JP5584606B2 - LCD shutter device - Google Patents

Description

  The present invention relates to a liquid crystal shutter device used in combination with an image display device that allows a user to perceive a stereoscopic display.

  JP-A-6-178325 (Patent Document 1) and JP-A-2002-82307 (Patent Document 2) use liquid crystal shutter glasses that open and close the left and right shutters in synchronization with the left and right images for stereoscopic display. 3D display technology has been disclosed.

  The prior examples represented by Patent Documents 1 and 2 are excellent technologies that can be widely applied to display devices other than liquid crystal display devices. However, Patent Document 1 does not disclose a specific configuration of the shutter glasses. Similarly, Patent Document 2 does not disclose the specific configuration of shutter glasses, but in view of the description in paragraph 0037 and the like of the document, the substance of the liquid crystal-encapsulated glass constituting the shutter glasses is a TN type. Presumed to be a liquid crystal element.

  On the other hand, it is also conceivable to use a vertical alignment type liquid crystal element as the liquid crystal element constituting the shutter glasses (liquid crystal shutter device). In general, a vertical alignment type liquid crystal element has an excellent light-shielding property and has a feature of having a very wide viewing angle, and has an advantage that crosstalk in which left and right images for stereoscopic display are mixed is less likely to occur. .

  By the way, when a vertical alignment type liquid crystal element is used and its excellent light shielding property is to be utilized, there is a setting (so-called normally black) which becomes a light shielding state when the voltage applied to the liquid crystal element is turned off. desirable. However, in this case, when the voltage supply to the liquid crystal element is stopped, such as after the end of viewing of the 3D image, the shutter glasses are in a dark state (low transmittance state). There is an inconvenience that it is difficult to move from the seat while wearing. On the other hand, there is an idea that voltage application to the liquid crystal element may be continued, but in this case, there is a disadvantage that the battery is consumed even when the shutter glasses are not used. Usually, a battery such as a button battery or a rechargeable battery is used as a power source for the shutter glasses, so it is important to suppress power consumption.

JP-A-6-178325 JP 2002-82307 A

  A specific aspect of the present invention is to provide an easy-to-use liquid crystal shutter device that reduces power consumption while maintaining good light shielding properties.

A liquid crystal shutter device according to an aspect of the present invention is a liquid crystal shutter device that is used in combination with an image display device that alternately displays a right-eye image and a left-eye image, and includes: (a) a pair of shutter elements; ) Including a control device that selectively operates the pair of shutter elements in response to switching between the image for the right eye and the image for the left eye by the image display device, and each of the pair of shutter elements includes (c) And (d) a liquid crystal layer that is substantially vertically aligned when no voltage is applied and whose alignment is uniformly inclined when a voltage is applied. to which, the voltage is applied during such a manner the second and the first polarization plate with an angle of approximately 45 ° orientation direction with respect to the absorption axis of each of said second polarizer and said first polarizer Arranged between polarizing plates Comprising a liquid crystal element, (e) said controller, wherein each on-voltage alternately to the liquid crystal element of the pair of shutter elements when the image display is being performed by the image display device and the off-voltage And when the image display by the image display device is stopped , the on- voltage is applied to both of the liquid crystal elements of each of the pair of shutter elements, and the electrical connection between both of the liquid crystal elements is performed. Is a liquid crystal shutter device.

  According to the above liquid crystal shutter device, when the image display is stopped, the liquid crystal element is disconnected from the electrical connection with the liquid crystal element while applying a driving voltage to the liquid crystal element, so that the liquid crystal layer has a voltage holding characteristic of the liquid crystal layer. The state close to the state in which the drive voltage is applied is maintained for a time corresponding to. As a result, the liquid crystal shutter device remains transparent or close to a certain amount of time. That is, the above-described liquid crystal shutter device exhibits excellent light shielding properties by using a vertical alignment type liquid crystal element during image display, and is transparent without consuming power for a while after the voltage supply to the liquid crystal element is stopped. Or keep it close. For this reason, a liquid crystal shutter device with low power consumption and easy to use for the user is realized. Note that in order to extend the time during which the transparent state or the state close thereto is maintained, a liquid crystal element may be configured by selecting a liquid crystal material, an alignment film, or the like that has a higher voltage holding ratio.

