KR100602355B1 - Data driving chip and light emitting driver - Google Patents

Abstract

The present invention relates to a data driving chip and a light emitting display device, and more particularly, to a data driving chip and a light emitting display device which can improve the uniformity of a reference current.

The present invention provides a scan driver for sequentially applying scan signals to a plurality of scan lines, a data driver for applying a data current to a plurality of data lines, and a scan signal applied to the plurality of scan lines and data applied to the plurality of data lines. And an image display unit for displaying an image according to a current, wherein the data driver comprises: a first data driving chip for outputting a differential reference current determined by a reference voltage and a resistance; and second data receiving the output differential reference current; A light emitting display device including a driving chip is provided.

The data driving chip and the light emitting display device according to the present invention have an advantage of improving the uniformity of image quality by reducing the error of the reference current used in each data driving chip. In addition, the data driving chip and the light emitting display device according to the present invention have an advantage of increasing the CMRR by using a differential reference current as a current transferred between the data driving chip.

Description

DATA DRIVING CHIP AND LIGHT EMITTING DRIVER             

1 is a view schematically showing a data driver using a plurality of data driver chips according to the prior art.

2 is a diagram illustrating a light emitting display device according to an exemplary embodiment of the present invention.

3 is a diagram schematically illustrating a data driver including a plurality of data driver chips employed in the light emitting display device of FIG. 2.

4 is a diagram illustrating an example of a data driver chip employed in the data driver of FIG. 3.

FIG. 5 is a diagram illustrating an example of a bias circuit employed in FIG. 4.

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

100: scan driver 200: data driver

300: image display unit 400: pixel

500: timing controller 210 to 240: data driving chip

260: shift register 270: data latch

280: D / A converter 290: bias circuit

291 current generation circuit 292 single / differential conversion circuit

293: mode selection circuit 294: differential / single conversion circuit

295: reference current and output differential reference current forming circuit

The present invention relates to a data driving chip and a light emitting display device, and more particularly, to a data driving chip and a light emitting display device which can improve the uniformity of a reference current.

Recently, various flat panel displays have been developed to reduce weight and volume, which are disadvantages of cathode ray tubes. The flat panel display includes a liquid crystal display, a field emission display, a plasma display panel, a light emitting display, and the like.

Among the flat panel displays, a light emitting display device is a self-light emitting device that emits a fluorescent material by recombination of electrons and holes, and includes an inorganic light emitting display device including an inorganic light emitting layer and an organic light emitting layer according to materials and structures. It is roughly divided into. Organic light emitting displays are sometimes referred to as organic electroluminescent displays. Such a light emitting display device has an advantage of having a fast response speed, such as a cathode ray tube, compared to a passive light emitting device requiring a separate light source like a liquid crystal display device.

The driving method of the light emitting display device is a passive matrix method and an active matrix method. Among these, the passive matrix method is a method in which the anode and the cathode are formed to be orthogonal and the lines are selected and driven. The active matrix method is a method of controlling the amount of current flowing through the light emitting device using the active device. As an active device, a thin film transistor (hereinafter referred to as TFT) is mainly used. The active matrix method is somewhat complicated but has the advantage of low current consumption and long light emission time.

Writing methods of a light emitting display device include a voltage programming method and a current programming method. Among these, the voltage write method is a method in which the data driver outputs a voltage corresponding to the data signal. The voltage writing method has an advantage that the data driver used in a liquid crystal display device can be used as it is, but it is difficult to express a uniform screen due to variations in threshold voltages and mobility of TFTs used as active elements. The current write method is a method in which the data driver outputs a current corresponding to the data signal. Since the current writing method has an advantage that a uniform screen can be expressed by easily compensating for variations in the threshold voltage and mobility of the TFT, it requires development of a data driver that outputs a data current.

On the other hand, as the size of the display device increases and the resolution increases, the number of data lines used increases, and accordingly, it is technically easier to implement using a plurality of data driving chips than to implement the data driving unit on a single chip. There was a side.

1 is a view schematically showing a data driver using a plurality of data driver chips according to the prior art.

Referring to FIG. 1, the data driver includes first to fourth data driver chips 10 to 40. Since each data driving chip 10 to 40 has an output of 300 channels, the data driving unit may have an output of up to 1200 channels. Each data driving chip 10 to 40 forms a reference current using the reference voltage Vref and the external resistors Rext1 to Rext4. The formed reference current is used in a D / A converter (not shown) located in the data driving chips 10 to 40, and when the reference current changes, the data current value corresponding to each grayscale is changed, so that the luminance of the pixel connected to the data line is changed. Will change. Therefore, if the reference current values differ between the data driving chips, a difference occurs in the luminance of the pixels connected to each of the data driving chips 10 to 40, resulting in non-uniformity of image quality. In general, the external resistance value may be different due to factors such as deviation and temperature caused by the manufacturing process, which may cause a difference in the reference current between each data driving chip 10 to 40, resulting in non-uniformity of image quality. There is a problem.

