JP2007114394A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device that can prevent a mobile phone, a PDA, a tablet PC, etc., used in a public place from increasing in thickness and weight, and have display characteristics controlled. <P>SOLUTION: The display device is equipped with a display panel which displays an image, a color filter which is provided on the display panel and includes a mixture of a plurality of luminance and visual angle control liquid crystal materials capable of controlling a diffusion state of transmitted light are mixed, a phase control panel having another liquid crystal layer capable of controlling a phase state of light projected from the display panel, a back light unit, a first polarizer arranged between an array substrate and the back light unit, and a second polarizer arranged on the opposite side from the display panel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device.

  In recent years, liquid crystal display devices, organic EL display devices, and the like have been used as display devices. For example, liquid crystal display devices are applied to various fields and are used in electronic devices such as notebook computers, monitors, car navigation systems, scientific calculators, small and medium-sized TVs, large-sized TVs, mobile phones, and electronic notebooks.

  Among these electronic devices, electronic notebooks, PDAs (Personal Digital Assistants), mobile phones, tablet personal computers (PCs), notebook PCs, and the like are frequently used by being carried around because of their small and thin features. In addition, liquid crystal display devices used for POP (point of purchase) applications, ATM (automated teller machine) applications, and ticket vending machine applications are often used in public places.

  In these applications, it may be difficult for others to identify the display contents depending on the usage situation. For example, it is a case where private contents are displayed on a mobile phone, PDA, or tablet PC in a public place. In such a case, it is desirable that the viewing angle is narrow. However, since there are opportunities for a plurality of people to observe the display image, it is desired to have a function of controlling the viewing angle. The problem of viewing angle characteristics is a problem common to mobile devices and public information terminal devices.

  In recent years, a detachable louver sheet (for example, a 3M light control film) has been used as a means for controlling the viewing angle of a liquid crystal display device or a cathode ray tube (CRT) (for example, see Patent Document 1). In addition, in a liquid crystal display device using a polarizing plate, a system in which a polarizing plate on the viewer side is not provided and the display can be identified only when polarizing glasses are applied is also applied.

The conventional louver sheet is provided with a light shielding layer of about several millimeters in the normal direction of the sheet in order to make the viewing angle sufficiently narrow. For this reason, the method using the louver sheet has a problem of low light transmittance. The louver sheet manufacturing process is complicated and the manufacturing cost is high. There is also a problem that it takes time to attach and remove the louver sheet. In addition, the method using polarized glasses has a problem that a display image cannot be shown to an unspecified person.
JP 2003-58066 A

  In order to solve the above-mentioned problem of viewing angle characteristics, a liquid crystal display device has been developed in which a liquid crystal element for viewing angle control is provided on a liquid crystal display panel to control the viewing angle. However, since a plurality of liquid crystal elements are provided, the entire liquid crystal display device becomes thick and heavy. For example, when a liquid crystal display device capable of controlling the viewing angle is formed by adding an optical phase control liquid crystal element for controlling the viewing angle and a luminance viewing angle controlling liquid crystal element for controlling the light diffusion to a normal liquid crystal display panel, It becomes very thick compared to the device, and the weight also increases.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a display device capable of suppressing thickness and weight and controlling display characteristics.

In order to solve the above-described problem, a display device according to an aspect of the present invention includes:
A display panel for displaying images,
The display panel is provided with a color filter mixed with a plurality of luminance viewing angle control liquid crystal materials capable of controlling the diffusion state of transmitted light.

In addition, a display device according to another aspect of the present invention includes:
A display panel comprising: an array substrate; a counter substrate disposed opposite to the array substrate with a gap; and a liquid crystal layer sandwiched between the array substrate and the counter substrate;
A color filter provided with the display panel and mixed with a plurality of luminance viewing angle control liquid crystal materials capable of controlling a diffusion state of transmitted light;
A phase control liquid crystal panel having another liquid crystal layer disposed opposite to the counter substrate and capable of controlling a phase state of light emitted from the display panel;
A backlight unit disposed opposite to the array substrate and emitting light with high parallelism to the array substrate;
A first polarizing plate disposed between the array substrate and the backlight unit;
A second polarizing plate disposed on the opposite side of the display panel with respect to the phase control liquid crystal panel is provided.

  According to the present invention, it is possible to provide a display device capable of suppressing thickness and weight and capable of controlling display characteristics.

Hereinafter, a first embodiment in which a display device according to the invention is applied to a liquid crystal display device will be described in detail with reference to the drawings.
As shown in FIG. 1, the liquid crystal display device includes a liquid crystal display panel 1 as a display panel for displaying an image, a phase control liquid crystal panel 3, a backlight unit 4, a first polarizing plate 5, a second polarizing plate 6, and a driving unit. 7 is provided.