  The control device includes, for example, (f) a driving device that supplies a driving voltage to each of the liquid crystal elements, (g) a switching element connected between each of the liquid crystal elements and the driving device, and (h) ) A display detection unit that detects that image display by the image display device has stopped; and (i) a switching control unit that controls the switching element to a conductive state or a cut-off state.

Further, the control device applies the on- voltage to each of the liquid crystal elements of the pair of shutter elements when a predetermined time has elapsed after electrically disconnecting from the liquid crystal element. It is also preferable to disconnect the electrical connection between the two .

  Thereby, the liquid crystal shutter element can be refreshed again to a transparent state or a state close thereto before the transmittance of the liquid crystal shutter element is lowered.

  The control device further includes, for example, (j) a time measurement unit that measures an elapsed time in response to the switching element being controlled to be in a cut-off state by the switching control unit.

The driving method of the liquid crystal shutter device according to one aspect of the present invention is any one of the above-described driving methods of the liquid crystal shutter device, and the pair of the liquid crystal shutter devices when the image display by the image display device is performed by the control device. When an on-voltage and an off-voltage are alternately applied to the liquid crystal elements of each of the shutter elements, and image display by the image display device is stopped , both of the liquid crystal elements of each of the pair of shutter elements On the other hand, this is a driving method in which the electrical connection between both of the liquid crystal elements is interrupted while an on- voltage is applied.

  According to the above-described driving method of the liquid crystal shutter device, when the image display is stopped, the liquid crystal element is disconnected from the liquid crystal layer by cutting off the electrical connection with the liquid crystal element while applying the driving voltage to the liquid crystal element. The state close to the state where the drive voltage is applied is maintained for a time corresponding to the voltage holding characteristic. As a result, the liquid crystal shutter device remains transparent or close to a certain amount of time. That is, the above-described driving method of the liquid crystal shutter device exhibits an excellent light shielding property by using a vertical alignment type liquid crystal element, and does not consume power for a while after the voltage supply to the liquid crystal element is stopped. Maintain transparency or close to it. For this reason, a liquid crystal shutter device with low power consumption and easy to use for the user is realized. In order to extend the time during which the transparent state or the state close thereto is maintained, a liquid crystal element may be configured by selecting a liquid crystal material, an alignment film, or the like that has a higher voltage holding ratio.

It is a typical perspective view showing a schematic structure of a liquid crystal shutter device of one embodiment. It is typical sectional drawing which shows the detailed structure of each shutter element. It is a figure which shows the example of arrangement | positioning of the optical axis in each structure of a shutter element. It is a block diagram which shows the structural example of the control apparatus of a liquid-crystal shutter apparatus. It is a flowchart which shows about the drive methods other than the time of image appreciation of a liquid-crystal shutter device. It is a block diagram which shows the other structural example of the control apparatus of a liquid-crystal shutter apparatus. It is a figure explaining arrangement | positioning of the transmission axis of a polarizing plate. It is a figure which shows the voltage retention rate dependence of the charging time of the liquid crystal layer with respect to static electricity. It is a figure which shows the relationship between the post-baking temperature of an alignment film, and charging time. It is a figure which shows the relationship between the post-baking temperature of an alignment film, and charging time. It is a figure which shows the solid content concentration dependence of the charging time of alignment film.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic perspective view illustrating a schematic configuration of a liquid crystal shutter device according to an embodiment. The liquid crystal shutter device 1 of this embodiment shown in FIG. 1 has a pair of shutter elements 11a and 11b. The pair of shutter elements 11a and 11b are arranged side by side in one direction across a predetermined position corresponding to the average distance between both eyes of a human, and are configured in glasses, for example, as shown in FIG. . The liquid crystal shutter device 1 is used in combination with an image display device 3 that alternately displays a right-eye image and a left-eye image.

  FIG. 2 is a schematic cross-sectional view showing a detailed configuration of each shutter element. As shown in FIG. 2, each shutter element 11a, 11b has an upper polarizing plate 13, an optical compensation plate 14, a liquid crystal cell (liquid crystal element) 15, an optical compensation plate 16, and a polarizing plate 17.

