KR100366300B1 - System for controlling image display in a thin film transistor liquid crystalline display device - Google Patents

Abstract

The present invention optimally controls the color image display of the reflection mode TFT LCD by adjusting the output of the internal light source and the liquid crystal pixel in the reflection mode thin film transistor liquid crystal display (TFT LCD) according to the state of the external light source detected using the optical sensor. A control system for controlling an image display of a reflection mode thin film transistor liquid crystal display device displaying a color image by using an internal light source and control means for controlling the internal light source and the liquid crystal pixel, wherein the brightness of external light is controlled. And an optical sensor unit for detecting red light, green light, and blue light, wherein the control means performs an arithmetic processing according to a state of external light detected from the optical sensor and a predetermined display mode. And controlling an image display by adjusting an output of the liquid crystal pixel. Shall be. By such a configuration, the desired optimal color image display can be automatically realized under any external lighting environment, and power consumption efficiency can be maximized.

Description

Image display control system of thin film transistor liquid crystal display device and similar image display device {SYSTEM FOR CONTROLLING IMAGE DISPLAY IN A THIN FILM TRANSISTOR LIQUID CRYSTALLINE DISPLAY DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display control system of a reflective mode thin film transistor liquid crystal display (TFT LCD), and in particular, the brightness and the liquid crystal pixel of an internal light source according to the state of an external light source detected using an optical sensor. A control system of a reflection mode thin film transistor liquid crystal display device which controls color image display of a TFT LCD in accordance with a mode and a calculation method preset by a user by adjusting the brightness, chromaticity, and contrast of the display device.

At present, a liquid crystal display (LCD) which displays an image as an optical signal output in accordance with liquid crystal alignment by application of an electrical image signal occupies an increasingly important position in the display device industry. In particular, recently developed thin-film transistor (TFT) LCD is a stack of field effect transistor for each electrode of the liquid crystal cell (cell), which has been spotlighted as a next-generation LCD that can reduce the power consumption more compact and thinner than the conventional LCD have.

The current development and commercialization of such a TFT LCD is a transmission mode TFT LCD.

Fig. 1 schematically shows the configuration of such a transmissive mode TFT LCD, and shows the path of the light emitted from the light source. As shown in Fig. 1, the transmissive mode TFT LCD is configured to implement an image while the light emitted from the light source 30 passes through the light guide plate 20 and the TFT 10 sequentially stacked from below. However, such a transmissive mode TFT LCD can use only the internal light source 30 for displaying an image, and cannot use any natural light such as the sun or an external light source such as indoor lighting. Accordingly, in the case of the transmission mode TFT LCD, since only the power supply device such as a battery is required to supply power to the internal light source 30, there is no effective way to reduce power during use. . This may cause great inconvenience for users of portable devices such as LCD computers, notebook computers, cellular phones, PDAs, camcorder viewfinders, and liquid crystal TVs, especially considering the battery life available today. This may cause an increase in the maintenance cost of the device.

The reflection mode TFT LCD has been developed to overcome the disadvantages of the transmissive mode TFT LCD.

Fig. 2 schematically shows the configuration of such a reflection mode TFT LCD, in which the path of light from the light source is shown.

As shown in FIG. 2, light emitted from the light source 300 is reflected by the TFT 100, and the reflected light is configured to implement an image while passing through the light guide plate 200 disposed on the TFT 100.

Unlike the transmissive mode TFT LCD of FIG. 1, the reflection mode TFT LCD may selectively or simultaneously use an internal light source 300 and an external light source (such as sunlight or a lighting) to display an image. Therefore, the reflective mode TFT LCD can display a color image by using only an external light source without operating the internal light source in a bright environment such as a day or a bright room, and an internal light source in a dark environment such as a night or a dark room. Therefore, there is an advantage in that power can be used more efficiently than a transmission mode TFT LCD using only an internal light source without using an external light source.

