KR20060014795A - Power supply and display device using the supply - Google Patents

Abstract

The present invention relates to a power supply device and a display device using the same.

A display device according to the present invention includes a display panel including a plurality of pixel circuits; A data driver; A scan driver; A panel controller configured to control the data driver and the scan driver according to a plurality of signals including an applied dot clock signal; And a power supply device configured to supply a voltage having a predetermined level to at least one of the display panel, the data driver, the scan driver, and the panel controller. The power supply device may include an oscillator for outputting a first clock signal, an external clock input unit for outputting a second clock signal based on a dot clock signal applied from the outside, and the first clock signal or the first clock signal according to an applied clock control signal. And a latch for selecting and outputting two clock signals, and a charge pump circuit for outputting a predetermined level of voltage based on the voltage output from the latch.

According to the present invention, the clock signal input to the driving unit for driving the display panel in the display device is the same as the clock signal for driving the power supply device, it is possible to prevent the generation of noise due to the asynchronous of the signals.

LED display, power supply, dot clock

Description

Power supply and display device using same {POWER SUPPLY AND DISPLAY DEVICE USING THE SUPPLY}

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

2 is a structural diagram of a voltage supply device according to an embodiment of the present invention.

3 is a circuit diagram of an oscillator according to an embodiment of the present invention.

4 is a structural diagram of a panel controller according to an exemplary embodiment of the present invention.

The present invention relates to a display device, and more particularly, to a power supply for a display device and a display device using the same.

The use of flat panel display devices instead of cathode ray tubes (CRTs) is increasing day by day, and active matrix type liquid crystal displays (LCDs) using thin film transistors (TFTs) are doubled. Liquid crystal displays are widely used, and recently, organic electroluminescent (EL) display devices have been developed and used as next generation displays. In particular, organic EL displays have high quality panel characteristics (low power, high brightness, high response speed, low weight), and thus are mainly used in electronic applications such as mobile communication terminals, CNS, PDAs, camcorders, and Palm PCs.

Such display devices generally provide a display panel, a plurality of drive integrated circuits (eg, data driver, scan driver, etc.) for driving the display panel, and image signals and control signals to be displayed by each drive integrated circuit. And a power supply for supplying a plurality of voltages to each driving integrated circuit.

When the controller stores image data applied from the outside and outputs the image data to the driving integrated circuit, the controller performs image data output in accordance with a clock signal whose phase is synchronized with a horizontal or vertical synchronization signal input from the outside. For example, the horizontal synchronizing signal HSYNC provided from an external image signal source is input, and the image data is output to the driving integrated circuit in synchronization with a clock signal generated in synchronization.

However, the power supply unit includes an oscillator for generating a clock signal and a charge pump circuit, and the charge pump circuit operates according to the clock signal provided from the oscillator to generate a voltage required for the driving integrated circuits to operate. At this time, since the clock signal (first clock signal) applied to an external image signal source is not synchronized with the clock signal (second clock signal) generated and output from the oscillator, the driving integrated circuit causes the first clock signal. By operating in accordance with the above and supplying a voltage synchronized with the second clock signal to the display panel, asynchronous noise may occur, and as a result, the resolution of the display device is reduced.

Therefore, an object of the present invention is to prevent asynchronous noise between each driving integrated circuit and a power supply in a display device.

Another object of the present invention is to provide a display device having excellent resolution.

In order to achieve the above object, a power supply according to an aspect of the present invention comprises an oscillator for outputting a first clock signal; An external clock input unit configured to output a second clock signal based on a dot clock signal applied from the outside; A latch configured to select and output the first clock signal or the second clock signal according to an applied clock control signal; And a charge pump circuit outputting a predetermined level of voltage based on the voltage output from the latch.

In addition, a comparison unit for comparing the output voltage and the reference voltage output from the charge pump circuit, and outputs a comparison voltage according to the comparison result; And a controller configured to output the clock control signal according to the comparison voltage. For example, when it is determined that the output voltage is lower than or higher than the reference voltage by a predetermined level or higher according to the comparison voltage, the controller may output a clock control signal to select the first clock signal with the latch.

