JP2003167228A - Semitransmission type liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semitransmission type liquid crystal display device in which visibility is improved under any indoor and outdoor environment for the liquid crystal display mounted on a mobile equipment that is especially movable for indoor and outdoor use such as a portable telephone, a personal digital assistance (a PDA) and a digital still camera (a DSC) having both a transmission mode that conducts transmission display and a reflection mode that performs reflection display. <P>SOLUTION: In the liquid crystal display device, pixel electrodes are formed on one of the pair of substrates that are arranged in a mutually opposing manner while sandwiching a liquid crystal layer. Within one pixel of the pixel electrodes, a reflection section having a light reflection function and a transmission section having a light transmission function are provided. A back light is arranged to illuminate one of the substrates from the back. The device is provided with a display selecting means that is used to select a reflection type display means in which the reflection section functions as the pixel electrodes and a transmission type display means in which the transmission section functions as the pixel electrodes. When the back light is turned on, the display selection means selects the transmission type display means. When the back light is turned off, the reflection type display means is selected. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transflective liquid crystal display device, and more particularly to a mobile phone and a PDA.
(Personal Digital Assistant
nce), DSC (Digital Still C)
A liquid crystal display equipped with both a transparent mode for transmissive display and a reflective mode for reflective display, which is mounted on a mobile device that can be moved indoors and outdoors, and has visibility in all indoor and outdoor environments. The present invention relates to an enhanced transflective liquid crystal display device.

[0002]

2. Description of the Related Art Among conventional mobile devices such as mobile phones, information terminal devices, digital still cameras, digital video cameras and the like, devices used indoors and outdoors require a display for visibility in all environments. In recent years, a transflective liquid crystal display device having both characteristics in addition to the transmissive type and the reflective type has begun to attract attention.

However, the semi-transmissive liquid crystal display device has reflection and transmission portions and has characteristics of liquid crystal applied voltage and brightness, that is, an applied voltage-transmittance characteristic (VT characteristic) of the transmitting portion.
There is a difference between the applied voltage and the reflectance characteristic (VR characteristic) of the reflecting portion. Hereinafter, a specific description will be given using graphs.

FIG. 7 is a graph showing a transmission type applied voltage-transmittance characteristic (VT characteristic). When the applied voltage gradually rises from 0 volt, the first relative transmittance is shown. Keeps 100%, but the relative transmittance drops sharply from around 1.0 volt and draws an inverse normal line to around 10% up to around 3.0 volt, and the applied voltage 3.
It becomes 0% as it goes over 0 volts. Here, in the vicinity of the applied voltage of about 1.8 V, the relative transmittance maintains the intermediate position of 50%.

On the other hand, FIG. 8 is a graph showing a reflection type applied voltage-reflectance characteristic (VR characteristic). When the applied voltage gradually rises from 0 volt, the first relative The reflectivity is maintained at 100%, but the relative reflectivity drops sharply from about 1.5 V, and the inverse normal line is drawn to about 10 V near about 3.0 V. It becomes 0% as the voltage rises above 3.0 volts. Here, the relative reflectance is 50 when the applied voltage is approximately 2.0 volts.
Maintain the middle position of%.

As described above, the characteristics of the relative transmittance of the applied voltage-transmittance characteristic (VT characteristic) of the transmitting portion and the applied voltage of the reflecting portion-relative reflectance of the reflectance characteristic (VR characteristic) are obtained. Has a deviation of 0.2 volts as the applied voltage,
As shown in FIG. 9, the setting of the picture making (γ characteristic) and the like is made when the transmissive type and the reflective type are used, and the picture making (γ characteristic) is set to an intermediate value. It is set. Here, the picture making (γ characteristic) corresponds to the applied voltage-transmittance characteristic (VT characteristic) of the transmissive portion and the applied voltage-reflectance characteristic (VR characteristic) of the reflective portion in the liquid crystal display device. Input / output characteristics of the circuit part that controls the video output,
Setting of hue, BRIGHT, etc.

[0007]

However, the setting of the picture making (γ characteristic) described in the prior art is such that the applied voltage-transmittance characteristic (VT characteristic) of the transmissive portion and the applied voltage-reflectance of the reflective portion. Since the applied voltage in the characteristic (VR characteristic) is deviated, the intermediate position is set as shown in FIG.
If you set (Characteristics), it affects the reflection type picture, and conversely, if you set the picture making (γ characteristic) according to the reflection type, it affects the transmission type picture.
There is a problem that problems such as whitish screens cannot be avoided.

