JP6135793B1 - Light control system, light control device, light control film, and light control film driving method - Google Patents

Abstract

According to the present invention, uneven brightness that temporarily occurs when the transmittance is variable in a light control film using liquid crystal is prevented. SOLUTION: A light control film 10 for controlling transmitted light by aligning liquid crystals of a liquid crystal cell 14 sandwiched between linearly polarizing plates 12 and 13 by a VA method, and a driving power source for outputting a rectangular wave signal to the light control film 10 A light control device 3 having a generation unit 5, and the light control device 3 varies the amplitude of the rectangular wave signal in response to the operation of the operation elements 2U and 2D, thereby increasing the transmittance of the light control film 10. When the amplitude of the rectangular wave signal is increased, the amplitude of the rectangular wave signal is gradually increased. [Selection] Figure 9

Description

  The present invention relates to a light control film that can be used for, for example, an electronic blind that is attached to a window to control the transmission of extraneous light.

  Conventionally, for example, various devices relating to a light control film that is attached to a window to control the transmission of external light have been proposed (Patent Documents 1 and 2). One such light control film uses liquid crystal. The light control film using the liquid crystal is prepared by sandwiching a liquid crystal material with a transparent film material having a transparent electrode and an alignment layer, and a liquid crystal cell between the linear polarizing plates. As a result, in the light control film using this liquid crystal, the orientation of the liquid crystal can be changed by changing the electric field applied to the liquid crystal to block or transmit extraneous light, and further the amount of transmitted light can be changed. Control the transmission of extraneous light.

  The light control film using this liquid crystal has the advantage of responding at high speed in principle as compared with a configuration using electrochromic or the like which is a similar configuration for controlling external light.

  In addition, a liquid crystal display panel, which is one of image display panels, includes a liquid crystal cell sandwiched between a pair of glass plates made of transparent electrodes and alignment films, and the liquid crystal cell is sandwiched between linear polarizing plates. Configured. The liquid crystal display panel displays a desired image by changing the electric field applied to the liquid crystal in units of pixels by patterning the transparent electrode.

  Like the liquid crystal display panel, the light control film is configured to control the transmitted light by controlling the orientation of the liquid crystal molecules, so that various driving methods proposed for the image display panel can be used. It is done. Of the drive methods proposed for this liquid crystal display panel, the VA (Virtical Alignment) method can be configured by a normally black method in which a non-transmission state (light-shielding state) occurs when no electric field is applied. In addition, there is a feature that the light blocking ratio in this light blocking state is high. Thus, in the case of controlling the transmission of extraneous light by applying to a sunroof of a vehicle, it is conceivable to use a VA-type light control film. The VA method is a method of controlling transmitted light by changing the alignment of liquid crystal between vertical alignment and horizontal alignment. Generally, the liquid crystal layer is vertically aligned by vertically aligning the liquid crystal when no electric field is applied. A liquid crystal cell is formed by sandwiching the liquid crystal material, and the liquid crystal material is horizontally aligned by application of an electric field.

  However, when the light control film was configured by the VA method and experimented, the speed of change from the light-shielding state to the light-transmitting state when an electric field was applied to increase the transmittance was different in each part of the light control film. It was found that uneven brightness occurred temporarily. Such luminance unevenness occurs temporarily when the transmittance is variable, but it significantly reduces the quality of the light control and impairs the advantage of the liquid crystal light control film responding at high speed.

JP 03-47392 A Japanese Patent Laid-Open No. 08-184273

  The present invention has been made in view of such a situation, and an object of the present invention is to prevent luminance unevenness that temporarily occurs when the transmittance is variable in a light control film using liquid crystal.

  The present inventor has conducted extensive research to solve the above problems, and has come to the idea of gradually increasing the amplitude of the applied voltage, thus completing the present invention.

  Specifically, the present invention provides the following.

(1) a light control film for controlling transmitted light by aligning liquid crystals of a liquid crystal cell sandwiched by linearly polarizing plates by a VA method;
A light control device having a drive power generation unit that outputs a rectangular wave signal to the light control film;
The light control device is:
By varying the amplitude of the rectangular wave signal in response to the operation of the operation element, the transmittance of the light control film is varied,
A dimming system that gradually increases the amplitude of the rectangular wave signal when increasing the amplitude of the rectangular wave signal.

  According to (1), by gradually increasing the amplitude of the rectangular wave signal from the drive power supply (the amplitude of the applied voltage), the liquid crystal can be tilted in a state where the directions of the major axis directions of the liquid crystal are aligned. As a result, it is possible to shorten the time until the tilted liquid crystal orientations are aligned, and to prevent uneven brightness that temporarily occurs when the transmittance is variable. Here, “gradually” means not only continuous increase but also stepwise increase.

(2) In (1),
The light control device is:
A dimming system that gradually increases the amplitude of the rectangular wave signal by sequentially increasing the amplitude in a plurality of cycles of the rectangular wave signal.

  According to (2), the luminance that is temporarily generated when the transmittance is variable by increasing the amplitude of the rectangular wave signal stepwise in a plurality of cycles or continuously in a plurality of cycles. Unevenness can be prevented.

