forming an electric field according to the voltage provided by the power supply unit S.

[0054] The second film 200 may be disposed to face the first film 100 and be spaced apart from the first film 100 by a predetermined distance. The first adhesive layer 310, the second adhesive layer 320, and the light conversion layer 500 may be disposed between the first film 100 and the second film 200.

[0055] The second film 200 may be disposed at the uppermost side of the viewing angle control film 10. When the viewing angle control film 10 is coupled to the display panel, the second film 200 may be the part through which the light emitted from the display panel finally passes.

[0056] The second film 200 may have the same shape and thickness as the first film 100. The second film 200 includes a second base film 210 and a second electrode 220. The second electrode 220 may be disposed on the lower surface of the second base film 210. Like the first electrode 120, the second electrode 220 may include a transparent conductive material. The second electrode 220 may form an electric field together with the first electrode 120 by being connected to the power supply unit S. When an electric field is formed between the first electrode 120 and the second electrode 220 according to the voltage applied by the power supply unit S, the shared mode may be achieved as shown in Figure 4 Moreover, since no electric field is formed between the first electrode 120 and the second electrode 220 when the power supply unit S does not apply a voltage, the private mode may be achieved as shown in Figure 3 shown.

[0057] The light conversion layer 500 may be disposed between the first film 100 and the second film 200. Specifically, the light conversion layer 500 may be disposed between the first electrode 120 and the second electrode 220. The light conversion layer 500 includes a plurality of accommodation parts 550 and a louver layer 510 surrounding the plurality of accommodation parts 550.

[0058] The accommodating portion 550 is partitioned into a plurality of zones by the shutter layer 510. The accommodating portion 550 includes a dispersion liquid and light-shielding particles CB.

[0059] The dispersion liquid may be a material for dispersing the light-shielding particles CB. The dispersion liquid may include a transparent material. The dispersion liquid may include a non-polar solvent. The dispersion liquid may include a material capable of transmitting light. For example, the dispersion liquid may include at least one of a halogenated hydrocarbon oil, a paraffin-based oil, and isopropyl alcohol. The light-shielding particles CB may be light-absorbing particles.

[0060] The light-shielding particles CB may have a color. The light-shielding particles may have a black-based color. For example, the light-shielding particles CB may include an opaque material such as a metal material, a metal oxide material, or a nitride material. More specifically, the light-shielding particles CB may include any one selected from the following: carbon, silicon nitride (SiN), titanium nitride (TiN), silicon carbide (SiC), tantalum (Ta), titanium (Ti), tungsten (W), copper oxide (CuO), aluminum oxide (Al 2 O 3 )), iron oxide (Fe 3 O 4 )) and tantalum oxide (Ta 2 O 5 )). In addition, the light-shielding particles CB may be formed of an organic material having excellent light absorption properties. The light-shielding particles CB may be charged at their surfaces. The light-shielding particles CB may move in one direction according to the applied electric field. The light-shielding particles CB may be provided as a material including a plurality of carbon particles in oil, and the carbon particles may block light by absorbing light. In this case, a private mode can be achieved.

[0061] Hereinafter, the description will be made on the assumption that the light-shielding particles CB include carbon particles and are negatively charged on their surfaces. In addition, for ease of description, the movement and arrangement of the light-shielding particles CB will be described based on the electric force EF rather than the term "electric field". Since the light-shielding particles CB are negatively charged, the electric force EF received by the light-shielding particles is opposite to the direction of the electric field, which will make it inconvenient to understand the present disclosure. The shutter layer 510 includes a plurality of partition walls 511, and the plurality of partition walls 511 are formed to be spaced apart from each other at uniform intervals. In the light conversion layer 500, the partition walls 511 and the accommodating portion 550 may be alternately arranged along one direction. The partition walls 511 and the accommodating portion 550 may have the same or different widths with respect to one direction. In one example, the shutter layer 510 may further include a base layer 515 connecting the partition walls 511 to each other. The base layer 515 is a feature of the imprint manufacturing method and is not a necessary component for forming the viewing angle control film 10.

