JP2000162585A - Liquid crystal display - Google Patents

Abstract

(57) [Problem] To provide a high-resolution, low-power-consumption, low-cost reflective liquid crystal display device and a transflective liquid crystal display device. SOLUTION: In a liquid crystal display device including a reflective liquid crystal panel 10 for monochrome display and a polarizing plate 20, or a liquid crystal display device including a transflective liquid crystal panel 110 for monochrome display and a polarizer 140, the incident light Color separating means 4 for sequentially separating the transmitted white light into red light, green light and blue light and transmitting the red light, green light and blue light
0 and 150 are arranged on the front surface of the liquid crystal panel, and color display is performed using color mixture by time division.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display, and more particularly to a reflective or transflective liquid crystal display.

[0002]

2. Description of the Related Art In recent years, various reflective and transflective liquid crystal display devices have been proposed as display devices for portable information terminals such as mobile phones and mobile PCs. In these liquid crystal display devices, there is no need to turn on the illumination device when using when there is sufficient external light, and when using in a dark place where external light is not sufficient, lighting such as a front light and a backlight is required. Since the device only needs to be turned on, low power consumption can be achieved.

In order to color these liquid crystal display devices, a red (R), green (G), and blue (B) color filter is used for each pixel in a liquid crystal cell to transmit each color pixel. There is known a color filter system capable of displaying an arbitrary color by additive color mixture by separately controlling the ratio by a liquid crystal cell.

[0004]

However, in this method, the color filters of each color absorb light having a spectrum equal to or more than two-thirds of the incident light, and the light use efficiency is low. There is a problem that display cannot be achieved. In the color filter method, one pixel is composed of three pixels of red (R), green (G), and blue (B), and requires three times the number of pixels. A large number of drive circuits for supplying wirings and image signals are also required, and there is a problem that they are expensive.

Accordingly, the present invention solves these problems of the conventional reflective and transflective liquid crystal display devices, and provides a high resolution,
It is an object of the present invention to provide a low power consumption, low cost reflective or transflective liquid crystal display device.

[0006]

In order to achieve the above object, a reflection type liquid crystal display device according to the present invention includes a reflection type liquid crystal panel for displaying black and white and a polarizing plate, and converts incident white light into red light and green light. And a color separation means for sequentially separating and transmitting the blue light is disposed on the front surface of the liquid crystal panel, and color display is performed by using color mixture by time division. Further, the transflective liquid crystal display device according to the present invention includes a transflective liquid crystal panel for displaying black and white and a polarizing plate, and sequentially separates and transmits incident white light into red light, green light and blue light. A color separating means for performing color display is provided on the front surface of the liquid crystal panel, and color mixing is performed by time division.

In the above-mentioned reflection type liquid crystal display device, it is preferable to provide illumination means between the liquid crystal panel and the color separation means. Further, in the transflective liquid crystal display device described above, it is preferable to provide an illuminating means on the back surface of the liquid crystal panel.

The color separation means is in an ON state or an OF state.
First and second liquid crystal shutters that transmit the incident light without changing the vibration direction in one state of the F state and transmit the light by rotating the vibration direction of the incident light by 90 degrees in the other state; Transmits a polarized light component that oscillates in a first direction of one of red, green, and blue light and oscillates in a second direction perpendicular to the first direction of the other two colors of light. A first color polarizer that transmits a polarized light component, and a polarized light component that oscillates in a first direction out of light of one color other than the one color light of red light, green light, and blue light, and And a second color polarizer that transmits a polarized light component that vibrates in the second direction of the two colors of light. In addition, the polarizing plate transmits white light vibrating in the first direction, and the color separating unit transmits the incident light in the ON state without changing the vibration direction of the incident light.
In the OFF state, first and second liquid crystal shutters for transmitting incident light by rotating the vibration direction by 90 degrees, and blue light vibrating in the first direction disposed between the first and second liquid crystal shutters. A first color polarizer that transmits red light and green light vibrating in a second direction perpendicular to the first direction while transmitting light, and a first color polarizing plate that is disposed on a front surface of the second liquid crystal shutter; It may be constituted by a second color polarizer that transmits red light oscillating in the direction and transmits blue light and green light oscillating in the second direction. The first and second liquid crystal shutters can be constituted by π cells.