However, although the above-described reflection mode TFT LCD uses an external light source but does not use the internal light source flexibly according to the intensity of the external light source, it is simply turned on or off according to a user's manual operation or setting conditions built into the equipment. It is to decide whether to use the internal light source of the equipment by using only the switch of (OFF) function. Therefore, when the reflective mode TFT LCD is mounted on a portable device as well as a fixed device such as a desktop computer, the monochrome mode image may be changed in a variable environment where the illuminance and chromaticity change depending on the external light source surrounding the equipment. Unlike the case, the display of the color image as well as the reproduction of the natural color is large due to the change in the illuminance or chromaticity of the external light incident on the TFT LCD, so that high quality color images cannot be guaranteed.

Moreover, even when the internal light source can be used as the main / secondary light source depending on the state of the external light source, only the internal light source that consumes more power than the general digital device can be used, which is an important variable for the competitiveness of portable equipment. As a result, it is a major obstacle to the application of the reflection mode TFT LCD to portable equipment.

Therefore, by using the internal light source more efficiently in displaying a color image on a TFT LCD, the luminance, chromaticity, contrast, etc. of the color image can be optimally displayed according to the condition of the external light, and the color image can be reduced. A control system is required.

The present invention is to solve the disadvantages of the conventional TFT LCD as described above, the object of the present invention is to actively cope with the change in the brightness and chromaticity of the external incident light according to the change of the external environment, to improve the color characteristics of the TFT LCD It aims to stably reproduce natural colors and reduce power consumption while keeping it constant.

In order to achieve the above object, an image display control system of a thin film transistor liquid crystal display device according to the present invention is a reflection mode thin film transistor liquid crystal for displaying a color image using an internal light source and control means for controlling the internal light source and the liquid crystal pixel. A system for controlling image display of a display device, the system comprising: an optical sensor unit for detecting the luminance of external light into red light, green light, and blue light, wherein the control means includes a state of external light detected from the optical sensor part and a predetermined predetermined value; And controlling the image display of the reflective mode thin film transistor liquid crystal display device by performing arithmetic processing in accordance with the display mode of the control panel to adjust the image display by adjusting the brightness of the internal light source and the output of the liquid crystal pixel. do.

Preferably, the image display control system of the thin film transistor liquid crystal display device according to the present invention further includes a timer connected to the control means, wherein the control means performs the set display mode according to the time detected by the timer. The light intensity of the internal light source and the light intensity, chromaticity, and contrast of the liquid crystal pixel are adjusted by the determination.

Preferably, in the image display control system of the thin film transistor liquid crystal display according to the present invention, the operation processing in the control means is divided into various stages according to the detection result of the luminance according to the color of the external light. The brightness of the internal light source and the brightness of the liquid crystal pixel according to the determination result obtained by the step of calculating the "mode", comparing and determining the initially set display mode and the determination result mode; And generating a control signal for controlling the chromaticity and contrast according to a preset value or a result of performing an operation according to an expression required for control.

Preferably, the image display control system of the thin film transistor liquid crystal display device according to the present invention is characterized in that the internal light source driving frequency of the reflection mode thin film transistor liquid crystal display device is synchronized with the driving frequency or higher frequency of the liquid crystal pixel. .

Preferably, the image display control system of the thin film transistor liquid crystal display device according to the present invention is characterized in that the thin film transistor is made of one of a polysilicon crystal and an amorphous crystal.

Preferably, the image display control system of the thin film transistor liquid crystal display device according to the present invention, the control means to prevent the brightness of the screen unnaturally flashing when the change in the brightness of the external light is flashing momentarily or high frequency flashing state And a delay circuit and an algorithm according thereto.

Preferably, in the image display control system of the thin film transistor liquid crystal display device according to the present invention, the optical sensor unit selects only incident light in a solid angle of a certain angle or incident light in a specific polarization state among the external light irradiated onto the reflection mode TFT LCD surface. Characterized in that can be detected as.

