KR100602064B1 - Gamma Voltage Generator - Google Patents

Abstract

The present invention relates to a gamma voltage generating device that can simplify the structure by reducing the number of parts.

The gamma voltage generating apparatus according to the present invention includes at least one variable resistance element for generating a plurality of red gamma voltages and controlling a plurality of red gamma voltages so that luminance values can be changed corresponding to each mode. A red gamma voltage generator for generating a plurality of red gamma voltages corresponding to each mode by at least two resistors connected in series between the variable resistance element and the base voltage source, and a luminance value corresponding to each mode may be changed. A plurality of green gamma voltages may be generated to control the plurality of green gamma voltages, and each of the at least two resistors connected in series between the variable resistance element and the base voltage source. A green gamma voltage generator configured to generate a plurality of green gamma voltages corresponding to the modes; At least one variable resistance element for generating a plurality of blue gamma voltages and controlling a plurality of green gamma voltages so as to change the luminance value corresponding to A blue gamma voltage generator generates a plurality of blue gamma voltages corresponding to respective modes by two or more resistor elements.

Description

Gamma Voltage Generator {APPARATUS OF GENERATING GAMMA VOLTAGE}             

1 is a cross-sectional view showing the structure of a conventional organic electro-luminescence device.

2 is a view showing a driving device of a conventional organic electroluminescent display panel.

3 is a circuit diagram illustrating in detail a gamma voltage generator shown in FIG. 2 when a first mode is selected.

FIG. 4 is a circuit diagram illustrating in detail a gamma voltage generator shown in FIG. 2 when a second mode is selected.

5 is a circuit diagram illustrating a gamma voltage generator according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

2: cathode 4: electron injection layer

6: electron transport layer 8: light emitting layer

10 hole transport layer 12 hole injection layer

14 anode 20 electro-luminescence panel

22: scan driver 24: data driver

26 gamma voltage generator 28 EL cell

32,42: red gamma voltage generator 33,44: green gamma voltage generator

36,46: blue gamma voltage generator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for generating a gamma voltage for use in a display device, and more particularly, to a gamma voltage generation device for simplifying a structure by reducing the number of parts.

Recently, various flat panel display devices that can reduce weight and volume, which are disadvantages of cathode ray tubes, have emerged. Such flat panel displays include a liquid crystal display, a field emission display, a plasma display panel, and an electro-luminescence (hereinafter, EL). And a display device.

Among them, an EL display device is a self-luminous element that emits a phosphor by recombination of electrons and holes, and is classified roughly into an inorganic EL using an inorganic compound and an organic EL using an organic compound as the phosphor. Such an EL display device has an advantage that the response speed is as fast as that of a cathode ray tube as compared to a passive light emitting device requiring a separate light source like a liquid crystal display device. In addition, the EL display device has many advantages such as low voltage driving, self-luminous, thin film type, wide viewing angle, fast response speed, high contrast, and the like, and is expected to be the next generation display device.

1 is a cross-sectional view showing a general organic EL structure for explaining the light emission principle of an EL display device. The organic EL includes an electron injection layer 4, an electron transport layer 6, a light emitting layer 8, a hole transport layer 10, and a hole injection layer 12 stacked between the cathode 2 and the anode 14.

When a voltage is applied between the anode 14, which is a transparent electrode, and the cathode 2, which is a metal electrode, electrons generated from the cathode 2 are directed toward the light emitting layer 8 through the electron injection layer 4 and the electron transport layer 6. Move. In addition, holes generated from the anode 14 move toward the light emitting layer 8 through the hole injection layer 12 and the hole transport layer 10. Accordingly, in the light emitting layer 8, light is generated by collision between electrons and holes supplied from the electron transport layer 6 and the hole transport layer 10 and recombination, and the light is externally transmitted through the anode 14 which is a transparent electrode. Is emitted so that the image is displayed. The luminescence brightness of such an EL organic element is not proportional to the voltage across the element but proportional to the supply current, so that the anode 14 is usually connected to a constant current source.