According to the reflective or transflective liquid crystal display device of the present invention having the above-mentioned structure, the color filter is not used, and color mixing by time division is used to perform a field sequential (time division color mixture) method. Full color display can be performed. That is, for example, the ON state and the OFF state of the first and second liquid crystal shutters are synchronized with the color separation unit.
When the liquid crystal panel is driven by the liquid crystal driving circuit in synchronization with the switching of the state, the red image, the green image, and the blue image are visually mixed with a time difference, and three pixels are sequentially displayed by one pixel by the afterimage effect. Display in full color. Therefore, as compared with the conventional color filter method, the manufacturing process is simplified, the transmittance is greatly improved, the number of pixels and the driving circuit can be reduced to 1/3 with the same resolution, and high resolution and low resolution can be achieved. A liquid crystal display system with low power consumption and low cost can be provided.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a reflection type and transflective type liquid crystal display device according to the present invention.

FIG. 1 is an exploded perspective view schematically showing components of an embodiment of a reflection type liquid crystal display device according to the present invention. As shown in FIG. 1, a reflective liquid crystal display device according to the present embodiment includes a liquid crystal panel 10 for displaying black and white, and a liquid crystal panel 1.
0, a front light 30 as illumination means disposed on the front of the polarizing plate 20,
Color separation means 40 arranged in front of front light 30
And a liquid crystal drive circuit for driving the liquid crystal panel 10 which will be described later.

The liquid crystal panel 10 includes a liquid crystal that operates in a liquid crystal display mode such as a TN (twisted nematic) mode, and a reflection type liquid crystal panel of a black and white display in which a reflector that reflects light transmitted through the liquid crystal is disposed on the back surface. Consists of

The polarizing plate 20 is oriented in a predetermined direction (for example, FIG. 1).
In this case, only the polarized light component that vibrates in the horizontal direction is transmitted.

The front light 30 is composed of a light guide plate (not shown) for emitting light incident from the side in the direction of the liquid crystal panel 10, and a white light source such as a fluorescent tube (not shown) arranged on the side surface of the light guide plate. I have. When the liquid crystal display device is used in a dark place where the external light is not sufficient, the front light 30 is turned on. When the liquid crystal display device is used when the external light is sufficient, the front light 30 may be turned off. The light guide plate is made of a transparent material, and has a function of transmitting light reflected by the reflection plate with almost no dispersion. Therefore, when the liquid crystal display device is used by turning off the front light 30 when there is sufficient external light, the light guide plate functions as a mere transparent plate, and the display quality is improved without lowering the visibility of the display device. Has no effect. On the other hand, when the liquid crystal display device is used by turning on the front light 30 in a dark place where the external light is not sufficient, the light guide plate acts as a transparent plate and does not affect the display quality without lowering the visibility of the display device. I will not give.

The color separating means 40 has a function of sequentially separating incident white light into red light (R), green light (G) and blue light (B) and transmitting the same, and is synchronized with the color separating means 40. By displaying a black-and-white image on the liquid crystal panel 10, three-color images can be sequentially displayed by one pixel to perform full-color display. For example, the color separating means 40
A first liquid crystal shutter 41 composed of cells, a first color polarizer 42, a second liquid crystal shutter 43 composed of π cells,
And the second color polarizing plate 44. In this case, the first and second liquid crystal shutters 41, 4
Reference numeral 3 denotes a configuration in which light is transmitted as it is in the ON state, and light is transmitted by being twisted by 90 degrees in the OFF state. In addition, the first color polarizing plate 42 transmits red light (R) and green light (G) vibrating in the vertical direction in FIG. 1 and transmits blue light (B) vibrating in the horizontal direction in FIG. It is configured. Further, the second color polarizer 44 transmits blue light (B) and green light (G) vibrating in the vertical direction in FIG. 1 and transmits red light (R) vibrating in the horizontal direction in FIG. It is configured. Therefore, the light vibrating in the horizontal direction that has passed through the polarizing plate 20 cannot be transmitted when the first liquid crystal shutter 41 is in the ON state and the second liquid crystal shutter 43 is in the ON state (becomes black), and the first liquid crystal does not. When the shutter 41 is ON and the second liquid crystal shutter 43 is OFF, the light is transmitted as blue light (B) and
When the second liquid crystal shutter 43 is in the OFF state and the second liquid crystal shutter 43 is in the ON state, the light is transmitted as green light (G),
When the first liquid crystal shutter 41 is in the OFF state and the second liquid crystal shutter 43 is in the OFF state, the light is transmitted as red light (R). Of these, three conditions except for black are switched at high speed, and the liquid crystal panel 10 is driven by a liquid crystal driving circuit described later in synchronization with the switching, so that the red image, the green image, and the blue image are visually recognized with a time difference. And full-color display can be performed by sequentially displaying three-color images with one pixel by the afterimage effect. The color separation means 4
0 is driven by a color separation unit driving circuit described later.