  The liquid crystal display panel 1 is configured as a TN (twisted nematic) mode liquid crystal display panel. The liquid crystal display panel 1 includes an array substrate 11, a counter substrate 12, a first liquid crystal layer 13, and a color filter 2. The array substrate 11 is a rectangular glass substrate 14 as a transparent insulating substrate, a plurality of pixel electrodes 15 formed in a matrix on the glass substrate, and an orientation formed on the glass substrate including these pixel electrodes. And a film 16. The array substrate 11 has various wirings (not shown) formed on the glass substrate 14, TFTs (thin film transistors) as switching elements, and the like.

  The counter substrate 12 is a transparent glass substrate 17 having a rectangular shape, a counter electrode 20 formed on the glass substrate, a color filter 2 formed on the counter electrode, and the color filter. The common electrode 18 is formed, and the alignment film 19 is formed on the common electrode and the glass substrate. The pixel electrode 15, the counter electrode 20, and the common electrode 18 are formed of a transparent conductive material such as ITO (indium tin oxide). The alignment film 16 and the alignment film 19 are rubbed so that the pretilt angle is 5 °.

  The color filter 2 includes a plurality of red coloring layers 2R, a plurality of green coloring layers 2G, and a plurality of blue coloring layers 2B. For this reason, the counter electrode 20 and the common electrode 18 are disposed to face each other with the colored layers 2R, 2G, and 2B interposed therebetween. As shown in FIGS. 1 and 2, in addition to the colored layer 2R, the colored layers 2G and 2B are mixed with a plurality of granular luminance viewing angle control liquid crystal materials 2a. The colored layers 2R, 2G, and 2B are formed by sequentially patterning colored resist mixed with the luminance viewing angle control liquid crystal material 2a. The luminance viewing angle control liquid crystal material 2 a is formed of a liquid crystal polymer 30.

  As shown in FIG. 1, the array substrate 11 and the counter substrate 12 are arranged to face each other with a predetermined gap held by a plurality of spacers 21. The array substrate 11 and the counter substrate 12 are opposed to the pixel electrode 15 and the common electrode 18 and have a display region R1 for displaying an image. Since the color filter 2 is disposed in the display region R1, the liquid crystal display panel 1 can perform color display. In this embodiment, the color filter 2 has a light diffusion control region R2 that overlaps the display region R1. Therefore, as will be described later, the liquid crystal polymer 30 forming the luminance viewing angle control liquid crystal material 2a can control the diffusion state of light emitted from the backlight unit 4 that transmits the luminance viewing angle control liquid crystal material in the light diffusion control region R2. It is. The diffusion state is controlled by applying a voltage to the liquid crystal polymer 30 to control the potential difference between the common electrode 18 and the counter electrode 20.

  The array substrate 11 and the counter substrate 12 are joined to each other by a rectangular sealing material 22 disposed on the outer peripheral portion of both substrates outside the display region R1. The first liquid crystal layer 13 is sandwiched between the array substrate 11, the counter substrate 12, and the sealing material 22.

  The layer thickness of the first liquid crystal layer 13 is 5.0 μm. A predetermined chiral material is added to the liquid crystal material constituting the first liquid crystal layer 13 so as to obtain the following characteristics. The difference in refractive index anisotropy (Δn) of the liquid crystal material is 0.092 for a wavelength of 590 nm. The twist angle of the liquid crystal molecules is 90 °, and the twist pitch is 60 μm. The twist of the liquid crystal molecules is counterclockwise.

  The phase control liquid crystal panel 3 includes a first substrate 41, a second substrate 42 and a second liquid crystal layer 43 that are disposed opposite to each other while holding a predetermined gap with respect to the first substrate. The first substrate 41 is formed of, for example, a rectangular first sheet 44a made of a polyester film or glass as a transparent insulating substrate, and a transparent conductive material such as ITO disposed on the first sheet. The first electrode 46a and a first alignment film 47a disposed on the first electrode.

  The second substrate 42 is formed as a transparent insulating substrate by a rectangular second sheet 44b made of, for example, a polyester film or glass, and a transparent conductive material such as ITO disposed on the second sheet. And a second alignment film 47b disposed on the second electrode 46b. The first alignment film 47a and the second alignment film 47b are rubbed so as to have a pretilt angle of 5 °. In this embodiment, the glass substrate 17 and the first sheet 44a are integrally formed. For this reason, the counter substrate 12 of the liquid crystal display panel 1 and the first substrate 41 of the phase control liquid crystal panel 3 have a transparent common substrate 51, and are configured by the same substrate.