[0062] The adhesive layer may be disposed between the light conversion layer 500 and the first film 100 or between the light conversion layer 500 and the second film 200. For example, the first adhesive layer 310 may be inserted between the light conversion layer 500 and the first electrode 120. In addition, the second adhesive layer 320 may be inserted between the light conversion layer 500 and the second electrode 220.

[0063] The adhesive layers 310 and 320 may be an optically clear adhesive OCA or an optically clear resin OCR, but are not limited thereto, and may be formed of different materials capable of attaching the light conversion layer 500 and the first film 100 to each other or attaching the light conversion layer 500 and the second film 200 to each other. The adhesive layers 310 and 320 may be formed of a transparent material.

[0064] The power supply unit S is connected to the first electrode and the second electrode, and thus provides a driving voltage for the viewing angle control film 10. The power supply unit S supplies a first voltage to the first electrode and a second voltage to the second electrode.

[0065] The controller 700 may control the voltage applied to the viewing angle control film 10 such that the viewing angle is adjusted based on the operation mode of the viewing angle control film 10. The controller 700 may determine the operation mode of the viewing angle control film 10 as a first mode, a second mode, and a third mode. The controller 700 controls the output voltage of the power supply unit S according to the operation mode of the viewing angle control film 10. The controller 700 may adjust the voltage applied between the first electrode and the second electrode according to the operation mode of the viewing angle control film 10.

[0066] Note that although the viewing angle control film 10 is described above as including the controller 700, in some embodiments the viewing angle control film 10 may not include the controller 700. For example, the viewing angle control film 10 may be controlled by a controller externally connected to the viewing angle control film 10.

[0067] Reference will be made to Figure 2 and Figure 3 to describe the operation of the viewing angle control film 10 in the private mode, and reference will be made to Figure 2 and Figure 4 to describe the operation of the viewing angle control film 10 in the shared mode.

[0068] The first mode is the private mode, the second mode is the switching-to-shared mode for switching the private mode to the shared mode, and the third mode is the maintaining-shared mode for maintaining the shared mode. The voltage V is the voltage value between the first electrode 120 and the second electrode 220, i.e., V = Vb - Va.

[0069] Reference Figure 2 and Figure 3, in the first mode, the power supply unit S supplies the same voltage to the first electrode 120 and the second electrode 220. That is, the potential difference V between the first electrode 120 and the second electrode 220 is 0V. Therefore, no electric field is formed between the first electrode 120 and the second electrode 220, and the light-shielding particles CB in the accommodation part 550 remain in a dispersed state. Since the light-shielding particles CB in the accommodation part 550 absorb light, the accommodation part 550 blocks light. In the private mode, the viewing angle control film 10 provides a narrow viewing angle of θ1.

[0070] Referring to Figure 2 and Figure 4 , in the second mode and the third mode, the power supply unit S supplies different voltages to the first electrode 120 and the second electrode 220. The potential difference V between the first electrode 120 and the second electrode 220 is V1 or V2. Therefore, an electric force EF acts between the first electrode 120 and the second electrode 220, and the light-shielding particles CB in the accommodation part 550 aggregate on the upper side in the Z-axis direction. In the shared mode, since the light-shielding particles CB that absorb light aggregate on the upper side, the viewing angle control film 10 allows most of the oblique light L to pass through. Therefore, in the shared mode, the viewing angle control film 10 provides a wide viewing angle of θ2.

[0071] The controller 700 can drive the viewing angle control film 10 with a stronger voltage in the second mode than in the third mode to quickly switch from the private mode to the shared mode. Therefore, the voltage V1 in the second mode can be greater than the voltage V2 in the third mode.

[0072] Figure 5 is a diagram showing the state of the light-shielding particles CB in the accommodation part 550.