Therefore, in the semi-transmissive liquid crystal display device having both the transmissive type and the reflective type, when the respective functions can be driven, the picture making of the driving side (γ characteristic) There is a problem that has to be solved.

[0009]

In order to solve the above-mentioned problems, the transflective liquid crystal display device according to the present invention has the following constitution.

(1) In a semi-transmissive liquid crystal display device, a reflecting portion having a light reflecting function and a light transmitting function are provided on one substrate of a pair of substrates arranged to face each other with a liquid crystal layer interposed therebetween. A liquid crystal display device in which a pixel electrode that forms a transmissive portion having a pixel in one pixel is formed, and a backlight that illuminates one of the substrates from the back surface is arranged, wherein the reflective portion functions as a pixel electrode. It has a display selecting means for selecting a reflective display means and a transmissive display means that causes the transmissive portion to function as a pixel electrode, and the display selection means is a transmissive display means when the backlight is turned on. Selected,
The reflective display means is selected when the backlight is turned off, and (2) the backlight is manually turned on / off, and (3) the display selection means is The backlight on / off information is transmitted to the transmissive display means and the reflective display means by serial communication.

As described above, the transmissive and reflective γ characteristics are used in accordance with the turning on / off of the backlight, so that the brightness (γ characteristic) and the color setting suitable for the environment can be set. Therefore, it is possible to prevent the influence of the image quality such as the whiteness of the screen when the light is reflected, the contrast reduction, and the darkness of the screen when the light is transmitted.

(4) In the semi-transmissive liquid crystal display device, a reflecting portion having a light reflecting function and a light transmitting function are provided on one substrate of a pair of substrates arranged to face each other with a liquid crystal layer interposed therebetween. A liquid crystal display device in which a pixel electrode that forms a transmissive portion having a pixel in one pixel is formed, and a backlight that illuminates one of the substrates from the back surface is arranged, wherein the reflective portion functions as a pixel electrode. There is a display selection means for selecting a reflection type display means and a transmission type display means for making the transmission part function as a pixel electrode, and the display selection means selects the transmission type display means when the illuminance sensor is turned on. However, the reflection type display means is selected when the illuminance sensor is turned off, and (5) the display selection means is
The information of the illuminance sensor is transmitted to the transmissive display unit and the reflective display unit by serial communication.

As described above, since it is possible to perform setting using the transmission type or reflection type γ characteristic in accordance with the turning on / off of the illuminance sensor, automatic illuminance measurement is made possible and a picture is produced according to the ambient illuminance. It becomes possible to assign (γ characteristic) settings, etc., and it becomes possible to ensure fine visibility.

(6) In the semi-transmissive liquid crystal display device, a reflecting portion having a light reflecting function and a light transmitting function are provided on one substrate of a pair of substrates arranged to face each other with a liquid crystal layer interposed therebetween. A liquid crystal display device in which a pixel electrode that forms a transmissive portion having a pixel in one pixel is formed, and a backlight that illuminates one of the substrates from the back surface is arranged, wherein the reflective portion functions as a pixel electrode. It has a display selection means for selecting a reflection type display means and a transmission type display means for causing the transmission part to function as a pixel electrode, and the display selection means has the illumination sensor turned off when the backlight is turned on. The transmissive display means is selected under the above condition, and the reflective display means is selected under the condition that the backlight is turned off or the illuminance sensor is turned on. The backlight is manually turned on / off. (8) The display selection means serially communicates the on / off information of the backlight and the information of the illuminance sensor to the transmissive display means and the reflective display means. That is to send it.

As described above, when the backlight is turned on / off and the illuminance sensor is turned on / off, the setting is switched so as to use the reflection type and the transmission type γ characteristics. Even when the light is turned on and off, the automatic illumination sensor is turned on and off,
It is possible to switch and set the reflective type or the transmissive type γ characteristic, and it becomes possible to ensure the visibility by finely allocating the setting of the picture making (γ characteristic).

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of a transflective liquid crystal display device according to the present invention will be described with reference to the drawings.