  The first substrate 41 and the second substrate 42 are arranged to face each other so that the first alignment film 47a and the second alignment film 47b face each other, and are held by a plurality of spacers 48 with a predetermined gap. The spacer 48 is made of an insulating material. The first electrode 46a and the second electrode 46b are maintained in an insulated state. The first substrate 41 and the second substrate 42 are regions where the first electrode 46a and the second electrode 46b are opposed to each other, and the phase control capable of controlling the phase state of the light transmitted between the first substrate and the second substrate. It has area | region R3. In this embodiment, the phase control region R3 overlaps the display region R1 and the light diffusion control region R2 described above.

  The first substrate 41 and the second substrate 42 are joined to each other by a rectangular sealing material 49 arranged on the outer periphery of the first electrode 46a and the second electrode 46b outside the phase control region R3. The second liquid crystal layer 43 is sandwiched between the first substrate 41, the second substrate 42 and the sealing material 49.

  The layer thickness of the second liquid crystal layer 43 is 5.0 μm. A predetermined chiral material is added to the liquid crystal material constituting the second liquid crystal layer 43 so as to obtain the following characteristics. The difference in refractive index anisotropy (Δn) of the liquid crystal material is 0.072 for a wavelength of 590 nm. The twist angle of the liquid crystal molecules is 450 ° and the twist pitch is 3.92 μm. The twist of the liquid crystal molecules is counterclockwise.

  The second liquid crystal layer 43 described above has a function of controlling the phase state of light transmitted between the first substrate 41 and the second substrate 42. More specifically, the second liquid crystal layer 43 controls the viewing angle by controlling the alignment of liquid crystal molecules. When controlling the orientation of the liquid crystal molecules in the second liquid crystal layer 43, a voltage is applied to the phase control liquid crystal panel 3 to control the potential difference between the first electrode 46a and the second electrode 46b.

  The backlight unit 4 is provided on the outer surface side of the array substrate 11. The backlight unit 4 includes a light guide 4a that is disposed to face the array substrate 11 and includes a light guide plate, and a light source 4b and a reflector 4c that are disposed to face one side edge of the light guide. Yes.

  The backlight unit 4 has a highly condensing prism sheet 4d disposed to face the surface of the light guide 4a. The prism sheet 4d has a function of improving the parallelism (directivity) of the backlight light emitted from the light guide 4a. The prism sheet 4d has a structure in which the degree of parallelism is higher than that of a prism sheet normally used in a liquid crystal display device for a notebook PC or the like. As the prism sheet 4d, a collimate sheet manufactured by Nagase Sangyo Co., Ltd. is used that has a very high parallelism of the emitted backlight light. For this reason, the backlight unit 4 can emit light with high parallelism to the array substrate 11.

  The first polarizing plate 5 is disposed between the array substrate 11 and the backlight unit 4. More specifically, the first polarizing plate 5 is disposed on the outer surface of the array substrate 11. The first polarizing plate 5 may be bonded to the outer surface of the array substrate 11 via glue. The second polarizing plate 6 is disposed on the opposite side of the liquid crystal display panel 1 with respect to the phase control liquid crystal panel 3. More specifically, the second polarizing plate 6 is disposed on the outer surface of the second substrate 42. Note that the second polarizing plate 6 may be bonded to the outer surface of the second substrate 42 via glue. The first polarizing plate 5 and the second polarizing plate 6 are arranged in crossed Nicols. For this reason, the liquid crystal display panel 1 becomes normally white display which becomes black display in a voltage application state.

  The drive unit 7 controls the display state by applying a drive voltage to the liquid crystal display panel 1. The drive unit 7 applies a drive voltage to the color filter 2 and the phase control liquid crystal panel 3 corresponding to the display mode.

  Here, the inventors of the present application display an image using a liquid crystal display device in two states, a state in which a driving voltage is applied to the color filter 2 and the phase control liquid crystal panel 3, and a state in which a driving voltage is not applied. Various display characteristics such as viewing angle, contrast viewing angle, front luminance and front contrast characteristics were investigated.

  At that time, the driving unit 7 drives the liquid crystal display panel 1 with a driving voltage of 4 V via the TFT. A driving voltage of 10 V was applied to the color filter 2, and a driving voltage of 10 V was also applied to the phase control liquid crystal panel 3. The backlight unit 4 was turned on, and the liquid crystal display device was placed in an environment with an illuminance of 0 lx (lux).

  First, various displays in the first display method in a state where no driving voltage is applied to the color filter 2 (between the common electrode 18 and the counter electrode 20) and the phase control liquid crystal panel 3 (between the first electrode 46a and the second electrode 46b). The characteristics will be described.

