KR100627407B1 - Plasma display device and driving method thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display device and a driving method thereof. In particular, when excessive current flows in the plasma display device, the plasma display device and the driving method thereof automatically reduce the amount of current flowing by reducing the number of sustain discharge pulses per frame. It is about.

According to the present invention, when excessive current flows in the plasma display device, the plasma display device can be prevented from suddenly stopping the display by reducing the amount of current flowing by automatically reducing the number of sustain discharge pulses per frame.

Plasma display, sustain pulse, SMPS, gradation value, power

Description

Plasma display device and driving method thereof {PLASMA DISPLAY DEVICE AND DRIVING METHOD THEREOF}

1 is a timing diagram for driving a plasma display device according to an exemplary embodiment of the present invention.

2 is a schematic diagram of a plasma display device according to an embodiment of the present invention.

3 is a schematic block diagram of an SMPS and a controller of a plasma display device according to an exemplary embodiment of the present invention.

4 is a table showing an example of the number of sustain discharge pulses for each subfield according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display device and a driving method thereof. In particular, when excessive current flows in the plasma display device, the plasma display device and the driving method thereof automatically reduce the amount of current flowing by reducing the number of sustain discharge pulses per frame. It is about.

Recently, flat display devices such as a liquid crystal display (LCD), a field emission display (FED), and a plasma display have been actively developed. Among these flat panel display devices, the plasma display device has advantages of higher luminance and luminous efficiency and a wider viewing angle than other flat panel display devices. Accordingly, the plasma display device is in the spotlight as a display device to replace a conventional cathode ray tube (CRT) in a large display device of 40 inches or more.

Plasma display devices are flat display devices that display characters or images using plasma generated by gas discharge, and dozens to millions or more of pixels are arranged in a matrix form according to their size.

The gas discharge in the plasma display device has a strong nonlinearity in which the discharge does not occur to the applied voltage below the discharge start voltage even when a voltage is applied. The discharge start voltage of the gas discharge is generally a high voltage of 100 V or more, and the plasma display device has a switching mode power supply (SMPS) for applying the voltage.

The plasma display device must continuously generate the gas discharge to display an image or a character, and a lot of power is consumed to display the image or the character. In addition, when a video signal in which noise is mixed suddenly is input to the plasma display device or an abnormal signal that the entire screen becomes bright is input, a situation occurs in which the SMPS supplies an excessive current exceeding a rated current, thereby overheating the SMPS. Or breakage.

In order to prevent this, the SMPS is equipped with a protection circuit for stopping the supply of electric power when a current higher than the rated current flows. However, this causes a problem that the plasma display device suddenly stops displaying the screen during the screen display.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a plasma display device and a method of driving the same, which automatically reduce the number of sustain discharge pulses per frame when excessive current flows in the plasma display device.

A driving method of a plasma display device according to a feature of the present invention for achieving the above object is

A driving method of a plasma display device, comprising: a first electrode and a second electrode, a driving circuit for driving the electrodes, and a power supply device for supplying power to the driving circuit.

(a) calculating an APC level according to an input video signal and obtaining a number of sustain pulses per frame according to the calculated APC level;

(b) detecting the amount of current supplied by the power supply and reducing the number of sustain discharge pulses per frame if the current is above a predetermined current;

(c) driving a sustain pulse to the electrode according to the number of sustain pulses per frame.

Plasma display device according to another aspect of the present invention

A plasma panel in which discharge cells are formed in an area where a plurality of address electrodes, a plurality of scan electrodes, and a sustain electrode cross each other;

A power supply device configured to supply power to the plurality of electrodes of the plasma panel and each portion of the plasma display device, and detect whether the supplied current is greater than or equal to a predetermined current; And

The APC level is calculated according to the input image signal, the number of sustain pulses per frame is calculated according to the calculated APC level, and if it is detected that the current supplied by the power supply is greater than or equal to a predetermined current, the sustain discharge pulses per frame. It includes a control unit for controlling the driving to reduce the number.

DETAILED DESCRIPTION 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.

Now, a plasma display device and a driving method thereof according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3.

1 is a timing diagram related to driving of a plasma display device.

Referring to the drawing, the unit frame is divided into eight subfields SF1-SF8 to realize time division gray scale display. Each subfield SF1-SF8 is divided into a reset period R1-R8, an address period A1-A8, and a sustain period S1-S8.

In the reset period, the state of each discharge cell is initialized to smoothly perform the addressing operation on the discharge cells. In the address period, the discharge cells that are turned on to select the discharge cells that are turned on and the discharge cells that are not turned on (addressed discharge cells) ), The wall charges are accumulated by applying an address voltage. In the sustain period, the sustain discharge pulse is applied to all the scan electrodes and the sustain electrodes to discharge the addressed discharge cells to display an image.