(3) In (1),
The light control device is:
A dimming system that gradually increases the amplitude of the rectangular wave signal by gradually increasing the amplitude in each period of the rectangular wave signal by a time constant circuit.

  According to (3), the amplitude of the rectangular wave signal can be gradually increased by dulling the rise and fall of each cycle by the time constant circuit, and the luminance temporarily generated when the transmittance is variable. Unevenness can be prevented.

(4) In (3), the light control device is
The rectangular wave signal is emitted to the light control film through a resistor,
The time constant circuit is
A light control system formed by at least the resistor and the capacitance of the light control film.

  According to (4), it is possible to gradually increase the amplitude of the rectangular wave signal with a simple configuration by effectively using the capacitance of the light control film.

(5) a light control film for controlling transmitted light by aligning liquid crystals of a liquid crystal cell sandwiched by linearly polarizing plates by a VA method;
A light control device having a drive power generation unit that outputs a rectangular wave signal to the light control film;
The light control device is:
By varying the amplitude of the rectangular wave signal in response to the operation of the operation element, the transmittance of the light control film is varied,
The light control film is
A first laminate in which a transparent electrode and an alignment layer are arranged on a substrate made of a transparent film material;
A second laminate in which a transparent electrode and an alignment layer are arranged on a substrate made of a transparent film material;
A liquid crystal layer sandwiched between the first and second laminates,
Supplying the rectangular wave signal to the transparent electrodes of the first and second laminates to control the transmitted light;
A dimming system further comprising a time constant circuit that gradually increases the amplitude of the rectangular wave signal applied to the transparent electrodes of the first and second laminates at least when the amplitude of the rectangular wave signal is increased.

  According to (5), the amplitude of the rectangular wave signal applied to the transparent electrode is gradually increased by the time constant circuit of the light control film, and the liquid crystal is tilted in a state where the directions of the liquid crystal in the major axis direction are aligned. it can. As a result, it is possible to shorten the time until the tilted liquid crystal orientations are aligned and to prevent uneven brightness that temporarily occurs when the transmittance is variable.

(6) In (5),
The time constant circuit is
A dimming system formed by at least a resistor and a capacitance between the transparent electrodes of the first and second laminates.

  According to (6), the electrostatic capacity of the light control film can be effectively used to gradually increase the amplitude of the rectangular wave signal with a simple configuration.

(7) A light control device having a drive power generation unit that outputs a rectangular wave signal to the light control film,
The light control film is
Control the transmitted light by aligning the liquid crystal of the liquid crystal cell sandwiched by the linear polarizing plate by the VA method,
The light control device is:
By varying the amplitude of the rectangular wave signal in response to the operation of the operation element, the transmittance of the light control film is varied,
A dimming device that gradually increases the amplitude of the rectangular wave signal when increasing the amplitude of the rectangular wave signal.

  According to (7), by gradually increasing the amplitude of the rectangular wave signal, the liquid crystal can be tilted in a state where the directions of the major axis directions of the liquid crystal are aligned. As a result, it is possible to shorten the time until the tilted liquid crystal orientations are aligned, and to prevent uneven brightness that temporarily occurs when the transmittance is variable.

(8) In the light control film for controlling the transmitted light by aligning the liquid crystal of the liquid crystal cell sandwiched by the linear polarizing plates by the VA method,
A first laminate in which a transparent electrode and an alignment layer are arranged on a substrate made of a transparent film material;
A second laminate in which a transparent electrode and an alignment layer are arranged on a substrate made of a transparent film material;
A liquid crystal layer sandwiched between the first and second laminates,
Controlling transmitted light according to a rectangular wave signal applied to the transparent electrodes of the first and second laminates,
The light control film which increases gradually the amplitude of the said rectangular wave signal applied to the transparent electrode of the said 1st and 2nd laminated body by a time constant circuit when the amplitude of the said rectangular wave signal increases.

  According to (8), by gradually increasing the amplitude of the rectangular wave signal, the liquid crystal can be tilted in a state where the directions of the major axis directions of the liquid crystal are aligned. As a result, it is possible to shorten the time until the tilted liquid crystal orientations are aligned, and to prevent uneven brightness that temporarily occurs when the transmittance is variable.

(9) In the drive method of the light control film which controls the transmitted light by orienting the liquid crystal of the liquid crystal cell sandwiched by the linearly polarizing plates by the VA method,
In response to the operation of the operation element, by changing the amplitude of the rectangular wave signal by the rectangular wave signal output to the light control film, the transmittance of the light control film is changed,
A method for driving a light control film, wherein the amplitude of the rectangular wave signal is gradually increased when increasing the amplitude of the rectangular wave signal.

  According to (9), by gradually increasing the amplitude of the rectangular wave signal, the liquid crystal can be tilted in a state where the directions of the major axis directions of the liquid crystal are aligned. As a result, it is possible to shorten the time until the tilted liquid crystal orientations are aligned, and to prevent uneven brightness that temporarily occurs when the transmittance is variable.