[0073] (a) part shows the state of the light-shielding particles CB in the first mode, (b) part shows the state of the light-shielding particles CB in the third mode, and (c) part shows the state in which the aggregation phenomenon of the light-shielding particles CB occurs during long-term driving in the third mode.

[0074] In the first mode of (a), no electric force EF is applied in the accommodation part 550. Since the light-shielding particles CB are mixed with the dispersion liquid, they remain in a dispersed state.

[0075] In the third mode of (b), an electric force EF is applied in the accommodation part 550. The electric force EF is applied by the potential difference V applied between the first electrode 120 and the second electrode 220. The light-shielding particles CB aggregate toward the upper side of the accommodation part 550 under the influence of the electric force EF.

[0076] As shown in part (c), when the third mode is driven for a long period of time, the partially light-shielding particles CB that are aggregated on the upper side of the accommodation part 550 can be aggregated into groups with each other. The light-shielding particle group CB_M formed by the aggregated light-shielding particles CB has a reduced reactivity with respect to the electric power EF applied to the accommodation part 550. That is, even when the electric power EF is continuously applied within the accommodation part 550 in the third mode, the light-shielding particle group CB_M will not be affected by the electric power EF due to the increase in its size and mass. Therefore, in the third mode, the light-shielding particle group CB_M floats in a dispersed state within the accommodation part 550 and blocks the oblique light. This is manifested as a decrease in brightness or a dark spot at the side viewing angle of the viewing angle control film 10.

[0077] The present disclosure solves the problem of a decrease in brightness at the side viewing angle due to the aggregation phenomenon of the light-shielding particles CB when driven for a long period of time in the shared mode.

[0078] Figure 6 It is a waveform diagram showing the driving voltage of the viewing angle control film 10 according to the first embodiment of the present disclosure. Figure 7 It is a waveform diagram showing the driving voltage of the viewing angle control film 10 according to the second embodiment of the present disclosure.

[0079] The driving voltage of the viewing angle control film 10 according to an embodiment of the present disclosure can apply a pulse voltage in the third mode as Figure 6 shown. Although the driving voltage is shown as a pulse voltage of a square wave in the drawings including Figure 6 , this is exemplary. The driving voltage of the present disclosure does not necessarily have to be a square wave, but can be configured into various waveforms such as a triangular wave and a sine wave.

[0080] The inventors of the present disclosure have found a problem that when a DC voltage is applied in the third mode as Figure 2 shown, the light-shielding particles CB are continuously subjected to a force in one direction from the upper side (or the lower side) within the accommodation part 550, and when the light-shielding particles CB are exposed to the continuous force for a long period of time, an aggregation phenomenon of the light-shielding particles CB occurs due to aggregation.

[0081] In the present disclosure, as a means for preventing the aggregation phenomenon of the light-shielding particles CB, a pulse voltage can be applied in the third mode.

[0082] Specifically, the pulse voltage can swing between a second voltage V2 and a third voltage V3. The second voltage V2 can be a positive or negative voltage depending on the polarity of the first voltage. The polarities of the first voltage V1 and the second voltage V2 can be different depending on the polarity of the light-shielding particles CB and on whether the light-shielding particles CB are arranged on the upper side or the lower side in the second mode and the third mode. However, preferably, the second voltage V2 is set to have the same polarity as the first voltage V1.

[0083] In Figure 6 , the second voltage V2 has a positive voltage, and the third voltage V3 has a voltage of 0V. In the third mode, in the portion where the second voltage V2 is applied, an upward-pointing electric force EF is applied within the accommodation portion. In the third mode, in the portion where the third voltage V3 is applied, no electric force EF is applied within the accommodation portion 550. The light-shielding particles CB within the accommodation portion 550 do not continuously receive a force in the upward direction, but instead receive the force dispersed by the dispersion liquid in the portion where the third voltage V3 is applied and no upward force is received. That is, in the third mode, the light-shielding particles CB do not continuously receive a force in the upward direction, but instead have an idle period for releasing the aggregation of the light-shielding particles CB when the third voltage V3 is applied. Therefore, different from the conventional method of applying a DC voltage, the aggregation phenomenon of the light-shielding particles CB can be prevented in the third mode. The second voltage V2 can be referred to as a holding voltage because the second voltage V2 holds the arrangement of the light-shielding particles CB on the upper side within the accommodation portion 550. The third voltage can be referred to as an idle voltage because the third voltage releases the aggregation of the light-shielding particles CB.