  The upper polarizing plate 13 is disposed opposite to the lower polarizing plate 17 with the liquid crystal cell 15 or the like interposed therebetween. The upper polarizing plate 13 is disposed on the side far from the visual recognition position with respect to the visual recognition position, that is, the side close to the image display device 3 when the shutter elements 11a and the like are mounted on the user. Further, the lower polarizing plate 17 is arranged on the side closer to the visual recognition position with respect to the visual recognition position when the shutter elements 11a and the like are attached to the user, in other words, on the side far from the image display device 3. The The upper polarizing plate 13 and the lower polarizing plate 17 are arranged so that their absorption axes are substantially orthogonal.

  The optical compensation plate 14 is disposed between the upper polarizing plate 13 and the liquid crystal cell 15. Similarly, the optical compensation plate 16 is disposed between the lower polarizing plate 17 and the liquid crystal cell 15. Each of the optical compensation plates 14 and 16 in the present embodiment is an optical plate (biaxial plate) having negative biaxial optical anisotropy. The in-plane slow axis of the optical compensation plate 14 is disposed substantially parallel to the transmission axis of the upper polarizing plate 13. Similarly, the in-plane slow axis of the optical compensation plate 16 is arranged substantially parallel to the transmission axis of the lower polarizing plate 17. Each of the optical compensation plates 14 and 16 has, for example, an in-plane retardation of about 45 nm and a thickness direction retardation of about 120 nm.

  The liquid crystal cell 15 has a uniaxial alignment state in which the alignment state of the liquid crystal layer when no voltage is applied is substantially vertical. As shown, the liquid crystal cell 15 includes an upper substrate 21, an upper electrode 22, an alignment film 23, a lower substrate 24, a lower electrode 25, an alignment film 26, and a liquid crystal layer 27.

  The upper substrate 21 and the lower substrate 24 are transparent substrates such as a glass substrate and a plastic substrate, respectively. Since the plastic substrate has advantages such as being light, difficult to break, and easy to bend, it is more preferable for forming the shutter elements 11a and 11b into glasses. In this case, a plastic substrate having a gas barrier layer or the like is more preferable. Between the upper substrate 21 and the lower substrate 24, spacers (granular bodies) are dispersed and arranged. By these spacers, the gap between the upper substrate 21 and the lower substrate 24 is kept at a predetermined distance (for example, about 2.0 μm).

  The upper electrode 22 is provided on one surface of the upper substrate 21. Similarly, the lower electrode 25 is provided on one surface of the lower substrate 24. Each of the upper electrode 22 and the lower electrode 25 is configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example.

  The alignment film 23 is provided on one surface side of the upper substrate 21 so as to cover the upper electrode 22. Similarly, the alignment film 26 is provided on one surface side of the lower substrate 24 so as to cover the lower electrode 25. In the present embodiment, as the alignment film 23 and the alignment film 26, a film (vertical alignment film) that restricts the alignment state of the liquid crystal layer 27 in the initial state (when no voltage is applied) to a substantially vertical alignment is used. Each alignment film 23, 26 is subjected to an alignment process (for example, a rubbing process). Each alignment film 23, 26 gives a pretilt angle to the liquid crystal molecules of the liquid crystal layer 27 in the vicinity of the interface of the liquid crystal layer 27. In the present embodiment, a pretilt angle of about 89 ° is given. The upper substrate 21 and the lower substrate 24 are aligned so that the alignment processing direction (for example, the rubbing direction) for the alignment films 23 and 26 is in an anti-parallel state. Thereby, the liquid crystal layer 27 is controlled to a substantially vertical alignment having a pretilt angle smaller than 90 °. Note that only one of the alignment films 23 and 26 may be subjected to alignment treatment. Further, the alignment treatment is not limited to the rubbing treatment, and may be a photo-alignment method or the like.