  According to the present invention, it is possible to prevent uneven brightness that temporarily occurs when the transmittance is variable in a light control film using liquid crystal.

It is sectional drawing which shows the light control film which concerns on 1st Embodiment of this invention. It is a figure where it uses for description of a measurement of brightness nonuniformity. It is a graph which shows the measurement result of the response speed at the time of sticking a light control film on curved glass. It is a graph which shows the measurement result of the response speed at the time of sticking a light control film on plane glass. It is a characteristic curve figure which shows the measurement result of the change of an electrostatic capacitance, and the change of the transmittance | permeability of a light control film. It is a figure which shows the behavior of the horizontal alignment of a liquid crystal. It is a characteristic curve figure which shows the amplitude of a rectangular wave signal. It is a figure which shows the light control system which concerns on 1st Embodiment of this invention. It is a figure where it uses for description of the drive power supply in the light modulation system of FIG. It is a figure which shows the change of the transmittance | permeability by the drive power supply of FIG. It is a figure which shows the light control system which concerns on 2nd Embodiment of this invention. It is a figure where it uses for description of the drive power supply in the light modulation system of FIG. It is a figure which shows the change of the transmittance | permeability by the drive power supply of FIG. It is a figure where it uses for description of starting of the drive power supply which concerns on 4th Embodiment of this invention. It is a figure where it uses for description of a modulation degree and a tilt angle. It is a figure which shows the relationship between the amplitude value of a rectangular wave signal, and the transmittance | permeability.

[First Embodiment]
[Light control film]
FIG. 1 is a cross-sectional view showing a light control film applied to the light control system of the present invention. This light control film 10 is a film material that controls transmitted light using liquid crystal, and controls the transmitted light by changing the orientation of the liquid crystal by the VA method by changing the applied voltage.

  The light control film 10 is configured by sandwiching a liquid crystal cell 14 for light control film between linear polarizing plates 12 and 13. Here, the linear polarizing plates 12 and 13 are formed by impregnating polyvinyl alcohol (PVA) with iodine or the like and then stretched to form an optical functional layer that performs an optical function as a linear polarizing plate. TAC (triacetyl cellulose) The optical functional layer is sandwiched between base materials made of a transparent film material such as the above. The linearly polarizing plates 12 and 13 are arranged in the liquid crystal cell 14 by an adhesive layer made of an ultraviolet curable resin or the like in a crossed Nicol arrangement. The linear polarizing plates 12 and 13 are provided with retardation films 12A and 13A for optical compensation on the liquid crystal cell 14 side, respectively, but the retardation films 12A and 13A may be omitted as necessary.

  The liquid crystal cell 14 controls the polarization plane of the transmitted light by an applied voltage to the transparent electrode described later. Thereby, the light control film 10 is comprised so that transmitted light can be controlled and various light control can be aimed at.

[Liquid crystal cell]
The liquid crystal cell 14 is configured by sandwiching a liquid crystal layer 18 between a lower laminate 15D and an upper laminate 15U which are first and second laminates in a film shape. The lower laminate 15D is formed by forming the transparent electrode 21, the spacer 22, and the alignment layer 23 on the base material 16 made of a transparent film material. The upper laminate 15U is formed by laminating a transparent electrode 26 and an alignment layer 27 on a substrate 25 made of a transparent film material. The liquid crystal cell 14 controls the orientation of the liquid crystal provided in the liquid crystal layer 18 by the VA method by driving the transparent electrodes 21 and 26 provided in the lower stacked body 15D and the upper stacked body 15U. Control the plane of polarization. In this embodiment, the liquid crystal cell 14 is configured by a single domain method, but may be configured by a multi-domain method.

  Although various transparent film materials applicable to this type of film material can be applied to the base materials 16 and 25, it is desirable to apply a film material having a small optical anisotropy. In this embodiment, although a polycarbonate film is applied to the substrates 16 and 25, a COP (cycloolefin polymer) film or the like may be applied.

  Various electrode materials applied to this kind of film material can be applied to the transparent electrodes 21 and 26. In this embodiment, the transparent electrodes 21 and 26 are formed of a transparent electrode material made of ITO (Indium Tin Oxide). The spacer 22 is provided to define the thickness of the liquid crystal layer 18 and various resin materials can be widely applied. However, in this embodiment, the spacer 22 is made of a photoresist, and is made of a transparent electrode 21. It is produced by applying a photoresist on 16 and exposing and developing. The spacer 22 may be provided on the upper laminate 15U, or may be provided on both the upper laminate 15U and the lower laminate 15D. The spacer 22 may be provided on the alignment layer 23. Further, a so-called bead spacer may be applied as the spacer.

  The alignment layers 23 and 27 are formed of a photo-alignment layer. Here, as the photo-alignment material applicable to the photo-alignment layer, various materials to which the photo-alignment technique can be applied can be widely applied. However, in this embodiment, for example, a light dimerization type material is used. . The light dimerization type material is described in “M. Schadt, K. Schmitt, V. Kozinkov and V. Chigrinov: Jpn. J. Appl. Phys., 31, 2155 (1992)”, “M. Schadt, H. Seiberle and A. Schuster: Nature, 381, 212 (1996) "and the like.