2 is a diagram showing a general EL display device.

The EL display device illustrated in FIG. 2 includes an EL display panel 20 including EL cells 28 arranged at each intersection of the scan electrode line SL and the data electrode line DL, and the scan electrode lines SL. ), A data driver 24 for driving the data electrode lines DL, and a gamma voltage generator 26 for supplying a plurality of gamma voltages to the data driver 24. ).

Each of the EL cells 28 is selected when a scan pulse is applied to the scan electrode line SL, which is a cathode, to generate light corresponding to a pixel signal, that is, a current signal, supplied to the data electrode line DL, which is an anode. Each of the EL cells 28 is represented by a diode equivalently connected between the data electrode line DL and the scan electrode line SL. Each of the EL cells 28 is supplied with a negative scan pulse to the scan electrode line SL and emits light when a positive current is applied to the data electrode line DL and a forward voltage is applied thereto. In contrast, the reverse direction voltage is applied to the EL cells 28 included in the unselected scan lines so as not to emit light. In other words, the EL cells 28 that emit light are charged with forward charges, while the EL cells 28 that do not emit light are charged with reverse charges.

The scan driver 22 sequentially supplies the negative scan pulses to the plurality of scan electrode lines SL in line order.

The data driver 24 converts the digital data signal input from the outside into an analog data signal by using the gamma voltage from the gamma voltage generator 26. The data driver 24 supplies the analog data signal to the data lines DL every time a scan pulse is supplied.

In this manner, the conventional EL display device displays an image by supplying a current signal proportional to the input data to each of the EL cells 28 and causing the EL cells 28 to emit light. In addition, the EL cells 28 are R cells having a red (hereinafter referred to as R) phosphor, G cells having a green (hereinafter referred to as G) phosphor, and blue (hereinafter referred to as B) for color implementation. It consists of B cells which have a phosphor. In addition, three R, G, and B cells are combined to implement a color for one pixel. Here, each of the R, G, and B phosphors has different luminous efficiency. In other words, when the same level of data signal is supplied to the R, G, and B cells, the luminance levels of the R, G, and B cells are different. Accordingly, for the white balance of the R, G, and B cells, gamma voltages of the same luminance are set differently for each of the R, G, and B cells. Therefore, the gamma voltage generator 26 supplying gamma voltages to the data driver 24 generates gamma voltages for each of R, G, and B.

3 and 4 are circuit diagrams showing in detail the gamma voltage generator shown in FIG. 2.

3 and 4, the conventional gamma voltage generators provide the gamma voltage generator 32, the G gamma voltage generator 34, and the B gamma voltage to supply gamma voltages for R, G, and B cells, respectively. The generating unit 36 is provided. 3 illustrates a first mode gamma voltage generator and FIG. 4 illustrates a second mode gamma voltage generator.

The R gamma voltage generator 32 includes voltage dividers r_R1, r_R2, and r_R3 connected in series between the supply voltage source VDD and the ground voltage source GND. Here, voltages from the common terminals n1 and n2 of the divided resistors r_R1, r_R2 and r_R3 are input to the data driver 24 as gamma voltages. At this time, the low grayscale R gamma voltage VH_R is generated by Equation 1 below, and the high grayscale R gamma voltage VL_R is generated by Equation 2 below.

The G gamma voltage generator 34 includes voltage dividers r_G1, r_G2, and r_G3 connected in series between the supply voltage source VDD and the ground voltage source GND. Here, voltages from the common terminals n3 and n4 of the divided resistors r_G1, r_G2 and r_G3 are input to the data driver 24 as gamma voltages. At this time, the low grayscale G gamma voltage VH_G is generated by Equation 3 below, and the high grayscale G gamma voltage VL_G is generated by Equation 4 below.

The B gamma voltage generator 36 includes voltage dividers r_B1, r_B2, and r_B3 connected in series between the supply voltage source VDD and the ground voltage source GND. Here, voltages from the common terminals n5 and n6 of the divided resistors r_B1, r_B2 and r_B3 are input to the data driver 24 as gamma voltages. At this time, the low gray level B gamma voltage VH_B is generated by Equation 5 below, and the high gray level B gamma voltage VL_B is generated by Equation 6 below.