  The liquid crystal layer 27 is provided between the upper electrode 22 of the upper substrate 21 and the lower electrode 25 of the lower substrate 24. In the present embodiment, the liquid crystal layer 27 is configured using a liquid crystal material (nematic liquid crystal material) having a negative dielectric anisotropy Δε (Δε <0). The thick line shown in the liquid crystal layer 27 schematically shows the alignment direction (director) of liquid crystal molecules when no voltage is applied. In the liquid crystal display device of the present embodiment, the alignment state of the liquid crystal molecules of the liquid crystal layer 27 is set to a substantially vertical alignment having a pretilt angle of about 89 ° in the initial state (no voltage applied state). When a voltage is applied to the liquid crystal layer 27, the alignment state of the liquid crystal layer 27 changes so that the major axis direction of the liquid crystal molecules intersects the electric field direction. The retardation of the liquid crystal layer 27 is about 300 nm.

  FIG. 3 is a diagram illustrating an arrangement example of the optical axes in each configuration of the shutter element. The reference (0 °) of the orientation of each optical axis is as shown in the figure. A state is assumed in which the shutter elements 11a and 11b are arranged in a substantially horizontal direction (left and right direction of the image display device 3). In this state, for example, when the shutter elements 11a and 11b are configured in the shape of glasses as described above, the user wears them in the same manner as the glasses and looks at the image display device 3 without tilting the neck. Corresponds to the state.

  The liquid crystal cell 15 is arranged so that the alignment direction of the liquid crystal molecules at the approximate center in the layer thickness direction of the liquid crystal layer 27 is the 12 o'clock direction. The orientation direction of the liquid crystal molecules is preferably the above 12 o'clock direction or 6 o'clock direction if importance is attached to the left and right viewing angle characteristics, but is not limited thereto. The alignment directions of the liquid crystal molecules in the liquid crystal cells 15 of the shutter element 11a and the shutter element 11b may be different from each other.

  The upper polarizing plate 13 is disposed at a position where its transmission axis is rotated approximately 45 ° counterclockwise from the 12 o'clock direction. In contrast, the lower polarizing plate 17 is disposed at a position where its transmission axis is rotated approximately 45 ° clockwise from the 12 o'clock direction. As a result, the upper polarizing plate 13 and the lower polarizing plate 17 are arranged so that their transmission axes are substantially orthogonal.

  The optical compensation plate 14 is arranged so that its in-plane slow axis is substantially parallel to the transmission axis of the upper polarizing plate 13. On the other hand, the optical compensation plate 16 is arranged so that its in-plane slow axis is substantially parallel to the transmission axis of the lower polarizing plate 17. As illustrated, the in-plane slow axes of the optical compensator 14 and the optical compensator 16 are arranged so as to be substantially orthogonal to each other.

  One (or both) of the optical compensators 14 and 16 may be omitted. In addition, the thickness direction retardation of each optical compensator 14, 16 (the total when two are used) is set to about 0.5 to about 1 times the retardation Δnd of the liquid crystal cell 15. Is preferred. The in-plane retardation of each of the optical compensation plates 14 and 16 is preferably set to about 30 nm to about 65 nm.

  FIG. 4 is a diagram illustrating a configuration example of a control device provided in the liquid crystal shutter device 1. The control device 2 controls the shutter elements 11a and 11b, and includes the drive device 12 and two switching elements 33a and 33b. As each of the switching elements 33a and 33b in the present embodiment, a field effect transistor is used.

  The driving device 12 supplies a predetermined driving voltage to the liquid crystal cells 15 of the shutter elements 11a and 11b in synchronization with the image display timing of the image display device 3. The drive device 12 supplies, for example, a rectangular wave voltage with a drive frequency of 1000 Hz to the liquid crystal cell 15. The drive voltage can be, for example, an off voltage of 0 V and an on voltage of 10 V (static drive). The driving device 12 is integrated with the shutter element 11a and the like. For example, as shown in FIG. 1, the image display device 3 and the driving device 12 are connected by wireless communication using radio waves or infrared rays. Note that the both may be wired.