The luminance of the plasma display device is proportional to the length of the sustain periods S1-S8 in the unit frame. The length of the sustain periods S1-S8 in the unit frame is 255T (T is the unit time). In this case, the length of the sustain period Sn of the nth subfield SFn may be 2 ^n-1 T. The n-th subfield has a weight value proportional to the length of the sustain period of the corresponding subfield. Accordingly, if the subfields for discharging the discharge cells are appropriately selected from the eight subfields, display of 256 gray levels is possible including all zero (zero) gray levels in which no discharge cells are discharged in any of the subfields.

FIG. 2 is a schematic diagram of a plasma display device driven at the timing shown in FIG. 1. The plasma display device includes a plasma panel 100, an address driver 200, a scan / hold driver 300, a controller 400, and an SMPS 500.

The plasma panel 100 includes a plurality of electrodes. The electrodes are arranged in a matrix of m × n. Specifically, address electrodes (hereinafter referred to as 'A electrodes') A1-Am are arranged in a column direction, and n rows of scan electrodes are arranged in a row direction. Hereinafter, the Y electrodes (Y1-Yn) and the sustain electrodes (hereinafter referred to as 'X electrodes') (X1-Xn) are arranged in a zigzag. Here, the discharge space at the intersection of the A electrodes A1-Am and the X and Y electrodes X1-Xn and Y1-Yn forms a discharge cell.

The SMPS 500 supplies power required to drive the plasma display device. Specifically, power is supplied to the address driver 200 and the scan / maintenance driver 300 for driving the plurality of electrodes of the plasma panel using an external AC power source, and to the other parts. In addition, the SMPS 500 according to the embodiment of the present invention stops the supply of power when a current equal to or greater than the rated current flows, and continuously checks the amount of the current and approaches the rated current (at least 95% of the rated current). The detection information is transmitted to the controller 400.

The controller 400 receives an R, G, B image signal and a synchronization signal from the outside, divides one frame into several subfields, and divides each subfield into a reset period, an addressing period, and a sustain period to drive the plasma display device. To control. At this time, the controller 400 adjusts the number of sustain discharge pulses in each sustain period of the subfield in one frame and supplies the necessary control signals to the address driver 200 and the scan / sustain driver 300.

In addition, the control unit 400 according to an embodiment of the present invention, when receiving the detection information that the amount of current is close to the rated current (for example, 95% or more of the rated current) from the SMPS 500, the holding per frame Control to reduce the number of discharge pulses.

The address driver 200 receives an address driving control signal from the controller 400 and applies a display data signal for selecting a discharge cell to be displayed to each address electrode A1-Am.

The scan and sustain driver 300 receives a control signal from the controller 400 and alternately inputs a sustain discharge pulse voltage Vs to the scan electrodes Y1-Yn and the sustain electrodes X1-Xn to the discharge cells selected. Perform sustain discharge.

3 is a schematic block diagram of an SMPS and a controller of a plasma display device according to an exemplary embodiment of the present invention.

As shown in FIG. 3, the SMPS 500 of the plasma display device according to the exemplary embodiment of the present invention includes a power supply circuit 510, a protection circuit 520, and a detection circuit 530. In addition, the control unit 400 of the plasma display device according to the embodiment of the present invention includes an inverse gamma correction unit 410, an error diffusion unit 420, a memory control unit 430, an APC unit 440, and a scan / maintenance drive control unit. (450).

The power supply circuit 510 supplies electric power to the address driver 200, the scan / sustain driver 300, and other parts by using an external AC power source.

The protection circuit 520 performs a protection operation such as stopping supply of power when a current equal to or higher than a rated current flows in the power supply circuit 510.

The detection circuit 530 checks the amount of current flowing in the power supply circuit 510 and transmits the detection information to the APC unit 440 of the control unit when it approaches a predetermined rated current (95% or more of the rated current). .

The inverse gamma correction unit 410 maps the image data having the gray level value of n bits currently input to the inverse gamma curve and corrects the image data having the gray level value of m bits (m≥n). In this case, the image data input to the inverse gamma correction unit 410 is a digital image signal. When an analog image signal is input to the plasma display device, the analog image signal is converted into a digital image signal by an analog-to-digital converter (not shown). Needs to be.

The error diffusion unit 420 performs reverse gamma correction by the inverse gamma correction unit 410 to store data of lower m-n bits (m≥n) of the image data having an expanded m-bit gray value. Error diffusion into pixels) to convert the image data into n-bit grayscale values. The error diffusion is a method of displaying the data for the lower bits as an image by separating the data for the lower bits from the image data to be error-spread and spreading them to adjacent discharge cells (pixels). 10-2002-0014766.

The memory controller 430 rearranges the image data error-proliferated by the error diffusion unit 420 into address data for driving the address driver 200.

The APC unit 440 first extracts a load ratio proportional to the average gradation value of the entire screen from the image data output from the inverse gamma correction unit 410. This can be obtained by averaging the respective gray scale values of all the discharge cells. The APC level is calculated according to the load factor, and the number of sustain discharge pulses per frame is calculated according to the APC level. In other words, when the load ratio is high, the power consumption is reduced by reducing the number of sustain discharge pulses per frame, and when the load rate is low, the number of sustain discharge pulses per frame is increased to improve luminance at low gradations.