[0084] Figure 7 The embodiment of Figure 6 differs from Figure 7 in that the third voltage V3 has a negative-polarity voltage. When the third voltage V3 with a negative polarity is applied, a downward-pointing electric force EF is applied within the accommodation portion 550, and the light-shielding particles CB aggregated on the upper side receive a force in the downward direction. Therefore, in the portion where the third voltage V3 is applied, there is an idle period for releasing the aggregation of the light-shielding particles CB aggregated on the upper side of the accommodation portion 550. In Figure 6 , compared with

[0085] Preferably, the magnitude of the absolute value of the second voltage V2 is greater than the magnitude of the absolute value of the third voltage V3. This is because when the magnitude of the absolute value of the third voltage V3 is greater than the magnitude of the absolute value of the second voltage V2, the aggregation of the light-shielding particles CB is excessively released, and the degree of aggregation of the light-shielding particles CB on the upper side of the accommodation portion 550 is reduced. When the degree of aggregation of the light-shielding particles CB on the upper side of the accommodation portion 550 is too low, there is a problem of reduced brightness in the lower side view angle in the third mode.

[0086] Figure 8 is a diagram showing a state in which the light-shielding particles CB are dispersed in the accommodation portion 550 in the third mode. Figure 9 is a diagram showing a state in which the light-shielding particles CB are aggregated in groups in the accommodation portion 550 in the third mode.

[0087] Figure 8 and Figure 9 LL of represents the lower limit level of the minimum brightness specification required to satisfy the side viewing angle in the shared mode. In the shared mode, as the light-shielding particles CB in the accommodation portion 550 are more widely dispersed outside the range of LL, the brightness at the side viewing angle in the shared mode becomes lower.

[0088] The inventors of the present disclosure further found the following problem: When a pulsed voltage that swings between a second voltage V2 having a positive polarity and a third voltage V3 having a negative polarity is applied in the third mode as in Figure 7 the embodiment of, the same phenomenon as in Figure 8 or 9 occurs.

[0089] Figure 8 shows the problem in the case where the second voltage V2 as the holding voltage is low. When the second voltage V2 is low, the light-shielding particles CB in the accommodation portion 550 can be gradually dispersed as shown in Figure 8 . In the shared mode, since the light-shielding particles CB in the accommodation portion 550 are more widely distributed outside the range of LL, the minimum brightness specification required for the side viewing angle cannot be satisfied.

[0090] Contrary to Figure 8 Figure 9 shows the problem in the case where the second voltage V2 is too large. When the second voltage V2 is too large, the light-shielding particles CB in the accommodation portion 550 receive an excessive force in the upper side direction. In the shared mode, the light-shielding particles CB in the accommodation portion 550 are subjected to an excessive aggregation pressure in the upper side direction, so they are more aggregated on the side above LL. Even when the third voltage V3 is applied during the idle period, due to the excessive magnitude of the second voltage V2, the light-shielding particles CB receive a continuous force in the upper side direction on average. Therefore, compared with Figure 2 ​Similarly, the problem of aggregation of the light-shielding particles CB also occurs in the conventional driving method.

[0091] As is known from Figure 8 and Figure 9 when driving for a long period of time in the third mode, the second voltage V2 should not be too small to meet the condition (the first condition) for the minimum brightness specification required to achieve a side viewing angle, and the second voltage V2 should not be too large to meet the condition (the second condition) for preventing the aggregation of the light-shielding particles CB.