  Various liquid crystal materials applicable to this type of light control film can be widely applied to the liquid crystal layer 18. Specifically, a liquid crystal material such as MLC 2166 manufactured by Merck Co., for example, can be applied to the liquid crystal layer 18. In the liquid crystal cell 14, a sealing material 29 is disposed so as to surround the liquid crystal layer 18, and the upper stacked body 15 </ b> U and the lower stacked body 15 </ b> D are integrally held by the sealing material 29, thereby preventing leakage of the liquid crystal material. . Here, as the sealing material 29, for example, an epoxy resin, an ultraviolet curable resin, or the like can be applied.

  Thus, the light control film 10 controls the alignment of the liquid crystal provided in the liquid crystal layer 18 by the applied voltage V1 between the transparent electrodes 21 and 26 of the upper laminate 15U and the lower laminate 15D. Here, the applied voltage V <b> 1 is applied between the transparent electrodes 21 and 26 by the drive power source S <b> 1 using a rectangular wave signal whose polarity is switched at regular time intervals. In this embodiment, by applying the VA method, the liquid crystal molecules of the liquid crystal layer 18 are vertically aligned when no electric field is applied when the amplitude of the drive power supply S1 is 0 V (when the applied voltage V1 is 0 V), Thereby, the light control film 10 light-shields incident light, and will be in the light-shielding state. Further, when the amplitude of the driving power source S1 is increased and the applied voltage V1 is raised, the liquid crystal of the liquid crystal layer 18 is horizontally aligned, and the light control film 10 transmits incident light.

[Brightness unevenness]
FIG. 2 is a diagram for explaining the light control film 10 used for checking luminance unevenness that occurs when the transmittance is variable. In this confirmation, the light control film 10 having the configuration described above with reference to FIG. 1 was manufactured with a size of 300 mm × 300 mm. Furthermore, this light control film 10 was divided equally in the horizontal direction, and five areas indicated by reference signs A1, A2, A3, A4, and A5 were set. In addition, each region set in the horizontal direction in this way was divided into equal parts in the vertical direction, and three regions indicated by reference numerals B1, B2, and B3 were set. Further, the change in transmittance with respect to the change in the applied voltage V1 was measured at the center of each region set in this way. The driving power source S1 related to the applied voltage V1 was supplied from the center in the horizontal direction and the lower end in the vertical direction. In the light control film 10, the liquid crystal molecules were set so as to be horizontally aligned in the direction from the upper left to the lower right.

  3 and 4 are charts showing the measurement results. 3 and 4 show the results of measuring the time required for the transmittance to change to a value corresponding to the rise of the amplitude after the amplitude of the applied voltage V1 is raised. The time required for the change in transmittance described in FIGS. 3 and 4 is the time required until 90% of the transmittance corresponding to the raised amplitude is obtained. In the following, the time required to reach 90% will be appropriately referred to as response speed.

  FIG. 3 is a measurement result of the response speed when the light control film is attached to the curved glass, and FIG. 4 is a measurement result of the response speed when the light control film is attached to the flat glass. . In the measurement results of FIG. 3 and FIG. 4, although differences are seen in the regions A3 and B1 and the regions A4 and B1, the time required for the change in transmittance is from 22 milliseconds to 150 in both FIG. 3 and FIG. It turns out that it varies in the range up to milliseconds. In the light control film, due to this variation, in the region where the time required for the change is short, the region where the time required for the change is still maintained in the light-shielded state even though the light-shielding state has already been switched from the light-shielding state to the light-transmitting state. As a result, it was found that uneven brightness occurred temporarily when the transmittance was variable. It has been confirmed that this luminance unevenness does not depend on the power supply location because it occurs even when the power supply location is changed. Further, even if the thickness of the transparent electrodes 21 and 26 is changed, it is not caused by the influence of the resistance of the transparent electrodes 21 and 26.

  As a result, the investigation at the time of starting up the drive power source S1 was further advanced. FIG. 5 shows the measurement results of the change ΔC in capacitance of the liquid crystal cell constituting the light control film and the change ΔT in transmittance of the light control film. This measurement result of the transmittance is a measurement result of the central regions A3 and B2 when the light control film is attached to the flat glass. In FIG. 5, the vertical axis represents the capacitance and transmittance expressed by normalizing the measured value at each time point by setting the capacitance and transmittance corresponding to the raised amplitude to a value of 1.

  According to FIG. 5, it can be seen that the capacitance of the liquid crystal cell is saturated in a very short time, as indicated by the period T1. On the other hand, as shown by the period T2, it can be seen that the transmittance takes 300 msec or more until the saturation finally occurs after the period T1 elapses.