According to another aspect of the present invention, a display device includes a display panel including a plurality of pixel circuits; A data driver for applying a data signal to the display panel; A scan driver for applying a selection signal to the display panel; A panel controller configured to control the data driver and the scan driver according to a plurality of signals including an applied dot clock signal; And a power supply device supplying a voltage having a predetermined level to at least one of the display panel, the data driver, the scan driver, and the panel controller, wherein the power supply device includes: an oscillator for outputting a first clock signal, and an external device. An external clock input unit for outputting a second clock signal based on a dot clock signal applied from the second latch; a latch for selecting and outputting the first clock signal or the second clock signal according to the applied clock control signal; And a charge pump circuit for outputting a predetermined level of voltage based on the voltage.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification. When a part is connected to another part, this includes not only a directly connected part but also an electrically connected part with another element in between.

A display device according to an exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings. In the embodiment of the present invention, an organic EL display device using electroluminescence of an organic material is described as an example, and the present invention is not limited thereto.

1 schematically illustrates a display device according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a display device according to an embodiment of the present invention is

The display panel 100 is provided with a plurality of pixel circuits, a plurality of data lines for transmitting data signals to the pixel circuits, and a plurality of scanning lines for transmitting selection signals to the pixel circuits (not shown).

The data driver 200 applies a data signal to the display panel 100, and the scan driver 300 applies a selection signal.

The panel controller 400 controls the data driver 200 and the scan driver 300, and the data driver 200 displays the image data R, G, and B data in synchronization with the vertical synchronization signal V_sync. 100, and the scan driver 300 applies a selection signal to the display panel 100 in synchronization with the horizontal synchronization signal H_sync.

The power supply device 500 outputs a desired voltage by using a DC-DC converter, and supplies an appropriate power voltage to the display panel 100, the respective driving units 200 and 300, and the panel controller 400.

The data driver 200, the scan driver 300, and / or the panel controller 400 may be electrically connected to the display panel 100 or may be bonded to the display panel 100 and electrically connected to the tape carrier package. tape carrier package, TCP) or the like in the form of a chip. Alternatively, a flexible printed circuit (FPC) or a film may be mounted on the display panel 100 in the form of a chip or the like, and may be mounted on a chip on flexible board, chip on film). Alternatively, the data driver 200, the scan driver 300, and / or the panel controller 400 may be directly mounted on the glass substrate of the display panel 100, or the scan line, the data line, and the thin film transistor may be disposed on the glass substrate. It may be replaced or directly mounted with a driving circuit formed of the same layers.

2 illustrates a power supply apparatus according to an embodiment of the present invention.

As shown in FIG. 2, a power supply device according to an embodiment of the present invention includes an oscillator 510, an inverter IN1, a latch 520, a charge pump circuit 530, a comparator 540, and an external clock. The input unit 550 is included.

The oscillator 510 generates the clock signal clk1 in response to the output signal of the comparator 540, and the inverter IN1 inverts the clock signal clk1 of the oscillator 510 to output the clock signal clk2. .

The latch 520 matches the synchronization of the input clock signal and compensates for the distortion of the clock signal. In particular, the latch 520 according to the exemplary embodiment of the present invention may include the first clock signals clk1 and clk2 and the external clock provided from the oscillator 510 according to the clock control signal Ccon applied from the panel controller 400. One clock signal is selected from the second clock signals clk3 and clk4 provided from the input unit 550 and supplied to the charge pump circuit 530.

The charge pump circuit 530 outputs a voltage Vout having a desired level by using the first clock signals clk1 and clk2 or the second clock signals clk3 and clk4 provided from the latch 520.

