JP2940482B2 - Display element device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a display device using a liquid crystal having a ferroelectric phase.

[0002]

2. Description of the Related Art Instead of a liquid crystal display device using a nematic liquid crystal, which has been widely used, a ferroelectric liquid crystal and an antiferroelectric liquid crystal, which are expected to have a high-speed response characteristic and a wide viewing angle characteristic, are used. Liquid crystal display devices have been developed. In these liquid crystal display elements, a ferroelectric liquid crystal or an antiferroelectric liquid crystal is interposed between a pair of substrates having electrodes formed on opposing surfaces.

In a device using a ferroelectric liquid crystal, a predetermined voltage of one polarity is applied between opposing electrodes to bring a first alignment stable state in which liquid crystal molecules are aligned to one ferroelectric phase. By applying a predetermined voltage of the other polarity between the electrodes, the liquid crystal molecules are driven by utilizing the bistability with the second alignment stable state in which the liquid crystal molecules are aligned in the other ferroelectric phase. Is displayed.

[0004] In the case of using an antiferroelectric liquid crystal,
By applying a predetermined voltage of one polarity between the opposing electrodes, the first liquid crystal molecules are aligned in one ferroelectric phase.
And a second stable state in which liquid crystal molecules are oriented in the other ferroelectric phase by applying a predetermined voltage of the other polarity between the electrodes, and a reverse state when no electric field is applied. 3 with the third orientation stable state oriented in the ferroelectric phase
A desired image is displayed by driving using stability.

In these liquid crystal display devices, liquid crystal molecules are aligned in a stable state of a ferroelectric phase or an antiferroelectric phase,
The binary display is performed using the memory effect.
It is difficult to perform gradation display with good reproducibility.

A DHF liquid crystal (Deformed Helical Ferroelectric L
Liquid crystal display devices using iquid crystal) have been proposed. A DHF liquid crystal display element has a liquid crystal from one ferroelectric phase to another ferroelectric phase by interposing a ferroelectric liquid crystal between substrates in the presence of a helix drawn by molecules and distorting the helix according to an electric field. It changes the director of the molecule continuously.

Further, recently, an antiferroelectric liquid crystal display device which performs gradation display using an intermediate alignment state of some antiferroelectric liquid crystals has been proposed.

[0008]

In the above-mentioned ferroelectric liquid crystal and antiferroelectric liquid crystal, liquid crystal molecules have a permanent dipole in a direction substantially orthogonal to the molecular long axis. Liquid crystal molecules behave due to a natural interaction. For this reason, the response speed is high, and the director changes of the liquid crystal molecules move in a plane parallel to the substrate, so that the viewing angle is widened.

However, since these liquid crystals have spontaneous polarization due to permanent dipoles of liquid crystal molecules, charges having the opposite polarity to the spontaneous polarization are accumulated on the substrate side, and the interaction with the substrate becomes large. The display burn-in phenomenon occurs in that the liquid crystal molecules cannot behave sufficiently freely in response to the electric field and an image remains as an afterimage.

As a method for reducing the image sticking phenomenon, a driving method for inverting the polarity of the voltage applied to the liquid crystal for each frame or for each line has been proposed. Also,
A driving method for applying a compensation pulse of the opposite polarity for each driving pulse has also been proposed. However, in these methods, the bias of the charges cannot be sufficiently eliminated, and the burn-in cannot be eliminated. In addition, there is a problem that flicker occurs due to a difference in response of the liquid crystal to a pulse having a positive polarity and a pulse having a reverse polarity.

Further, the liquid crystal having spontaneous polarization has its temperature and temperature.
The orientation state changes according to a change in the operating environment such as the degree of deterioration. For this reason, even when the same driving voltage is applied, the display gradation varies in accordance with the change in the operating environment, and furthermore, the lowest gradation and the highest gradation cannot be displayed accurately. There is a problem that image quality is degraded.

The present invention has been made in view of the above circumstances, and provides a display element device using a liquid crystal having a ferroelectric phase, which can reduce a display burn-in phenomenon and can display a high-quality image. The purpose is to do. Also,
An object of the present invention is to provide a display device using a liquid crystal exhibiting a ferroelectric phase, which can display a high-quality image regardless of a change in an operating environment.

[0013]

In order to achieve the above object, a display device according to a first aspect of the present invention has a structure in which an active element and pixel electrodes connected to the active element are arranged in a matrix. Substrate, and the other substrate on which a common electrode facing the pixel electrode is formed, disposed between the one and the other substrates, one of the polarities applied between the pixel electrode and the common electrode In accordance with a first alignment state indicating a first ferroelectric phase in which liquid crystal molecules are substantially aligned in a first direction in response to a first voltage, and a second voltage of the other polarity applied between the electrodes, In response to application of a second alignment state indicating a second ferroelectric phase in which liquid crystal molecules are substantially aligned in a second direction and application of an arbitrary third voltage intermediate between the first voltage and the second voltage. The liquid crystal molecules move the director between the first direction and the second direction. And a liquid crystal exhibiting a ferroelectric phase oriented in a third orientation state oriented in an intermediate direction between the first and second substrates. A pair of polarizers whose axes are disposed within an angle range sandwiched by the first and second directions, and wherein the optical axis of the other polarizer is disposed substantially orthogonal or parallel to the one optical axis; to the liquid crystal between the electrodes, before
The first and second directions are relative to the optical axis of one of the polarizing plates.
The die of the liquid crystal molecules at an angle smaller than
Drive means for applying a voltage to change the reflector, light intensity detection means for detecting the intensity of light passing through a liquid crystal display panel comprising the one and the other substrates, the liquid crystal, and the pair of polarizing plates. And voltage compensating means for compensating the voltage applied to the liquid crystal by the driving means according to the intensity detected by the light intensity detecting means.

According to this configuration, the driving unit drives the liquid crystal without aligning the liquid crystal in the ferroelectric phase. Therefore, the display burn-in phenomenon can be suppressed. Further, since the display gradation is uniquely determined according to the applied voltage, flicker can be suppressed. Furthermore, by using a liquid crystal exhibiting a ferroelectric phase, high-speed response and wide viewing angle characteristics can be ensured. Furthermore, since the applied voltage is adjusted in accordance with the intensity of light transmitted through the liquid crystal display panel, it is possible to remove the influence of a change in the operating environment such as a change in temperature and to appropriately display a desired gradation.

The light intensity detecting means guides the light passing through the liquid crystal display panel to the display panel, for example.
Is composed of a light transfer means such as a photocoupler for transferring light, and a light intensity detecting element arranged on the one substrate and receiving light from the light transfer means.