Accordingly, an object of the present invention is to provide a data driving chip and a light emitting display device which can improve the uniformity of image quality by reducing the error of the reference current used in each data driving chip.

As a technical means for achieving the above object, the first aspect of the present invention provides a scan driver for sequentially applying a scan signal to a plurality of scan lines, a data driver for applying a data current to the plurality of data lines, and a plurality of scan lines. An image display unit for displaying an image according to an applied scan signal and a data current applied to the plurality of data lines, wherein the data driver is a first data driver chip for outputting a differential reference current determined by a reference voltage and a resistance; And a second data driving chip configured to receive the output differential reference current.

A second aspect of the present invention provides a shift register for outputting a latch control signal in response to a clock signal and a synchronization signal, a data latch for sequentially receiving video data according to the latch control signal and outputting the data data in parallel, and outputting the data latch. D / A converter for outputting the analog-converted data current, and when the control signal corresponding to the first mode is applied, the reference current and the output differential reference current are formed using the reference voltage and the resistance, and correspond to the second mode. And a bias circuit configured to form the reference current and the output differential reference current using an input differential reference current, and transmit the reference current to a D / A converter and output the differential reference current. It provides a data driving chip.

Hereinafter, preferred embodiments of the present invention may be easily implemented by those skilled in the art with reference to FIGS. 2 to 5 as follows.

2 is a diagram illustrating a light emitting display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the light emitting display device includes a scan driver 100, a data driver 200, an image display unit 300, and a timing controller 500.

The scan driver 100 drives the scan lines S1 to Sn. The scan driver 100 generates a scan signal in response to the scan driver control signals SCS and sequentially supplies the generated scan signals to the scan lines S1 to Sn.

The data driver 200 drives the data lines D1 to Dm. The data driver 200 generates data currents in response to the data driver control signals DCS and the video data Data, and supplies the generated data currents to the data lines D1 to Dm. The data driver 200 includes a plurality of data driver chips (not shown), and at least one of the plurality of data driver chips forms a differential reference current using a reference voltage and an external resistor. The remaining data driver chip uses the differential reference current received from another data driver chip.

The image display unit 300 includes a plurality of pixels 400 defined by the scan lines S1 to Sn and the data lines D1 to Dm. In addition, the image display unit 300 receives the first power supply voltage VDD and the second power supply voltage VSS from the outside. Here, the first power supply voltage VDD and the second power supply voltage VSS are transferred to the respective pixels 400. Each of the pixels 400 displays an image corresponding to a data signal supplied thereto.

The timing controller 500 supplies the scan driver control signal SCS to the scan driver 100, and supplies the data driver control signal DCS and video data Data to the data driver.

3 is a diagram schematically illustrating a data driver including a plurality of data driver chips employed in the light emitting display device of FIG. 2.

Referring to FIG. 3, the data driver 200 includes first to fourth data driver chips 210 to 240.

The first data driving chip 210 forms the differential reference currents Iref1 and Iref2 by using the reference voltage Vref and the external resistor Rex and transfers them to the second data driving chip 220. As such, the data driving chip that forms the differential reference currents Iref1 and Iref2 using the reference voltage Vref and the external resistor Rex is called a master data driving chip. The relationship between the differential reference currents Iref1 and Iref2 and the reference voltage Vref and the external resistance Rex may be expressed as in Equation 1.

(Iref2-Iref1) ∝ (Vref / Rext)

That is, the difference between the differential reference currents Iref1 and Iref2 has a relationship proportional to the value obtained by dividing the reference voltage Vref by the external resistance Rex. The differential reference current may have a value such as Equation 2, for example.

Iref1 = (Vref / Rext)

Iref2 = 2 × (Vref / Rext)

The second data driver chip 220 forms the differential reference currents Iref1 and Iref2 using the input differential reference currents Iref1 and Iref2 and transfers them to the third data driver chip 230. In the same manner, the third data driving chip 230 forms the differential reference currents Iref1 and Iref2 using the input differential reference currents Iref1 and Iref2 and transfers them to the fourth data driving chip 240. The data driving chip forming the differential reference current output using the differential reference current input as described above is called a slave data driving chip.

Since each data driving chip 210 to 240 has an output of 300 channels, the data driving unit may have a maximum channel output of 1200. Each data driving chip 210 to 240 supplies a current corresponding to the differential reference currents Vref1 and Vref2 or a reference current corresponding to the difference between the differential reference currents Vref1 and Vref2 to a D / A converter (not shown). . In the D / A converter, the current value corresponding to each gray scale is determined by the supplied reference current.

