KR100347868B1 - Liquid crystal display panel driving circuit capable of adjusting brightness and adjusting method of the same - Google Patents

Abstract

The gray voltage generator of the liquid crystal display (LCD) panel driving circuit disclosed herein selects the highest gray voltage and the lowest gray voltage in response to a luminance selection signal provided from the outside, and divides the voltage between the highest gray voltage and the lowest gray voltage. To generate intermediate gray voltages. As a result, the luminance of the LCD panel is adjusted in accordance with the luminance mode selected by the user. Furthermore, since it is not necessary to adjust the current of the fluorescent lamp to adjust the brightness, the brightness can be adjusted even in a reflective type LCD device that does not use a backlight.

Description

Liquid crystal display panel driving circuit with adjustable brightness and its adjustment method {LIQUID CRYSTAL DISPLAY PANEL DRIVING CIRCUIT CAPABLE OF ADJUSTING BRIGHTNESS AND ADJUSTING METHOD OF THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display (LCD). More particularly, the present invention relates to a gray scale voltage generating circuit and a method thereof of a liquid crystal display device capable of adjusting a range of gray voltages according to a user's selection of a luminance mode. will be.

1 is a view showing the configuration of a general TFT-LCD (Thin Film Transistor Liquid Crystal Display) module. Referring to FIG. 1, the LCD module 1 is largely composed of a driving circuit unit 2, an LCD panel 5, and a backlight unit 7.

The driving circuit unit 2 is a printed circuit board to which various circuit elements such as a plurality of row drive ICs 6A-6B, a column drive IC 6C-6E, and a timing controller for driving the panel 5 are attached. Circuit Board (PCB) (3) and 4, the LCD panel 5 is formed of a liquid crystal is injected between the substrate and the two glass (glass) between the substrate. The LCD panel 5 expresses a color image by controlling the light transmitted through the white planar light incident on the backlight unit 7 in response to each pixel signal voltage input from the driving circuit unit 2. It plays a role. The backlight unit 7 is composed of a lamp 8, a reflector 9, and the like, and serves to make plane light with uniform brightness from the fluorescent lamp 8 used as a light source.

An example of a circuit for adjusting the brightness of a fluorescent lamp is described in U. S. Pat. No. 5,754,012, "Primary side lamp current sensing for minature cold cathode fluorescent lamp system."

In general, the brightness of the LCD panel 5 is adjusted by adjusting the current of the fluorescent lamp 8, wherein the amount of current flowing into the fluorescent lamp 8 is adjusted by the user. For example, in the case of a portable computer having an LCD panel, the brightness is controlled by a user operating a sliding switch or the like provided in an outer case of the LCD panel. This method is inconvenient for the user to manually adjust while viewing the screen.

In addition, in the reflective type device that does not use a backlight such as a small electronic calculator, there is a disadvantage in that the brightness cannot be adjusted by the conventional method.

Accordingly, an object of the present invention has been proposed to solve the above-mentioned problems, and to provide a liquid crystal display panel driving circuit and a method of adjusting the luminance capable of variously adjusting the luminance of the LCD panel according to the screen luminance mode. have.

Another object of the present invention is to provide a liquid crystal display panel driving circuit and a method of adjusting the brightness of the reflective LCD device which does not use a backlight.

1 is a view for showing the configuration of a general TFT-LCD (Thin Film Transistor Liquid Crystal Display) module;

2 is a block diagram showing an LCD panel driving circuit according to a preferred embodiment of the present invention;

3 is a block diagram showing a configuration of a gray voltage generator shown in FIG. 2;

FIG. 4 is a circuit diagram showing a detailed circuit configuration of the gradation voltage range selection circuit shown in FIG.

5 is a circuit diagram showing a detailed configuration of the voltage distribution circuit shown in FIG.

