Electrically controllable beam divergence angle nematic liquid crystal device

Abstract

The present invention discloses a beam divergence angle electrically controllable nematic liquid crystal device, which includes stacked liquid crystal cells. The liquid crystal cell includes two stacked liquid crystal cells. The liquid crystal cell includes upper and lower substrates, a nematic liquid crystal layer is provided between the upper and lower substrates, an upper ITO electrode is plated on one side of the upper substrate, a lower ITO electrode is plated on one side of the lower substrate, and openings are provided on the upper ITO electrode and / or the lower ITO electrode. Looking from the direction perpendicular to the upper ITO electrode, the openings on the upper and lower ITO electrodes complement each other to form a regular array, and the upper and lower substrates and the nematic liquid crystal layer form a micro liquid crystal lens through the openings. The outgoing light beams emitted by adjacent micro liquid crystal lenses of the incident light beam overlap with each other in a divergent shape, and the divergence angle size is controllable. The present invention realizes the effective control and adjustment of the divergence angle size of the outgoing light beam, is easy to implement, has a low cost, and is suitable for popularization and popularization.

Description

Technical Field

[0001] The present invention relates to a nematic liquid crystal dimming device, and more particularly to a nematic liquid crystal device for non-mechanically adjusting the divergence angle of a light beam. Background Art

[0002] Illumination devices such as spotlights, flashlights, and projectors commonly used in daily life usually come with a light beam focusing lens. When in use, by adjusting the distance between the light source and the light beam focusing lens (or lens group), the adjustment of the divergence angle (or spot size) of the emitted light beam can be achieved. However, this traditional light beam focusing lens technology usually adopts a manual adjustment method or a motor automatic adjustment method for adjusting the spot size. The manual adjustment method is not precise enough, time-consuming and laborious, and the application scenarios are limited. The motor automatic adjustment method has disadvantages such as a complex drive structure, large volume, and high cost, making it difficult to popularize.

[0003] The invention patent application with the application number 201880024971.6 discloses a liquid crystal light beam broadening device with improved beam uniformity. It realizes the function of adjusting the spot size by driving the liquid crystal to form a special arrangement structure through a specially designed electrode. However, due to the influence of the driving principle, this device has a high driving voltage, a complex driving signal (4 square waves with different phases), a high cost, and the application scenarios are also limited, making it difficult to popularize. Summary of the Invention

[0004] The purpose of the present invention is to provide a nematic liquid crystal device with electronically controllable beam divergence angle, which effectively controls and adjusts the divergence angle of the emitted light beam, is easy to implement, has a low cost, and is suitable for popularization.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A beam divergence angle electrically controllable nematic liquid crystal device, characterized in that: it includes at least one liquid crystal cell stacked coaxially, wherein: the liquid crystal cell includes two liquid crystal cells arranged in layers; the liquid crystal cell includes an upper substrate and a lower substrate, a nematic liquid crystal layer is provided between the upper substrate and the lower substrate, the nematic liquid crystal layer includes nematic liquid crystal, the side of the upper substrate facing the nematic liquid crystal layer is plated with an upper ITO electrode, the side of the lower substrate facing the nematic liquid crystal layer is plated with a lower ITO electrode, and there are openings on the upper ITO electrode and / or the lower ITO electrode. Among them, when viewed from a direction perpendicular to the upper ITO electrode, the openings on the upper ITO electrode and the lower ITO electrode complement each other to form a regular array. The upper substrate, the lower substrate and the nematic liquid crystal layer therebetween form a micro liquid crystal lens through each opening. The outgoing light beams emitted after the incident light beam passes through adjacent micro liquid crystal lenses overlap each other and diverge, and the size of the divergence angle is controlled by the amplitude of the voltage signal input to the upper ITO electrode and the lower ITO electrode; when the upper ITO electrode and the lower ITO electrode are in the non-energized state, the long axis directions of the nematic liquid crystals in the two liquid crystal cells of the liquid crystal cell are perpendicular to each other.