A viewing angle having a luminance of 30 cd / m ² or more is as wide as ± 60 ° in the left-right direction, and a viewing angle with a contrast ratio of 10: 1 or more is sufficiently wide as ± 80 ° in the left-right direction. Further, the front luminance is sufficiently high at 300 cd / m ² . From this, the front luminance and the luminance viewing angle equivalent to the case where an image is displayed using a liquid crystal display device configured without providing the color filter 2 and the phase control liquid crystal panel 3 mixed with the luminance viewing angle control liquid crystal material 2a are obtained. You can see that Further, the front contrast is 500: 1, and a high value equivalent to the structure without the phase control liquid crystal panel 3 is obtained.

  Next, a driving voltage of 10V is applied to the color filter 2 (between the common electrode 18 and the counter electrode 20), and a driving voltage of 10V is applied to the phase control liquid crystal panel 3 (between the first electrode 46a and the second electrode 46b). Various display characteristics in the second display method in the active state will be described.

A viewing angle having a luminance of 30 cd / m ² or more is sufficiently narrow as ± 20 ° in the left-right direction, and a viewing angle having a contrast ratio of 10: 1 or more is sufficiently narrow as ± 15 ° in the left-right direction. The viewing angle with a contrast ratio of 1: 1 or more was sufficiently narrow as ± 20 ° in the left-right direction, and the display image could not be identified at all when the left-right viewing angle was 20 ° or more.

Further, the front luminance is 600 cd / m ² , and the front luminance is double that when an image is displayed using a conventional liquid crystal display device configured without the color filter 2 mixed with the luminance viewing angle control liquid crystal material 2a. Is obtained. The front contrast is 1000: 1, and a higher value can be obtained than when the phase control liquid crystal panel 3 is not provided or when no driving voltage is applied to the phase control liquid crystal panel.

  Next, the principle of controlling the viewing angle of the liquid crystal display device by the phase control liquid crystal panel 3 controlling the phase state of the light transmitted through the phase control liquid crystal panel will be described with reference to FIGS.

  Among the viewing angle characteristics, particularly important characteristics are contrast viewing angle characteristics and luminance viewing angle characteristics. Among these, the contrast viewing angle characteristic greatly depends on the viewing angle characteristic during black display. In the display mode using the state in which the liquid crystal molecules 13a of the first liquid crystal layer 13 are arranged substantially vertically as in the TN mode, in order to obtain excellent black display characteristics, the black color is obtained in a state in which the liquid crystal molecules 13a are arranged almost vertically. It is often displayed. However, in a state where the liquid crystal molecules 13a are arranged almost vertically, a phase difference occurs in an oblique visual field. A phase difference is generated by multiplying the difference in refractive index anisotropy (Δn) of the liquid crystal material by the thickness of the liquid crystal layer and the viewing angle.

  As shown in FIGS. 5 and 6, in the case of the present embodiment, a phase difference of +480 nm (× viewing angle) is generated. However, as shown in FIGS. 1, 3, and 4, the phase difference of the second liquid crystal layer 43 in the state where the drive voltage is not applied between the first electrode 46 a and the second electrode 46 b is −480 nm (× viewing field). Therefore, the phase difference combined with the phase difference of the first liquid crystal layer 13 becomes zero. As described above, by providing the phase control liquid crystal panel 3 including the second liquid crystal layer 43 in the liquid crystal display device, the contrast viewing angle characteristic is widened as compared with the case where the phase control liquid crystal panel is not provided. Can do.

  On the other hand, as shown in FIGS. 1, 7 and 8, a driving voltage is applied between the first electrode 46a and the second electrode 46b to untwist the liquid crystal molecules 43a and to align the liquid crystal molecules 43a almost vertically. In the state, like the first liquid crystal layer 13, it is positive uniaxial (+640 nm). For this reason, the phase difference combined with the phase difference of the first liquid crystal layer 13 is +1120 nm. As described above, by providing the phase control liquid crystal panel 3 provided with the second liquid crystal layer 43 in the liquid crystal display device, the contrast viewing angle characteristic is remarkably narrowed as compared with the case where the phase control liquid crystal panel is not provided. be able to.

  Here, the liquid crystal polymer 30 forming the luminance viewing angle control liquid crystal material 2a will be described. As shown in FIGS. 9 and 10, a polymer (polymer network) 31 is formed in the liquid crystal polymer 30, and liquid crystal molecules 32 are deposited. The alignment of the liquid crystal molecules 32 of the liquid crystal polymer 30 can be regarded as almost random. The refractive index of the polymer 31 is equal to the ordinary light refractive index of the liquid crystal molecules 32.

  The luminance viewing angle control liquid crystal material 2a irradiates a liquid crystal material in which 2 wt% of a photocrosslinkable polymer (polymer) is dissolved in nematic liquid crystal having a difference in refractive index anisotropy (Δn) of 0.23 with ultraviolet rays. A material in which a polymer (polymer network) 31 is formed and liquid crystal molecules 32 are deposited is solidified.