The active element includes a gate electrode formed on the one substrate, a gate insulating film formed covering the gate electrode, and a semiconductor layer formed on the gate insulating film and forming a channel. And electrodes connected to both ends of the channel of the semiconductor layer.
T, the light intensity detecting element is a light receiving semiconductor layer formed on the gate insulating film, electrodes connected to both ends of the light receiving semiconductor layer, and a liquid crystal formed on the one substrate. A light shielding film for preventing light incident on the display panel from directly irradiating the light receiving semiconductor layer. According to this configuration, for example, the light intensity detecting element can be formed in the process of forming the active element, and the present invention can be realized without increasing the number of manufacturing steps of the liquid crystal display panel.

The light detecting means detects, for example, light passing through a pixel displaying a predetermined gradation. As the predetermined gradation, the lowest gradation (black) is desirable.

The liquid crystal preferably has an intersection angle between the first direction and the second direction that is larger than 45 °.
In this case, the direction of the optical axis of the one polarizing plate is arranged in a range of an angle obtained by subtracting 45 ° from the intersection angle with respect to any one of the first direction and the second direction, The driving unit is configured to control the director of the liquid crystal molecules to the first
And a voltage that changes in an angle range of approximately 45 ° within an angle range sandwiched by the second direction and the second direction, the voltage compensating means removes the influence of a change in the operating environment such as a temperature change, The voltage applied to the driving means is compensated so as to change the director of the liquid crystal molecules in the angle range of 45 °.

The driving means is for setting the director of the liquid crystal molecules in the direction of the optical axis of the one polarizing plate, for example, to display one of the “darkest” image and the “brightest” image. Applying a first predetermined voltage, "darkest"
In order to display the other of the image and the “brightest” image, a second predetermined voltage is applied to set the director of the liquid crystal molecules in a direction at 45 ° to the direction of the optical axis of the one polarizing plate. . In this case, the voltage compensating means compensates for the first and second predetermined voltages of the driving means such that the influence of a temperature change or the like is removed and the director of the liquid crystal molecules is set in a desired direction.

In a display device according to a second aspect of the present invention, a pair of substrates each having an electrode formed on an opposing surface is disposed between the pair of substrates, and a voltage is applied between the electrodes. A first alignment state indicating a first ferroelectric phase in which liquid crystal molecules are substantially aligned in a first direction in response to a first voltage having one polarity, and a second voltage having the other polarity applied between the electrodes A second orientation state in which liquid crystal molecules exhibit a second ferroelectric phase substantially aligned in a second direction intersecting with the first direction at an intersection angle greater than 45 ° , and the first voltage and Second
A third alignment state in which the liquid crystal molecules align their directors in a direction between the first direction and the second direction in response to application of an arbitrary third voltage intermediate to the third voltage. And a liquid crystal exhibiting a ferroelectric phase, each of which is oriented, is disposed with the pair of substrates interposed therebetween, and one of the pair of polarizing plates is arranged in one of the first direction and the second direction. In a range of angles obtained by subtracting 45 ° from the intersection angle, the direction of the optical axis is arranged, and a pair of optical axes of the other polarizing plate are arranged substantially orthogonal or parallel to the optical axis of the one polarizing plate. and a polarizing plate, and a backlight disposed on the back of one of the said pair of polarizing plates, the liquid crystal between the electrodes, the one
The first and second directions form with respect to the optical axis of the other polarizing plate.
At a smaller angle than the angle of the liquid crystal molecules.
Light for detecting the intensity of light from the backlight that has passed through a liquid crystal display panel including a driving unit for applying a voltage that changes the data, the pair of substrates, the liquid crystal, and the pair of polarizing plates. In response to the light intensity and the image data detected by the light intensity detecting means, the direction of the liquid crystal molecules is applied to the optical axis of the one polarizing plate and the optical axis.
In the range of 5 °, the director of liquid crystal molecules is set substantially in the direction of the optical axis of the one polarizing plate to display one of the highest gradation and the lowest gradation. In order to display the other of the lowest gradation, the director of the liquid crystal molecules is set at 45 ° with respect to the direction of the optical axis of the one polarizing plate.
Driving means for controlling the value of the voltage corresponding to the image data and applying the voltage to the liquid crystal so as to be substantially set in the direction of
It is characterized by comprising.

According to this structure, the image sticking phenomenon is prevented without the liquid crystal being oriented in the ferroelectric phase. Furthermore, since the applied voltage is adjusted according to the intensity of the transmitted light,
Appropriate gradation can be displayed regardless of changes in the environment.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a display element of this embodiment, and FIG. 2 is a plan view of a transparent substrate on which pixel electrodes and active elements are formed. This display element is of an active matrix type, and as shown in FIG. 1, a pair of transparent substrates (for example, glass substrates) 11 and 12, a liquid crystal 21 disposed between the transparent substrates 11 and 12, and A pair of polarizing plates 23, 2 disposed with the transparent substrates 11, 12 interposed therebetween
4 and a backlight 26.

In FIG. 1, a lower transparent substrate (hereinafter referred to as a lower substrate) 11 has a pixel electrode 13 made of a transparent conductive material such as ITO and a thin film transistor (hereinafter a TFT) having a source connected to the pixel electrode 13. 14 are formed in a matrix.

As shown in FIG. 2, a gate line (scanning line) 15 is arranged between rows of the pixel electrodes 13, and a data line (gradation signal line) 16 is arranged between columns of the pixel electrodes 13. The gate electrode of each TFT 14 is connected to a corresponding gate line 15, and the drain electrode is connected to a corresponding data line 16.

The gate line 15 is connected to a row driver 31 and the data line 16 is connected to a column driver 32. The row driver 31 scans the gate line 15 by applying a gate signal described later. On the other hand, the column driver 32 receives a display signal (gradation signal) and applies a data signal corresponding to the display signal to the data line 16.

The row driver 31 and column driver 32
It may be arranged on the lower substrate 11 by a G (chip-on-glass) method or the like.

In the non-display area of the lower substrate 11, a dummy pixel electrode 13D for data signal compensation and a photo sensor 3 are provided.
3 are arranged adjacent to each other. The photo sensor 33 is connected to a compensation circuit 34 for compensating the data signal. Further, the compensation circuit 34 applies a voltage signal for displaying the lowest gray level “black” to the dummy pixel electrode 13D.

The TFT 14 is, as shown in FIG.
A gate electrode 311 formed on the lower substrate 11, a gate insulating film 312 formed covering the entire lower substrate 11, an intrinsic (intrinsic) semiconductor layer 313 formed on the gate insulating film 312; A blocking layer 314 formed on a channel region of the semiconductor layer 313; contact layers 315 and 316 formed on a source region and a drain region of the intrinsic semiconductor layer 313;
5 and 316 are connected to a source electrode 317 and a drain electrode 318. The pixel electrode 13 is connected to the source electrode 317.