[0007] The advantages of the present invention are:

[0008] The structure of the present invention is simple. Through a non-mechanical voltage control method, effective control and adjustment of the divergence angle of the outgoing light beam are achieved. It is easy to implement, easy to drive, low in cost, can be mass-produced, and can be widely used in lighting fixtures such as spotlights, flashlights, and projectors. Description of the Drawings

[0009] Figure 1 is a schematic structural diagram of an existing liquid crystal cell.

[0010] Figure 2 is Figure 1 a schematic structural diagram of the lower ITO electrode of the liquid crystal cell shown.

[0011] Figure 3 is a schematic structural diagram of the nematic liquid crystal device of the present invention.

[0012] Figure 4 is a schematic structural diagram of an embodiment of the liquid crystal cell in the nematic liquid crystal device of the present invention.

[0013] Figure 5 is Figure 4 a schematic structural diagram of the upper ITO electrode of the liquid crystal cell shown.

[0014] Figure 6 is Figure 4 a schematic structural diagram of the lower ITO electrode of the liquid crystal cell shown.

[0015] Figure 7 is from Figure 4Schematic diagram of a regular array formed by complementary openings on the upper ITO electrode and the lower ITO electrode when viewed in the Y direction.

[0016] Figure 8 It is a schematic diagram for explaining the optical principle of the micro liquid crystal lens realized by the nematic liquid crystal device of the present invention. Detailed implementation manners

[0017] In the research on the focusing performance of liquid crystal lenses in this industry, the single-round-hole electrode liquid crystal lens is one that has been studied more. Its structure is simple and the driving is simple, and the focal length can be continuously adjusted. As Figure 1 shown, the liquid crystal cell shown in the figure is designed as a single-round-hole electrode liquid crystal lens. This liquid crystal cell includes an upper substrate 11 and a lower substrate 12. A nematic liquid crystal layer 30 is provided between the upper substrate 11 and the lower substrate 12. The surface of the upper substrate 11 facing the nematic liquid crystal layer 30 is coated with an upper ITO electrode 21, and the upper ITO electrode 21 is a whole-piece electrode. The surface of the lower substrate 12 facing the nematic liquid crystal layer 30 is coated with a lower ITO electrode 22, and the lower ITO electrode 22 is an electrode with a round hole 40 opened, as Figure 2 .

[0018] In actual application, the disadvantage of this single-round-hole electrode liquid crystal lens is that the size of the round hole 40 is small (usually the diameter is less than 1 mm), and the size cannot be enlarged. This is because when the size of the round hole 40 is enlarged, the focal length adjustment ability is greatly weakened. When the size of the round hole 40 is enlarged to the millimeter level (the diameter is greater than 1 mm), the single-round-hole electrode liquid crystal lens is limited by the refractive index adjustment range of the liquid crystal material itself and almost loses the focusing function. Therefore, although the single-round-hole electrode liquid crystal lens was studied more in the early stage, it still has little practical value so far.

[0019] The present invention is exactly inspired by this single-round-hole electrode liquid crystal lens and is designed to improve the single-round-hole electrode liquid crystal lens into a porous electrode liquid crystal lens array, and uses the porous electrode liquid crystal lens array to replace the single-round-hole electrode liquid crystal lens. In this way, the increase in size is no longer limited, and the problem of weakened focal length adjustment ability is solved.