  The drive device 12 includes a display detection unit 30, a switching control unit 31, and a time measurement unit 32 therein. The display detection unit 30 determines whether or not a signal (image signal as an example) indicating image display timing is supplied from the image display device 3, that is, whether or not an image is displayed by the image display device 3. The switching control unit 31 controls the disconnection state / conduction state (on / off state) of each of the switching elements 33a and 33b according to the detection result by the display detection unit 30. The time measuring unit 32 measures that a certain time has elapsed since the switching control unit 31 puts the switching elements 33a and 33b in the shut-off state.

  Next, a driving method at the time of video viewing of the liquid crystal shutter device 1 of the present embodiment will be exemplified. The above-described image display device 3 alternately displays the right-eye image and the left-eye image while switching them at a predetermined cycle in order to perform stereoscopic display. The display switching frequency is 120 Hz, for example. In this case, the image for the right eye and the image for the left eye are switched every about 8.3 milliseconds. When the image display device 3 performs what is called double speed display, the display switching frequency is 240 Hz. In this case, the image for the right eye and the image for the left eye are switched every about 4.2 milliseconds.

  At this time, in the liquid crystal shutter device 1, the driving device 12 drives the shutter elements 11 a and 11 b in accordance with the display switching timing of the image display device 3. For example, in the frame in which the image for the right eye is displayed, an ON voltage is applied from the driving device 12 to the shutter element 11b associated with the user's right eye, and the shutter element 11a associated with the user's left eye is applied. The off voltage is applied from the drive unit 12. As a result, the shutter element 11b is in a light transmission state and the shutter element 11a is in a light-shielding state, so that the user can see the right-eye image only with the right eye. Conversely, in the frame in which the image for the left eye is displayed, an ON voltage is applied from the driving device 12 to the shutter element 11a associated with the user's left eye, and the shutter element 11b associated with the user's right eye. The off voltage is applied from the driving device 12 to the motor. Accordingly, the shutter element 11a is in a light transmission state and the shutter element 11b is in a light-shielding state, so that the user can visually recognize the left-eye image only with the left eye. By performing these operations in synchronization with the switching timing of the right-eye image and the left-eye image by the image display device 3, the user can visually recognize a three-dimensional display.

  Next, a driving method of the liquid crystal shutter device 1 other than during video viewing will be described with reference to the flowchart shown in FIG. It is assumed that the liquid crystal shutter device 1 and the image display device 3 are connected by wireless communication or wired communication.

  When the display detection unit 30 detects that the image signal is in a non-output state, that is, the image display is stopped (step S11), the driving device 12 applies an on-voltage to the liquid crystal cells 15 of the shutter elements 11a and 11b. Is supplied (step S12). At this time, the switching elements 33a and 33b are in a conductive state.

  Next, in a state where the supply of the on-voltage is maintained, the switching control unit 31 disconnects the switching elements 33a and 33b (step S13). As a result, the liquid crystal cell 15 is electrically opened, and the operation state (ON state) at that time is kept long. For this reason, the shutter elements 11a and 11b are kept in a high transmittance state (transparent state) for a while. The length of time for which the transparent state is maintained is mainly influenced by the voltage holding ratio of the liquid crystal cell 15. For this reason, as the liquid crystal cell 15, it is preferable to use a liquid crystal material having a very high resistance value, and use an alignment film having a higher voltage holding ratio and a thinner film thickness.

  Next, the driving device 12 stops the supply of the on-voltage to the liquid crystal cell 15 (step S14).

  The time measuring unit 32 measures that a predetermined time (for example, several minutes to several tens of minutes) has elapsed after the switching elements 33a and 33b are controlled to be disconnected and the voltage supply to the liquid crystal cell 15 is stopped. Then (step S15), the switching control unit 31 again controls the switching elements 33a and 33b to be in a conductive state (step S16).

  Thereafter, the process returns to step S12 and the subsequent operations are repeated. Thereby, each shutter element 11a, 11b can be maintained in a transparent state semipermanently. In addition, since the electrode supply to the liquid crystal cell 15 is intermittent, the power consumption is extremely small.