The semi-transmissive liquid crystal display device according to the present invention, as shown in FIG.
The RGB driver unit 11 that drives GB, the display switching control unit 21 that sends out the reflective or transmissive γ characteristic by turning on / off the illuminance sensor 22 and the backlight switch 24, and the timing of displaying on the display screen 35 are displayed. A liquid crystal control unit 28 for generating, a lighting circuit 30, a backlight 34, a liquid crystal display unit 31 having a horizontal shift register 32, a vertical shift register 33, and a display screen 34, each of which is for display switching control. Various data can be transmitted and received by serial communication connected to the section 21.

The RGB driver unit 11 includes a digital processing unit 12 capable of setting picture making (γ characteristic) and an analog processing unit 19 for analog-processing the digital signal of the γ characteristic generated by the digital processing unit 12. Become.

The digital processing section 12 receives the luminance signal and controls the automatic gain thereof. The automatic gain control (AGC) section 1
3, an automatic phase control unit 14 that controls the phase of the signal automatically gained by the automatic gain control unit 13, a color gain unit 15 that inputs a correction signal to gain color, and a hue of the gained color signal. A hue control unit 16 for controlling the color tone, a gamma correction unit 17 for performing γ correction based on the phase and the hue, and a D / A conversion unit 18 for converting the γ-corrected signal into an analog value.

The analog processing unit 19 is the digital processing unit 1.
The configuration is provided with a contrast / brightness adjusting unit 20 that adjusts the contrast / brightness from the data converted into the analog value in 2. The contrast and the brightness data are supplied to the display screen 35.

The display switching control section 21 includes an illuminance sensor 22.
A / D converter 23 for converting the data from the data into a digital value
And a control unit 2 including a microcomputer for inputting the signal of the backlight switch 24 and the digital value of the illuminance sensor 22.
7, a RAM 25 in which reflective γ characteristic data input by the control unit 27 is stored, and a RAM 26 in which transmissive γ characteristic data is stored.

The liquid crystal controller 28 has a timing generator 29 for generating the input timing of the horizontal shift register 32 and the vertical shift register 33 of the display screen 35.

As shown in FIG. 5, the display screen of the liquid crystal display section 31 has a reflective electrode 45a formed of a material having a relatively high reflectance such as Al and Ta on one substrate 46, and ITO.
Transparent electrode 4 made of a material having a relatively high transmittance such as
5b is provided, a counter electrode 43 is formed on the other substrate 42 facing the substrate 46, and a negative electrode is provided between the counter electrode 43 and the reflective electrode 45a and the transparent electrode 45b. A liquid crystal layer 44 made of a liquid crystal material exhibiting dielectric anisotropy is sandwiched. In addition, the reflective electrode 45a,
Vertically-aligned alignment films (not shown) are formed on the surfaces of the transparent electrode 45b and the counter electrode 43 that are in contact with the liquid crystal layer 44. After applying this alignment film, at least one alignment film is formed. Is subjected to orientation treatment such as rubbing.

Here, the reflection electrode 45a as a reflection plate
Is used as an electrode for applying a voltage to the liquid crystal layer 44, but the transparent electrode 4 is not used as the reflective electrode 45a.
5b may be extended to above the reflective electrode 45a to serve as an electrode for applying a voltage to the liquid crystal layer 44 at the reflective portion.

These electrodes are connected to a switching element using a TFT, and a voltage for displaying an image is applied to the electrodes. The reflective electrode 45a and the transparent electrode 45b corresponding to one pixel area are electrically short-circuited.

A λ / 4 wavelength plate 41 is arranged on the surface of the substrate 42 opposite to the surface on which the counter electrode 43 is formed. The slow axis of the λ / 4 wave plate 41 is 45 with respect to the long axis direction of the liquid crystal molecules when a voltage is applied to the liquid crystal layer 44.
° It is attached to the substrate so that it is tilted. A λ / 4 wave plate 47 is arranged on the surface of the substrate 46 opposite to the side where the reflective electrode 45a and the transparent electrode 45b are formed, and the slow axis of the λ / 4 wave plate 47 is λ / It is attached in a direction parallel to the slow axis of the four-wave plate 47.

Further, a polarizing plate 40 is formed on the surface of the λ / 4 wavelength plate 41 opposite to the substrate 42, and similarly, λ /
A polarizing plate 48 is provided on the surface of the four-wave plate 47 opposite to the substrate 46.
Are formed. At this time, the transmission axes of the polarizing plate 40 and the polarizing plate 40 are arranged so as to be parallel to the long axis direction of the liquid crystal molecules when a voltage is applied to the liquid crystal layer 44. The axis is set in the same direction as the slow axis of the λ / 4 wave plate 41 and the λ / 4 wave plate 47.