[0020] Specifically, as Figures 3 to 8 shown, the beam divergence angle electronically controllable nematic liquid crystal device of the present invention includes at least one liquid crystal unit 80 stacked coaxially together, Figure 3Shows a situation where multiple liquid crystal cells 80 are stacked together along axis L, where: The liquid crystal cell 80 includes two liquid crystal cells 70 arranged in a stacked manner; The liquid crystal cell 70 includes an upper substrate 11 and a lower substrate 12. A nematic liquid crystal layer 30 is provided between the upper substrate 11 and the lower substrate 12. The nematic liquid crystal layer 30 includes nematic liquid crystal. The nematic liquid crystal layer 30 includes nematic liquid crystal and conductive ions mixed together. The conductive ions are used to move under the drive of a voltage signal and drive the nematic liquid crystal nearby to deflect. The side of the upper substrate 11 facing the nematic liquid crystal layer 30 is coated with an upper ITO electrode 51, and the side of the lower substrate 12 facing the nematic liquid crystal layer 30 is coated with a lower ITO electrode 52. Openings 60 are provided on the upper ITO electrode 51 and / or the lower ITO electrode 52. Among them, when viewed from a direction perpendicular to the upper ITO electrode 51 (or the lower ITO electrode 52, the upper substrate 11), that is, from Figure 4 the Y direction shown in Figure 4 the X direction shown is parallel to the upper substrate 11 or the lower substrate 12), the openings 60 on the upper ITO electrode 51 and the lower ITO electrode 52 complement each other to form a regular array. The upper substrate 11, the lower substrate 12, and the nematic liquid crystal layer 30 therebetween form a micro liquid crystal lens 90 through each opening 60. That is, the liquid crystal cell 70 forms a porous electrode liquid crystal lens array. The outgoing light beams emitted after the incident light beam passes through adjacent micro liquid crystal lenses 90 overlap with each other and diverge, and the size of the divergence angle is controlled by the amplitude of the voltage signals input to the upper ITO electrode 51 and the lower ITO electrode 52; When the upper ITO electrode 51 and the lower ITO electrode 52 are in the non-energized state, the long axis directions of the nematic liquid crystal in the two liquid crystal cells 70 of the liquid crystal cell 80 are orthogonal to each other.

[0021] For the liquid crystal cell 70, the area corresponding to each opening 60 can be equivalently regarded as a variable-focus micro liquid crystal lens 90. That is, the upper substrate 11, the lower substrate 12, and the nematic liquid crystal layer 30 therebetween form a micro liquid crystal lens 90 through each opening 60. The optical principle of the micro liquid crystal lens 90 can be referred to Figure 8 for understanding. It can be seen that the liquid crystal cell 70 forms a porous electrode liquid crystal lens array. By controlling the focal length of each micro liquid crystal lens 90, the purpose of controlling the divergence angle of the entire outgoing light beam can be achieved. Importantly, the focal length adjustment ability is no longer limited by the size of the micro liquid crystal lens 90 itself, and the problem of weakening of the focal length adjustment ability can be solved by increasing the number of micro liquid crystal lenses 90.

[0022] The application scenario of the present invention is to control the divergence angle of the light beam rather than imaging, so the requirements are relatively low. The present invention adopts a voltage control method to continuously adjust the outgoing angle size of the outgoing light beam, and the intensity of the light beam emitted after adjustment can meet the lighting needs of users.

[0023] For the liquid crystal cell 70, by controlling the amplitude of the voltage signals input to the upper ITO electrode 51 and the lower ITO electrode 52, the deflection angle of the nematic liquid crystal in the nematic liquid crystal layer 30 corresponding to each micro liquid crystal lens 90 can be controlled, achieving the purpose of controlling the focal length of each micro liquid crystal lens 90, that is, achieving the purpose of controlling the overall divergence angle of the outgoing light beam emitted from the liquid crystal cell 70.

[0024] In the actual design, two liquid crystal cells 70 in each liquid crystal unit 80 and adjacent liquid crystal units 80 are bonded together by an optical adhesive (existing adhesive) to improve the light transmittance.