The photo sensor 33 includes, as shown in FIG. 3B, a light-shielding film 321 formed on the lower substrate 11, an intrinsic semiconductor layer 322 formed on the gate insulating film 312,
Contact layers 323, at both ends of the intrinsic semiconductor layer 322,
It is composed of electrodes 325 and 326 connected via 324.

The gate electrode 311 and the light-shielding film 321 are made of, for example, aluminum alloy, tantalum, tungsten or the like. Note that the light-shielding film 321 may be formed using a so-called black mask material. Intrinsic semiconductor layer 313
And 322 are made of, for example, amorphous silicon, polycrystalline silicon, single crystal silicon, or the like, which hardly contains impurities. Also, contact layers 315 and 316,
323 and 324 are made of, for example, amorphous silicon to which n-type impurities are added, polycrystalline silicon, single crystal silicon, or the like.

The carrier density and carrier mobility in the intrinsic semiconductor layer 322 change according to the intensity of the irradiation light, and the substantial resistivity of the intrinsic semiconductor layer 322 also changes according to the intensity of the irradiation light. Therefore, when a constant voltage is applied to the intrinsic semiconductor layer 322, the current flowing through the semiconductor layer 322 changes according to the intensity of the irradiation light, as shown in FIG. Therefore, the intensity of the irradiation light can be determined by determining the current flowing through the semiconductor layer 322 or its resistance value.

In FIG. 1, an upper transparent substrate (hereinafter referred to as an upper substrate) 12 is opposed to each pixel electrode 13 of the lower substrate 11 and a dummy pixel electrode 13D, and is opposed (common) to which a reference voltage is applied. An electrode 17 is formed. Common electrode 17
Is a transparent electrode made of, for example, ITO.
The opposing portion of each pixel electrode 13 and the common electrode 17 forms a pixel region constituting each display pixel, and the dummy pixel electrode 13
The opposing portion of D and the common electrode 17 forms a pixel region of a dummy pixel for compensation.

On the polarizing plate 24, as shown in an enlarged view in FIG.
A photocoupler 35 is disposed opposite to. The photocoupler 35 irradiates the light emitted from the backlight 26 and passed through the dummy pixel to the photosensor 33. An opening may be formed in the portion of the polarizing plate 24 facing the photosensor 33 so that the light emitted from the photocoupler 35 reaches the photosensor 33 without passing through the polarizing plate 24.

The backlight 26 includes, for example, an EL panel, a light guide plate for guiding light from a cold cathode ray tube, and the like.

On the electrode forming surfaces of the lower substrate 11 and the upper substrate 12, alignment films 18 and 19 are provided, respectively. The alignment films 18 and 19 are horizontal alignment films made of an organic polymer compound such as polyimide, and at least one of the opposing surfaces has been subjected to an alignment process of rubbing once in a direction parallel to and opposite to each other. .

The lower substrate 11 and the upper substrate 12 are adhered to each other at the outer peripheral edge thereof via a frame-shaped sealing material 20 to form a liquid crystal cell 25. The distance between the alignment films 18 and 19 is set to, for example, 1.4 μm by the sealing material 20 and the spacer 22.
m to 2.4 μm, and the liquid crystal 21
Are sealed in a region surrounded by the substrates 11 and 12 and the sealing material 20.

The liquid crystal 21 has a single helical structure (in the case of ferroelectric liquid crystal) or a double helical structure (in the case of antiferroelectric liquid crystal) in a bulk state, and the gap length of the liquid crystal cell 25 is small. Since the pitch is shorter than the helical pitch, the helical pitch is sealed in the liquid crystal cell 25.

In the liquid crystal 21, each molecule has a spontaneous polarization Ps.
And a chiral smectic C phase or a CA phase (SmC) that is twice as large as the angle (tilt angle) θ formed by the cone and the cone drawn by the molecule (tilt angle) 2 (cone angle) is larger than 45 ° (preferably 60 ° or more) ^* Or SmCA ^* ) (ferroelectric liquid crystal or antiferroelectric liquid crystal). Liquid crystal 2
The horizontal component (the direction projected on a plane parallel to the main surfaces of the substrates 11 and 12) of one director (the average orientation direction of the liquid crystal molecules) changes continuously according to the applied voltage.

As the liquid crystal having such characteristics, for example, liquid crystal substances I to II having a skeletal structure represented by Chemical Formula 1
There is an antiferroelectric liquid crystal obtained by mixing I at a ratio of 20% by weight, 40% by weight, and 40% by weight, respectively.

[0040]

Embedded image

Next, the relationship between the direction of the alignment treatment applied to the alignment films 18 and 19, the optical axes of the polarizing plates 23 and 24, and the alignment direction of the liquid crystal molecules of the liquid crystal 21 will be described with reference to FIG.

In FIG. 6, reference numeral 21C denotes an alignment film 18,
19 shows the direction of the alignment treatment performed, and the liquid crystal 21 adjusts the normal of the layer of the layer structure of the chiral smectic C phase or CA phase within the range of about ± 2 ° to ± 5 °. It is oriented toward 21C.

When a voltage lower than the predetermined negative voltage -VS is applied to the liquid crystal 21, the liquid crystal 21 enters the first alignment state (ferroelectric phase), and the alignment direction of the liquid crystal molecules is substantially in the first direction 21A. Becomes When a voltage higher than the predetermined positive voltage + VS is applied to the liquid crystal 21, the liquid crystal 21 enters the second alignment state, and the alignment direction of the liquid crystal molecules is substantially the second direction 21.
B. On the other hand, when the applied voltage is 0, the average alignment direction (director) of the liquid crystal molecules is almost the normal direction of the smectic phase layer of the liquid crystal 21, that is, the first and second directions 21.
Almost intermediate direction between A and 21B (almost the direction of alignment treatment) 2
1C.

The deviation angle 2θ between the first direction 21A and the second direction 21B is 45 ° or more, preferably 60 ° or more. The optical axis (transmission axis in this embodiment) 23A of the polarizing plate 23 is composed of a first direction 21A and an alignment processing direction 21A.
C, approximately 22.5 ° with respect to the alignment direction 21C.
The direction is set. Transmission axis 24A of polarizing plate 24
Is set in a direction substantially orthogonal to the transmission axis 23A of the polarizing plate 23.