The comparator 540 controls the operation of the oscillator 510 by comparing the output voltage Vout and the reference voltage Vref of the charge pump circuit 530. Specifically, the output voltage Vout of the charge pump circuit 530 is compared with the reference voltage Vref, and the absolute value of the output voltage Vout is smaller than the absolute value of the reference voltage Vref (that is, the output The oscillator 510 causes the clock signal clk1 to be generated when the voltage Vout is lower than the reference voltage Vref. The oscillator 510 when the output voltage Vout is higher than or equal to the reference voltage Vref. ) Outputs a fixed voltage rather than the clock signal clk1.

Meanwhile, the external clock input unit 550 receives the dot clock signal DotClk provided from the panel controller 400 and outputs the clock signal CLK3, and the inverter IN2 inverts the clock signal clk3. The clock signal clk4 is output.

According to an embodiment of the present invention, as shown in FIG. 3, the resistors R1 and R2 for distributing the output voltage Vout of the charge pump circuit 530 may be further included.

3 exemplarily shows an internal circuit of the oscillator 510 shown in FIG. 2.

As shown in FIG. 3, the oscillator 510 of the power supply device 500 may be formed using a ring oscillator, and the output signal of the comparator 540 is input as an enable signal. To output a clock signal clk1 or a fixed voltage signal.

Specifically, the oscillator 510 includes a NAND gate 511, a plurality of inverters 512, and a plurality of capacitors 513. The NAND gate 511 inputs an output signal of the oscillator 510 and an enable signal (Enable) to perform a NAND operation, and an output signal of the NAND gate 511 is input to the inverter 511 and inverted.

The capacitor 513 is charged when the inverting signal of the inverter 511 is a high level voltage, and is connected between the output terminal of several inverters 512 and the ground to increase the delay of the oscillator 510 and lower the frequency. do.

Next, the structure of the panel controller 400 for controlling the clock signal input to the voltage supply device will be described.

4 illustrates a structure of a panel controller according to an exemplary embodiment of the present invention.

The panel controller 400 may include an external display interface 410 that receives a plurality of synchronization signals V_sync and H_sync, image data R, G, and B data, and dot clock signal Dotclk provided from an external image signal source. The timing controller 420 drives the data driver 200 and the scan driver 300 based on a plurality of signals and data applied from the interface 410.

In particular, the timing controller 420 powers the clock control signal Ccon such that the power supply 500 operates according to a dot clock signal Dotclk provided from the outside or in response to a clock signal output from its own oscillator. It is provided to the supply device 500.

Hereinafter, the operation of the power supply device 500 will be described in more detail.

A plurality of synchronization signals V_sync and H_sync, image data R, G and B data, and dot clock signals Dotclk provided from an external signal source from an external display interface 410 of the panel controller 400 of the display device. When receiving the, the panel controller 420 generates a plurality of control signals for operating the drivers 200 and 300 based on the synchronization signals V_sync and H_sync and the dot clock signal Dotclk, and then generates a plurality of control signals according to the generated control signals. The scan driver 300 is operated while providing the image data R, G, and B data to the data driver 200.

In addition, the dot clock signal Dotclk is a power supply device 500 that generates a plurality of voltages (for example, a gray scale voltage input to the data driver, a scan driver driving voltage, etc.) by the data driver 200 and the scan driver 300. Outputs a clock control signal Ccon for generating the voltages according to In this case, the panel controller 400 may change the state of the clock control signal CCon to generate the voltages according to the clock signal output from the oscillator.

The clock control signal Con is input to the latch 520 of the power supply device 500 and the dot clock signal Dotclk is input to the external clock input part 550 of the power supply device 500. The external clock input unit 550 generates a clock signal Clk3 according to the dot clock signal Dotclk, and the clock signal Clk3 is inverted by the inverter IN2 and output as the clock signal Clk4.

On the other hand, the latch 520 of the power supply device 500 selects a clock signal according to the clock control signal Ccon. For example, when the clock control signal Ccon is at a high level, the latch 520 is output from the oscillator 510. Select and input the first clock signals clk1 and clk2. When the clock control signal Ccon is at a low level, the second clock signals clk3 and clk4 output from the external clock input unit 550 are selected and input. do.