  FIG. 6 is a block diagram showing another configuration example of the control device for the liquid crystal shutter device. The control device 2a illustrated in FIG. 6 includes a drive device 12a, a display detection unit 30a, a switching control unit 31a, and a time measurement unit 33a. In this example, the display detection unit 30a, the switching control unit 31a, and the time measurement unit 33a are integrally configured, and are separated from the driving device 12a. The function of each part is the same as described above. In this way, a configuration in which the drive device and the other device are separated may be employed.

(Example)
Hereinafter, embodiments of the liquid crystal shutter device, particularly embodiments of the shutter elements 11a and 11b will be described.

  First, ITO (indium tin oxide), which is a transparent electrode, is formed on a glass substrate (plate thickness: 0.7 mm) to a film thickness of about 500 mm to 1000 mm by a method such as vapor deposition or sputtering, and a desired shape is formed by a photolithography process. Shaped. An insulating film is formed on the glass substrate with the ITO film at a predetermined position by vapor deposition, sputtering or flexographic printing. Specifically, it is formed in the shutter pixel portion and the main seal portion, but not in the conducting portion and the terminal portion. This insulating film is not always necessary, but it is desirable to form it in order to prevent a short circuit between the upper and lower substrates. In the example, an insulating film was formed by sputtering. Next, a vertical alignment film having substantially the same pattern is formed on the insulating film. This is formed in the shutter pixel portion and not in the main seal portion, the conductive portion, and the terminal portion. As a method for obtaining uniform monodomain alignment, for example, a method described in JP-A-2005-234254 may be used. In the examples, alignment films were formed using several commercially available alignment film materials. After the film formation, baking was performed at 160 to 200 ° C. for 30 to 120 minutes.

  Next, a rubbing process which is one of the alignment processes was performed. The rubbing process is a process in which a cylindrical roll wound with a cloth is rotated at a high speed and rubbed on the alignment film, whereby liquid crystal molecules can be aligned uniaxially. In the example, the rubbing process was performed so that the alignment state between the upper and lower substrates was in an antiparallel (antiparallel) state. About the pushing amount which is one of the parameters of a rubbing process, it was about 0.3 mm-0.6 mm. In addition, the numerical value of this pushing amount is an example. In addition, although rubbing is given as an example of the alignment treatment here, a photo-alignment method, an ion beam alignment method, a plasma beam alignment method, an oblique deposition method, or the like may be used.

Next, a sealant for bonding the upper and lower substrates was printed in a predetermined pattern. When a vacuum injection method is used in the subsequent step of injecting the liquid crystal material, a pattern having an injection port is used. When an ODF method is used, a closed pattern without an injection port is used. The screen printing method is used for printing here, but a dispenser or the like may be used. Although the thermosetting material is used as the sealant, a photocurable sealant or a combined light / heat type sealant may be used. As the sealant, a material of a type that can be pushed into a thin gap is desirable. This sealant contains 1-3 wt% of silica balls having a particle diameter of 2 μm. Alternatively, a sealant including a plastic ball coated with gold as a conductive material may be printed at a predetermined position. Here, screen printing was performed by using 2 wt% of gold balls with a particle size of 2 μm contained in the same sealant as described above as a conductive material between the electrodes of the upper and lower substrates. A sealant pattern (and a conductive material pattern) was formed only on one substrate, and a gap control agent was sprayed on the opposite substrate by a dry spraying method. As the gap agent, 2 μm plastic balls were used, but silica balls may be used. The gap agent used was a surface treatment that did not disturb the alignment of the liquid crystal molecules, and a treatment that was fixed on the substrate by heat treatment after spraying. The application rate was set to about 300 to 700 pieces / mm ² .

  After spraying, the substrate was heat-treated (100 ° C. to 150 ° C. for 30 minutes to 60 minutes) to fix the gap agent on the substrate. The upper and lower substrates were superposed at predetermined positions to form cells, and the sealing agent was cured by heat treatment in a pressed state. Next, the glass substrate was scratched with a scriber device and divided into a predetermined size and shape by breaking. A liquid crystal material of Δε <0 was injected into this liquid crystal cell by a method such as vacuum injection, and the injection port was sealed with an end sealant. Thereafter, chamfering and cleaning are performed, and a polarizing plate with an optical compensator is bonded in a crossed Nicol arrangement so as to be approximately 45 ° with respect to the rubbing direction of the upper and lower substrates (see FIG. 7). A shutter element having