[0092] The inventors of the present disclosure recognized that it is difficult to set the value of the second voltage V2 that simultaneously meets the first condition and the second condition because various variables should be considered. The various variables may be, for example, the size of the light-shielding particles CB disposed in the accommodation portion 550, the degree of dispersion of the light-shielding particles CB by the dispersion liquid, the size of the accommodation portion 550, the dielectric constant of the partition wall, and the like.

[0093] The inventors of the present disclosure found that the same effect can be achieved by alternately driving a pulse voltage of a holding voltage that meets the first condition and a holding voltage that meets the second condition instead of applying a holding voltage that simultaneously meets the first condition and the second condition. Hereinafter, a detailed description will be made with reference to Figures 10 to 12 for details.

[0094] Figure 10 FIG. is a waveform diagram showing the driving voltage of the viewing angle control film 10 according to the third embodiment of the present disclosure.

[0095] The controller 700 alternately provides a first pulse voltage and a second pulse voltage. The second voltage V2 is a holding voltage that meets the above-mentioned second condition, and the fourth voltage V4 is a holding voltage that meets the first condition. The first pulse voltage is a pulse voltage that swings between the second voltage V2 and the third voltage V3 using the second voltage V2 as the holding voltage. The second pulse voltage is a pulse voltage that swings between the fourth voltage V4 and the fifth voltage V5 using the fourth voltage V4 as the holding voltage. The first pulse voltage is applied during the first period P1, and the second pulse voltage is applied during the second period P2. The first pulse voltage and the second pulse voltage are alternately applied.

[0096] Preferably, the second period P2 is longer than the first period P1. In addition, preferably, the amplitude of the fourth voltage V4 is greater than the amplitude of the second voltage V2. When the second period P2 is shorter than the first period P1, the aggregation stress applied to the light-shielding particles CB is too low, so that the brightness of the side viewing angle may gradually decrease when driving for a long period of time. Even in the case where the amplitude of the fourth voltage V4 is smaller than the amplitude of the second voltage V2, the aggregation stress applied to the light-shielding particles CB is too low, and thus the brightness of the same side viewing angle may decrease.

[0097] Figure 11 FIG. is a diagram showing the state of the light-shielding particles CB in the accommodation part 550 according to the third embodiment.

[0098] The degree of aggregation of the light-shielding particles CB on the upper side of the accommodation part 550 is determined according to the amplitude of the holding voltage. In the first period P1, the light-shielding particles CB are relatively widely distributed to the line V2 according to the second voltage V2 as the holding voltage. In the second period P2, the light-shielding particles CB are relatively concentratedly distributed to the line V4 according to the fourth voltage V4 as the holding voltage. In the first period P1, the distance between the light-shielding particles CB is relatively increased, and in the second period P2, the distance between the light-shielding particles CB is relatively decreased. In other words, the aggregation stress of the light-shielding particles CB is reduced in the first period P1, and the aggregation stress of the light-shielding particles CB is increased in the second period P2.

[0099] Figure 12 FIG. is a graph comparing the luminance changes in the side view in the third mode according to the respective amplitudes of the holding voltage.

[0100] First, curves A and B represent the case where a pulse voltage with a holding voltage having one level is applied, and curve C represents the case where a pulse voltage with a holding voltage having two levels is applied.

[0101] Curve A represents the case where the holding voltage is too large. Curve A shows that the light-shielding particles CB in the accommodation part 550 are excessively aggregated in the upper side direction, so that the lateral luminance increases with time. When this state continues for a long period of time, problems such as the aggregation phenomenon of the light-shielding particles CB occur as described with reference to Figure 8 and Figure 9 .

[0102] Curve B represents the case where the holding voltage is too small. Curve B shows that the light-shielding particles CB in the accommodation part 550 are gradually dispersed in the lower side direction, so that the lateral luminance decreases with time.