1 is a schematic model diagram of a general transmission mode TFT LCD showing a path of light from an internal light source;

2 is a schematic model diagram of a general reflection mode TFT LCD showing a path of light from an internal light source and an external light source;

FIG. 3 is a schematic model diagram for explaining an internal light source and a liquid crystal pixel control according to light intensity from an optical sensor for detecting light of an external light source in a reflection mode TFT LCD device according to the present invention;

4 is a detailed circuit block diagram for controlling an internal light source in FIG. 3;

FIG. 5 is a control flowchart for explaining arithmetic processing in the TFT LCD controller shown in FIG. 4; FIG.

6 is a circuit block diagram for controlling a conventional TFT LCD.

7 is a block diagram of a circuit for controlling an internal light source and a liquid crystal pixel with a controller or an external CPU according to the light intensity from an optical sensor for detecting light of an external light source according to the present invention.

<Explanation of symbols for the main parts of the drawings>

1, 11: TFT LCD 21, 31: Central Processing Unit (CPU)

2, 12: light sensor 22. 32: controller

3, 13: internal light source 23, 33: gate driver

4, 14: internal light source driver 24, 34: data driver

15: conversion control unit 25, 35: power supply device

5-1: A / D converter 26, 36: Internal light source

5-2: TFT LCD controller 27, 37: TFT LCD

5-3, 5-4: D / A converter 28, 38: Optical sensor

5-5: TFT driver 39: converter

6: display mode setting unit 40: internal light source conversion unit

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described with reference to an accompanying drawing.

3 is according to the embodiment of the present invention, in the reflection mode TFT LCD, in accordance with the amount of light of the external light source detected by the light sensor unit. It is a figure for demonstrating notionally the system which adjusts an internal light source and controls a color image display.

As shown in FIG. 3, in the reflection mode TFT LCD 11 according to the present invention, an optical sensor unit 12, an internal light source 13, an internal light source driver 14, and a conversion / control unit 15 are combined. It is.

The optical sensor unit 12 converts the incident external light into an electrical signal corresponding thereto. The optical sensor unit 12 uses photodiodes, phototransistors, cds, etc., which are small optical sensors, and red light (R), Optical filters for selectively passing green light (G) and blue light (B). In addition, the optical sensor unit may be configured as a single optical sensor that responds to visible light or may be provided with a polarization filter to detect the polarization state of the external light. And it may be provided with an optical sensor that can selectively detect only the external light in a certain solid angle.

The electrical signal output from the optical sensor unit 12 is input to the conversion / control unit 15.

The conversion / control unit 15 determines the luminous intensity and chromaticity of the external light source according to the magnitude of the electrical signal from the light sensor unit 12 and determines the luminous intensity and liquid crystal of the internal light source according to the image display mode set by the user (or manufacturer). A signal for controlling the brightness, chromaticity and contrast of the pixel is output.

The control signal output from the converter / control unit 15 adjusts the brightness of the internal light source, the brightness, chromaticity, and contrast of the internal light source through the internal light source driver 14 and the liquid crystal pixel signal driver (not shown).

FIG. 4 shows an example of a specific circuit block diagram for controlling the internal light source in FIG. 3.

As shown in FIG. 4, the conversion / control unit 5 shown in FIG. 3 is specifically connected to an output of the optical sensor unit 2, and is a digital signal that can process an optical signal, which is an analog signal, in a controller. A / D converter 5-1 for converting to a signal, a TFT LCD controller 5-2 for processing a digital signal from the A / D converter 5-1 to generate control signals, and a TFT LCD controller ( D / A converter 5-3 for converting the digital control signal from 5-2) into an analog signal capable of driving the TFT LCD 1, for driving the TFT LCD 1 in accordance with this analog control signal. The light amount of the internal light source is controlled by the digital control signal output from the TFT driver 5-5 and the TFT LCD controller 5-2 in accordance with the calculation processing of the electrical signal corresponding to the light intensity detected by the optical sensor unit 2. And a D / A converter 5-3 for converting to an analog signal.

