Patent Application
20060170618
1. Field of the Invention
The present invention relates to a driving method and a driving circuit of plasma display panel. More particularly, the present invention relates to a driving method and a driving circuit for adjusting the power consumption of display panels.
2. Description of Related Art
A picture frame displayed on the conventional plasma display panels comprises a plurality of sub-fields, wherein each sub-field comprises a reset period, an address period and a sustain period. The residual wall charge of the former sub-field is cancelled during the reset period, so that each display unit of the plasma display panels has the same initial condition in order to have a uniform display. In addition, an address pulse is applied to an address electrode during the address period and a scan pulse is inputted into a scan electrode in sequence at the same time to accumulate the wall charge of the pre-display unit. Furthermore, a sustain pulse is alternatively applied to the scan electrode and the sustain electrode during the sustain period, so that the display unit with the wall charge keeps on discharging. The brightness of the sub-field is directly proportional to the time-length of the sustain period. Accordingly, the picture frame will have different display gray levels due to the assembly of different display brightness of these sub-fields.
Generally speaking, the power consumption of plasma display panels during their sustain period is directly proportional to the product multiplied by the display loading and the sustain frequency, wherein the sustain frequency represents the most number of the sustain pulses can be afforded in a picture frame. The display loading is the ratio of the quantity of the lightening sustain pulses to the quantity of the provided sustain pulses in one picture frame. For example, the display loading is 0 while the panels display all black, whereas the display loading is 1 while the panels display all white. Therefore, in the same display loading, when the sustain frequency is increased, the quantity of the sustain pulse used in a picture frame will increase and the higher power consumption is achieved. Hence, in order to effectively control the power consumption during the sustain period, the power output is controlled by an automatic control power curve.
It should be noted that despite the power consumption of the plasma display panels can be controlled under a certain value by means of the foregoing automatic control power curve, different plasma display panels using the same automatic control power curve will have different power consumption due to different manufacturing processes thereof. As shown in
In order to solve the aforementioned problem, the method often used is to adjust the drive work voltage in order for the power consumption to have the same rated value.
Accordingly, the present invention is directed to a driving method of a plasma display panel, used for controlling a power consumption of plasma display panels to conform to a rated power consumption.
The present invention is also directed to a driving circuit of a plasma display panel, adapted for gain-controlling a display loading to adjust a power consumption of the plasma display panel, and for overcoming the power consumption deviation between different display panels in order to produce a more uniform display.
According to an embodiment of the present invention, a driving method of a plasma display panel is provided. The driving method is adapted for power control of a plasma display panel by an automatic control power curve, wherein the automatic control power curve is a relationship curve of a display loading and a sustain frequency of the plasma display panel. The driving method includes inputting an image signal into the plasma display panel. A first display loading is obtained according to the image signal. The first display loading is then multiplied by a gain constant to obtain a second display loading. Thereafter, the plasma display panel is driven according to the second display loading for the power consumption of the plasma display panel to conform to a rated power consumption.
According to an embodiment of the present invention, a driving circuit of a plasma display panel is disclosed, wherein the driving circuit is adapted for controlling a power consumption of a plasma display panel. The driving circuit includes, for example, a calculating unit, a gain unit, and a control unit, wherein the calculating unit is used for outputting a first display loading according to an image signal. The gain unit is used for receiving the first display loading, wherein the first display loading is multiplied by a gain constant to output a second display loading. In addition, the control unit is used for receiving the second display loading to correspondingly output a sustain frequency, wherein the power consumption of the plasma display panel can conform to a rated power consumption based on the sustain frequency.
According to an aspect of the present invention, the driving method and the driving circuit of a plasma display panel can gain-control the inputted display loading according to the electrical characteristics of plasma display panels. Further, the corresponding sustain frequency can be obtained from the automatic control power curve so that the power consumption of the plasma display panels can conform to a rated value.
Various specific embodiments of the present invention are disclosed below, illustrating examples of various possible implementations of the concepts of the present invention. The following description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
An image signal is transmitted into a plasma display panel (step 302). A first display loading is then obtained according to the image signal (step 304), wherein the quantity of lightening sustain pulses in a picture frame is dependent on the first display loading. As shown in
Accordingly, the first display loading DL1 is multiplied by a gain constant to obtain a second display loading DL2 (step 306). When the plasma display panels are quality control tested for lightening, a test signal is inputted to the plasma display panels. The gain constant value obtained based on the calculation on the power consumption determined during lightening test and the rated power consumption. Hence, the gain constant is different due to the different electrical characteristics of plasma display panels. For instance, when the power consumption P1 generated from the first sustain frequency Fsus1 is larger than the rated power consumption Pr, the gain constant will be larger than 1. Accordingly, the second display loading DL2 will be larger than the first display loading DL1.
Thereafter, the plasma display panels are driven according to the second display loading DL2 (step 308). A second sustain frequency Fsus2 corresponding to the second display loading DL2 is obtained from the automatic control power curve 402. Because the second display loading DL2 is larger than the first display loading DL1, the second sustain frequency Fsus2 is smaller than the first sustain frequency Fsus1. Accordingly, when the plasma display panels are driven by the second sustain frequency Fsus2 and the first display loading DL1, the number of the sustain pulses allocated to each of the sub-fields is fewer, and the power consumption P2 generated will conform to the rated power consumption Pr.
According to the aforementioned disclosure, a driving circuit of a plasma display panel of the present invention is used for the foregoing driving method to control the power consumption of the plasma display panels.
In accordance with the present invention, the display loading is gain-controlled according to the electrical characteristics of the plasma display panels. If the original power consumption is too high, the display loading is increased by the gain constant in order to maintain a lower sustain frequency for the power consumption to conform to a rated value. Accordingly, the driving method and the driving circuit of a plasma display panel of the present invention provide at least the following characteristics and advantages:
1. By adjusting the power consumption of the panels with the gain control of the display loading, the conventional adjustment method of varying the work voltage can be replaced. In a practical application, the power control can be optimized by adjusting the gain-control of the display loading and the work voltage.
2. The power consumption can be adjusted by changing the display loading. Therefore, the situation when the work voltage falls outs the normal display margin can be avoided. Accordingly, the yield rate and the life span of the panels can be enhanced effectively.
3. The different gain constants can be provided by plasma display panels of different characteristics in order to conform to the rated power consumption. As a result, the power consumption of each panel will be more even.
The above description provides a full and complete description of the preferred embodiments of the present invention. Various modifications, alternate construction, and equivalent may be made by those skilled in the art without changing the scope or spirit of the invention. Accordingly, the above description and illustrations should not be construed as limiting the scope of the invention which is defined by the following claims.