[0103] Curve C shows that the lateral luminance is maintained within a certain range in the case of repeatedly increasing and decreasing, which means that the light-shielding particles CB in the accommodation part 550 maintain an appropriate distance.

[0104] Therefore, according to the third embodiment of the present disclosure, the problem of the aggregation phenomenon of the light-shielding particles CB caused by the gradual aggregation of the light-shielding particles CB can be prevented, and at the same time, the problem of the decrease in the lateral luminance caused by the gradual dispersion of the light-shielding particles can be solved.

[0105] Figure 13 FIG. is a cross-sectional view of a display device according to an embodiment.

[0106] Referring to Figure 13, the display device 7 may include a display panel 1, a viewing angle control film 10, and a cover substrate 30.

[0107] The display panel 1 may include a plurality of pixels disposed in a display area of a base substrate and a driving unit (not shown) for driving the pixels disposed in a non-display area around the display area. The pixels may include a transistor TFT connected to the driving unit through a control signal line and a light emitting diode OLED connected to the transistor. The transistor is turned on or off according to a control signal applied through the control signal line, and thus adjusts the amount of current applied to the light emitting diode. The light emitting diode may emit light having a brightness corresponding to the amount of current applied through the transistor. The display panel 1 may further include a protective layer Encap for encapsulating the light emitting diode OLED and an upper protective substrate Pol.

[0108] The viewing angle control film 10 may be disposed on the display panel 1. The viewing angle control film 10 may control the light path generated in the display panel 1 according to the operation mode of the display device 7. For example, when the display device 7 operates in a private mode as a first mode, the light conversion layer 500 of the viewing angle control film 10 is controlled to a light-shielding mode, and thus the viewing angle may be opened with respect to the front surface of the display device 7 and the viewing angle may be blocked with respect to the side surface. In the private mode, the viewing angle control film 10 may be disposed on the display panel and may control the light emitted from the display panel to be emitted only within a predetermined angle range. When the display device 7 operates in a shared mode as a second mode, the light conversion layer 500 of the viewing angle control film 10 is controlled to a light-transmissive mode, and thus the viewing angle may be opened with respect to the front surface and the side surface of the display device 7. In the shared mode, the viewing angle control film 10 may control the light emitted from the display panel to be emitted beyond a predetermined angle range.

[0109] The cover substrate 30 may be disposed on the viewing angle control film 10. The cover substrate 30 may be provided to protect the display device 7 from external shocks or foreign substances. The cover substrate 30 may be a light-transmissive substrate, and may be a rigid substrate including glass or tempered glass or a flexible substrate made of a plastic material.

[0110] In an embodiment, the display device 7 may further include a touch panel 40. The touch panel 40 may be configured as a capacitive type or a resistive film type, and thus may sense a touch input of a user.

[0111] The display panel 1, the viewing angle control film 10, the touch panel 40, and the cover substrate 30 may be attached to each other through an adhesive layer 50. The adhesive layer 50 may be an optically clear adhesive (OCA) or an optically clear resin (OCR).

[0112] Those skilled in the art will understand that the present disclosure can be implemented in other specific forms without changing the technical concept or essential characteristics of the present disclosure. Therefore, it should be understood that the above aspects are exemplary in all respects and not restrictive. The scope of the present disclosure is characterized by the appended claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the appended claims and their equivalents should be construed to fall within the scope of the present disclosure.