FIG. 2 is an exploded perspective view schematically showing components of a transflective liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 2, the transflective liquid crystal display device of the present embodiment has a monochrome display liquid crystal panel 11.
0, a transflective polarizing plate 120 disposed on the back of the liquid crystal panel 110, a backlight 130 as an illumination means disposed on the back of the transflective polarizing plate 120, and the liquid crystal panel 11.
0, a color separation means 150 disposed in front of the polarizing plate 140, and a liquid crystal panel 11
And a liquid crystal driving circuit to be described later. Among them, the liquid crystal panel 110, the polarizing plate 140, and the color separating means 150 are the same as the liquid crystal panel 10, the polarizing plate 20, and the color separating means 40 in the reflective liquid crystal display device of the above-described embodiment, respectively. Description is omitted.

The backlight 130 comprises a light guide plate (not shown) for emitting light incident from the side in the direction of the liquid crystal panel 110, and a white light source such as a fluorescent tube (not shown) arranged on the side surface of the light guide plate. I have. When the liquid crystal display device is used in a dark place where external light is not sufficient, the backlight 130 is turned on. When the liquid crystal display device is used when external light is sufficient, the backlight 130 may be turned off.

The transflective polarizing plate 120 is used for the backlight 13.
It is configured such that a specific polarization component of light from 0 is transmitted and a specific polarization component of light from the opposite side of the backlight 130 is reflected.

With such a configuration, the color separating means 150
The liquid crystal panel 11 is synchronized with the liquid crystal driving circuit to be described later.
By driving 0, a red image, a green image, and a blue image are visually mixed with a time difference, and a full-color display can be performed by sequentially displaying three-color images with one pixel by an afterimage effect.

FIG. 3 is a block diagram showing a driving circuit of the liquid crystal display device shown in FIG. 1 or FIG. As shown in FIG. 3, in the liquid crystal display device of the present embodiment, the liquid crystal drive circuit includes a timing controller 210 and a field memory 220 for storing image data corresponding to each of the three primary colors.
R, 220G, 220B and liquid crystal panel 10 (110)
And a data driver 240 for writing image data. On the other hand, the color separation means 40 (150) is connected to the timing controller 210 via the color separation means driving circuit 250.
It is connected to the.

In the liquid crystal display device having such a configuration,
White light that has entered the color separation means 40 (150) from a white light source (not shown) is red light (R), green light (G), and blue light by the color separation means 40 (150) driven by the color separation means drive circuit 250. The light is sequentially separated and transmitted as light (B). On the other hand, the image signal is sampled by a sampling circuit (not shown), and the field memories 220R, 220G, and 22 corresponding to R, G, and B, respectively.
0B. The image signal stored in the field memory is controlled by the timing controller 210 so as to be sent to the data driver 240 for each color.
The scanning driver 230 sequentially selects scanning lines one by one, and an image signal is written from the data driver 240 to the pixel in synchronization with the selection pulse. The writing of the image signal of each color is controlled by the timing controller 121 so as to be synchronized with the switching of the light of each color by the color separation means 40 (150), and the red, green and blue images are visually mixed with a time difference. , 1 by the afterimage effect
Full-color display can be performed by sequentially displaying three-color images with pixels.