In the display screen having such a structure, both the reflection characteristic and the transmission characteristic are displayed in black when no voltage is applied,
White display can be performed when a voltage is applied, and gradation display can be performed by adjusting the applied voltage. Therefore, in the area where the reflective electrode 45a is formed, a reflective liquid crystal display is provided, and the other transparent electrode 45b is provided.
In the area where is formed, it can be used as a transmissive liquid crystal display. Therefore, the liquid crystal layer 4 is formed in both the region where the reflective electrode 45a is formed and the region where the transparent electrode 45b is formed.
When no voltage is applied to No. 4, black display is obtained because there is no birefringence in the liquid crystal layer 44, and gradation display is possible by applying a voltage to the liquid crystal layer 44.

However, as described with reference to FIG. 9 and FIG. 10 above, in such a liquid crystal display, the dependence of the voltage and the transmittance and the reflectance on the reflective portion and the transmissive portion is different. This is because light passes once through the liquid crystal layer 44 for liquid crystal display when performing transmissive display, whereas it passes twice through the liquid crystal layer 44 for liquid crystal display when performing reflective display. Therefore, when the reflective display is performed, the reflectance changes sharply with respect to the voltage. As a result, although there is no change in the relationship between black and white, there arises a problem that the gradation characteristics are different. In particular, when displaying 16 gradations or more, the difference between the two is the display quality. It becomes a big problem in terms.

Further, when the transmissive display is performed as compared with the reflective display, the transmittance of the liquid crystal can be increased by setting a higher driving voltage. As a measure against such a problem, in the present invention, the γ characteristic of the reflective type and the transmissive type is switched in conjunction with turning on / off of the backlight switch 24. Further, by using the illuminance sensor 22, I decided to switch automatically.

In the above-described configuration, the reflection type and transmission type γ characteristic data from the display switching control unit 21 is sent through the serial communication bus to the digital processing unit 12, analog processing unit 19, liquid crystal control unit 28, lighting. Sent to each of the circuits 30. Briefly, as shown in FIG.
The information by serial communication is sent to the RGB driver unit 11 and the timing generator unit 29, and the picture making data set by the γ characteristic is sent to the liquid crystal display unit 31 and displayed.

The backlight switch 24 is basically turned on / off manually, and as shown in FIG. 3, the control unit 27 detects the on / off information of the backlight switch 24 and serializes the information. To send over.
In the case of the illuminance sensor 22, as shown in FIG. 4, the control unit 27 receives information about the illuminance sensor 22, for example, ON / OFF information about the illuminance sensor 22, and transmits the information via serial communication. .

For example, when the backlight switch 24 is off, the data is supplied to the lighting circuit 30 through serial communication, and the backlight 34 is actually turned off or maintained, and the control is performed. The RAM 25 in which the reflection type γ characteristic data is stored in the section 27
To obtain the data and send the reflection type γ characteristic data to the color gain unit 15, the hue control unit 16, and the gamma correction unit 17 of the digital processing unit 12 via serial communication.

On the contrary, when the backlight switch 24 is turned on, the data is transmitted to the lighting circuit 30 through serial communication, and the lighting circuit 30 supplies the power supply voltage to turn on the backlight 34. Together with the control unit 2
In FIG. 7, transmission type γ characteristic data is stored in R
The color gain section 15 of the digital processing section 12 is accessed through the serial communication by accessing the AM 26 to obtain the data.
And the hue control unit 16 and the gamma correction unit 17
Send characteristic data.

In this way, the backlight switch 2
As for the on / off information of No. 4, the backlight switch 24 is turned on by sending the reflection type and transmission type γ characteristic data to the digital processing unit 12 and the lighting circuit 30 via the serial communication bus. In this case, the backlight 34 is turned on (see FIG. 1), and at the same time, it is possible to make a picture by the transmission type γ characteristic. If the backlight switch 24 is turned off, the backlight 34 is turned off and the reflection type γ characteristic is set. You can make a picture based on your characteristics.