  Next, the principle that the liquid crystal polymer 30 can control the luminance viewing angle of the liquid crystal display device by controlling the diffusion state of the light transmitted through the liquid crystal polymer will be described with reference to FIG. 1, FIG. 9, and FIG.

  In a state where a drive voltage is not applied between the common electrode 18 and the counter electrode 20 (FIG. 9), the alignment of the liquid crystal molecules 32 is almost random. For this reason, the refractive index is the average of the ordinary light refractive index and the extraordinary light refractive index. On the other hand, the refractive index of the polymer 31 is equal to the ordinary light refractive index of the liquid crystal molecules 32. Therefore, the difference in refractive index anisotropy (Δn) is half of the above difference in refractive index anisotropy (Δn), that is, about 0.115, and a difference in refractive index is generated.

  Further, since the polymer 31 has a random three-dimensional structure, backlight light having a high degree of parallelism transmitted through the prism sheet 4d is diffused by the liquid crystal polymer 30. Therefore, a wide luminance viewing angle can be obtained as in the case of using a conventional liquid crystal display device configured without providing the color filter 2 mixed with the luminance viewing angle control liquid crystal material 2a.

  In a state where a sufficient driving voltage is applied between the common electrode 18 and the counter electrode 20 (FIG. 10) so that the liquid crystal molecules 32 of the liquid crystal polymer 30 are aligned substantially vertically, the alignment of the liquid crystal molecules 32 is substantially vertical. . For this reason, the refractive index with respect to the traveling direction of the light incident on the liquid crystal polymer 30 becomes the ordinary light refractive index. On the other hand, the refractive index of the polymer 31 is equal to the ordinary light refractive index of the deposited liquid crystal molecules 32. Therefore, there is no difference in refractive index between the polymer 31 and the liquid crystal molecules 32, and the backlight light transmitted through the prism sheet 4d passes through the liquid crystal polymer 30 as it is.

  As described above, light with high parallelism sufficiently enhanced by the prism sheet 4 d is emitted from the liquid crystal display panel 1. For this reason, a much narrower luminance viewing angle can be obtained than in the case of using a conventional liquid crystal display device configured without providing the color filter 2 mixed with the luminance viewing angle control liquid crystal material 2a. At this time, the front luminance is much higher than when the conventional liquid crystal display device is used because the luminance viewing angle is reduced.

  According to the liquid crystal display device configured as described above, the liquid crystal display panel 1 of the liquid crystal display device includes the color filter 2 in which the luminance viewing angle control liquid crystal material 2a is mixed. In a state where a driving voltage is applied between the common electrode 18 and the counter electrode 20 and the viewing angle is controlled to be narrow by the liquid crystal polymer 30, the emitted light can be concentrated in the front direction of the display screen. Since the liquid crystal display device can control the luminance viewing angle without providing a separate panel for controlling the luminance viewing angle, the overall thickness and weight can be suppressed, and the display characteristics can be controlled. In addition, when the emitted light is concentrated in the front direction of the display screen, sufficient luminance can be obtained even if the backlight intensity is reduced, so that power consumption can be reduced.

  The liquid crystal display device includes a phase control liquid crystal panel 3. The phase control liquid crystal panel 3 has a second liquid crystal layer 43. The second liquid crystal layer 43 can control the phase difference and traveling direction of the backlight light transmitted through the liquid crystal display panel 1. As described above, the phase control liquid crystal panel 3 can also control the viewing angle and the contrast viewing angle.

  For this reason, even if it is used in public places such as mobile PCs, mobile phones, PDAs, electronic notebooks, and tablet PCs, it is difficult to identify the display contents by others by switching the display method. Can narrow the viewing angle, and can widen the viewing angle when a display image is observed by a plurality of observers. As a result, it is possible to eliminate the worry of others looking into the display contents. It is also possible for a plurality of observers to view the display screen simultaneously and satisfactorily. At this time, the viewing angle can be easily controlled by controlling the voltage applied between the first electrode 46a and the second electrode 46b. When controlling such display characteristics, it is possible to control without substantially increasing power consumption. When the display method of the liquid crystal display device is controlled, it can be controlled by a switch or a single volume.

  In a liquid crystal display device that controls nematic liquid crystal from substantially vertical to horizontal alignment, tilt alignment, and alignment having twist in these, such as MVA mode, TN mode, homogeneous mode (HOMO mode), and hybrid aligned nematic mode, the first polarizing plate 5 and the 2nd polarizing plate 6 are arrange | positioned so that it may become black display in the state (drive voltage application state) in which the nematic liquid crystal was orientated substantially perpendicularly. In this state, the first liquid crystal layer 13 can be regarded as a substantially positive uniaxial crystal when viewed optically. Therefore, since a phase difference occurs in the visual field in the oblique direction of the display screen, the contrast ratio is lower than that observed from the front of the display screen.