6 is a block diagram showing the configuration of the column drive IC shown in FIG. 1; And

7 is a flowchart illustrating an operation procedure of a gray voltage generator according to an exemplary embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10: timing controller 20: gray voltage generator

22: gradation voltage range selection circuit 23: switching circuit

24: voltage distribution circuit 30: column drive IC

32: shift register 34: D / A converter

36: output buffer 40: low drive IC

50: LCD panel

According to one aspect of the present invention for achieving the object of the present invention as described above, the LCD panel driving circuit: determines the output timing of the digital video signal and the horizontal / vertical synchronization signals, and drive the digital video signal and low line A timing controller for outputting a signal and a gray level voltage generating a middle gray voltage by selecting a highest gray voltage and a lowest gray voltage in response to a luminance selection signal provided from the outside and dividing the gray level voltage between the highest gray voltage and the lowest gray voltage. Means, a column drive IC which receives the gradation voltages from the gradation voltage generating means and provides analog video signals corresponding to the digital video signal from the timing controller to column lines of an LCD panel, and a row from the timing controller Accepts a line drive signal, the LC And a row drive IC sequentially outputting the row line driving signal to each of the row lines of the D panel.

In a preferred embodiment, the gradation voltage generating means includes gradation voltage range selection means for outputting the highest gradation voltage and the lowest gradation voltage in response to the brightness selection signal, and divides the voltage between the highest gradation voltage and the lowest gradation voltage. And voltage distribution means for outputting intermediate gray voltages for providing to the column drive IC.

In this embodiment, the gradation voltage range selecting means includes one of a plurality of resistors sequentially connected in series between a power supply voltage and a ground voltage, and one of voltages of the connection nodes of the resistors in response to the brightness selection signal. And switching means for selecting and outputting the highest gray voltage to the lowest gray voltage.

In a preferred embodiment, the voltage distribution means is composed of a plurality of resistors sequentially connected in series between the highest gray voltage and the lowest gray voltage.

According to another aspect of the present invention, a method of adjusting the brightness of a liquid crystal display panel includes: determining whether a brightness selection signal is input from an external device, and when the brightness selection signal is input, corresponding to the input brightness selection signal. Selecting a highest gray voltage and a lowest gray voltage, and dividing the selected highest gray voltage with the lowest gray voltage to generate gray voltages for providing to the column drive IC of the LCD panel.

By such an apparatus and method, not only can the brightness of the LCD panel be adjusted in an easy manner, but also the LCD display device capable of adjusting the brightness can be implemented in a reflective LCD device that does not use a backlight.

(Example)

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 7.

2 is a block diagram showing an LCD panel driving circuit according to a preferred embodiment of the present invention.

Referring to FIG. 2, the LCD panel driving circuit includes a timing controller 10, a gamma voltage generator 20, column drive ICs 30_1-30_n, and row drive ICs 40_1. 40_m).

The timing controller 10 is a digital video signal (R: red, G: greeen, B: blue), a horizontal synchronous signal (H_sync: horizontal synchronous signal), and a vertical synchronous signal (V_sync) provided from a host (not shown). It receives a: vertical synchronous signal, determines an output timing of the digital video signals R, G, and B, and outputs a low line driving signal.

The gray voltage generator 20 selects the highest gray voltage V_MAX and the lowest gray voltage V_MIN in response to the luminance selection signal B_MODE provided from the outside, and selects the highest gray voltage V_MAX and the lowest grayscale. The plurality of intermediate gray voltages V1-V9 are output by dividing the voltages V_MIN.

The luminance selection signal B_MODE is a signal for selecting one of various luminance modes, for example, 'bright', 'dark', and 'normal mode'. When the present invention is applied to a TFT-LCD monitor of a computer system, the brightness selection signal B_MODE can be selected by the user pressing a selection switch provided on the exterior of the monitor. On the other hand, in a computer system employing a remote controller function, a signal input from a remote controller is received by the host (computer body) and converted into a luminance selection signal (B_MODE) suitable for signal processing, and the signal is converted into an LCD module. This can be implemented by providing to the gradation voltage generator 20 of. Since the methods as described above can be easily implemented by those skilled in the art, more detailed description will be omitted.

The column drive ICs 30_1-30_n receive the gray voltages V0-V10 from the gray voltage generator 20, and digital video signals R, G, and B from the timing controller 10. Analog video signals) are provided to the column lines of the LCD panel 50.

The row drive ICs 40_1-40_m receive the row line driving signal from the timing controller 10 and sequentially provide the row line driving signal to each of the row lines of the LCD panel 50.