As shown in FIG. 6, in the display device in which the transmission axes 23A and 24A of the polarizing plates 23 and 24 are set, the average alignment direction (director) of the liquid crystal molecules is changed by the transmission axis 2 of the polarizing plate 23.
3A, the transmittance is lowest (the display is darkest), and the average alignment direction of the liquid crystal molecules is changed to the polarization plate 2.
The transmittance becomes highest (brightest) when the direction 21D is set at 45 ° with respect to the transmission axis 23A of No.3.

That is, when the average orientation direction of the liquid crystal molecules is oriented in the direction of the transmission axis 23A, the linearly polarized light passing through the polarizing plate 23 on the incident side is hardly affected by the polarization action of the liquid crystal 21, and the linearly polarized light is The light passes through the layer of the liquid crystal 21 as it is, and is absorbed by the polarizing plate 24 whose transmission axis 24A is set in the perpendicular direction, and the display becomes dark.

On the other hand, in a state where the average orientation direction of the liquid crystal molecules is oriented at 45 ° with respect to the transmission axis 23A, the linearly polarized light passing through the polarizing plate 23 on the incident side is
And the component parallel to the transmission axis 24A of the output side polarizing plate 24 is
4 and is emitted. Therefore, the display becomes the brightest. In other orientation states, the light becomes non-linearly polarized light according to the orientation state due to the birefringence action, and a component parallel to the transmission axis 24A of the emission-side polarization plate 24 passes through the polarization plate 24 and exits. Therefore, the display has a brightness according to the orientation state.

Therefore, when a sawtooth voltage of a relatively low frequency (approximately 0.1 Hz) is applied between the pixel electrode 13 and the common electrode 17, the change in transmittance as shown by the solid line in FIG. It changes continuously. The transmittance is determined by the liquid crystal 2
When one director is parallel to the transmission axis 23A of the polarizing plate 23, it becomes the minimum Tmin, and when it exceeds this, it becomes bright again.
Further, the transmittance becomes the maximum Tmax when the director of the liquid crystal 21 crosses the transmission axis 23 of the polarizing plate 23 at 45 °,
Beyond this, it becomes dark again.

That is, the transmittance of the liquid crystal element is minimum when the director of the liquid crystal is parallel to the transmission axis 23A of the polarizing plate 23,
Since it becomes the maximum when crossing at 45 °, the voltages VTmin and V at which the transmittance of the liquid crystal element becomes an alignment state showing Tmin and Tmax are obtained.
By applying a voltage during Tmax to the liquid crystal 21, the liquid crystal 21 can be driven without being aligned in the first and second alignment states. The first and second alignment states are states in which all molecules in the layer of the liquid crystal 21 exhibit a ferroelectric phase in which the molecules are almost completely aligned in the same direction. It is less likely to occur and it is easier to burn. However, if the liquid crystal molecules are not completely aligned, the charge due to spontaneous polarization hardly accumulates.
Burn-in is reduced. That is, the applied voltages are VTmax and VTm.
By changing within the range of in, the liquid crystal 21 can be driven without using a ferroelectric phase, and further, continuous gradation can be displayed.

Since this display element is of the active matrix type, the liquid crystal 21 can be used even during the non-selection period.
Can be maintained at a voltage for maintaining an arbitrary orientation state. For this reason, the liquid crystal display element having the above configuration can perform gradation display by changing the transmittance.

On the other hand, the cone angle 2θ of the liquid crystal 21 changes according to the temperature, and the magnitude of the change differs depending on the material of the liquid crystal 21. That is, the tilt angle of the liquid crystal (the tilt angle θ of the liquid crystal molecule with respect to the axis of the cone drawn by the liquid crystal molecule) is
When the temperature of the liquid crystal increases, the spontaneous polarization decreases because the fluctuation of the liquid crystal molecules increases. As a result, the tilt angle θ decreases and the cone angle 2θ decreases. In addition, when the temperature is high, the liquid crystal molecules move easily, so that the director of the liquid crystal can be swung at a large angle at a low voltage.

FIG. 6 shows an example of such a change in the electro-optical characteristics due to a change in the temperature of the liquid crystal 21. 6, the solid line indicates the electro-optical characteristics when the temperature of the liquid crystal 21 is room temperature (25 ° C.), and the dashed line indicates the low temperature (10 ° C.) where the temperature of the liquid crystal 21 is lower than room temperature.
And the two-dot chain line show the electro-optical characteristics at a high temperature (50 ° C.) where the temperature of the liquid crystal 21 is higher than usual. In these electro-optical characteristics, when a voltage VTmin at which the transmittance exhibits a minimum value is applied, the director of the liquid crystal molecules substantially coincides with the direction of the transmission axis 23A of the polarizing plate 23, and a voltage VTmax at which the transmittance exhibits a maximum value is applied. Then, the director of the liquid crystal molecules is oriented in a direction 21D that intersects the direction of the transmission axis 23A of the polarizing plate 23 at almost 45 °,
By changing the applied voltage from the voltage VTmin to the voltage VTmax, the director of the liquid crystal molecules changes its direction by approximately 45 °.

As is clear from FIG. 6, when the temperature of the liquid crystal is low, the cone angle 2θ increases, and the transmittance T
The absolute value of the voltage for obtaining min and Tmax is large, and the voltage modulation range is widened. When the liquid crystal temperature is high, the cone angle 2θ is small, the absolute value of the voltage for obtaining the transmittances Tmin and Tmax is small, and the voltage modulation range is narrow. As described above, the transmittance changes with respect to the same applied voltage in accordance with a change in the operating environment such as a change in temperature, progress of deterioration, elapse of time, and the like, so that image quality is deteriorated and contrast is reduced.

In order to eliminate the problem that the display gradation changes for the same applied voltage, in this embodiment, a predetermined gradation is always displayed on the dummy pixel, and the actual display gradation is detected by the photo sensor 33. Then, the detection result is fed back to adjust the voltage of the data signal applied to the liquid crystal 21 so that a desired gradation is displayed.

The voltage adjustment of the data signal is to substantially match the predetermined gradation with the brightness of the predetermined gradation, and when the predetermined gradation is the lowest gradation, the lowest transmittance is obtained. The voltage of the signal is adjusted so that a voltage at which the transmittance Tmin is obtained is applied to the liquid crystal 21 in accordance with the image data designating. That is, when the image data designating the lowest transmittance Tmin is supplied, the shift is performed by shifting the voltage of the data signal so that the brightness detected by the photosensor 33 is minimized. At this time, the director of the liquid crystal molecules is oriented in a direction substantially coincident with the direction of the transmission axis 23A of the polarizing plate 23. Then, the modulation width of the data signal is adjusted such that the director of the liquid crystal molecules is oriented in a direction intersecting the direction of the transmission axis 23A of the polarizing plate 23 at approximately 45 ° when image data designating the highest transmittance is applied. I do.