As such, only the master data driving chip 210 forms the reference current and the differential reference currents Vref1 and Vref2 by using the reference voltage Vref and the external resistor Rex, and the slave data driving chips 220 to 240 may be used. By forming the reference current and the differential reference current (Vref1, Vref2) by using the differential reference current (Vref1, Vref2) transmitted from the master data driver chip 210 or another slave data driver chip (220 to 240), each data Since the identity of the reference currents used in the driving chips 210 to 240 can be maintained, as a result, the uniformity of the image quality can be increased. In addition, by using the differential reference currents Vref1 and Vref2 as currents transferred between the data driving chips 210 to 240, an in-phase component rejection ratio (hereinafter referred to as CMRR) can be increased.

4 is a diagram illustrating an example of a data driver chip employed in the data driver of FIG. 3.

Referring to FIG. 4, the data driving chip includes a shift register 260, a data latch 270, a D / A converter 280, and a bias circuit 290.

The shift register 260 controls the data latch 270 in response to the horizontal clock signal HCLK and the horizontal synchronization signal HSYNC. The horizontal clock signal HCLK and the horizontal synchronization signal HSYNC are one of the data driver control signals DCS of FIG. 2.

The data latch 270 sequentially receives the video data Data and outputs them in parallel to the D / A converter 280. The data latch 270 is controlled by a control signal output from the shift register 260.

The D / A converter 280 converts a signal output in parallel from the data latch 270 into an analog current and outputs the analog current. The current corresponding to each grayscale is determined by the reference current Iref transmitted from the bias circuit 290.

The bias circuit 290 is a bias circuit 290 that can be used for both the master data driver chip and the slave data driver chip. When the bias circuit 290 is operated in the master mode, that is, when the mode control signal Ctrl corresponding to the first mode, that is, the master mode is applied, the bias circuit 290 is connected to the reference voltage Vref and the external resistance ( The reference current Iref is formed using Rext and transferred to the D / A converter 280. The output differential reference currents Iref1 (out) and Iref2 are also obtained using the reference voltage Vref and the external resistor Rext. (out)) is formed and output to the outside of the data driving chip. When the bias circuit 290 is operated in the slave mode, that is, when the mode control signal Ctrl corresponding to the second mode, that is, the slave mode, is applied, the bias circuit 290 receives the input differential reference current Iref1 (in). , Iref2 (in) is used to form a reference current (Iref) and transfer it to the D / A converter 280, and also output differential reference using the input differential reference currents (Iref1 (in), Iref2 (in)). Currents Iref1 (out) and Iref2 (out) are formed and output to the outside of the data driving chip.

FIG. 5 is a diagram illustrating an example of a bias circuit employed in FIG. 4.

Referring to FIG. 5, the bias circuit 290 includes a current generation circuit 291, a single / differential conversion circuit 292, a mode selection circuit 293, a differential / single conversion circuit 294, and a reference current and an output differential reference. A current forming circuit 295.

The current generation circuit 291 is a circuit that generates the first current I1 using the reference voltage Vref and the external resistor Rex. The first current has a value such as Equation 3, for example.

I1 = (Vref / Rext)

The single / differential conversion circuit 292 is a circuit for converting the first current into differential currents I2 and I3. The differential current output from the single / differential conversion circuit 292 has a value as shown in Equation 4, for example.

I2 = I1

I3 = 2 × I1

The mode selection circuit 293 is one of the differential currents I2 and I3 and the input differential reference currents Iref1 (in) and Iref2 (in) output from the single / differential conversion circuit 292 according to the mode control signal Ctrl. Output either differential current. When the mode control signal Ctrl corresponding to the master mode is input, the mode selection circuit 293 outputs the differential currents I2 and I3 output from the single / differential conversion circuit 292 and corresponds to the slave mode. When the mode control signal Ctrl is input, all the selection circuits 293 output the input differential reference currents Iref1 (in) and Iref2 (in). The differential currents I4 and I5 output from the mode selection circuit 293 have a value as shown in Equation 5 as an example.

I4 = I2, I5 = I3 (when in master mode)

I4 = Iref1 (in), I5 = Iref2 (in) (in slave mode)

The differential / single conversion circuit 294 is a circuit for converting the differential currents I4 and I5 output from the mode selection circuit 293 into a single current I6. The single current I6 output from the differential / single conversion circuit 294 has, for example, a value as shown in Equation (6).

I6 = I5-I4

The reference current and output differential reference current forming circuit 295 forms a reference current Iref and an output differential reference current Iref1 (out) and Iref2 (out) from a single current I6 output from the differential / single conversion circuit. It is a circuit. The reference current Iref and the output differential reference currents Iref1 (out) and Iref2 (out) have values such as Equation 7 as an example.