  In the second liquid crystal layer 43, the difference in refractive index anisotropy (Δn) of the liquid crystal material is small, the twist pitch of the liquid crystal molecules is short, and the twist angle of the liquid crystal molecules is 450 °. The second liquid crystal layer 43 is sufficiently low in optical rotation even when compared with the first liquid crystal layer 13. Therefore, the second liquid crystal layer 43 is a retardation plate that can be regarded as a negative uniaxial crystal in a state where no voltage is applied between the first electrode 46a and the second electrode 46b.

  Therefore, in this state, the second liquid crystal layer 43 compensates for the phase difference of the first liquid crystal layer 13 in a substantially vertically aligned state, so that it is possible to suppress a decrease in contrast in an oblique visual field. In particular, when the absolute value of the phase difference of the first liquid crystal layer 13 and the absolute value of the phase difference of the second liquid crystal layer 43 match, the effect is maximized. Further, by making the twist directions of the first liquid crystal layer 13 and the second liquid crystal layer 43 coincide with each other, the second liquid crystal layer 43 acts to enlarge the left-right viewing angle of the liquid crystal display panel 1 (TN mode).

  The effect described above is effective when the twist angle of the liquid layer molecules of the second liquid crystal layer 43 is controlled as follows. The liquid crystal molecules are aligned substantially perpendicular to the planes of the first substrate 41 and the second substrate 42 with the driving voltage applied to the phase control liquid crystal panel 3 and twisted without applying the driving voltage. When aligning at an angle of 360 ° or more. Alternatively, the liquid crystal molecules are aligned substantially perpendicular to the planes of the first substrate 41 and the second substrate 42 without applying a driving voltage to the phase control liquid crystal panel 3, and the liquid crystal molecules are aligned with the driving voltage applied. In this case, the twist angle is set to 360 ° or more.

  The phase control liquid crystal panel 3 is disposed between the liquid crystal display panel 1 and the second polarizing plate 6. Thereby, the 2nd polarizing plate 6 plays the role of a polarizer. In this case, it is desirable to affix the second polarizing plate 6 on the outer surface of the second sheet 44b on the display screen side via a paste (not shown). If not attached, an air interface exists between the phase control liquid crystal panel 3 and the second polarizing plate 6, and if the gap is narrow, Newton ring stripes will be visually recognized. Conversely, if the gap between the phase control liquid crystal panel 3 and the second polarizing plate 6 is wide, a spacer for maintaining the gap is required, and the thickness of the entire liquid crystal display device is increased.

  The counter substrate 12 and the first substrate 41 have a common substrate 51, and are configured by the same substrate. Since the liquid crystal display panel 1 and the phase control liquid crystal panel 3 are formed using the three substrates of the glass substrate 14, the second sheet 44b, and the common substrate 51, the thickness and weight of the entire liquid crystal display device are further reduced. be able to. When the liquid crystal display device does not have the common substrate 51, it is desirable to bond the liquid crystal display panel 1 and the phase control liquid crystal panel 3 without providing a gap. When the first sheet 44a and the second sheet 44b of the phase control liquid crystal panel 3 are made of flexible plastic or thin glass, the phase control liquid crystal panel is attached to the liquid crystal display panel 1 via an adhesive (not shown). It ’s fine.

  By providing both the color filter 2 and the phase control liquid crystal panel 3 mixed with the luminance viewing angle control liquid crystal material 2a, the contrast viewing angle and the luminance viewing angle can be controlled simultaneously. These controls can be freely performed in an analog manner between the widest viewing angle state and the narrowest viewing angle state by controlling the drive voltage applied to both the liquid crystal polymer 30 and the second liquid crystal layer 43.

  Next, a liquid crystal display device according to a second embodiment of the present invention will be described in detail. In this embodiment, other configurations are the same as those of the first embodiment described above, and the same parts are denoted by the same reference numerals and detailed description thereof is omitted.

  As shown in FIG. 11, the liquid crystal display device includes a liquid crystal display panel 1, a phase control liquid crystal panel 3, a backlight unit 4, a first polarizing plate 5, a second polarizing plate 6, and a driving unit 7. The color filter 2 is provided on the array substrate 11.