FIG. 8 shows the configuration of the compensation circuit 34. As shown, the compensation circuit 34 includes a reference signal generation circuit 51
, A compensation driver circuit 52, an amplifier 53, a black level reference circuit 54, a comparator 55, and a controller 56.

The reference signal generation circuit 51 generates a voltage signal for displaying the lowest gradation, that is, "black" under reference conditions (reference temperature, reference deterioration degree, reference magnetic field strength, etc.).
The compensating driver circuit 52 amplifies this voltage signal at the amplification factor α and further adds the bias voltage Vb to “black”
Is generated and applied to the dummy pixel electrode 13D.

By the application of the reference waveform signal, the director of the liquid crystal molecules of the liquid crystal 21 of the dummy pixel is set parallel to the transmission axis 23A of the polarizing plate 23. Therefore, the light emitted from the backlight 26 is substantially absorbed by the dummy pixels, and the display becomes substantially “black”. The light that has passed through the dummy pixels enters the photocoupler 35, passes through the inside of the photocoupler 35, is emitted again, and enters the photosensor 33. The photo sensor 33 converts the intensity of the incident light, that is, the “black” gradation displayed by the dummy pixel into a current signal and outputs the current signal. Amplifier 5
Reference numeral 3 converts the output of the photosensor 33 from current to voltage, and amplifies the output. The black level reference circuit 54 generates a reference level of a preset gray level of the lowest gray level “black” or a reference signal set by a user by operating a volume or the like according to his / her preference.

The comparator 55 calculates the difference (deviation) between the reference level from the black level reference circuit 54 and the actually displayed gradation detected by the photo sensor 33, and generates a difference signal Se. The controller 56 sets the difference signal Se output from the comparator 55 to zero level, that is, the deviation is set to 0.
The amplification factor α of the compensation driver circuit 52 and the bias voltage Vb are set so that Further, the controller 56
As described later with reference to FIG.
The amplification factor α and the bias voltage Vb of each driver circuit 46 arranged for each are set in the same manner.

By performing such processing, the lowest gray level “black” is applied to the dummy pixels without being affected by environmental changes.
Can be displayed.

Next, FIG. 9 shows a configuration example of the column driver 32 for adjusting the voltage of the data signal in accordance with the instruction of the compensation circuit 34. The column driver 32 includes a first sample and hold circuit 41 and a second sample and hold circuit 42
, An A / D (analog / digital) converter 43, a timing circuit 44, a voltage conversion circuit 45, and a driver circuit 46.

The first sample / hold circuit 41, the second sample / hold circuit 42, the A / D (analog / digital) converter 43, the voltage conversion circuit 45, and the driver circuit 46 are connected to a data line. It is arranged every 16
The timing circuit 44 is arranged commonly to the plurality of data lines 16.

The first sample and hold circuit 41 samples and outputs a signal component (one image data) VD ′ for a corresponding pixel from an externally supplied analog display signal.
Hold. The second sample-and-hold circuit 42 receives the hold signal VD 'from the first sample-and-hold circuit 41.
Sample hold.

The A / D converter 43 A / D converts the hold signal of the second sample / hold circuit 42 and converts it into digital gradation data DG. The timing circuit 44
During each selection period TS, a timing control signal for instructing sampling and holding is supplied to the first and second sample and hold circuits 41 and 42.

The voltage conversion circuit 45 converts the digital gradation data DG output from the A / D converter 43 into a voltage necessary for displaying the gradation designated by the digital gradation data DG under standard conditions. The voltage conversion circuit 45 separates the power supply system of the signal processing system from the power supply system of the drive system.

The driver circuit 46 is composed of an operational amplifier (operational amplifier) having a relatively large driving capability, and the like.
The pulse signal VD ″ is amplified at the amplification rate α, and the bias voltage V
The data line 16 is driven by adding b. The amplification factor α and the bias voltage Vb of the driver circuit 46 are set to the same values as the amplification factor α and the bias voltage Vb of the compensation driver circuit 52 by the controller 56 in the compensation circuit 34.

Next, a method of driving the display element device having the above configuration will be described with reference to FIG. Reference signal generation circuit 51
Generates a voltage signal for displaying the lowest gradation under the reference condition, and the compensation driver circuit 52 amplifies the voltage signal at an amplification factor α, and further adds a bias voltage Vb to generate a voltage signal. VTmin is generated, and the dummy pixel electrode 13D is generated.
Is applied. By applying the voltage signal VTmin, the dummy pixel displays black of the lowest gradation. The light that has passed through the dummy pixels enters the photo sensor 33 via the photo coupler 35. The photo sensor 33 converts the intensity of the incident light into a current signal and outputs it. The amplifier 53 converts the output of the photosensor 33 into a current and a voltage, and amplifies and outputs the output. The comparator 55 calculates the deviation between the reference level from the black level reference circuit 54 and the actually displayed gradation detected by the photosensor 33, and the controller 56 sets the compensation driver so that the deviation becomes zero. The amplification factor α of the circuit 52 and the bias voltage Vb are set. That is, the compensation circuit 34 forms a feedback loop, and dynamically controls the amplification factor α and the bias voltage Vb of the compensation driver circuit 52 so that “black” of the lowest gradation is always displayed.

On the other hand, the first sample and hold circuit 41
Samples and holds the corresponding pixel signal component (one image data) VD ′ of the analog display signal supplied from the outside in accordance with the timing signal from the timing circuit 44. In the next horizontal scanning period, the first sample and hold circuit 41 according to the timing signal
Of the second sample-and-hold circuit 42
Is transferred to and held. The A / D converter 43 converts the hold signal of the second sample and hold circuit 42 into an A / D signal.
Conversion to digital gradation data.

The voltage conversion circuit 45 generates a voltage corresponding to the digital gradation data output from the A / D converter 43 (the driving necessary for displaying the gradation indicated by the digital gradation data under the reference condition). System voltage) VD ", and outputs the converted voltage.
Is amplified by the amplification factor α set by the controller 56 of the compensation circuit 34, and the bias voltage Vb set by the controller 56 is added to generate a data signal composed of the data shown in FIG. To the corresponding data line 16.

The row driver 31 applies a gate pulse to the gate line 15 of the selected row, substantially in synchronization with the application of the pulse voltage VD to the data line 16 by the driver circuit 46, as shown in FIG. I do. The pulse voltage VD of the data pulse is determined by the TF of the corresponding row by the gate pulse.
During the writing period in which T14 is on, the voltage is applied to the liquid crystal 21, and while the TFT 14 is off, the opposite electrode 13 is applied.
And 17 are maintained. Therefore, as shown in FIG. 10C, the transmittance corresponding to the holding voltage is held until the next selection period of this row.