  Here, as indicated by arrows in FIG. 6, in the light control film 10, the liquid crystal molecules 18 </ b> A of the liquid crystal layer 18 fall from the vertical alignment state to the horizontal alignment state in a short time by raising the amplitude of the applied voltage V <b> 1. A period required for the collapse is a period T1 during which the capacitance changes. However, the liquid crystal molecules 18A tilted in the horizontal direction vary in the direction of the major axis, and this variation is corrected by the alignment regulating force related to the pretilt of the alignment layers 23 and 27 as indicated by the arrows for the period T2. Thus, the major axis direction of the liquid crystal molecules 18A is aligned with the direction related to the pretilt. The period required for correction after falling down in the horizontal direction is the period T2, and as a result, the period T2 requires a time of about 200 msec at the maximum. Further, when this period T2 is different in each part, luminance unevenness occurs. FIG. 6 is a diagram showing the behavior of the liquid crystal molecules 18A in the periods T1 and T2, the Z direction is the thickness direction of the liquid crystal layer 18, and the X direction and the Y direction are described above with reference to FIGS. Horizontal and vertical directions.

  Here, various causes can be considered for the variation in the period T2. However, if the liquid crystal is tilted so that the orientation of the major axis direction of the liquid crystal does not vary (horizontal alignment), the period T2 can be shortened, and further, the period T2 can be prevented from varying. Thus, it is considered that luminance unevenness when the transmittance is reduced can be prevented. Further, if the period T2 is shortened in this way, luminance unevenness can be made difficult to visually recognize. For this purpose, it is considered that if the amplitude of the applied voltage is gradually increased, the orientation of the liquid crystal in the major axis direction does not vary when the liquid crystal falls down.

  Here, FIG. 7A shows a change in the amplitude of the applied voltage V1 during the measurement described above with reference to FIGS. In the examples of FIGS. 2 and 3, the transmittance is increased by raising the amplitude of the applied voltage V1 from 0 V to 10 V, the above-described luminance unevenness occurs, and the period T2 varies.

  Therefore, in this embodiment, as shown in FIG. 7B, the amplitude of the drive voltage V1 is gradually increased by increasing the amplitude of the drive voltage V1 stepwise, for example, in three steps at short time intervals. Here, according to the results of experiments conducted by changing the time interval related to the step-up of the amplitude, the response speed could be 50 msec or less, and the luminance unevenness could not be visually recognized.

  In the case where the amplitude is gradually increased as described above, when the amplitude is increased in three steps as shown in FIG. 7B, the liquid crystal molecules 18A fall down in three steps in the period T1 described in FIG. The liquid crystal molecules 18A are tilted while being aligned in the same direction, and in this case, it is not necessary to change the orientation of the liquid crystal molecules 18A in the in-plane direction. it is conceivable that.

  Here, as shown in FIG. 7C, the increase in the amplitude may be continuously increased by the characteristic of the linear function, the characteristic of the logarithmic function, or the like instead of the stepwise increase.

[Light control system]
FIG. 8 is a diagram showing a light control system according to this embodiment. The dimming system 1 is applied to, for example, a passenger car, and holds and holds the dimming film 10 on a curved surface glass of a sunroof, and the dimming system 1 is adjusted by operating up and down operators 2U and 2D provided in a console box or the like. The transmittance of the light control film 10 is controlled by the optical device 3. For this reason, the light control device 3 outputs the drive power source S1 to the light control film 10, and varies the amplitude of the drive power source S1 in response to the operation of the operation elements 2U and 2D.

  That is, in the light control device 3, the drive power generation unit 5 is a power supply circuit that generates and outputs the drive power S1. The drive power generation unit 5 generates the drive power S1 from a rectangular wave signal having a duty ratio of 50% and a frequency of 30 Hz, and outputs the drive power S1 to the light control film 10. In addition, this frequency can be set to a low frequency in a range that does not cause deterioration of the liquid crystal in the light control film 10, and power loss due to the capacitance of the light control film 10 can be reduced. It is desirable to output at a frequency of 1 Hz to 120 Hz, more preferably 1 Hz to 30 Hz. The drive power generator 5 varies the amplitude of the drive power S 1 under the control of the controller 4.

  The controller 4 is a control circuit that controls the operation of the light control device 3, and records and holds information related to light control of the light control film 10 in a storage unit (not shown). Here, the information related to the dimming control is information specifying the relationship between the amplitude of the drive power source S1 and the transmittance, for example. When the supply of power from the vehicle is started, the controller 4 outputs the drive power S1 according to the default setting. Thereby, in this light control system 1, for example, the drive power supply S1 is output according to the setting at the time of power-off, or the drive power supply S1 is output so as to be in a light shielding state.

  When the drive power source S1 is output in this way and the up operation element 2U or the down operation element 2D is pressed, the amplitude of the drive power supply S1 is increased or decreased to correspond to this operation, and the operation is thereby performed. The transmittance is varied in response to the operation of the children 2U and 2D. In this process, the controller 4 changes the amplitude of the drive power source S1 so that the transmittance is sequentially changed by a constant value by the operation of the operation elements 2D and 2U based on the information relating to the light control stored and held in the storage means. To do.