When the APC unit 440 according to an embodiment of the present invention receives the detection information from the detection circuit 530 of the SMPS 500 that the amount of current is close to the rated current (95% or more of the rated current), the image is input. By increasing the calculated APC level in accordance with the signal, the power consumption is reduced by controlling to reduce the number of sustain discharge pulses per frame. The APC unit 440 may reduce the number of sustain discharge pulses per frame by increasing the calculated APC level by 1 to 10 in order to reduce the number of sustain discharge pulses. The number of sustain discharge pulses for each subfield is calculated according to the number of sustain discharge pulses per frame.

The scan and sustain drive control unit 450 generates a control signal corresponding to the number of sustain discharge pulses for each subfield calculated from the APC unit 440 and outputs the control signal to the scan and sustain drive unit 300.

The driving method of such a plasma display device is as follows.

First, it is checked whether the amount of current supplied by the SMPS 500 is 95% or more of the rated current.

Next, when it is checked that the amount of current supplied by the SMPS 500 is 95% or more of the rated current, the number of sustain discharge pulses per frame is reduced. The number of sustain discharge pulses for each subfield is calculated according to the number of sustain discharge pulses per frame.

An example of calculation of the number of sustain discharge pulses for each subfield is shown in FIG. 4. As shown in Fig. 4, the APC level is calculated according to the load ratio, and the number of sustain discharge pulses per frame is determined according to the APC level. That is, a high APC level decreases the number of sustain discharge pulses per frame, and a low APC level increases the number of sustain discharge pulses per frame. The number of sustain discharge pulses for each subfield is calculated according to the number of sustain discharge pulses per frame.

As a method of reducing the number of sustain discharge pulses per frame, there is a method of reducing the number of sustain discharge pulses per frame calculated by 50 to 100.

In addition, as another method of reducing the number of sustain discharge pulses per frame, the number of sustain discharge pulses per frame may be reduced by increasing the calculated APC level by 1 to 10.

In the present embodiment, the plasma display device expresses 256 gray scales, and the number of subfields for expressing the 256 gray scales is expressed as eight, but the number of gray scales and the number of subfields are not limited thereto.

In the present embodiment, the number of sustain discharge pulses per frame is reduced by about 50 to 100 when the amount of current supplied from the SMPS is 95% or more, but the present invention is not limited thereto.

In addition, the present embodiment shows that the calculated APC level is reduced by about 1 to 10 when the amount of current supplied from the SMPS is 95% or more, but is not limited thereto.

In the present embodiment, the amount of current detected by the detection circuit is represented by 95% or more of the rated current, but the amount of current detected by the detection circuit is not limited thereto.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, according to the present invention, when excessive current flows in the plasma display device, the plasma display device is prevented from suddenly stopping the display by reducing the amount of current flowing by automatically reducing the number of sustain discharge pulses per frame. Can be.

Claims (7)

A driving method of a plasma display device, comprising: a first electrode and a second electrode, a driving circuit for driving the electrodes, and a power supply device for supplying power to the driving circuit. (a) calculating an APC level according to an input video signal and obtaining a number of sustain pulses per frame according to the calculated APC level; (b) detecting the amount of current supplied by the power supply and increasing the calculated APC level if the current is greater than or equal to a predetermined current to reduce the number of sustain discharge pulses per frame; and (c) driving a sustain pulse to the electrode according to the number of sustain pulses per frame. The method of claim 1, And reducing a predetermined number of sustain discharge pulses from the calculated number of sustain discharge pulses per frame. delete A plasma panel in which discharge cells are formed in an area where a plurality of address electrodes, a plurality of scan electrodes, and a sustain electrode cross each other; A power supply device configured to supply current to the plurality of electrodes of the plasma panel and each portion of the plasma display device, and detect whether the supplied current is equal to or greater than a predetermined current; And The APC level is calculated according to the input image signal, the number of sustain pulses per frame is calculated according to the calculated APC level, and when it is detected that the current supplied by the power supply is greater than or equal to a predetermined current, the calculated APC level is calculated. And a control unit which controls the driving to increase by reducing the number of sustain discharge pulses per frame. The method of claim 4, wherein The power supply device, A power supply circuit for supplying power to the plurality of electrodes of the plasma panel and each portion of the plasma display device using an external AC power source; And And a detection circuit for detecting whether a current supplied by the power supply circuit is equal to or greater than a predetermined current. The method according to claim 4 or 5, The control unit, The APC level is calculated according to the input image signal, the number of sustain pulses per frame is calculated according to the calculated APC level, and if it is detected that the current supplied by the power supply is greater than or equal to a predetermined current, the calculated per frame And controlling the number of sustain discharge pulses to be subtracted from the number of discharge pulses. delete

Images