6 876 342

6,876,342 Title:

Plasma display apparatus and driving method thereof

According to a plasma display apparatus of the present invention, at least in one sub-field, a driving signal applied to retain data written in each pixel has a frequency applied first and a frequency applied thereafter, the frequencies being different from each other. The first frequency is controlled to be low and the frequency thereafter is controlled to be high, for example (two-frequency driving method). With a first low-frequency pulse, initial discharge in a sustaining period is started stably, and with a high-frequency pulse thereafter, the discharge is sustained. Use of the high-frequency pulse increases the number of light emissions, thus leading to improvement in brightness. Thus, the present invention enables both discharge stabilization and increase in brightness, and can therefore improve picture quality of the plasma display apparatus.

What is claimed is:

1. A plasma display apparatus comprising: a panel including a dischargeable gas sealed between a pair of substrates joined to each other, a first electrode and a secondelectrode located at one substrate in correspondence with each scanning line, and a third electrode located at the other substrate in correspondence with each data line; and a driving unit for driving the first electrode, the second electrode, and thethird electrode, sequentially writing and retaining data at an intersection of each scanning line and each data line; wherein said driving unit includes input means, coding means, timing means, addressing means, and sustaining means; said input meansinputs multiple-gradation-step data obtained by quantizing a signal; said coding means codes one field of the quantized data by a predetermined rule to thereby convert into data distributed over a plurality of sub-fields; said timing means sequentiallyoutputs a timing signal for each of the sub-fields in synchronism with the coding; said addressing means scans scanning lines in each of the sub-fields in response to the timing signal while writing data assigned to the sub-field via data lines; andsaid sustaining means includes frequency control means, and applies a driving signal to the first electrode and the second electrode according to a weight of each of the sub-fields, and thereby retains the data written by the addressing means, thedriving signal applied to retain the data having, at least in one sub-field, a frequency applied first and a frequency applied thereafter, the frequencies being different from each other.

2. A plasma display apparatus as claimed in claim 1, wherein said sustaining means applies a driving signal having a number of pulses corresponding to a weight of the written data to the first electrode and the second electrode; and saidfrequency control means adjusts a pulse interval of the driving signal in each of the sub-fields such that the pulse interval is shortened in a sub-field lengthened in a sub-field having a small number of pulses.

3. A driving method of a plasma display apparatus, said plasma display apparatus having a panel including a dischargeable gas sealed between a pair of substrates joined to each other, a first electrode and a second electrode formed on onesubstrate in correspondence with each scanning line, and a third electrode formed on the other substrate in correspondence with each data line, and said plasma display apparatus driving the first electrode, the second electrode, and the third electrode,sequentially writing and retaining data at an intersection of each scanning line and each data line, and thereby displaying one field of image, wherein said driving method includes an input step, a coding step, a timing step, an addressing step, and asustaining step; said input step inputs multiple-gradation-step data obtained by quantizing a signal representing an image; said coding step codes one field of the quantized data by a predetermined rule to thereby convert into data distributed over aplurality of sub-fields; said timing step sequentially outputs a timing signal for each of the sub-fields in synchronism with the coding; said addressing step scans scanning lines in each of the sub-fields in response to the timing signal while writingdata assigned to the sub-field via data lines; and said sustaining step includes a frequency control step, applies a driving signal to the first electrode and the second electrode according to a weight of each of the sub-fields, and thereby retains thedata written by the addressing step, the driving signal applied to retain the data having, at least in one sub-field, a frequency applied first and a frequency applied thereafter, the frequencies being different from each other.

4. A panel including a dischargeable gas sealed between a pair of substrates joined to each other, a first electrode and a second electrode located at one substrate in correspondence with each scanning line, and a third electrode located at theother substrate in correspondence with each data line; and a driving unit for driving the first electrode, the second electrode, and the third electrode, sequentially writing and retaining data at an intersection of each scanning line and each dataline; wherein said driving unit includes addressing means and sustaining means, and further wherein said sustaining means includes frequency control means, and the sustaining signal is applied at a first and a second frequency, the first and secondfrequencies being different from each other.

5. A driving method of a plasma display apparatus, said plasma display apparatus having a panel including a dischargeable gas sealed between a pair of substrates joined to each other, a first electrode and a second electrode located at onesubstrate in correspondence with each scanning line, and a third electrode located at the other substrate in correspondence with each data line, and said plasma display apparatus driving the first electrode, the second electrode, and the third electrode,sequentially writing and retaining data at an intersection of each scanning line and each data line, wherein said driving method includes an addressing step, and a sustaining step; said sustaining step includes a frequency control step wherein thesustaining signal is applied at a first and a second frequency, the frequencies being different from each other.