When using the illuminance sensor 22, various arrangements are conceivable, which can be achieved by programming in the control unit 27. Broadly speaking, the backlight switch 24 can be automatically turned on / off mainly by the illuminance sensor 22, and the backlight switch 24 is manually turned on / off, and switching by the illuminance sensor 22 is added thereto. It is thought that it was done. Hereinafter, with reference to FIG. 1, description will be given based on the flowcharts of FIGS. 7 and 8.

As shown in FIG. 7, first, the backlight switch 24, which mainly includes the illuminance sensor 22 and can be automatically turned on and off, operates according to whether the illuminance sensor 22 is on or off. Different (step ST
11).

When the illuminance sensor 22 is on, the control unit 27 selects the reflective γ characteristic and transmits the data to the RGB driver unit 11 through serial communication.
The backlight switch 24 is automatically turned off to turn off the backlight 34 (step ST12,
ST13).

Then, in the digital processing section 12 of the RGB driver section 11, a picture is drawn by the γ characteristic using the reflection type γ characteristic data and displayed on the display screen 35 (step ST14).

In step ST11, when the illuminance sensor 22 is off, the backlight switch 24 is automatically turned on, and the control unit 21 selects the transmissive γ characteristic and the RGB driver is transmitted through the serial communication. The γ characteristic data is transmitted to the section 11 (step STS
T15, ST16).

Then, in the digital processing section 12,
A picture is made using the transmission type γ characteristic data and is displayed on the liquid crystal (step ST17).

In this way, by using the illuminance sensor 22, when the peripheral brightness becomes small, the transmission mode,
It can be controlled so that it becomes the reflection mode when it becomes larger.

Next, the backlight switch 24 is manually turned on / off, and in the case where the ambient brightness of the illuminance sensor 22 is taken into consideration, as shown in FIG. 8, first, the backlight switch 24 is manually turned on. When the illuminance sensor 22 detects the amount of ambient brightness and is turned on in the transparent mode, the screen display state at that time is checked to see if the screen display is defective or good. Make a decision (step ST21, ST
22, ST23).

When the screen display is good in step ST23, the process returns to step ST22 to detect the state of the illuminance sensor 22. When it is determined that the screen display is defective, a message such as "Please turn off the backlight switch." Is issued (step ST24). Here, the quality of the screen display may be automatically performed, or the backlight switch 24 may be automatically turned on only under this condition with or without issuing a message.

In step ST21, when the backlight switch 22 is manually turned off and the illuminance sensor 22 is turned on, the process returns to step ST21, and when the illuminance sensor 22 is off, it is determined that the state of the screen display is defective. In that case, a message such as "Please turn on the backlight switch." Is issued (steps ST25, ST26, ST27). Here, the quality of the screen display may be automatically performed, or the backlight switch may be automatically turned on only under this condition with or without issuing a message.

[0046]

As described above, in the transflective liquid crystal display device according to the present invention, the backlight on / off is sensed to switch the image formation (γ characteristic) at the time of transmission / reflection, and It is suitable for each of the characteristics / transmission (γ
By performing the (characteristics) and color setting, there is an effect that it is possible to prevent image quality effects such as a white screen during reflection, a reduction in contrast, and a dark screen during transmission, which are problems in setting.

Further, by allowing the user to arbitrarily switch by the backlight switch, there is an effect that the visibility can be optimized.

Further, in the case where a plurality of image forming settings are provided and automatic illuminance measurement is performed, by assigning the image forming settings according to the environmental illuminance, it is possible to further secure the visibility.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram schematically showing a transflective liquid crystal display device according to the present invention.

FIG. 2 is an explanatory diagram showing the principle of the present invention.

FIG. 3 is an explanatory diagram showing the principle of communication output switching by turning on / off the backlight switch of the present invention.

FIG. 4 is an explanatory diagram showing the principle of switching communication output by the illuminance sensor of the present invention.

FIG. 5 is an explanatory diagram showing a structure of a display screen of the present invention.

FIG. 6 shows γ in the reflection mode and the transmission mode of the present invention.
6 is a graph showing setting of characteristics.

FIG. 7 is a flowchart showing an operation of automatically switching between a reflection mode and a transmission mode by the illuminance sensor.

[Figure 8] Manually turning on the backlight switch /
7 is a flowchart showing an operation when the illumination sensor is set to turn off and ambient brightness is detected.

FIG. 9 is a graph showing a relationship between an applied voltage and a transmittance characteristic (VT characteristic) in the same transmission mode.