Here, the resistances included in the gamma voltage generator for each mode are set so that luminance corresponding to an environment (light) such as night, day, outside, and inside may be generated.

For example, the R gamma voltage generator 32 of the second mode gamma voltage generator illustrated in FIG. 4 may include the divided resistors r_R4, r_R5, which are connected in series between the supply voltage source VDD and the ground voltage source GND. r_R6). Here, the resistance values of the divided resistors r_R4, r_R5, and r_R6 are set differently from the resistance values of the divided resistors r_R1, r_R2, and r_R3 included in the R gamma voltage generator 32 of FIG. 3. Therefore, the gamma voltage value generated from the second mode gamma voltage generator is set to be different from the gamma voltage value generated by the R gamma voltage generator 32 shown in FIG. 3, and the gamma voltage value corresponds to the environment. By supplying to the EL display device, an optimum brightness corresponding to the external environment can be generated in the EL display device. Here, the resistance values of the divided resistors r_R7, r_R8, and r_R9 are measured by the divided resistors r_R1, r_R2, r_R3, r_R4, r_R5, and r_R6 included in the R gamma voltage generator 32 of FIGS. 3 and 4. It is set differently from the resistance value.

However, the gamma voltage generation unit corresponding to each mode is a high gray scale R gamma voltage VL_R and a low gray scale R gamma voltage VH_R supplied to the R cell, and a high gray scale G gamma voltage supplied to the G cell. (VL_G) and the low grayscale G gamma voltage (VH_G) and the high grayscale B gamma voltage (VL_B) and the low grayscale B gamma voltage (VH_B) should be generated. That is, the high gray level gamma voltages VL_R, VL_G, and VL_B and the low gray level gamma voltages VH_R, VH_G, and VH_B supplied to each of the R, G, and B cells must be generated. To this end, the R, G, and B gamma voltage generators 32, 34, and 36 of the gamma voltage generator are each of the high gray gamma voltages VL_R, VL_G, VL_B and low gray gamma between three resistors connected in series. Since voltages VH_R, VH_G, and VH_B are generated, a total of nine resistors for each mode are installed. Therefore, when two modes are used, the conventional gamma voltage generator needs to have a total of 18 resistors. Accordingly, there is a problem that the structure is complicated by the large number of parts that differ on the module.

Accordingly, it is an object of the present invention to provide a gamma voltage generating device which can simplify the structure by reducing the number of parts.

In order to achieve the above object, a gamma voltage generating device operating in various modes so that the luminance value can be changed in response to an external environment according to an embodiment of the present invention can be changed in response to the respective modes. At least two resistance elements including at least one variable resistance element for generating a plurality of red gamma voltages and adjusting the plurality of red gamma voltages and connected in series between the variable resistance element and a base voltage source. A red gamma voltage generation unit generating the plurality of red gamma voltages corresponding to each mode, and generating a plurality of green gamma voltages so that the luminance values can be changed corresponding to the respective modes; At least one variable resistance element for controlling a green gamma voltage, and the variable resistance element A green gamma voltage generator for generating the plurality of green gamma voltages corresponding to the respective modes by at least two resistors connected in series between a ground voltage source and a ground voltage source, and the luminance value corresponding to each of the modes; At least two resistance elements including at least one variable resistance element for generating a plurality of blue gamma voltages and controlling the plurality of green gamma voltages, and connected in series between the variable resistance element and the base voltage source. And a blue gamma voltage generator for generating the plurality of blue gamma voltages corresponding to the respective modes.

In the gamma voltage generator, each of the red, green, and blue gamma voltage generators is connected in series between a supply voltage source, a first resistance element and a variable resistance element connected to the supply voltage source, and the variable resistance element and a base voltage source in series. I (i is a natural number) series resistance elements.