FIG. 3 is a block diagram illustrating a configuration of a gray voltage generator shown in FIG. 2. As illustrated in FIG. 3, the gray voltage generator 20 outputs the highest gray voltage V_MAX and the lowest gray voltage V_MIN corresponding to the luminance selection signal B_MODE. Outputs gray voltages (V0-V10) for dividing the range selection circuit 22 and the highest gray voltage (V_MAX) and the lowest gray voltage (V_MIN) to provide the column drive ICs (30_1-30_n). The voltage distribution circuit 24 is comprised.

Referring to FIG. 4, which shows the configuration of the gray voltage range selection circuit shown in FIG. 3 in detail, the gray voltage range selection circuit 22 includes three serially connected in series between the power supply voltage AVDD and the ground voltage VSS. A switching circuit 23 composed of three resistors 103, 102, 101 and first and second switches SW1, SW2.

The first switch SW1 selects one of the power supply voltage AVDD and the voltage of the second node N2 in response to the brightness selection signal B_MODE and outputs the highest gray voltage V_MAX. The second switch SW2 selects one of the voltage of the first node N1 and the ground voltage VSS in response to the brightness selection signal B_MODE and outputs the lowest gray voltage V_MIN. The highest gray level voltage V_MAX and the lowest gray voltage V_MIN are voltage levels for completely blocking light of the liquid crystal, and are voltages of opposite polarities alternately provided to the liquid crystal every field to prevent deterioration of the liquid crystal.

For example, the power supply voltage AVDD is 7V, the voltage of the second node N2 is 6V, the voltage of the first node N1 is 1V, and the ground voltage VSS is 0V.

When the luminance selection signal B_MODE corresponds to the 'normal mode', the first switch SW1 outputs the voltage 6V of the second node N2 as the highest gray voltage V_MAX, The second switch SW2 outputs the voltage 1V of the first node N1 as the lowest gray voltage V_MIN. On the contrary, when the luminance selection signal B_MODE corresponds to a 'dark view', the first switch SW1 outputs the power voltage 7V as the highest gray voltage V_MAX, and the second switch ( SW2 outputs the ground voltage 0V as the lowest gray voltage V_MIN. It is well known that the range of the gradation voltage provided to the color drive ICs 30_1-30_n looks darker than the case of (6V-1V).

In this embodiment, the case where the luminance mode is two modes, that is, the 'normal mode' and the 'dark view' has been described. However, when the luminance mode is K, the power supply voltage AVDD and the ground voltage VSS are separated. The number of resistors connected to the circuit is set to (2 * K-1), and the first switch SW1 sets the voltage of one node among a group of nodes (nodes close to the power supply voltage) to the highest gray voltage (V_MAX). The second switch SW2 is connected to output the voltage of one node among the other groups (nodes close to the ground voltage) to the lowest gray voltage V_MIN.

The intermediate gray voltage between the highest gray voltage V_MAX and the lowest gray voltage V_MIN is generated by the voltage divider circuit 24. FIG. 5 is a circuit diagram illustrating a detailed configuration of the voltage divider circuit shown in FIG. 3. Referring to FIG. 5, the voltage distribution circuit 24 includes ten resistors 201-210 sequentially connected in series between the highest gray voltage V_MAX and the lowest gray voltage V_MIN. The resistors 201-210 divide the voltage between the highest gray voltage V_MAX and the lowest gray voltage V_MIN to generate intermediate gray voltages V1-V9. The highest gray voltage V_MAX is output as a gray voltage V10, and the lowest gray voltage V_MIN is output as a gray voltage V0.

FIG. 6 is a block diagram showing the configuration of the column drive IC shown in FIG.

Referring to FIG. 6, the column drive IC 30 includes a shift register 32, a digital / analog converter 34, and an output buffer 36.

The shift register 32 shifts and stores the 6-bit digital video signals R, G, and B provided from the timing controller 10 in order. The 4-bit enable signal EN provided from the timing controller 10 is a signal for sequentially enabling the n column drive ICs 30_1-30_n. When the digital video signal is filled in the first column drive IC 30_1, the second column drive IC 30_2 is enabled so that the digital video signal provided from the timing controller 10 is supplied to the second drive IC 30_2. Stored. When the digital video signal is stored in the last column drive IC 30_n in this manner, the digital video signal stored in all the column drive ICs 30_1-30_n is simultaneously provided to the digital / analog converter 34.

The digital / analog converter 34 receives gray voltages V0 to V10 provided from the gray voltage generator 20 and outputs analog video signals corresponding to the digital video signal from the shift register 32. do.