[0025] Referring to the principle of the micro lens, assuming the diameter of the circular opening 60 is D, the cell thickness of the liquid crystal cell 70 is d, and the refractive index difference of the liquid crystal for ordinary light and extraordinary light is Δn. Then, in the ideal case, the maximum optical path difference between the center and the edge of the light passing through the micro liquid crystal lens is Δn×d. According to the principle of wave optics, the focal length f of the micro liquid crystal lens can be calculated by the following formula:

[0026]

[0027] Then, under the condition of parallel light incidence, the divergence angle θ of the outgoing light can be calculated by the following formula:

[0028] θ = arctan(D / 2f)

[0029] During actual operation, the liquid crystal molecules at the edge of the opening 60 cannot be completely perpendicular to the upper and lower substrates 11 and 12, and the liquid crystal molecules at the center of the opening 60 will also have a certain inclination angle under the influence of the lateral electric field. Therefore, the optical path difference between the center and the four edges of the light passing through the opening 60 will be smaller than the above theoretical calculated value, that is, the divergence angle will also be smaller.

[0030] In order to ensure that the liquid crystal molecules at the center and the four edges of the micro liquid crystal lens can be arranged as ideally as possible, it is necessary to perform matching optimization on the diameter of the opening 60 and the cell thickness of the liquid crystal cell during the actual design.

[0031] In the present invention, the thickness of the liquid crystal cell 70 is 2 μm to 100 μm, the opening 60 is circular, the diameter of the opening 60 is 10 μm to 200 μm, and the distance between adjacent two openings 60 is 1 μm to 50 μm.

[0032] In actual implementation, the opening 60 can also be triangular, square, regular pentagonal or any regular polygon, as long as the shape and size of this opening 60 are comparable to those of the circular hole. Specifically, the thickness of the liquid crystal cell 70 is 2 μm to 100 μm, the opening 60 is a triangular, square or approximately circular regular polygon, the maximum diameter of the opening 60 is 10 μm to 200 μm, and the distance between two adjacent openings 60 is 1 μm to 50 μm.

[0033] In actual design, the upper ITO electrode 51 and the lower ITO electrode 52 can be designed as follows:

[0034] There are no openings on the upper ITO electrode 51, which is a whole electrode, and the openings 60 on the lower ITO electrode 52 form a regular array. Or, there are no openings on the lower ITO electrode 52, which is a whole electrode, and the openings 60 on the upper ITO electrode 51 form a regular array. Or, both the upper ITO electrode 51 and the lower ITO electrode 52 have openings, and the openings 60 on the upper ITO electrode 51 and the openings 60 on the lower ITO electrode 52 are complementary to form a regular array.

[0035] For example, as Figure 5 shows the openings 60 provided on the upper ITO electrode 51, Figure 6 shows the openings 60 provided on the lower ITO electrode 52. From Figure 5 and Figure 6 it can be seen that there are no openings at the positions on the upper ITO electrode 51 corresponding to the openings 60 of the lower ITO electrode 52. Similarly, there are no openings at the positions on the lower ITO electrode 52 corresponding to the openings 60 of the upper ITO electrode 51, that is, the openings 60 on the upper ITO electrode 51 and the lower ITO electrode 52 are complementary. Looking from the direction perpendicular to the upper ITO electrode 51 (or the lower ITO electrode 52), the openings 60 on the upper ITO electrode 51 and the lower ITO electrode 52 are complementary to form a regular array, as Figure 7 shown.

[0036] In the present invention, the regular array can be in the form of a matrix of several rows × several columns, or in other regular arrangement forms. For example, Figure 7 shown in the 4-column form of the arrangement of 3, 2, 3, 2 openings.

[0037] In the present invention, the upper substrate 11 and the lower substrate 12 of the liquid crystal cell 70 can be made of transparent glass material, etc. The upper ITO electrode 51 and the lower ITO electrode 52 are made of ITO (indium tin oxide) material existing in the art. Additionally, auxiliary metals such as aluminum, copper, silver, etc. can be used as needed. The nematic liquid crystal layer 30 is an existing technology in the art, and insulating support balls, etc. can also be provided therein.