In addition, the TFT LCD controller 5-2 is connected with a display mode setting section 6 which allows a user or manufacturer to input a display mode such as power saving, standard, or optimal according to the selection.

As shown in Fig. 4, the optical sensor unit 2 composed of an optical filter for selectively detecting R (red light), G (green light) and B (blue light) receives light from an external light source. Separate detection by color generates an analog electrical signal corresponding to the intensity of the detected light component. This electrical signal is converted into an electrical signal in digital form by the A / D converter 5-1 so that it can be processed by the TFT LCD controller 5-2. The digital signal converted by the A / D converter 5-1 is input to the TFT LCD controller 5-2, and arithmetic processing is performed in accordance with a predetermined control program built in the TFT LCD controller 5-2. This operation processing will be described later with reference to FIG.

The TFT LCD controller 5-2 generates two control signals according to the intensity of the electrical signal corresponding to the brightness of the external light source and the display mode (power saving, standard, optimal) set by the user. 1) to drive itself, and another to control the internal light source.

The TFT LCD 1 driving control signal is converted into an analog signal by the D / A converter 5-3, and this signal drives the TFT LCD 1 through the TFT driver 5-5. At the same time, an internal light source control signal, which is another control signal output through the TFT LCD controller 5-2, is converted into an analog signal through another D / A converter 5-4, and this signal is converted into an internal light source driver ( 4) the internal light source is controlled. Since these control signals are simultaneously output from the TFT LCD controller, the driving of the TFT LCD works in conjunction with the driving of the internal light source.

According to the configuration and operation of the present invention described above, the TFT LCD controller 5-2 determines the luminous intensity and color intensity of the external light detected by the optical sensor unit 2 and the image display mode set by the user or the manufacturer. By adjusting the output of the internal light source and the output of the liquid crystal pixel according to the set display mode, the brightness, chromaticity, and contrast of the color image of the TFT LCD 1 are controlled appropriately.

Next, the method of controlling the internal light source according to the above-described brightness and setting display mode according to the arithmetic processing operation according to a predetermined control program built in the TFT LCD controller 5-2 will be described.

FIG. 5 is a control flowchart for explaining arithmetic processing in the TFT LCD controller shown in FIG.

The calculation process comprises the steps of calculating a "judgment result mode" divided into various stages according to the detection result of the luminance according to the color of the external light, and comparing and determining the initially set display mode and the judgment result mode. And control for controlling the luminous intensity of the internal light source and the luminous intensity, chromaticity, and contrast of the liquid crystal pixel to a predetermined value or a result of performing an operation according to a calculation formula required for the control according to the determination result from the comparing and determining. It characterized in that it comprises a step of generating a signal and described as divided into more subdivided steps as follows.

When the TFT LCD 1 is started to be driven by powering up (step S1), the user enters one of the display modes for displaying a desired color image, for example, power saving, standard, or optimal mode, when necessary, and re-entry later. The input mode is maintained until step S2. When the TFT LCD 1 starts to be driven, RGB values are input to the TFT LCD controller 5-2 as digital signals by A / D conversion through the R, G, and B optical filters of the optical sensor unit 2. (Step S3).

The TFT LCD controller 5-2 detects the intensity of the external light, that is, the RGB value in accordance with the digital input signal, determines the brightness of the external light, and calculates the determination result mode (step S4). The judgment result mode is shown in three cases, for example, 'very dark', 'normal', and 'sufficiently bright'. Of course, the result of the determination can be finely adjusted by further subdividing the mode into three or more types.

The RGB parameter values required for making this determination are defined as follows.