  On the other hand, when the operation elements 2D and 2U are pressed for a long time, the amplitude of the drive power source S1 is varied so that the transmittance is largely changed. In increasing the amplitude of the drive power source S1, when increasing the amplitude, the controller 4 gradually increases the amplitude of the rectangular wave signal, thereby preventing luminance unevenness.

  Specifically, as shown in FIG. 9, the controller 4 gradually increases the amplitude of the rectangular wave signal in a plurality of cycles of the drive power source S1 that is a rectangular wave signal. That is, in the example of FIG. 9, the amplitude is increased in a linear function in three cycles of the drive power source S1. In this way, the change ΔT in the passage rate is changed to 90% transmittance in a period of approximately two cycles, which is three cycles or less, thereby preventing luminance unevenness.

  FIG. 10 is a characteristic curve diagram showing the change in transmittance with the amplitude change in FIG. 9 by comparison with the measurement result in FIG. The measurement result in FIG. 5 is indicated by reference numeral T1, and the change in transmittance in the example of FIG. 9 is indicated by reference numeral T2. According to FIG. 10, it is possible to confirm a marked improvement in response speed.

  When the liquid crystal is driven by the AV method, the orientation of the liquid crystal molecules 18A is in a range where the amplitude of the rectangular wave signal is 25% or more and 50% or less with respect to the amplitude of the rectangular wave signal having a modulation degree of 100%. It can be said that the change in transmittance due to the change is a large range. In this range, the period T2 becomes longer due to a sudden increase in amplitude, and the variation in the period T2 also increases. The modulation degree is a ratio of the transmittance indicating that the transmittance is most increased as 100% modulation. When the transmittance is variable, the variation of the transmittance in each part increases.

  In the example of FIG. 9, when the amplitude of the drive voltage V1 is increased so as to cross the range of 25% or more and 50% or less, the amplitude is increased in three cycles to ensure the response speed in the period of two cycles. , Brightness unevenness can be prevented. As a result, the amplitude of the rectangular wave signal is gradually increased, such as by gradually increasing the amplitude of the rectangular wave signal only when the amplitude is varied within the range of 25% to 50%, for example, 10% or more. The application conditions in the case of making them can be set variously as needed.

  According to this embodiment, when the amplitude of the rectangular wave signal is increased, by gradually increasing the amplitude of the rectangular wave signal, the liquid crystal molecules fall down while being aligned in the same direction, and thereby the orientation of the liquid crystal molecules is bothered. Since there is no need to change so as to align in the in-plane direction, the response speed can be improved and luminance unevenness can be prevented.

  Further, at this time, the luminance unevenness can be prevented by a specific configuration by sequentially increasing the amplitude in a plurality of cycles of the driving power source by the rectangular wave signal.

[Second Embodiment]
FIG. 11 is a diagram showing a light control system according to the second embodiment of the present invention. The light control system 31 is configured in the same manner as the light control system 1 except that a light control device 33 is applied instead of the light control device 3. Here, in the dimming device 33, the drive power generation unit 35 outputs the drive power S1 with the amplitude varied under the control of the controller 34. The controller 34 responds to the operation of the operation elements 2U and 2D and controls each part. Control the behavior. In this embodiment, the light control device 33 includes a resistor R1 on the cold output line of the drive power source S1, and a rectangular wave is generated by a time constant circuit formed by the resistor R1 and the capacitance of the light control film 10. Brightness unevenness is prevented by gradually increasing the amplitude of the signal. This embodiment has the same configuration as that of the first embodiment except that the configuration related to the rise of the amplitude is different.

  That is, the light control film 10 is held so that the transparent electrodes 21 and 26 are opposed to each other with an interval depending on the thickness of the liquid crystal layer 18, thereby providing a capacitance. Thus, if the resistor R1 is provided on the ground side (cold side) output line of the drive power source S1 and the drive power source S1 is supplied via the resistor R1, the time constant circuit is formed by the capacitance and the resistor R1. Thus, the waveform of the driving power supply applied to the transparent electrodes 21 and 26 is blunted. As a result, as shown in FIG. 12B by comparison with a state where the waveform is not blunted (FIG. 12A), the polarity of the voltage V1 in each cycle of the driving power source S1 by the rectangular wave signal is changed. The amplitude of the rectangular wave signal will gradually increase. Here, the waveform dullness of the drive power supply can be adjusted by the resistor R1.

  Based on this principle, the light control device 33 gradually increases the amplitude of the drive power source S1 to prevent uneven brightness. However, when the waveform of the drive power source S1 is dulled as described above, power is consumed by the resistor R1, and the power consumption increases. Therefore, the dimmer 33 is provided with a switch circuit 37 in parallel with the resistor R1, and both ends of the resistor R1 are short-circuited by the switch circuit 37 to prevent useless power consumption. Specifically, the switch circuit 37 is set to an ON state except when it is necessary to prevent luminance unevenness, thereby preventing wasteful power consumption. When it is necessary to prevent this luminance unevenness, for example, as described above with respect to the first embodiment, the amplitude of the drive power source S1 is in the range of 25% to 50% with respect to the drive voltage with a modulation degree of 100%. In the case where the magnitude of the variable amplitude is 12.5% or more.