The amplification factor α and the bias voltage Vb of the driver circuit 46 in each column are set by the feedback circuit of the compensating circuit 34 so that the lowest gray level “black” can be appropriately displayed regardless of changes in the environment. Value. Therefore, the display gradation indicated by the analog display signal is also appropriately displayed regardless of the change in the environment.

That is, according to this drive circuit, a change in the applied voltage-transmittance characteristic due to a change in the environment is detected using a feedback loop, and the voltage of the drive pulse is adjusted according to the detection result. , And a desired gray scale can be appropriately displayed.

When the liquid crystal 21 has a large hysteresis in its electro-optical characteristics, in the driving method shown in FIG. 10, the display gradation for the same applied voltage is affected by the past applied voltage of the liquid crystal 21. There is a possibility that it cannot be uniquely determined. In such a case, for example, the driving method shown in FIG. 11 may be adopted.

In this driving method, the TFT 14 in the selected row is turned on by the gate pulse shown in FIG.
A data signal corresponding to the display gradation is applied between the pixel electrode 13 and the common electrode 17 via the turned-on TFT 14. As shown in FIG. 11B, the data signal has a set pulse VH for aligning the liquid crystal molecules in a predetermined alignment state.
And a reset pulse VL for canceling the DC component of the set pulse VH, and a gradation pulse VD corresponding to the display gradation.
Consists of The liquid crystal 21 sets the setting pulse VH during each selection period.
By this, it can be oriented to a substantially constant state. Therefore, even when there is hysteresis in the optical characteristics, the display gradation corresponding to the gradation pulse VD is uniquely determined.

When the gate pulse is turned off, the TFT 14 is turned off, and the voltage of the gradation pulse VD applied between the pixel electrode 13 and the common electrode 17 until that time is held in the pixel capacitance. Therefore, as shown in FIG. 11C, the transmittance corresponding to the holding voltage is held until the next selection period of this row. Therefore, according to this driving method, an arbitrary gradation image can be displayed by controlling the voltage of the data pulse VD. In addition, since the reset pulse VL is applied, the direct current component applied to the liquid crystal 21 can be canceled, and the burn-in of the display can be reduced.

Also in the case of this driving method, a high-contrast image can be displayed by adjusting the voltage of the reset pulse and the voltage of the setting pulse in accordance with the temperature.
Display burn-in can be prevented.

FIG. 12 shows a circuit configuration of the column driver 32 for realizing the driving method shown in FIG. FIG.
In FIG. 9, the same parts as those in FIG. The column driver 32 includes a first sample and hold circuit 41
, A second sample / hold circuit 42, an A / D (analog / digital) converter 43, and a voltage conversion circuit 45.
, A driver circuit 46, a voltage data generation circuit 47,
It comprises a timing circuit 48 and a multiplexer 49.

The first sample and hold circuit 41 samples and holds the signal component VD 'of the corresponding pixel in the display signal. Second sample and hold circuit 42
Samples and holds the hold signal of the first sample and hold circuit 41. The A / D converter 43 converts the hold signal of the second sample and hold circuit 42 into an analog / digital signal.
It is digitally converted and converted into digital gradation data DG. The voltage data generation circuit 47 generates setting pulse data DH corresponding to the setting pulse VH and reset pulse data DL corresponding to the reset pulse VL.

The timing circuit 48 supplies a timing control signal to the first and second sample-and-hold circuits 41 and 42, and also supplies timing control signals to three time slots t1, t2 and t3 constituting the selection period TS of each pixel row. Turn on the timing signals T1, T2, T3. Multiplexer 4
9 sequentially selects and outputs reset pulse data DL, set pulse data DH, and digital gradation data DG in each selection period TS in response to the timing signals T1 to T3. The voltage conversion circuit 45 converts the output data of the multiplexer 49 into a high voltage of the driving system and outputs the same.

The driver circuit 46 applies the voltage output from the voltage conversion circuit 45 to the controller 56 of the compensation circuit 34.
And the bias voltage Vb
Is applied to the data line 16 as pulse voltages VL, VH, and VD. Therefore, even in this driving method, the pulse voltages VL, VH, and VD are always set to almost optimum values, respectively, and appropriate display can be performed regardless of a change in environment.

In the driving method shown in FIG. 11, the reset pulse VL may be a voltage having a polarity opposite to the sum of the voltage of the setting pulse VH and the voltage of the gradation pulse VD. Further, the setting pulse may be VL and the reset pulse may be VH.

The present invention is not limited to the above-described embodiment, and various modifications and applications are possible. For example, if the director of the liquid crystal can be driven so as not to be in a ferroelectric phase within an angle range of 45 ° and the highest display gradation Tmax and the lowest display gradation Tmin can be obtained, an arbitrary element structure is adopted. It is possible. For example, the shift angle 2θ of the liquid crystal is 60
When the angle is equal to or more than the angle, the transmission axis 23A of the polarizing plate 23 is set at a position within an angle range of 60 ° -45 ° (= 15 °) (for example, 12.5 °) from the first direction 21A, The transmission axis 24A of the liquid crystal 21 is set so as to be orthogonal or parallel to the transmission axis 23A, and the director of the liquid crystal 21 is tilted by 45 ° with respect to the direction of the transmission axis 23A of the polarizing plate 23 and this direction.
D may be driven.

For example, a liquid crystal having a shift angle 2θ of 90 ° or more may be used. In this case, for example, the transmission axis of one polarizing plate may be set to the normal direction of the smectic layer, and the transmission axis of the other polarizing plate may be set to be orthogonal or parallel to the transmission axis of one polarizing plate.

The configurations of the column driver 32 and the compensating circuit 34 are not limited to the embodiments, and can be arbitrarily changed. Further, the light that has passed through the dummy pixel is
Any other configuration can be adopted as long as the intensity of the light guided to the photo sensor 33 but passed through the dummy pixel can be detected. For example, the transmitted light of the dummy pixel may be directed to the photo sensor 33 using a reflector. Further, a photo sensor 33 directed to the dummy pixel may be arranged on the polarizing plate 24. Further, although the amplification factor α and the offset voltage Vb of the driver circuit 46 are adjusted according to the error signal, for example, the conversion output voltage of the voltage conversion circuit 45 may be adjusted according to the error signal Se.