[0113] Reference numeral

[0114] 100: First film

[0115] 200: Second film

[0116] 310: First adhesive layer

[0117] 320: Second adhesive layer

[0118] 500: Light conversion layer

[0119] 510: Blinder layer

[0120] 550: Accommodating portion

[0121] 700: Controller

Claims

1. A viewing angle control film, comprising: a first electrode; a second electrode, the second electrode facing the first electrode and spaced apart from the first electrode; a light conversion layer disposed between the first electrode and the second electrode; and a controller configured to adjust the viewing angle of the light conversion layer by controlling the voltage applied between the first electrode and the second electrode, wherein the light conversion layer includes: a plurality of partition walls disposed spaced apart between the first electrode and the second electrode; a plurality of accommodation portions formed between the plurality of partition walls and arranged at uniform intervals along the first electrode; and light shielding particles disposed in each of the plurality of accommodation portions, wherein the controller applies a pulsed voltage in a shared mode of operation with a wide viewing angle, the pulsed voltage oscillating between a second voltage and a third voltage, and wherein when switching from a private mode of operation with a narrow viewing angle to the shared mode, the controller applies a first voltage for a predetermined period of time, the magnitude of the absolute value of the first voltage being greater than the magnitude of the absolute value of the second voltage.

2. The viewing angle control film according to claim 1, wherein, the third voltage is a 0V voltage.

3. The viewing angle control film according to claim 1, wherein, the second voltage has a positive polarity and the third voltage has a negative polarity.

4. The viewing angle control film according to claim 3, wherein, the magnitude of the absolute value of the second voltage is greater than the magnitude of the absolute value of the third voltage.

5. The viewing angle control film according to claim 1, wherein, the controller alternately provides a first pulsed voltage oscillating between the second voltage and the third voltage, and a second pulsed voltage oscillating between a fourth voltage and a fifth voltage in the shared mode, wherein the fourth voltage is greater than the second voltage.

6. The viewing angle control film according to claim 5, wherein, the controller: provides the first pulsed voltage during a first period; and provides the second pulsed voltage during a second period longer than the first period.

7. The viewing angle control film according to claim 5, wherein, the second voltage and the fourth voltage are positive polarity voltages, and wherein the third voltage and the fifth voltage are negative polarity voltages.

8. The viewing angle control film according to claim 7, wherein, the magnitude of the absolute value of the third voltage is greater than the magnitude of the absolute value of the fifth voltage.

9. The viewing angle control film according to claim 7, wherein, the magnitude of the absolute value of the second voltage is greater than the magnitude of the absolute value of the third voltage, and wherein the magnitude of the absolute value of the fourth voltage is greater than the magnitude of the absolute value of the fifth voltage.

10. The viewing angle control film according to claim 5, wherein, when switching from the private mode to the shared mode, the controller applies the first voltage greater than the fourth voltage for a predetermined period of time.

11. A viewing angle control film, comprising: a first electrode; A second electrode facing the first electrode; And A light conversion layer disposed between the first electrode and the second electrode, Wherein the light conversion layer includes a receiving portion and a shutter layer, the receiving portion is partitioned into a plurality of regions by the shutter layer, and the receiving portion includes a dispersion liquid and light-shielding particles, Wherein the viewing angle of the light conversion layer can be adjusted by adjusting the voltage applied between the first electrode and the second electrode, Wherein, in a shared mode of operation with a wide viewing angle, a pulsed voltage is applied between the first electrode and the second electrode, the pulsed voltage oscillates between a second voltage and a third voltage, and Wherein, when switching from a private mode of operation with a narrow viewing angle to the shared mode, a first voltage is applied for a predetermined period of time, and the magnitude of the absolute value of the first voltage is greater than the magnitude of the absolute value of the second voltage.

12. The viewing angle control film according to claim 11, Wherein, In the shared mode, a first pulsed voltage that oscillates between the second voltage and the third voltage, and a second pulsed voltage that oscillates between a fourth voltage and a fifth voltage are alternately applied between the first electrode and the second electrode, Wherein the fourth voltage is greater than the second voltage.

13. A display device, Comprising: A display panel including pixels disposed in the display panel and configured to display an image; And The viewing angle control film according to any one of claims 1 and 11, Wherein the viewing angle control film is disposed on the display panel and operates in a private mode or a shared mode. In the private mode, light emitted from the display panel is controlled to be emitted only within a predetermined angular range. In the shared mode, light emitted from the display panel is controlled to be emitted beyond the predetermined angular range.

Images