[0038] For example, as Figure 3, as shown in the figure, when the upper ITO electrode 51 and the lower ITO electrode 52 are in the non-energized state, the long axis directions (see reference numerals 31 and 31') of the nematic liquid crystals in the two liquid crystal cells 70 of the liquid crystal cell 80 are orthogonal to each other. According to the birefringence characteristics of the nematic liquid crystal, the liquid crystal cell 70 only acts on the light beam whose polarization direction is parallel to the long axis direction of the nematic liquid crystal. Therefore, for an ordinary unpolarized light source with any polarization direction, as long as the two liquid crystal cells 70 are stacked and the long axis directions of the nematic liquid crystals in the two are set to be orthogonal to each other, it can be used to control the divergence angle of the ordinary light source. Therefore, the present invention can be well used in lighting fixtures such as spotlights, flashlights, and projectors used in daily life.

[0039] For a liquid crystal cell 80, it is easy to synchronously control the voltage signals input to the two liquid crystal cells 70 of the liquid crystal cell 80 to reduce the driving difficulty. In other words, the two liquid crystal cells 70 are arranged in parallel, that is, the voltage signals input to the upper ITO electrodes 51 of the two liquid crystal cells 70 are the same and are input simultaneously, and the voltage signals input to the lower ITO electrodes 52 are the same and are input simultaneously. Each liquid crystal cell 70 requires 2 voltage signals for driving. Then, if the two liquid crystal cells 70 are arranged in parallel, 2 voltage signals are also required for driving, which is easy to implement.

[0040] In the present invention, in order to increase the control range of the divergence angle of the light beam emitted by the device, a method of stacking multiple liquid crystal cells together can be adopted. For the nematic liquid crystal, there is no requirement for the alignment angle between different liquid crystal cells. That is, when the present invention is designed with multiple liquid crystal cells, the long axis directions of the nematic liquid crystals between the respective liquid crystal cells are not restricted from each other, as long as the long axis directions of the nematic liquid crystals in the two liquid crystal cells 70 inside each liquid crystal cell are orthogonal to each other.

[0041] If multiple liquid crystal cells 80 are coaxially stacked together, synchronous control is performed between the respective liquid crystal cells 80, that is, the voltage signals input to the upper ITO electrodes 51 of the two liquid crystal cells 70 in each liquid crystal cell 80 are the same and are input simultaneously, and the voltage signals input to the lower ITO electrodes 52 are the same and are input simultaneously. In other words, if the liquid crystal cells in multiple liquid crystal cells 80 are configured identically, the liquid crystal cells 70 can also be arranged in parallel with each other. In this way, the entire device of the present invention still only requires 2 voltage signal lines to achieve driving, and the driving method is simple and practical.

[0042] In terms of voltage driving, the upper ITO electrode 51 and the lower ITO electrode 52 in the liquid crystal cell 70 receive a pair of AC voltage signals with the same frequency, the same voltage amplitude, and a phase difference of 90°. This AC voltage signal can be a positive and negative signal or a unidirectional signal (unidirectional positive / negative signal). Among them: the AC voltage signal is a square wave, and of course, it can also be designed as other waveforms according to needs.

[0043] In addition, in the present invention, the frequency of the AC voltage signal is not limited and is preferably designed to be between 10 Hz and 500 Hz. In actual implementation, the voltage amplitude of the AC voltage signal can be reasonably designed according to factors such as the diameter of the opening 60 and the cell thickness of the liquid crystal cell 70, without limitation, and is usually preferably designed to be between 3 V and 30 V, and can be reasonably adjusted according to the actual situation.

[0044] During use, a light source (such as unpolarized light) is placed on one side of the device of the present invention. Then, the light rays (incident light beams) emitted by the light source pass through each liquid crystal unit 80 in sequence and are emitted. The divergence angle (or spot size) of the emitted light rays (emergent light beams) can be adjusted by controlling the voltage signals input to each liquid crystal unit 80. Under the condition that the diameter of the opening 60 and the cell thickness of the liquid crystal cell 70 remain unchanged, and when the amplitude of the voltage signal is within a reasonable range, the larger the amplitude of the voltage signals input to the upper ITO electrode 51 and the lower ITO electrode 52, the larger the deflection angle of the nematic liquid crystal driven by the conductive ions in the vicinity thereof, and thus the larger the divergence angle of the emergent light beam emitted by the device of the present invention.