Ro, Go, Bo values are the luminance by each color (wavelength) by external incident light, Ri, Gi, Bi values are the luminance by each wavelength of internal light, Rp, Gp, Bp values are the TFT LCD displays the optimal mode image display. The wavelength, Rs, Gs, and Bs values for each wavelength required for the TFT LCD are the wavelength, Rs, Gs, and Bs values for each wavelength required for the TFT LCD to display the standard mode. Means the lowest brightness of the star.

In addition, the condition 'very dark' is Ro> XRe, Go> XGe, Bo> XBe (X is a variable less than 1), and the condition 'bright enough' is Ro> Rp, Go> Gp, Bo> Bp. The condition of 'medium' depends on the area between 'very dark' and 'bright enough' conditions. At this time, the values of Rp, Gp, Bp, Rs, Gs, Bs, Rs, Gs, and Bs are programmed to be set differently depending on the surrounding brightness state or day and night.

As a result of the determination in step S4, if it is determined as 'very dark', it is determined what mode the display mode set in step S2 is. (Step S5). As a result of the determination, in the power saving mode, the brightness (Ri, Gi, Bi) of the internal light is set to the lowest brightness (Re, Ge, Be) required for the power saving mode, that is, Ri = Re, Gi = Ge, Bi = Be An internal light source control signal is generated (S5-1). As a result of the determination in step S5, if the optimum mode, the luminance (Ri, Gi, Bi) of the internal light is set to the luminance (Rp, Gp, Bp) required for the optimal mode, that is, Ri = Rp, Gi = Gp, Bi = Bp Generate an internal light source control signal to be (S5-2). As a result of the determination in step S5, in the standard mode, the luminance (Ri, Gi, Bi) of the internal light is set to the luminance (Rs, Gs, Bs) necessary for the standard mode, that is, Ri = Rs, Gi = Gs, Bi = Bs An internal light source control signal is generated that satisfies the expression (S5-3).

As a result of the determination in step S4, if it is determined as 'normal', it is determined what mode the display mode set in step S2 is (step S6). As a result of the determination, in the power saving mode, the sum of the luminance (Ro, Go, Bo) of the external light and the luminance (Ri, Gi, Bi) of the internal light is the minimum luminance (Re, Ge, Be) required for the power saving mode, that is, Ro Luminance (Ri, Gi, Bi) of the internal light that satisfies the formula of + Ri = Re, Go + Gi = Ge, Bo + Bi = Be, and calculates the result as an internal light source control signal (S6- One). As a result of the determination in step S6, in the optimum mode, the sum of the luminance (Ro, Go, Bo) of the external light and the luminance (Ri, Gi, Bi) of the internal light is such that the luminance (Rp, Gp, Bp) necessary for the optimal mode is obtained. That is, the luminance (Ri, Gi, Bi) of the internal light that satisfies the formula of Ro + Ri = Rp, Go + Gi = Gp, Bo + Bi = Bp is calculated, and the calculated result is generated as an internal light source control signal. (S6-2). As a result of the determination in step S6, in the standard mode, the sum of the luminance (Ro, Go, Bo) of the external light and the luminance (Ri, Gi, Bi) of the internal light is such that the luminance (Rs, Gs, Bs) necessary for the standard mode is added. That is, the luminance (Ri, Gi, Bi) of the internal light that satisfies the formula of Ro + Ri = Rs, Go + Gi = Gs, Bo + Bi = Bs is calculated, and the calculated result is generated as an internal light source control signal. (S6-3).

As a result of the determination in step S4, if it is determined as 'bright enough', a control signal for turning off the internal light source is generated. In this case, while the power of the internal light source is turned off, a signal is generated by performing an operation of controlling the voltage for each pixel so as to optimize the color luminance for each liquid crystal pixel in the setting mode (step S7).

As described above, in accordance with the brightness of the external light and the set display mode, the brightness of the internal light to be controlled is calculated, and the internal light source control signal output accordingly is transferred through the D / A converter 5-3 to the TFT driver 5-5. Control the internal light source driver 4 via the D / A converter 5-4 while driving the TFT LCD 1 (step S8) to control the brightness (Ri, Gi, Bi) of the internal light source. (Step S9).