Further, in the above description, the dummy pixels are arranged separately from the normal pixels, but one of the normal pixels may be used for compensation. The display gradation of the dummy pixel and the compensation pixel is not limited to the lowest gradation, and an arbitrary gradation can be displayed. That is, the highest gradation or any intermediate gradation may be displayed. However, in order to increase the contrast of the displayed image, it is desirable to display the lowest gradation. In addition, it is desirable that the dummy pixel, the photocoupler, the photosensor, and the like be covered with a light-shielding cover so that the photosensor 33 does not receive general incident light.

The configurations of the TFT 14 and the photosensor 33 are not limited to the configuration shown in FIG. 3, but any configuration can be adopted, and the TFT 14 and the photosensor 33 can be manufactured in different steps.

In the above embodiment, the liquid crystal 2
Although the liquid crystal 21 is sealed in the liquid crystal cell 25 in a state where the spiral structure of FIG. 1 is released, the liquid crystal 21 may be sealed in the liquid crystal cell while maintaining the spiral structure. Also in this case, a liquid crystal having the basic structure shown in Chemical Formula 1 can be used.

The liquid crystal 21 has a cone angle 2θ.
Deformed Helical Ferroelectr
ic) It is also possible to use liquid crystals. DHF liquid crystal is
It is sealed between the substrates 11 and 12 while maintaining the helical structure of the liquid crystal molecules.

When a voltage having one polarity and an absolute value equal to or more than a predetermined value is applied, the DHF liquid crystal becomes the first ferroelectric phase in which the spiral is unwound, and the liquid crystal molecules move in the first direction 21 shown in FIG.
A is almost oriented. When a voltage having the other polarity and the absolute value of which is equal to or greater than a predetermined value is applied, the DHF liquid crystal becomes a second ferroelectric phase in which the spiral is unwound, and the liquid crystal molecules are substantially oriented in the second direction 21B shown in FIG. .

When an intermediate voltage is applied, the helical structure drawn by the liquid crystal molecules is distorted according to the applied voltage, and the average direction (director) in the major axis direction of the liquid crystal molecules is changed to the first direction 21.
The intermediate orientation state is set to an arbitrary direction between A and the second direction 21B.

Therefore, when a pair of polarizing plates 23 and 24 are arranged as shown in FIG. 6 and the applied voltage is changed, the transmittance changes as shown by a solid line in FIG. Therefore, the liquid crystal 21
When a DHF liquid crystal is used, the applied voltage is controlled between VTmin and VTmax so that the liquid crystal 21 does not exhibit a ferroelectric phase, and the director of the liquid crystal 21 is set at 45 ° with respect to the transmission axis 23A and the transmission axis 23A. , The image burn-in of the display can be prevented, and the maximum gradation width can be displayed.

The transmission axis 24A of the polarizing plate 24 and the transmission axis 23A of the polarizing plate 23 may be set in parallel. Further, an absorption axis may be used instead of the transmission axis. Also,
The present invention is not limited to a display element using a TFT as an active element, but is also applicable to a display element using an MIM as an active element. Further, the present invention, as shown in FIG.
The present invention is also applicable to a simple matrix type (passive matrix type) display element in which a scanning electrode 71 and a signal electrode 72 orthogonal to the scanning electrode 71 are arranged on the opposing surfaces of the opposing substrates 11 and 12. In addition, a color filter can be arranged and used as a color liquid crystal display element.

[0093]

As described above, according to the display device of the present invention, since the liquid crystal is driven without using a ferroelectric phase, it is possible to obtain a display device with less display sticking due to spontaneous polarization. it can. Moreover, the light actually passing through the liquid crystal display panel is measured, and based on the measurement result,
Since the voltage applied to the liquid crystal is controlled (adjusted), a desired gradation can always be appropriately obtained regardless of changes in the environment or progress of deterioration.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a display element according to an embodiment of the present invention.

FIG. 2 is a plan view showing a configuration of a lower substrate of the display element shown in FIG.

FIGS. 3A and 3B are TF diagrams of the display device shown in FIG.
FIG. 3 is a diagram illustrating a configuration of T and a photo sensor.

FIG. 4 is a diagram illustrating a relationship between a light receiving amount and a detection current of the photo sensor illustrated in FIG.

FIG. 5 is a diagram showing an arrangement of a photocoupler.

FIG. 6 is a diagram showing a relationship between a transmission axis of a polarizing plate and an alignment direction of liquid crystal molecules.

FIG. 7 is a diagram showing the relationship between the application method and the transmittance of the liquid crystal display element of this embodiment.

FIG. 8 is a block diagram illustrating a configuration example of a compensation circuit.

FIG. 9 is a circuit block diagram illustrating an example of a configuration of a column driver.

10 is a timing chart showing a waveform of a voltage applied to a pixel and a transmittance by a driving method using the column driver of FIG. 9;

FIG. 11 is a timing chart showing another example of a method of driving the liquid crystal display element of this embodiment and a change in transmittance.

12 is a circuit block diagram illustrating an example of a configuration of a column driver for realizing the driving method illustrated in FIG.

FIG. 13 is a sectional view showing another example of the structure of the display element according to the embodiment of the present invention.

[Explanation of symbols]

11: transparent substrate (lower substrate), 12: transparent substrate (upper substrate), 13: pixel electrode, 13D: dummy pixel electrode, 1
4 ... active element (TFT), 15 ... gate line (scan line), 16 ... data line (gradation signal line), 17 ... common electrode, 18 ... alignment film, 19 ..Alignment film, 20 seal material, 21 liquid crystal, 22 spacer, 23 polarizing plate (lower polarizing plate), 24 polarizing plate (upper polarizing plate), 25. ..Liquid crystal cell, 26 backlight, 31
... row driver, 32 ... column driver, 33 ... photosensor, 34 ... compensation circuit, 35 ... photocoupler, 41,
42 sample-hold circuit 43 analog-digital converter 44 timing circuit 45 voltage conversion circuit 46 driver circuit 47 voltage data generation circuit 48 .. Timing circuit, 49 multiplexer, 51 reference signal generation circuit, 52 compensation driver circuit, 53 amplifier, 54 black level reference circuit, 55
... Comparator, 56 ... Controller

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-334130 (JP, A) JP-A-5-80101 (JP, A) JP-A-6-2899367 (JP, A) JP-A-1- 288826 (JP, A) JP-A-63-226624 (JP, A) JP-A-5-297350 (JP, A) JP-A-5-303081 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) G02F 1/133 G02F 1/1335 510 G02F 1/141 G09G 3/36

Claims (10)