When a high level clock control signal Ccon is provided to allow the power supply device to operate according to a dot clock signal Dotclk input from the outside, the latch 520 is a second clock signal output from the external clock input unit 550. After selecting (clk3, clk4), for example, the clock signals (clk3, clk4) are individually inverted a number of times using an inverter or the like and inputted to the buffer. Will match and print.

The clock signals clk3 and clk4 output as described above are input to the charge pump circuit 530, and the charge pump circuit 530 is predetermined based on the clock signals clk3 and clk4 generated according to the dot clock signal Dotclk. Output the voltage Vout of the level.

The voltage Vout is input to each of the driving units 200 and 300 and used as a basic voltage of a gray voltage or a voltage applied to a scan line of the display panel 100. As such, the data driver 200 and the scan driver 300 process image data and control signals provided from the panel controller 400 according to the voltage Vout generated based on the dot clock signal Dotclk. ). Therefore, since the voltage Vout output from the voltage supply device 500 and the operation timing of the data driver 200 and the scan driver 300 are synchronized, the deterioration of image quality may be prevented by asynchronous.

On the other hand, the comparator 540 compares the output voltage Vout of the charge pump circuit 530 with the reference voltage Vref, and the high level voltage Vout when the output voltage Vout is lower than the reference voltage Vref. ') May be output and a low level voltage Vout' may be output when the output voltage Vout of the charge pump circuit 530 is higher than or equal to the reference voltage Vref. In this case, according to the voltage Vout 'output from the comparator 540, the timing controller 420 may determine whether the power supply device 500 operates according to which clock signal, for example. If the output voltage Vout is determined to be lower than or higher than the reference level Vref by a predetermined level or more, the clock control to operate the power supply 500 according to the clock signal Clk1.clk2 output from the oscillator 510. The signal CCon may be output. At this time, the output voltage Vout 'of the comparator 540 is input to the oscillator 510 and used as a control value for causing the oscillator 510 to output clock signals clk2 and clk3 of appropriate levels.

As in the above embodiment, the power supply device to operate according to the dot clock signal provided from an external signal source is not limited to the power supply device having the above-described structure.

In the above, the light emitting display device according to the exemplary embodiment of the present invention has been described. The embodiment described above is an embodiment to which the concept of the present invention is applied, and the scope of the present invention is not limited to the above embodiment, and various modifications may be made using the concept of the present invention.

According to the present invention, the asynchronous noise between each driving integrated circuit and the power supply device can be prevented in the display device. Therefore, image quality deterioration due to asynchronous signal cancellation can be eliminated, and a display device excellent in resolution can be provided.

Claims (5)

An oscillator for outputting a first clock signal; An external clock input unit configured to output a second clock signal based on a dot clock signal applied from the outside; A latch configured to select and output the first clock signal or the second clock signal according to an applied clock control signal; And Charge pump circuit for outputting a predetermined level of voltage based on the voltage output from the latch Power supply comprising a. The method of claim 1 A comparison unit comparing the output voltage output from the charge pump circuit with a reference voltage and outputting a comparison voltage according to a comparison result; And A controller for outputting the clock control signal according to the comparison voltage A power supply further comprising. The method of claim 2 And the controller outputs a clock control signal to select the first clock signal with the latch when it is determined that the output voltage is lower or higher than the reference voltage by a predetermined level according to the comparison voltage. A display panel including a plurality of pixel circuits; A data driver for applying a data signal to the display panel; A scan driver for applying a selection signal to the display panel; A panel controller configured to control the data driver and the scan driver according to a plurality of signals including an applied dot clock signal; And A power supply device for supplying a voltage of a predetermined level to at least one of the display panel, the data driver, the scan driver, and the panel controller. Including; The power supply may include an oscillator for outputting a first clock signal, an external clock input unit for outputting a second clock signal based on a dot clock signal applied from the outside, and the first clock signal or the second clock signal according to an applied clock control signal. A latch for selecting and outputting a clock signal, and a charge pump circuit for outputting a predetermined level of voltage based on a voltage output from the latch; Display device. The method of claim 6, The display device is an organic electroluminescent display.

Images