As described above, when the internal light source and the liquid crystal pixel are properly controlled in accordance with the state of the external light source, the display of the color image of the reflection mode TFT LCD can be controlled in accordance with the set display mode.

6 shows a circuit block diagram for controlling a conventional general reflection mode TFT LCD for comparison with the present invention.

As shown in FIG. 6, the CPU 21 is connected to the controller 22 to perform arithmetic control on the image data. The gate driver 23 is connected to the controller 22 to sequentially drive the gates of the TFTs located in each pixel to apply the image data processed and output by the controller 22 to the voltage of each pixel to provide the source of the TFT for each pixel. The image is reproduced by synchronizing with the data driver 24 which drives the voltage. The power supply device 25 is a device for supplying power to the TFT LCD and the internal light source. In addition, the light source 26 that is turned on by the controller and the CPU is turned on in synchronization with a switch of a device including a TFT LCD, for example, a key switch, a folder opening / closing switch, a power switch, and the like according to the use of the device. In addition, the reflection mode TFT LCD is optimized for a built-in light source in reproducing an image, and the external light is used as an auxiliary light, which is also optimized for virtually set external light, so that it cannot adequately actively respond to changing external light.

FIG. 7 is a block diagram of a circuit for controlling an internal light source and a liquid crystal pixel to a controller and a CPU according to color light intensity by receiving a signal of an optical sensor unit for detecting incident light of an external light source divided into red light, green light, and blue light according to the present invention. It is.

FIG. 7 is the same as the existing device of FIG. 6, but the optical sensor unit 38 for analyzing the luminance of each incident color of the visible light in the visible light region and the conversion unit 39 that can be converted into a digital signal that can be transferred to the control unit; The internal light source converting unit 40 converts the control signal into a driving signal to subdivide the image into various stages so as to optimize the image according to the analysis result of the external light, thereby adjusting the brightness of the internal light. Reference numeral 33 is a gate driver, 34 is a data driver, and 35 is a power supply device. At this time, the signal of the sensor output according to the incident of the external light may be connected to the controller 32 to perform arithmetic processing, or may be controlled in combination with the CPU 31 composed of a control circuit having a similar function.

The converter 39 not only converts the analog signal of the optical sensor into a digital signal but also removes external light of high frequency or pulse components that cannot be detected by the human eye or helpful in processing image signals. By incorporating a delay circuit, an integration circuit, a frequency band filter, and the like, it is possible to prevent arithmetic errors of the control unit due to unnecessary signals, thereby contributing to the stable image reproduction. Similarly, an external light that may negatively affect the signal calculation for image reproduction in an algorithm coupled to the controller 32 or the CPU 31 for a more active and versatile external light arithmetic processing for a variety of types of external light. By using digital data processing such as ignoring, averaging, integrating, undifferentiating, and band filter functions according to the signal type, the image computed in conjunction with external light is inappropriately changed to It may include features to prevent side effects such as shaking and sensitive changes in color.

On the other hand, the internal light source 36 uses a small, high speed, high efficiency, long life ultra-bright LED and similar light source. In particular, in the case of LED, in addition to the above characteristics, high brightness LEDs emitting wavelengths of LEDs, R, G, and B, which generate white light, may be applied. In this case, the high frequency driving function of LED which is more stable and responsive than any existing light source is used, which is more than 30-50Hz which is the limit of the frequency that human eyes feel. The internal light source converting unit 40 or the controller 32 may reduce the electric energy by the light source as much as the period of the on state and the off state of the flashing state when the light is blinked at a high frequency. And the CPU 31 or the like.