  The array substrate 11 includes a glass substrate 14, a plurality of counter electrodes 20 formed in a matrix on the glass substrate, a color filter 2 formed on the glass substrate and the counter electrodes, and a matrix on the color filter. A plurality of pixel electrodes 15 and an alignment film 16 are formed. The pixel electrode 15 and the counter electrode 20 are disposed to face each other with the colored layers 2R, 2G, and 2B interposed therebetween. Needless to say, a plurality of luminance viewing angle control liquid crystal materials 2a are mixed in the colored layers 2R, 2G, and 2B.

  Here, the inventors of the present application display an image using a liquid crystal display device in two states, a state in which a driving voltage is applied to the color filter 2 and the phase control liquid crystal panel 3, and a state in which a driving voltage is not applied. Various display characteristics such as viewing angle, contrast viewing angle, front luminance and front contrast characteristics were investigated.

  At that time, the driving unit 7 drives the liquid crystal display panel 1 with a driving voltage of 4 V via the TFT. A driving voltage of 10 V was applied to the color filter 2, and a driving voltage of 10 V was also applied to the phase control liquid crystal panel 3. The backlight unit 4 was turned on, and the liquid crystal display device was placed in an environment with an illuminance of 0 lx.

  First, various displays in the first display method in a state where a drive voltage is not applied to the color filter 2 (between the pixel electrode 15 and the counter electrode 20) and the phase control liquid crystal panel 3 (between the first electrode 46a and the second electrode 46b). The characteristics will be described.

A viewing angle having a luminance of 30 cd / m ² or more is as wide as ± 60 ° in the left-right direction, and a viewing angle with a contrast ratio of 10: 1 or more is sufficiently wide as ± 80 ° in the left-right direction. Further, the front luminance is sufficiently high at 300 cd / m ² . From this, the front luminance and the luminance viewing angle equivalent to the case where an image is displayed using a liquid crystal display device configured without providing the color filter 2 and the phase control liquid crystal panel 3 mixed with the luminance viewing angle control liquid crystal material 2a are obtained. You can see that Further, the front contrast is 500: 1, and a high value equivalent to the structure without the phase control liquid crystal panel 3 is obtained.

  Next, a driving voltage of 10V is applied to the color filter 2 (between the pixel electrode 15 and the counter electrode 20), and a driving voltage of 10V is applied to the phase control liquid crystal panel 3 (between the first electrode 46a and the second electrode 46b). Various display characteristics in the second display method in the active state will be described.

A viewing angle having a luminance of 30 cd / m ² or more is sufficiently narrow as ± 20 ° in the left-right direction, and a viewing angle having a contrast ratio of 10: 1 or more is sufficiently narrow as ± 15 ° in the left-right direction. The viewing angle with a contrast ratio of 1: 1 or more was sufficiently narrow as ± 20 ° in the left-right direction, and the display image could not be identified at all when the left-right viewing angle was 20 ° or more.

Further, the front luminance is 600 cd / m ² , and the front luminance is double that when an image is displayed using a conventional liquid crystal display device configured without the color filter 2 mixed with the luminance viewing angle control liquid crystal material 2a. Is obtained. The front contrast is 1000: 1, and a higher value can be obtained than when the phase control liquid crystal panel 3 is not provided or when no driving voltage is applied to the phase control liquid crystal panel.

  According to the liquid crystal display device configured as described above, the liquid crystal display panel 1 of the liquid crystal display device includes the color filter 2 in which the luminance viewing angle control liquid crystal material 2a is mixed. In a state where a driving voltage is applied between the pixel electrode 15 and the counter electrode 20 and the viewing angle is controlled to be narrow by the liquid crystal polymer 30, the emitted light can be concentrated in the front direction of the display screen. Since the liquid crystal display device can control the luminance viewing angle without providing a separate panel for controlling the luminance viewing angle, the overall thickness and weight can be suppressed, and the display characteristics can be controlled. In addition, when the emitted light is concentrated in the front direction of the display screen, sufficient luminance can be obtained even if the backlight intensity is reduced, so that power consumption can be reduced.

  The liquid crystal display device includes a phase control liquid crystal panel 3. The phase control liquid crystal panel 3 has a second liquid crystal layer 43. The second liquid crystal layer 43 can control the phase difference and traveling direction of the backlight light transmitted through the liquid crystal display panel 1. As described above, the phase control liquid crystal panel 3 can also control the viewing angle and the contrast viewing angle.

  By providing both the color filter 2 and the phase control liquid crystal panel 3 mixed with the luminance viewing angle control liquid crystal material 2a, the contrast viewing angle and the luminance viewing angle can be controlled simultaneously. These controls can be freely performed in an analog manner between the widest viewing angle state and the narrowest viewing angle state by controlling the drive voltage applied to both the liquid crystal polymer 30 and the second liquid crystal layer 43.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention. For example, the display device may be an organic EL display device. In this case, a color filter 2 in which a plurality of luminance viewing angle control liquid crystal materials 2a are mixed may be provided on an organic EL display panel as a display panel for displaying an image. In particular, this is effective when the organic EL element forming a plurality of pixels of the organic EL display panel emits white light.