(57) [Claims] A first substrate on which an active element and a pixel electrode connected to the active element are arranged in a matrix; a second substrate on which a common electrode opposed to the pixel electrode is formed; And a first ferroelectric phase in which liquid crystal molecules are substantially arranged in a first direction according to a first voltage of one polarity applied between the pixel electrode and the common electrode. A first alignment state, and a second alignment state indicating a second ferroelectric phase in which liquid crystal molecules are substantially aligned in a second direction in response to a second voltage of the other polarity applied between the electrodes. , An arbitrary third intermediate between the first voltage and the second voltage.
The ferroelectric phases in which the liquid crystal molecules are aligned in a third alignment state in which the liquid crystal molecules align the director in a direction intermediate between the first direction and the second direction in response to the application of a voltage of A liquid crystal to be shown, disposed between the one and the other substrates, and the optical axis of one of the polarizing plates is set within an angle range sandwiched by the first and second directions, and the optical axis of the other polarizing plate is A pair of polarizing plates whose axes are arranged substantially orthogonal or parallel to the one optical axis, the liquid crystal between the electrodes, and the optical axis of the one polarizing plate.
Each of which is smaller than the angle formed by the first and second directions.
A driving means for applying a voltage to change the director of the liquid crystal molecules at a small angle; and an intensity of light passing through a liquid crystal display panel including the one and the other substrates, the liquid crystal, and the pair of polarizing plates. A liquid crystal exhibiting a ferroelectric phase, comprising: a light intensity detecting means for detecting the intensity of light; Display device using the same. (2) The driving means is configured such that the liquid crystal molecules are first and second liquid crystal molecules.
Absolute values are higher than the first and second voltages
A voltage that changes in a small voltage range is applied to the liquid crystal.
The display device according to claim 1, wherein: 3. The light intensity detecting means includes: light transmitting means for guiding light passing through the liquid crystal display panel to the liquid crystal display panel side; and light transmitting means disposed on the one of the substrates to receive light from the light transmitting means. The display element device according to claim 1, comprising: a light intensity detecting element that receives light. 4. The active element includes a gate electrode formed on the one substrate, a gate insulating film formed to cover the gate electrode, and a channel formed on the gate insulating film. A semiconductor layer, and electrodes connected to both ends of a channel of the semiconductor layer, wherein the light intensity detecting element includes a light receiving semiconductor layer formed on the gate insulating film, and a light receiving semiconductor layer. An electrode connected to both ends, and a light-shielding film formed on the one substrate and preventing light incident on the liquid crystal display panel from directly irradiating the light-receiving semiconductor layer. The display element device according to claim 3 , wherein 5. The apparatus according to claim 1, further comprising a backlight disposed on one back surface of said pair of polarizing plates and generating illumination light transmitted through a liquid crystal display panel.
5. The display element device according to any one of 4 . 6. The one substrate includes a pixel electrode dedicated to transmittance detection, and the light transfer unit transfers light passing through the pixel electrode dedicated to transmittance detection to the light intensity detection unit. The display according to any one of claims 1 to 5 , wherein the driving means includes means for applying a reference voltage for displaying a predetermined gradation to the pixel electrode dedicated to transmittance detection. Element device. 7. The display device according to claim 6 , wherein said driving means includes means for applying a reference voltage for displaying the lowest gradation to the pixel electrode dedicated to transmittance detection. . 8. The liquid crystal has a ferroelectric phase in which an intersection angle between the first direction and the second direction is oriented at an angle larger than 45 ° . The direction of the optical axis is arranged in a range of an angle obtained by subtracting 45 ° from the intersection angle with respect to any of the direction of the second direction and the second direction. applying a voltage that changes at approximately 45 ° angle range in the angle range sandwiched by said second direction and the first direction, the voltage compensation means, regardless of the change in the operating environment, the director of the liquid crystal molecules The display element device according to any one of claims 1 to 7 , wherein the applied voltage of the driving unit is compensated so that is changed in the 45 ° angle range. 9. A first predetermined means for setting a director of the liquid crystal molecules in a direction of an optical axis of the one polarizing plate in order to display one of a darkest image and a brightest image. a voltage is applied, in order to display the other of the brightest image and the darkest image, direction relative to the second for setting the direction of 45 ° of the optical axis of the polarizer director of the one of the liquid crystal molecules The device according to any one of claims 1 to 8 , further comprising: a unit configured to apply a predetermined voltage, wherein the voltage compensating unit includes a unit configured to compensate an applied voltage of the driving unit according to a detection result of the light detecting unit. The display element device according to one of the above. 10. A pair of substrates each having an electrode formed on an opposing surface, and a liquid crystal molecule disposed between the pair of substrates, wherein liquid crystal molecules are formed in response to a first voltage of one polarity applied between the electrodes. In response to a first alignment state indicating a first ferroelectric phase substantially arranged in the first direction and a second voltage of the other polarity applied between the electrodes, liquid crystal molecules are moved in the first direction by 45 degrees. A second orientation state indicative of a second ferroelectric phase substantially aligned in a second direction intersecting at a greater intersection angle, and any third voltage intermediate the first and second voltages A liquid crystal exhibiting a ferroelectric phase in which liquid crystal molecules are aligned in a third alignment state in which liquid crystal molecules are oriented in a direction between the first direction and the second direction in response to the application of One of the pair of polarizing plates is disposed so as to sandwich the pair of substrates, and the one of the pair of polarizing plates is in front of the first direction. With respect to any of the second directions, the direction of the optical axis is arranged in a range of an angle obtained by subtracting 45 ° from the intersection angle, and the optical axis of the other polarizing plate is aligned with the optical axis of the one polarizing plate. A pair of polarizers disposed substantially orthogonally or in parallel, a backlight disposed on one back surface of the pair of polarizers, the liquid crystal between the electrodes, and an optical axis of the one polarizer.
Each of which is smaller than the angle formed by the first and second directions.
A driving means for applying a voltage that changes the director of the liquid crystal molecules at a small angle; and the light from the backlight passing through a liquid crystal display panel including the pair of substrates, the liquid crystal, and the pair of polarizing plates. Light intensity detecting means for detecting the light intensity; and responding to the light intensity and the image data detected by the light intensity detecting means, the direction of the liquid crystal molecules is set at 45 ° to the optical axis of the one polarizing plate and the optical axis. The direction of the liquid crystal molecules is set substantially in the direction of the optical axis of the one polarizing plate so as to display one of the highest gradation and the lowest gradation. The voltage value corresponding to the image data is controlled so that the director of the liquid crystal molecules is set substantially at a direction of 45 ° with respect to the direction of the optical axis of the one polarizing plate in order to display the other of the gradations. To the liquid crystal Display element device using a drive unit, a liquid crystal exhibiting a more composed ferroelectric phase.