[0045] When the light passes through the porous electrode liquid crystal lens array formed by the liquid crystal cell 70, the light is refracted by the nematic liquid crystal in each micro liquid crystal lens 90 and is emitted in a divergent manner. The light rays emitted by adjacent micro liquid crystal lenses 90 overlap each other, so that both the divergence angle and the light intensity of the light beam finally emitted by the device of the present invention meet the lighting requirements of the user. More importantly, compared with the prior art, the present invention is easy to implement, easy to drive, has a low cost, and can be mass-produced.

[0046] The above is the preferred embodiment of the present invention and the technical principles applied. For those skilled in the art, any obvious changes such as equivalent transformations and simple substitutions based on the technical solution of the present invention without departing from the spirit and scope of the present invention fall within the protection scope of the present invention.

Claims

1. A nematic liquid crystal device with electronically controllable beam divergence angle, characterized in that: It includes at least one liquid crystal cell stacked coaxially, where: the liquid crystal cell includes two liquid crystal cells arranged in a stacked manner; the liquid crystal cell includes an upper substrate and a lower substrate, and a nematic liquid crystal layer is provided between the upper substrate and the lower substrate. The nematic liquid crystal layer includes nematic liquid crystal. An upper ITO electrode is plated on the side of the upper substrate facing the nematic liquid crystal layer, and a lower ITO electrode is plated on the side of the lower substrate facing the nematic liquid crystal layer. Openings are provided on the upper ITO electrode and the lower ITO electrode. Among them, when viewed from a direction perpendicular to the upper ITO electrode, the openings on the upper ITO electrode and the lower ITO electrode complement each other to form a regular array. The upper substrate, the lower substrate, and the nematic liquid crystal layer therebetween form a micro liquid crystal lens through each opening. The outgoing light beams emitted after the incident light beam passes through adjacent micro liquid crystal lenses overlap with each other and diverge, and the size of the divergence angle is controlled by the amplitude of the voltage signals input to the upper ITO electrode and the lower ITO electrode. The larger the amplitude of the voltage signals input to the upper ITO electrode and the lower ITO electrode, the larger the divergence angle of the outgoing light beam; in the non-powered state of the upper ITO electrode and the lower ITO electrode, the long axis directions of the nematic liquid crystals in the two liquid crystal cells of the liquid crystal cell are perpendicular to each other; the thickness of the liquid crystal cell is 2μm - 100μm, where: the opening is circular, triangular, square, or a regular polygon approximately circular; when the opening is circular, the diameter of the opening is 10μm - 200μm; when the opening is triangular, square, or a regular polygon approximately circular, the maximum diameter of the opening is 10μm - 200μm; the distance between adjacent two openings is 1μm - 50μm; the voltage signals input to the two liquid crystal cells of the liquid crystal cell are synchronously controlled; the upper ITO electrode and the lower ITO electrode in the liquid crystal cell receive a pair of AC voltage signals with the same frequency, the same voltage amplitude, and a phase difference of 90°, where the AC voltage signal is a square wave, and the voltage amplitude is adjustable between 3V and 30V.

2. The nematic liquid crystal device with electronically controllable beam divergence angle according to claim 1, wherein: Between the two liquid crystal cells in each liquid crystal cell and between adjacent liquid crystal cells are bonded together by an optical adhesive.

3. The nematic liquid crystal device with electronically controllable beam divergence angle according to claim 1, wherein: Openings are provided on both the upper ITO electrode and the lower ITO electrode, and the openings on the upper ITO electrode and the openings on the lower ITO electrode complement each other to form a regular array.

Images