The gamma voltage generating device generates i gamma voltages corresponding to a first gray level from a common terminal between the first resistance element and the variable resistance element, and includes i series resistance elements connected in series between the variable resistance element and the base voltage source. The gamma voltage corresponding to the second grayscale is generated from each of the plurality of times.

In the gamma voltage generating device, the second gray level is generated from each of the i series resistance elements corresponding to each mode.

In the gamma voltage generator, resistance values of the first resistor, the variable resistor, and the i series resistors may be differently set in the red, green, and blue gamma voltage generators, respectively.

In the gamma voltage generator, resistance values of the resistance elements included in each of the red, green, and blue gamma voltage generators may be set to match the white balance of the red cells, the green cells, and the blue cells.

Other objects and features of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIG. 5.

5 is a circuit diagram illustrating a gamma voltage generator according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the gamma voltage generator of the present invention generates an R gamma voltage generator 42, a G gamma voltage generator 44, and a B gamma voltage to supply gamma voltages for R, G, and B cells, respectively. The unit 46 is provided. Here, each of the R, G, and B gamma voltage generators 42, 44, and 46 generates gamma voltages of various modes so as to correspond to an external environment.

The R gamma voltage generator 42 generates a low gray R gamma voltage VH_R and a high gray R gamma voltage VL_R to supply a low gray (Black) and high gray (White) to the R cell. To this end, the R gamma voltage generator 42 is provided between the first and second voltage divider resistors R1 and R2 connected in series with the supply voltage source VDD, and between the second voltage divider resistor R2 and the ground voltage source GND. And third and fourth voltage divider resistors R3 and R4 connected in series. Here, the second voltage divider R2 uses a variable resistor so that the gamma voltage generator can effectively respond to various panel conditions. On the other hand, since the low gradation R gamma voltage VH_R_Mode1 / 2 of the first and second modes represents black, the luminance difference does not significantly occur even when the same gamma voltage is supplied. Accordingly, the low grayscale R gamma voltage VH_R_Mode1 / 2 of the first and second modes output from the common terminal n1 between the first voltage divider R1 and the second voltage divider R2 is supplied to the R cell. To express low gradation. At this time, the low grayscale R gamma voltage VH_R_Mode1 / 2 of the first and second modes supplied to the Rcell to express the low grayscale is generated by the following equation (7).

In addition, the high gradation R gamma voltage VL_R_Mode1 of the first mode is output at any point of the second voltage divider R2, that is, the variable resistor so as to correspond to the panel condition, and is supplied to the R cell to express the high gradation. At this time, the high gradation R gamma voltage VL_R_Mode1 of the first mode supplied to the R cell to express the high gradation of the first mode is generated by Equation 8 as follows.

In addition, the high gradation R gamma voltage VL_R_Mode2 of the second mode is the third and fourth voltage divider R3 connected between the first mode high gradation R gamma voltage VL_R_Mode1 and the base voltage source GND to correspond to the panel conditions. It is output from the common terminal n2 of R4) and supplied to the R cell to express high gradation. At this time, the high gradation R gamma voltage VL_R_Mode2 of the second mode supplied to the R cell to express the high gradation of the second mode is generated by the following equation (9).

The G gamma voltage generator 44 generates a low gray G gamma voltage (VH_G) and a high gray G gamma voltage (VL_G) to supply a low gray (Black) and high gray (White) to the G cell. To this end, the G gamma voltage generator 44 is provided between the eleventh and twelfth voltage dividers R11 and R12 connected in series with the supply voltage source VDD, the twelfth voltage divider R12 and the ground voltage source GND. The thirteenth and fourteenth voltage divider resistors R13 and R14 connected in series are provided. Here, the twelfth voltage divider R12 uses a variable resistor so that the gamma voltage generator can effectively respond to various panel conditions. On the other hand, since the low grayscale G gamma voltage VH_G_Mode1 / 2 of the first and second modes represents black, the luminance difference does not significantly occur even when the same gamma voltage is supplied. Accordingly, the low grayscale G gamma voltage VH_G_Mode1 / 2 of the first and second modes output from the common terminal n11 between the eleventh voltage divider R11 and the twelfth voltage divider R12 is supplied to the G cell. To express low gradation. At this time, the low grayscale G gamma voltage VH_G_Mode1 / 2 of the first and second modes supplied to the Gcell to express the low grayscale is generated by the following equation (10).