  In the shutter element thus fabricated, the liquid crystal layer is filled with a liquid crystal material of Δε <0, the layer thickness is set to about 2 μm, Δnd is set to about 300 nm, and the liquid crystal molecule at the center in the layer thickness direction of the liquid crystal layer. The orientation direction is set to the same twelve o'clock direction (see FIG. 7) as the viewing angle direction. Crossed Nicols polarizing plates are arranged above and below the liquid crystal cell, and the transmission axis of the upper polarizing plate is set at a position rotated 45 ° counterclockwise from the 12 o'clock direction. An optical film having negative biaxial optical anisotropy as a viewing angle compensation plate is bonded between the liquid crystal cell and the upper and lower polarizing plates. The thickness direction retardation of the optical film is about 120 nm. The viewing angle compensation plate may be arranged only on the upper surface or the lower surface of the liquid crystal cell. In the above, the parameters of the fixed optical film are listed. As an appropriate value, the retardation in the film thickness direction (the total when two sheets are used) is about 0.5 to about 1 with respect to Δnd of the liquid crystal cell. It is preferable to set to 0 times. The in-plane retardation is preferably set to about 30 nm to about 65 nm.

  Next, the charging time of the liquid crystal cell of the produced shutter element was evaluated. The human body is easily charged with static electricity and tends to be in a relatively high charged state, but is hardly noticeable when the charged potential is 1 kV or less. Here, an experiment was conducted in the case of static electricity as relatively high as 10 kV (a level that can be obtained by rubbing glasses with a cloth or the like). The experiment was performed by applying static electricity to the liquid crystal cell in an electrically opened state with an electrostatic gun. FIG. 8 shows the voltage holding ratio dependence of the charging time of the liquid crystal layer with respect to static electricity. The horizontal axis of FIG. 8 shows the relative voltage holding ratio, and the larger value indicates the higher voltage holding ratio. In the drawing, “PI-A”, “PI-B”, and “PI-C” represent differences in the material of the alignment film (the same applies below). It can be seen that the charging time greatly depends on the voltage holding ratio. Here, since the liquid crystal material of the liquid crystal layer is common, it can be seen that it depends on the material of the alignment film. In the case of a liquid crystal cell manufactured under a condition with a high voltage holding ratio, it was confirmed that the shutter element was kept in a nearly transparent state for 2320 seconds (about 40 minutes). In addition, it was confirmed by another experiment that even when a relatively low static electricity of about 5 kV (contact discharge, 1 second, once) was applied, a state close to transparency was maintained for about 10 minutes. In addition, it was confirmed that the state of transparency was maintained for about 2 minutes even with static electricity of 2.5 kV. These are the amount of static electricity that can be obtained simply by rubbing the glasses or touching them with your fingers. That is, it can be seen that a transparent state can be maintained for a long time by periodically touching a part of the shutter element.

  Next, a case where the transparent state is maintained by electrically driving the shutter element will be described. As an example, the liquid crystal cell is opened by applying the ON voltage under the conditions of 1/4 duty, 1/3 bias drive, ON voltage 15V (equivalent to about 8.5V in static drive), and then shutting off the switching element. The experiment was conducted as a state. In this case, it was found that the higher the post-baking temperature of the alignment film, the longer the time during which the charged state, that is, the state in which the liquid crystal layer was operated, was maintained (see FIGS. 9 and 10). Although the holding time varies depending on the type of alignment film, the solid content concentration during film formation should be lowered (ie, the film thickness of the alignment film should be reduced) even with “PI-D” having the shortest holding time. It can be seen that the holding time can be remarkably increased (see FIG. 11). Specifically, the holding time is improved to several tens of times or more by setting the thickness of the alignment film to 50 to 100 mm. Therefore, it is considered that the holding time can be further increased for other alignment films. Specifically, it is considered that a holding time of at least 2 minutes can be secured. Therefore, it is understood that a transparent liquid crystal shutter device can be realized by applying a voltage to the liquid crystal cell at a very low frequency as described above and then opening the liquid crystal cell. It has been confirmed that even if the alignment film is very thin, the alignment of the liquid crystal layer is not significantly affected. In this embodiment, a liquid crystal material or an alignment film having a high voltage holding ratio is not positively selected for experiments, but rather a material for suppressing the influence of static electricity is selected. Therefore, it is considered that a more excellent liquid crystal shutter device can be realized by optimizing the material.