  Further, even when the switch circuit 37 is set to an off state in order to prevent uneven brightness, the switch circuit 37 is switched to an off state when the amplitude is increased and a certain time (for example, 200 msec) elapses. Prevents wasteful power consumption. Here, the resistor R1 and the switch circuit 37 may be provided on both of the drive power supply output lines or on the hot side. In addition, resistance R1 can be suitably set according to the electrostatic capacitance of the light control film which changes with the magnitude | size of a light control film according to the time constant desired. Note that the switch circuit 37 may be omitted as necessary.

  FIG. 13 is a characteristic curve diagram showing measurement results of transmittance and amplitude according to this embodiment. In the measurement result of FIG. 13, the time constant was set from 0.5 milliseconds to 2 milliseconds, and the response speed could be set to about 0.03 seconds. As a result, when the amplitude is gradually increased in each cycle of the drive power source by the time constant circuit in this way, the variation in response speed in each part is simply reduced by the liquid crystal molecules falling together, and the luminance unevenness is reduced. Can be prevented.

  According to this embodiment, the same effect as that of the first embodiment can be obtained by gradually increasing the amplitude in each cycle of the drive power supply by the time constant circuit.

  In addition, by forming this time constant circuit with the resistor provided in the output line of the drive power supply of the light control device and the electrostatic capacity of the light control film, the electrostatic capacity of the light control film can be effectively achieved with a simple configuration. It is possible to prevent luminance unevenness by using it.

[Third Embodiment]
In this embodiment, the resistor R1 described above for the second embodiment is provided on the light control film side. In this case, the switch circuit 37 may also be provided on the light control film, and the on / off control may be performed by the light control device. This embodiment has the same configuration as that of the second embodiment except that the configuration regarding the resistor R1 is different.

  In this embodiment, by providing a resistance to the light control film to form a time constant circuit, the light control device is commonly used in various light control films, and the same effect as in the second embodiment is obtained. be able to.

[Fourth Embodiment]
FIG. 14 is a diagram for explaining a light control system according to the fourth embodiment of the present invention. The dimming system according to this embodiment has the same configuration as that of the above-described embodiment except that the method of increasing the amplitude at the time of starting the amplitude shown in FIG. 14 is different.

  In this embodiment, as indicated by reference numeral V1B, when the amplitude is increased in a certain range, the driving power supply is increased by a certain value VA with a certain polarity in advance for a certain period TA. Thereafter, in this embodiment, the drive power supply is raised to an amplitude corresponding to the user's instruction and driven by a rectangular wave signal. As a result, in this embodiment, the amplitude of the rectangular wave signal is gradually increased by two steps based on the predetermined constant value VA and the amplitude corresponding to the user's instruction, and luminance unevenness that temporarily occurs when the transmittance is variable is reduced. To prevent. In FIG. 14, the applied voltage when driven by a driving power source using a rectangular wave signal is denoted by reference symbol V1A, and the change in transmittance in this case is denoted by reference symbol ΔT1.

  Here, the fixed period TA is a period of 5 to 10 milliseconds. If a shorter time is set, the liquid crystal molecules do not move and the response speed improvement effect cannot be obtained. Further, if the length is longer than this, it can be visually recognized that the liquid crystal molecules operate to a modulation degree lower than the desired modulation degree, and further operate to two stages up to the desired transmittance. In such a short time, it seems to operate continuously.

  Further, the predetermined range for increasing the amplitude in advance is the same as the case where the amplitude of the rectangular wave signal according to the above-described embodiment is gradually increased, and there is a possibility that uneven brightness may occur.

  The constant value VA is a voltage corresponding to a modulation degree of 0% or more and 80% or less. For example, a voltage that modulates about 20% according to a final amplitude value corresponding to a user's instruction. It can be set arbitrarily within the range.

  Here, as shown in FIG. 15, the modulation degree of the liquid crystal molecules changes due to the change of the tilt angle. When the tilt angle is 90 and the liquid crystal molecules are horizontally aligned, the modulation degree is 1 and the tilt angle is 0 degree. In the case of vertical alignment, the modulation degree is zero. Here, when the degree of modulation is 0% or more and 80% or less (the range indicated by the symbol M), the light control film has a high effect of reducing luminance unevenness by gradually increasing the amplitude. This is a case where the degree of modulation exceeds 80%. When the liquid crystal molecules are largely inclined, the liquid crystal molecules are already oriented in various directions, so that even if the amplitude is gradually increased, the driving unevenness can be improved. On the other hand, when the degree of modulation is 80% or less, the liquid crystal molecules are not tilted greatly, and the amplitude of the rectangular wave signal can be gradually raised to sufficiently align the liquid crystal molecules and bring down the brightness unevenness. Can be reduced. Here, this range is a range M of 5 degrees or more and 55 degrees or less according to the tilt angle.

  Here, in the range of the tilt angle, as shown in FIG. 16, the amplitude of the rectangular wave signal is in the range of 2.5V to 5V.