FIG. 10 is a graph showing an applied voltage and a reflectance characteristic (VR characteristic) in the same reflection mode.

FIG. 11 is a graph when the γ characteristic is set at an intermediate position between both the VT characteristic and the VR characteristic in the conventional technique.

[Explanation of symbols]

11; RGB driver section, 12; digital processing section, 1
3; automatic gain control unit, 14; automatic phase control unit, 15; color gain unit, 16; hue control unit, 17; gamma correction unit,
18; D / A conversion unit, 19; analog processing unit, 20; contrast / luminance adjustment unit, 21; display switching control unit, 2
2; Illuminance sensor, 23; A / D converter, 24; Backlight switch, 25; RAM (reflection type), 26; RA
M (transmissive type), 27; control unit (microcomputer), 28; liquid crystal control unit, 29; timing generator unit, 30; lighting circuit, 31; liquid crystal display unit, 32; horizontal shift register,
33; vertical shift register, 34; backlight, 3
5: Display screen.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 633 G09G 3/20 633B 641 641Q 642 642F 3/36 3/36 F term (reference) 2H091 FA14Y FA41Z FD04 GA02 GA11 LA16 2H092 GA12 HA03 HA05 JB07 NA01 PA06 PA12 PA13 2H093 NA06 NA51 NC13 NC45 NC55 NC59 NC62 NC90 ND02 ND06 NE03 NE06 5C006 AA22 AB03 AF13 AF46 AF63 AF81 AF82 BC06 BF01 BF39 5C080 AA10 BB05 CC03 DD01 EE28 FF11 GG12 JJ02 JJ05 JJ06 JJ07 KK07 KK43

Claims (8)

[Claims] 1. A reflective portion having a light reflecting function and a transmissive portion having a light transmitting function are provided in one pixel on one substrate of a pair of substrates arranged to face each other with a liquid crystal layer interposed therebetween. A liquid crystal display device in which a pixel electrode is formed, and a backlight for illuminating the one substrate from the backside is arranged, wherein a reflective display unit that causes the reflective portion to function as a pixel electrode, and the transmissive portion are provided. And a transmissive display unit that functions as a pixel electrode, the display selection unit selecting the transmissive display unit when the backlight is turned on and turning off the backlight. A transflective liquid crystal display device, characterized in that the reflective display means is selected when 2. The backlight is manually turned on / off.
The semi-transmissive liquid crystal display device according to claim 1, which is turned off. 3. The display selection means is adapted to transmit ON / OFF information of the backlight to the transmissive display means and the reflective display means by serial communication. Semi-transmissive liquid crystal display device. 4. A reflective section having a light reflecting function and a transmissive section having a light transmitting function are provided in one pixel on one substrate of a pair of substrates arranged to face each other with a liquid crystal layer interposed therebetween. A liquid crystal display device in which a pixel electrode is formed, and a backlight for illuminating the one substrate from the backside is arranged, wherein a reflective display unit that causes the reflective portion to function as a pixel electrode, and the transmissive portion are provided. And a transmissive display unit that functions as a pixel electrode. The display selection unit selects the transmissive display unit when the illuminance sensor is turned on, and the illuminance sensor is turned off. A transflective liquid crystal display device characterized in that a reflective display means is selected at times. 5. The semi-transmissive device according to claim 4, wherein the display selection unit is configured to transmit the information of the illuminance sensor to the transmissive display unit and the reflective display unit by serial communication. Type liquid crystal display device. 6. A reflective portion having a light reflecting function and a transmissive portion having a light transmitting function are provided in one pixel on one substrate of a pair of substrates arranged to face each other with a liquid crystal layer interposed therebetween. A liquid crystal display device in which a pixel electrode is formed, and a backlight for illuminating the one substrate from the backside is arranged, wherein a reflective display unit that causes the reflective portion to function as a pixel electrode, and the transmissive portion are provided. And a transmissive display means for functioning as a pixel electrode, the transmissive display means being provided on condition that the backlight is turned on or the illuminance sensor is turned off. Is selected, and the reflective display means is selected on condition that the backlight is turned off or the illuminance sensor is turned on. 7. The backlight is manually turned on / off.
7. The transflective liquid crystal display device according to claim 6, which is turned off. 8. The display selection means is adapted to transmit on / off information of the backlight and information of an illuminance sensor to the transmissive display means and the reflective display means by serial communication. The transflective liquid crystal display device according to claim 6.