  In addition, this invention is not limited to the content mentioned above, In the range of the summary of this invention, it can change and implement variously.

  For example, in the above-described embodiments and examples, the liquid crystal cell has been exemplified to have a liquid crystal layer having a substantially vertical alignment having a pretilt angle smaller than 90 °, but the liquid crystal element is not limited to this. For example, a liquid crystal element that includes a vertically aligned liquid crystal layer having a pretilt angle of approximately 90 ° and performs alignment control by an oblique electric field generated using a slit, a protrusion, or the like may be used.

  In the above-described embodiments and examples, the outer shape of the shutter element is not particularly mentioned. However, a desired shape such as a polygonal shape such as a rectangular shape or a pentagonal shape or an arbitrary curved shape can be selected.

1: Liquid crystal shutter device 2, 2a: Control device 3: Image display device 11a, 11b: Shutter element 12: Drive device 13: Upper polarizing plate 14: Optical compensator 15: Liquid crystal cell (liquid crystal device)
16: Optical compensator 17: Lower polarizing plate 21: Upper substrate 22: Upper electrode 23: Alignment film 24: Lower substrate 25: Lower electrode 26: Alignment film 27: Liquid crystal layer 30, 30a: Display detection unit 31, 31a: Switching control unit 32, 32a: Time measuring unit 33a, 33b: Switching element (field effect transistor)

Claims (5)

A liquid crystal shutter device used in combination with an image display device that alternately displays an image for the right eye and an image for the left eye,
A pair of shutter elements;
A control device that selectively operates the pair of shutter elements in response to switching between the image for the right eye and the image for the left eye by the image display device;
Including
Each of the pair of shutter elements is
A first polarizing plate and a second polarizing plate arranged with their respective absorption axes substantially orthogonal;
The liquid crystal layer has a substantially vertical alignment when no voltage is applied and the alignment is uniformly inclined when a voltage is applied. The alignment directions when the voltage is applied are the first polarizing plate and the second polarizing plate, respectively. A liquid crystal element disposed between the first polarizing plate and the second polarizing plate so as to form an angle of about 45 ° with respect to the absorption axis of
With
The control device alternately applies an on voltage and an off voltage to the liquid crystal elements of each of the pair of shutter elements when the image display is performed by the image display device, and the image by the image display device When the display is stopped , the on- voltage is applied to both of the liquid crystal elements of each of the pair of shutter elements, and the electrical connection between both of the liquid crystal elements is cut off.
Liquid crystal shutter device. The controller is
A driving device for supplying a driving voltage to each of the liquid crystal elements;
A switching element connected between each of the liquid crystal elements and the driving device;
A display detection unit for detecting that image display by the image display device is stopped;
A switching control unit for controlling the switching element to a conductive state or a cutoff state;
The liquid crystal shutter device according to claim 1, comprising: The control device applies both of the liquid crystal elements while applying an on- voltage to the liquid crystal elements of each of the pair of shutter elements when a predetermined time has elapsed after electrically disconnecting the liquid crystal elements. Breaking the electrical connection between,
The liquid crystal shutter device according to claim 1. The control device is a time measuring unit that measures an elapsed time corresponding to the switching element being controlled to be in a cut-off state by the switching control unit,
The liquid crystal shutter device according to claim 3, further comprising: A driving method of a liquid crystal shutter device according to claim 1 ,
When an image is displayed by the image display device by the control device, an on voltage and an off voltage are alternately applied to the liquid crystal elements of each of the pair of shutter elements, and the image display by the image display device is performed. Is stopped, while applying an ON voltage to both of the liquid crystal elements of each of the pair of shutter elements, the electrical connection between both of the liquid crystal elements is cut off.
Driving method of liquid crystal shutter device.

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