Iref = I6

Iref1 (out) = I6

Iref2 (out) = 2 × I6

By operating in this manner, the bias circuit 290 generates the first current I1 in the current generation circuit 291 in the master mode, and the single / differential conversion circuit 292 and the differential / single conversion circuit ( 294 converts the first current into differential currents I2 and I3 and then back to a single current I6, using the single current I6 in the reference current and output differential reference current forming circuit 295 The reference current Iref and the output differential reference currents Iref1 (out) and Iref2 (out) are formed. In the slave mode, the bias circuit 290 receives the input differential reference currents Iref1 (in) and Iref2 (in) from the mode selection circuit 293, and in the differential / single conversion circuit 294. Convert to current I6 and use the single current I6 in the reference current and output differential reference current forming circuit 295 to make reference current Iref and output differential reference currents Iref1 (out) and Iref2 (out) To form).

The above detailed description and drawings are merely exemplary of the present invention, which are used only for the purpose of illustrating the present invention and are not intended to limit the scope of the present invention as defined in the claims or the claims. Accordingly, 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 protection 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.

As described above, the data driving chip and the light emitting display device according to the embodiment of the present invention have an advantage of improving the uniformity of image quality by reducing the error of the reference current used in each data driving chip.

In addition, the data driving chip and the light emitting display device according to the embodiment of the present invention have an advantage of increasing the CMRR by using a differential reference current as a current transferred between the data driving chip.

Claims (15)

A scan driver for sequentially applying scan signals to the plurality of scan lines; A data driver for applying a data current to the plurality of data lines; And An image display unit for displaying an image in accordance with scan signals applied to the plurality of scan lines and data currents applied to the plurality of data lines, The data driver may include a first data driver chip configured to output a differential reference current determined by a reference voltage and a resistance; And a second data driving chip configured to receive the output differential reference current. The method of claim 1, The second data driving chip outputs a differential reference current corresponding to the input differential reference current, The data driver further includes a third data driver chip configured to receive a differential reference current output from the second data driver chip. The method of claim 1 or 2, The difference in the value of the differential reference current output from the first data driving chip is proportional to the value of the reference voltage divided by the value of the resistance. The method of claim 1 or 2, The value of one current among the differential reference currents output from the first data driving chip corresponds to the value of the reference voltage divided by the value of the resistor, and the value of the remaining current is the value of the reference voltage divided by the value of the resistor. A light emitting display device having a multiple of the value. The method of claim 1 or 2, And a value of the data current corresponding to each gray level in the first data driving chip is determined by the reference voltage and the resistance. The method of claim 1 or 2, And a value of a data current corresponding to each gray level in the second data driver chip is determined by a differential reference current input to the second data driver chip. The method of claim 1 or 2, The resistor is located outside the first data driving chip. The method according to claim 1 or 2, And a timing controller configured to transmit a scan driver control signal to the scan driver, to transmit a data driver control signal to the data driver, and to transmit video data to the data driver. The method of claim 2, And a differential reference current output from the second data driving chip is the same as the differential reference current output from the first data driving chip. The method of claim 2, And a value of a data current corresponding to each gray level in the third data driver chip is determined by a differential reference current input to the third data driver chip. A shift register configured to output a latch control signal in response to a clock signal and a synchronization signal; A data latch sequentially receiving video data according to the latch control signal and outputting the video data in parallel; A D / A converter for outputting a data current obtained by analog converting the output of the data latch; And When the control signal corresponding to the first mode is applied, the reference current and the output differential reference current are formed by using the reference voltage and resistance, and when the control signal corresponding to the second mode is applied, the input differential reference current is used. And a bias circuit to form the reference current and the output differential reference current, and transmit the reference current to a D / A converter and output the differential reference current. The method of claim 11, And a value of the data current corresponding to each gray level in the D / A converter is determined by the reference current. The method of claim 11, When the control signal corresponding to the first mode is applied to the bias circuit, the value of the reference current corresponds to a value obtained by dividing the value of the reference voltage by the value of the resistance, and the value of one of the output differential reference currents. Is a value obtained by dividing the value of the reference voltage by the value of the resistor, and a value of the remaining current corresponds to a multiple of the value of the reference voltage divided by the value of the resistance. The method of claim 11, When the control signal corresponding to the second mode is applied to the bias circuit, the value of the reference current corresponds to the difference of the value of the input differential reference current, and the value of the output differential reference current is the value of the input differential reference current. Data drive chip corresponding to the value. The method of claim 11, The resistor is a data driving chip located outside the first data driving chip.

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