The high gradation G gamma voltage VL_G_Mode1 of the first mode is output at any point of the twelfth voltage divider R12, that is, the variable resistor so as to correspond to the panel condition, and is supplied to the G cell to express the high gradation. At this time, the high gradation G gamma voltage VL_G_Mode1 of the first mode supplied to the G cell to express the high gradation of the first mode is generated by the following equation (11).

Further, the high gradation G gamma voltage VL_G_Mode2 of the second mode corresponds to the thirteenth and fourteenth voltage divider R13 connected between the first mode high gradation G gamma voltage VL_G_Mode1 and the base voltage source GND. It is output from the common terminal n12 of R14, and is supplied to the G cell to express high gradation. At this time, the high gradation G gamma voltage VL_G_Mode2 of the second mode supplied to the G cell to express the high gradation of the second mode is generated by the following equation (12).

The B gamma voltage generator 46 generates a low gray B gamma voltage VH_B and a high gray B gamma voltage VL_B to supply a low gray level to the B cell. To this end, the B gamma voltage generator 46 is provided between the twenty-first and twenty-second voltage divider resistors R21 and R22 connected in series to the supply voltage source VDD, and between the twenty-second voltage divider resistor R22 and the ground voltage source GND. And twenty-third and twenty-fourth voltage divider resistors R23 and R24 connected in series. Here, the 22nd voltage dividing resistor R22 uses a variable resistor so that the gamma voltage generator can effectively respond to various panel conditions. On the other hand, since the low gray level B gamma voltage VH_B_Mode1 / 2 of the first and second modes represents black, the luminance difference does not occur largely even when the same gamma voltage is supplied. Accordingly, the low gray level B gamma voltage VH_B_Mode1 / 2 of the first and second modes output from the common terminal n21 between the twenty-first voltage divider R21 and the 22nd voltage divider R22 is supplied to the B cell. To express low gradation. At this time, the low gray level B gamma voltage VH_B_Mode1 / 2 of the first and second modes supplied to the B cell to express the low gray level is generated by the following equation (13).

The high gray level B gamma voltage VL_B_Mode1 of the first mode is output at any point of the twenty-second voltage divider R22, that is, the variable resistor so as to correspond to the panel condition, and is supplied to the B cell to express a high gray level. At this time, the high gradation B gamma voltage VL_B_Mode1 of the first mode supplied to the B cell to express the high gradation of the first mode is generated by the following equation (14).

Further, the high gray level B gamma voltage VL_B_Mode2 of the second mode corresponds to the 23rd and 24th voltage divider resistors connected between the first mode high gray level B gamma voltage VL_B_Mode1 and the base voltage source GND to correspond to the panel conditions. It is output from the common terminal n22 of R23 and R24 and supplied to the B cell to express high gradation. At this time, the high gradation B gamma voltage VL_B_Mode2 of the second mode supplied to the B cell to express the high gradation of the second mode is generated by the following equation (15).

Meanwhile, when the first mode is selected, the high grayscale R, G, and B gamma voltages VL_R_Mode1, VL_G_Mode1, and VL_B_Mode1 generated by the R, G, and B gamma voltage generators 42, 44, and 46 are high gray, that is, white. (White) (the grays of the R, G, and B cells are combined to represent white.) Since the luminance difference occurs in correspondence to the luminous efficiency of each of the R, G, and B cells, the R cells, the G cells, and the The high gradation R gamma voltage VL_R_Mode1, the high gradation G gamma voltage VL_G_Mode1, and the high gradation B gamma voltages VL_B_Mode1 supplied to each B cell are set to match white balance.