The output buffer 34 latches the analog video signals provided from the digital / analog converter 34 and provides them to the column lines of the LCD panel 50 in response to a predetermined load signal.

7 is a flowchart illustrating an operation procedure of a gray voltage generator according to an exemplary embodiment of the present invention.

In step S310, it is determined whether or not the luminance selection signal B_MODE is input from the outside. When the luminance selection signal B_MODE is input from the outside, the control proceeds to step S320.

In step S320, in response to the input luminance selection signal B_MODE, one of the voltages of the plurality of nodes divided between the power supply voltage AVDD and the ground voltage VSS as the highest gray voltage V_MAX, and again. The other selects and outputs the lowest gray voltage (V_MIN).

In operation S330, the intermediate gray voltages V1 to V9 are generated by dividing the highest gray voltage V_MAX and the lowest gray voltage V_MIN. The highest gray voltage V_MAX (ie, V10), the lowest gray voltage (V_MIN: that is, V0), and the intermediate gray voltages (V1-V9) are provided to the column drive ICs 30_1-30_n.

According to the present invention as described above, the user can select the brightness mode in an easy way. Furthermore, since the range of the gradation voltages provided to the column drive ICs can be adjusted according to the selected luminance mode, the luminance can be adjusted even in a reflective LCD device that does not use a backlight.

In the above, the configuration and operation of the circuit according to the present invention are shown in accordance with the above description and drawings, but this is merely described, for example, and various changes and modifications are possible without departing from the spirit of the present invention. .

According to the present invention as described above, the user can select the brightness mode in an easy way. Furthermore, since the range of the gradation voltages provided to the column drive ICs can be adjusted according to the selected luminance mode, the luminance can be adjusted even in a reflective LCD device that does not use a backlight.

Claims (7)

In the liquid crystal display panel driving circuit: A timing controller which determines output timing of the digital video signal and the horizontal / vertical synchronization signals and outputs the digital video signal and the low line driving signal; Gradation voltage generating means for selecting a highest gradation voltage and a lowest gradation voltage and dividing the highest gradation voltage and the lowest gradation voltage in response to a luminance selection signal provided from the outside to generate intermediate gradation voltages; A column drive IC which receives gradation voltages from the gradation voltage generating means and provides analog video signals corresponding to the digital video signal from the timing controller to column lines of the LCD panel; And And a low drive IC which receives the low line driving signal from the timing controller and sequentially outputs the low line driving signal to each of the low lines of the LCD panel. Circuit. The method of claim 1, The gray voltage generation means, Gray voltage range selection means for outputting the highest gray voltage and the lowest gray voltage in response to the brightness selection signal; And And a voltage dividing means for dividing the highest gray voltage and the lowest gray voltage to output intermediate gray voltages for providing to the column drive IC. The method of claim 2, The gray voltage range selection means, A plurality of resistors sequentially connected in series between the power supply voltage and the ground voltage; And switching means for selectively outputting one of the voltages of the connection nodes of the resistors to the highest gray voltage in response to the brightness selection signal, and selectively outputting the voltage of another connection node to the lowest gray voltage. A liquid crystal display panel drive circuit capable of adjusting luminance. The method of claim 2, The voltage distribution means, And a plurality of resistors sequentially connected between the highest gray voltage and the lowest gray voltage in series. The method of claim 1, And the brightness selection signal is a signal for selecting one of K brightness modes. The method according to claim 2 or 5, The gray voltage range selection means, (2 * K-1) resistors sequentially connected in series between the supply voltage and the ground voltage; Switching means for selectively outputting one of the power supply voltage, the ground voltage, and voltages of the connection nodes of the resistors to the highest gray voltage in response to the brightness selection signal, and selectively outputting another voltage to the lowest gray voltage A liquid crystal display panel drive circuit capable of adjusting the brightness, characterized in that it comprises a. In the method of adjusting the brightness of the liquid crystal display panel: Determining whether or not a luminance selection signal has been input from the outside; Selecting the highest gray voltage and the lowest gray voltage corresponding to the input luminance selection signal when the brightness selection signal is input; And And dividing between the selected highest gray voltage and the lowest gray voltage to generate intermediate gray voltages for providing to the column drive IC of the LCD panel.