1 is a cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention. Sectional drawing which expanded the color filter shown in FIG. FIG. 3 is a schematic sectional view of a second liquid crystal layer in a state where no voltage is applied to the second liquid crystal layer shown in FIG. 1. The figure which shows the average refractive index ellipse of the liquid crystal molecule shown in FIG. FIG. 2 is a schematic sectional view of a first liquid crystal layer in a state where liquid crystal molecules of the first liquid crystal layer shown in FIG. 1 are vertically aligned. The figure which shows the average refractive index ellipse of the liquid crystal molecule shown in FIG. FIG. 2 is a schematic sectional view of a second liquid crystal layer in a state where a voltage is applied to the second liquid crystal layer shown in FIG. 1. The figure which shows the average refractive index ellipse of the liquid crystal molecule shown in FIG. FIG. 1 is a cross-sectional view of the brightness viewing angle control liquid crystal material in a state where no voltage is applied to the brightness viewing angle control liquid crystal material of the color filter, and the optical path of light emitted from the brightness viewing angle control liquid crystal material. Figure. FIG. 1 is a cross-sectional view of the luminance viewing angle control liquid crystal material in a state where a voltage is applied to the luminance viewing angle control liquid crystal material of the color filter and an optical path of light emitted from the luminance viewing angle control liquid crystal material. Figure. Sectional drawing of the liquid crystal display device which concerns on 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display panel, 2 ... Color filter, 2a ... Luminance viewing angle control liquid crystal material, 2R, 2G, 2B ... Colored layer, 3 ... Phase control liquid crystal panel, 4 ... Backlight unit, 5 ... 1st polarizing plate, 6 ... 2nd polarizing plate, 7 ... driving unit, 11 ... array substrate, 12 ... counter substrate, 13 ... first liquid crystal layer, 15 ... pixel electrode, 17 ... glass substrate, 18 ... common electrode, 20 ... counter electrode, 30 ... liquid crystal Polymer 31, polymer 41, first substrate 42, second substrate 43, second liquid crystal layer 44 a, first sheet 51, common substrate

Claims (9)

A display panel for displaying images,
A display device comprising: a color filter provided in the display panel and mixed with a plurality of luminance viewing angle control liquid crystal materials capable of controlling a diffusion state of transmitted light.   The display device according to claim 1, wherein the luminance viewing angle control liquid crystal material is formed of a liquid crystal polymer.   The display device according to claim 1, wherein the luminance viewing angle control liquid crystal material is formed in a granular shape. The display panel includes an array substrate, a counter substrate disposed opposite to the array substrate with a gap, and a liquid crystal layer sandwiched between the array substrate and the counter substrate,
The display device according to claim 1, wherein the color filter is provided on the array substrate or the counter substrate. The color filter is provided on the array substrate,
The array substrate includes a plurality of pixel electrodes and a plurality of counter electrodes arranged to face each other across the color filter,
The display device according to claim 3, wherein the luminance viewing angle control liquid crystal material can control a diffusion state of the transmitted light by controlling a potential difference between the pixel electrode and the counter electrode. The color filter includes a plurality of colored layers of red, green, and blue mixed with the luminance viewing angle control liquid crystal material,
The display device according to claim 5, wherein the plurality of pixel electrodes and the plurality of counter electrodes are arranged to face each other with the plurality of colored layers interposed therebetween.   5. The display device according to claim 4, further comprising a phase control liquid crystal panel having another liquid crystal layer disposed opposite to the counter substrate and capable of controlling a phase state of light emitted from the display panel. . The phase control liquid crystal panel includes a first substrate and a second substrate disposed to face each other with the other liquid crystal layer interposed therebetween,
The first substrate is disposed opposite to the counter substrate;
The display device according to claim 7, wherein the counter substrate and the first substrate have a common substrate. A display panel comprising: an array substrate; a counter substrate disposed opposite to the array substrate with a gap; and a liquid crystal layer sandwiched between the array substrate and the counter substrate;
A color filter provided with the display panel and mixed with a plurality of luminance viewing angle control liquid crystal materials capable of controlling a diffusion state of transmitted light;
A phase control liquid crystal panel having another liquid crystal layer disposed opposite to the counter substrate and capable of controlling a phase state of light emitted from the display panel;
A backlight unit disposed opposite to the array substrate and emitting light with high parallelism to the array substrate;
A first polarizing plate disposed between the array substrate and the backlight unit;
A display device comprising: a second polarizing plate disposed on the opposite side of the display panel with respect to the phase control liquid crystal panel.

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