When the second mode is selected, the high grayscale R, G, and B gamma voltages VL_R_Mode2, VL_G_Mode2, and VL_B_Mode2 generated by the R, G, and B gamma voltage generators 42, 44, and 46 are high gray, that is, white. ), The luminance difference occurs in response to the luminous efficiency of each of the R, G, and B cells, so that the high gradation R gamma voltage (VL_R_Mode2) and the high gradation The G gamma voltage VL_G_Mode2 and the high gradation B gamma voltages VL_B_Mode2 are set to match white balance.

Meanwhile, the first and second mode low grayscale R gamma voltages VH_R_Mode1 / 2 and the first and second mode low grayscale G gamma voltages generated by the R, G, and B gamma voltage generators 42, 44, and 46 are generated. (VH_G_Mode1 / 2) and the first and second mode low gray level B gamma voltages (VH_B_Mode1 / 2) represent a low gray level, that is, black (the grays of the R, G, and B cells are combined to represent black). .) Even if there is a voltage difference, it is hardly recognized by the eye, so it does not affect much.

The gamma voltage generator according to the present invention allows the R, G, and B gamma voltage generators 42, 44, and 46 to select the first and second modes, thereby generating a plurality of gamma voltages corresponding to the selected mode. Create At this time, by using the variable resistor when expressing high gradation, it is possible to cope with various panel conditions. The gamma voltages thus generated are supplied to the data driver shown in FIG. 1. The data driver generates an analog data signal using a gamma voltage corresponding to the input digital data signal among a plurality of gamma voltages, and supplies the generated analog data signal to the data line DL to be synchronized with the scan signal. The predetermined image is displayed.

As described above, the gamma voltage generating apparatus according to the present invention can reduce the number of parts in each of the red, green, and blue gamma voltage generating units, and can express gray scales, thereby simplifying the structure of the EL module. In addition, the number of components can be reduced, thereby reducing the manufacturing cost of the gamma voltage generator and reducing the number of output pins of the driver IC.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (6)

In the gamma voltage generator that operates in various modes to change the luminance value in response to the external environment, At least one variable resistance element for generating a plurality of red gamma voltages and controlling the plurality of red gamma voltages so that the luminance values can be changed in correspondence to the respective modes; A red gamma voltage generator configured to generate the plurality of red gamma voltages corresponding to the respective modes by at least two resistors connected in series between voltage sources; At least one variable resistance element for generating a plurality of green gamma voltages and controlling the plurality of green gamma voltages so that the luminance values can be changed in correspondence to the respective modes; A green gamma voltage generator configured to generate the plurality of green gamma voltages corresponding to the respective modes by at least two resistors connected in series between voltage sources; At least one variable resistance element for generating a plurality of blue gamma voltages and controlling the plurality of green gamma voltages so as to change the luminance value corresponding to each of the modes; And a blue gamma voltage generator configured to generate the plurality of blue gamma voltages corresponding to the respective modes by at least two resistors connected in series between voltage sources. The method of claim 1, Each of the red, green, and blue gamma voltage generators Supply voltage source, A first resistance element and a variable resistance element connected to the supply voltage source; And (i is a natural number) series resistance elements connected in series between said variable resistance element and a ground voltage source. The method of claim 2, A gamma voltage corresponding to a first grayscale is generated from a common terminal between the first resistance element and the variable resistance element, And a gamma voltage corresponding to the second gray level is generated from each of the i series resistance elements connected in series between the variable resistance element and the base voltage source. The method of claim 3, wherein And the second gray level is generated from each of the i series resistance elements corresponding to each of the modes. The method of claim 2, The gamma voltage generator of claim 1, wherein the resistance values of the first resistance element, the variable resistance element, and the i series resistance elements are set differently in the red, green, and blue gamma voltage generators. The method of claim 5, wherein The gamma voltage generator of claim 1, wherein the resistance values of the resistors included in each of the red, green, and blue gamma voltage generators are set to match the white balance of the red, green, and blue cells.

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