As described above, according to the present invention, the field sequential method is used, so that the manufacturing process is simplified and the transmittance is greatly improved as compared with the conventional color filter method. The number of pixels and the driving circuit are 1 at resolution
/ 3, high resolution, low power consumption,
A low-cost liquid crystal display device can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view schematically showing each component of an embodiment of a reflection type liquid crystal display device according to the present invention.

FIG. 2 is an exploded perspective view schematically showing components of an embodiment of a transflective liquid crystal display device according to the present invention.

FIG. 3 is a block diagram showing a driving circuit of the embodiment of the liquid crystal display device of the present invention.

[Explanation of symbols]

 10, 110 Liquid crystal panel 20, 140 Polarizer 30 Front light 40, 150 Color separation means 41, 151 First liquid crystal shutter 42, 152 First color polarizer 43, 153 Second liquid crystal shutter 44, 154 Second Color polarizer 120 Transflective polarizer 130 Backlight 210 Timing controller 220R, 220G, 220B Field memory 230 Scan driver 240 Data driver 250 Drive circuit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G09F 9/00 337 G09F 9/00 337D G09G 3/36 G09G 3/36 F-term (Reference) 2H091 FA02X FA08X FA08Z FA23Z FA41Z GA11 HA07 LA12 LA15 LA16 LA30 2H093 NA61 NC16 NC23 NC28 NC42 ND08 ND17 ND20 ND34 ND39 ND49 ND54 NE06 NF05 5C006 AA22 AF23 BB11 BB28 EA01 FA47 FA51 5G435 AA00 BB12 BB15 BB16 CC09 CC12 EE23 EE25 EE25

Claims (7)

[Claims] 1. A liquid crystal display device comprising a reflective liquid crystal panel for displaying black and white and a polarizing plate, wherein said liquid crystal panel includes a color separating means for sequentially separating incident white light into red light, green light and blue light and transmitting the same. A liquid crystal display device which is arranged on the front of the device and performs color display using color mixture by time division. 2. The liquid crystal display device according to claim 1, wherein illumination means is provided between the liquid crystal panel and the color separation means. 3. A liquid crystal display device comprising a transflective liquid crystal panel for displaying black and white and a transflective liquid crystal panel and a polarizing plate, wherein a color separating means for sequentially separating incident white light into red light, green light and blue light and transmitting the same is provided. A liquid crystal display device, which is arranged on the front surface of the liquid crystal panel and performs color display using color mixture by time division. 4. The liquid crystal display device according to claim 3, wherein an illuminating unit is provided on a back surface of the liquid crystal panel. 5. The apparatus according to claim 1, wherein said color separation means is in an ON state or an OF state.
First and second liquid crystal shutters that transmit the incident light without changing the vibration direction in one state of the F state and transmit the light by rotating the vibration direction of the incident light by 90 degrees in the other state; A polarized light component that oscillates in a first direction out of one color light of red light, green light and blue light is transmitted and in a second direction perpendicular to the first direction out of the other two colors of light. A first color polarizer that transmits a vibrating polarized light component; and the first color polarizer that transmits red light, green light, and blue light.
A second color that transmits a polarized light component that oscillates in the first direction among light of one color other than the light of the color and transmits a polarized light component that oscillates in the second direction of light of the other two colors. 4. The liquid crystal display device according to claim 1, comprising a polarizing plate. 6. The polarizing plate transmits white light vibrating in a first direction, and the color separation unit transmits the incident light in the ON state without changing the vibration direction of the incident light.
In the F state, first and second liquid crystal shutters that rotate the direction of vibration of incident light by 90 degrees and transmit the light, and are disposed between the first and second liquid crystal shutters and vibrate in the first direction. A first color polarizer that transmits light and transmits red light and green light that vibrate in a second direction perpendicular to the first direction, and a first color polarizer that is disposed on a front surface of the second liquid crystal shutter; 2. A second color polarizer that transmits blue light and green light oscillating in the second direction while transmitting red light oscillating in the first direction. 3. 4. The liquid crystal display device according to 3. 7. The liquid crystal shutter according to claim 1, wherein
7. The liquid crystal display device according to claim 5, comprising a cell.