Although the present invention has been described in detail by way of examples, it is intended to explain the nature of the present invention, and the scope of the present invention is not limited thereto. For example, the method of controlling the internal light source and the liquid crystal pixel by determining the brightness of external light has been described. However, the internal light source and the liquid crystal pixel are controlled by combining a time display mode such as day, night, morning, evening, or a specific time with a built-in timer. It is also possible. In addition, the liquid crystal of the TFT LCD in the present invention is applied to both polysilicon crystals and amorphous crystals, and can be applied to a reflection mode image display apparatus similar thereto. In addition, in the present embodiment, the display mode setting and the determination result mode have been described with three examples, but the present invention is not limited thereto and may be divided into more detailed steps. The present invention can be variously modified and modified by those of ordinary skill in the art without departing from the spirit and scope of the invention described in the claims, and such variations or modifications Make sure you belong to the range.

By providing an optical sensor unit for detecting the external light into red light, green light and blue light, and controlling means for controlling the internal light source and the liquid crystal pixel, the desired color image display can be automatically realized under any external lighting environment. It has an effect. In addition, the power consumption can be significantly reduced under the same conditions as compared to the control of a conventional manually set internal light source, thereby maximizing power consumption efficiency, which is the biggest problem of the liquid crystal display device mounted in a battery-powered portable equipment, and reflecting mode. Significantly improve the utilization efficiency of TFT LCD elements.

Claims (11)

delete delete delete delete delete delete delete A system for controlling image display of a reflection mode thin film transistor liquid crystal display device displaying a color image by using an internal light source and control means for controlling the internal light source and the liquid crystal pixel, It includes an optical sensor unit for detecting the intensity of the external light divided into red light, green light, blue light, The control means performs an image processing process according to the state of the external light detected from the optical sensor unit and a predetermined display mode to control image display by adjusting the brightness of the internal light source and the output of the liquid crystal pixel, And a timer connected to the control means, wherein the control means determines the set display mode according to the time detected by the timer to adjust the internal light source. Image display control system. A system for controlling image display of a reflection mode thin film transistor liquid crystal display device displaying a color image by using an internal light source and control means for controlling the internal light source and the liquid crystal pixel, It includes an optical sensor unit for detecting the intensity of the external light divided into red light, green light, blue light, The control means performs an image processing process according to the state of the external light detected from the optical sensor unit and a predetermined display mode to control image display by adjusting the brightness of the internal light source and the output of the liquid crystal pixel, The arithmetic processing in the control means includes the steps of calculating a "judgment result mode" divided into various stages according to the detection result of the luminance according to the color of the external light, the initially set display mode and the determination result mode. Comparing and determining the luminous intensity of the internal light source and the luminous intensity, chromaticity, and contrast of the liquid crystal pixel according to a predetermined value or an expression required for control according to the determination result from the comparing and determining. And generating a control signal for controlling to a value. An image display control system of a reflection mode thin film transistor liquid crystal display device. A system for controlling image display of a reflection mode thin film transistor liquid crystal display device displaying a color image by using an internal light source and control means for controlling the internal light source and the liquid crystal pixel, It includes an optical sensor unit for detecting the intensity of the external light divided into red light, green light, blue light, The control means performs an image processing process according to the state of the external light detected from the optical sensor unit and a predetermined display mode to control image display by adjusting the brightness of the internal light source and the output of the liquid crystal pixel, The control means includes a delay circuit for preventing the brightness of the screen from unnaturally blinking when the brightness change of the external light is momentarily flickering or the high frequency flickering state. Control system. A system for controlling image display of a reflection mode thin film transistor liquid crystal display device displaying a color image by using an internal light source and control means for controlling the internal light source and the liquid crystal pixel, It includes an optical sensor unit for detecting the intensity of the external light divided into red light, green light, blue light, The control means performs an image processing process according to the state of the external light detected from the optical sensor unit and a predetermined display mode to control image display by adjusting the brightness of the internal light source and the output of the liquid crystal pixel, And the optical sensor unit to selectively detect incident light in a solid angle at a specific angle or incident light in a specific polarization state from the external light radiated onto the reflection mode TFT LCD surface.