  Thereby, in this embodiment, the constant value VA is set to 2.5V or more and 5V or less in advance by increasing the driving power source by a constant value VA with a certain polarity.

  According to this embodiment, the drive power supply is increased by a fixed value VA with a fixed polarity in advance for a fixed period TA, and then the amplitude of the rectangular wave signal is gradually increased by driving with the rectangular wave signal. Even if it does, the effect similar to the above-mentioned embodiment can be acquired.

[Other Embodiments]
The specific configuration suitable for the implementation of the present invention has been described in detail above. However, the present invention can be variously combined and further modified without departing from the spirit of the present invention. .

DESCRIPTION OF SYMBOLS 1,31 Light control system 2D, 2U Operator 3, 33 Light control apparatus 4, 34 Controller 5, 35 Drive power generation part 10 Light control film 12, 13 Linearly polarizing plate 12A, 13A Phase difference film 14 Liquid crystal cell 15D Lower side Laminated body 15U Upper laminated body 16, 25 Base material 18 Liquid crystal layer 18A Liquid crystal molecule 21, 26 Transparent electrode 21 Dimming system 22 Spacer 23, 27 Alignment layer 29 Sealing material 37 Switch circuit

Claims (9)

A light control film for controlling the transmitted light by aligning the liquid crystal of the liquid crystal cell sandwiched by the linear polarizing plates by the VA method;
A light control device having a drive power generation unit that outputs a rectangular wave signal to the light control film;
The light control device is:
By varying the amplitude of the rectangular wave signal in response to the operation of the operation element, the transmittance of the light control film is varied,
A dimming system that gradually increases the amplitude of the rectangular wave signal when increasing the amplitude of the rectangular wave signal. The light control device is:
The dimming system according to claim 1, wherein the amplitude of the rectangular wave signal is gradually increased by sequentially increasing the amplitude in a plurality of cycles of the rectangular wave signal. The light control device is:
The dimming system according to claim 1, wherein the amplitude of the rectangular wave signal is gradually increased by gradually increasing the amplitude in each period of the rectangular wave signal by a time constant circuit. The light control device is:
The rectangular wave signal is emitted to the light control film through a resistor,
The time constant circuit is
The light control system according to claim 3, wherein the light control system is formed by at least the resistor and a capacitance of the light control film. A light control film for controlling the transmitted light by aligning the liquid crystal of the liquid crystal cell sandwiched by the linear polarizing plates by the VA method;
A light control device having a drive power generation unit that outputs a rectangular wave signal to the light control film;
The light control device is:
By varying the amplitude of the rectangular wave signal in response to the operation of the operation element, the transmittance of the light control film is varied,
The light control film is
A first laminate in which a transparent electrode and an alignment layer are arranged on a substrate made of a transparent film material;
A second laminate in which a transparent electrode and an alignment layer are arranged on a substrate made of a transparent film material;
A liquid crystal layer sandwiched between the first and second laminates,
Supplying the rectangular wave signal to the transparent electrodes of the first and second laminates to control the transmitted light;
A dimming system further comprising a time constant circuit that gradually increases the amplitude of the rectangular wave signal applied to the transparent electrodes of the first and second laminates at least when the amplitude of the rectangular wave signal is increased. The time constant circuit is
The light control system according to claim 5, wherein the light control system is formed by at least a resistor and a capacitance between the transparent electrodes of the first and second stacked bodies. A light control device having a drive power generation unit that outputs a rectangular wave signal to a light control film,
The light control film is
Control the transmitted light by aligning the liquid crystal of the liquid crystal cell sandwiched by the linear polarizing plate by the VA method,
The light control device is:
By varying the amplitude of the rectangular wave signal in response to the operation of the operation element, the transmittance of the light control film is varied,
A dimming device that gradually increases the amplitude of the rectangular wave signal when increasing the amplitude of the rectangular wave signal. In the light control film for controlling the transmitted light by aligning the liquid crystal of the liquid crystal cell sandwiched by the linear polarizing plates by the VA method,
A first laminate in which a transparent electrode and an alignment layer are arranged on a substrate made of a transparent film material;
A second laminate in which a transparent electrode and an alignment layer are arranged on a substrate made of a transparent film material;
A liquid crystal layer sandwiched between the first and second laminates,
Controlling transmitted light according to a rectangular wave signal applied to the transparent electrodes of the first and second laminates,
The light control film which increases gradually the amplitude of the said rectangular wave signal applied to the transparent electrode of the said 1st and 2nd laminated body by a time constant circuit when the amplitude of the said rectangular wave signal increases. In the drive method of the light control film which controls the transmitted light by orienting the liquid crystal of the liquid crystal cell sandwiched between the linear polarizing plates by the VA method,
In response to the operation of the operation element, by changing the amplitude of the rectangular wave signal by the rectangular wave signal output to the light control film, the transmittance of the light control film is changed,
A method for driving a light control film, wherein the amplitude of the rectangular wave signal is gradually increased when increasing the amplitude of the rectangular wave signal.

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