Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1998-09-25
2003-08-05
Hjerpe, Richard (Department: 2774)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S062000, C345S064000, C345S065000, C345S063000, C345S066000, C345S067000, C345S068000, C345S069000, C345S205000, C345S206000
Reexamination Certificate
active
06603446
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technology for driving a display panel composed of a set of cells that are display elements having a memory function. More particularly, this invention is concerned with a device for displaying an image on an alternating current (AC) type plasma display panel (PDP) with interlaced scanning.
2. Description of the Related Art
An AC type PDP sustains discharge by applying a voltage waveform alternately to two sustaining electrodes, and glows for display. One discharge completes in one to several microseconds immediately after application of a pulse. Positively charged ions that are derived from the discharge are accumulated on the surface of an insulating layer over electrodes to which a negative voltage is applied. Likewise, electrons carrying negative charges are accumulated on the surface of the insulating layer over electrodes to which a positive voltage is applied.
Discharge is effected with a high-voltage (writing voltage) pulse (writing pulse) in order to generate a wall charge. Thereafter, a pulse (retaining discharge pulse) of a voltage of opposite polarity (retaining discharge voltage), which is lower than the previous voltage, is applied. The accumulated wall charge is added to the voltage. The voltage in a discharge space therefore rises and exceeds the threshold value of a discharge voltage. Eventually, discharge starts. Display cells have the feature that once a display cell is discharged for writing and produces a wall charge, when sustaining discharge pulses of opposite polarities are applied alternately to the display cell, the display cell sustains discharge. This feature is called a memory effect or memory function. In general, the AC type PDP utilizes the memory effect to achieve display.
In an AC type PDP of a prior art, X electrodes that are one set of sustaining electrodes and Y electrodes that are the other set thereof are arranged alternately. Discharge occurs in regions between odd-numbered X electrodes and Y electrodes, and in regions between even-numbered X electrodes and Y electrodes. In other words, display cells are defined between the odd-numbered X electrodes and Y electrodes, and between the even-numbered X electrodes and Y electrodes. No display cell is defined between the odd-numbered Y electrodes and even-numbered X electrodes and between the odd-numbered X electrodes and even-numbered Y electrodes. However, this poses a problem of difficulty in attaining high definition and high luminance. The present applicant has disclosed a PDP for interlaced scanning and a driving method thereof in Japanese Unexamined Patent Publication No. 9-160525. The driving method is called an ALiS method (Alternate Lighting of Surfaces Method) and the PDP of this type is called an ALiS PDP. In the ALiS PDP, display cells are defined even by the odd-numbered Y electrodes and even-numbered X electrodes and by the odd-numbered X electrodes and even-numbered Y electrodes. Thus, high definition and high luminance are ensured. The present invention is adapted to an ALiS plasma display panel (PDP) in which, similarly to the one disclosed in the Japanese Unexamined Patent Publication No. 9-160525, regions defined by a Y electrode and X electrodes across the Y electrode are discharged in order to define display cells.
In the PDP of the prior art, a scan driver is formed with an IC mounted on one chip or ICs mounted on several chips in order to realize a compact design or reduced manufacturing cost. The scan driver is provided with a circuit for generating a scanning pulse as mentioned above. If the scan driver is not formed with an IC, the scan driver as well as the circuit must be composed of discrete parts. A problem arises in terms of circuit scale or cost. Even in the PDP to which the present invention is adapted, a scan driver should preferably be formed with an IC in order to realize a compact design and reduce manufacturing cost. However, a problem underlies the PDP to which the present invention is adapted. Namely, the wiring in a drive circuit for driving the X electrodes or Y electrodes is complex. There is therefore difficulty in forming the scan driver with an IC.
SUMMARY OF THE INTENTION
An object of the present invention is to simplify the wiring in a drive circuit for driving X electrodes or Y electrodes in a PDP in which different sustaining discharge signals are applied to odd-numbered and even-numbered X electrodes and Y electrodes respectively, and to permit formation of a scan driver with an IC.
To accomplish the above object, in a plasma display device of the present invention, a scan driver is divided into a circuit connected to odd-numbered Y electrodes and a circuit connected to even-numbered Y electrodes. Owing to this configuration, only one kind of sustaining discharge signal is present in a chip. A problem concerning durability to a high voltage will not occur. The scan driver can be formed with an IC. Moreover, similarly to the drive circuit for driving the Y electrodes, a drive circuit for driving X electrodes is divided into a circuit connected to odd-numbered X electrodes and a circuit connected to even-numbered X electrodes.
To be more specific, the plasma display device of the present invention has a display panel including first and second electrodes arranged in parallel with one another, and third electrodes arranged orthogonally to the first and second electrodes. With a scanning signal and addressing signal to be applied to the second and third electrodes, discharge cells are selected. By applying sustaining discharge signals to the first and second electrodes respectively, the selected cells sustain a discharge. The sustaining discharge signals that are mutually out of phase are applied alternately to a pair of adjoining first electrodes and a pair of adjoining second electrodes. Consequently, first display cells are defined between the second electrodes and the first electrodes on one side of the second electrodes. Second display cells are defined between the second electrodes and the first electrodes on the other side of the second electrodes. Interlacing, where the first display cells and second display cells are allowed to glow alternately and repeatedly, is carried out. A drive circuit for driving the second electrodes in the plasma display device includes a first drive circuit for outputting a pulsating voltage to be applied in common to the odd-numbered ones of the second electrodes, a second drive circuit for outputting a pulsating voltage to be applied in common to the even-numbered ones of the second electrodes, and third circuits associated with the second electrodes for applying the pulsating voltages output from the first drive circuit and second drive circuit to the second electrodes and for applying a scanning signal selectively to the second electrodes. In the plasma display device, the third circuits are grouped into third odd circuits connected to the odd-numbered ones of the second electrodes, and third even circuits connected to the even-numbered ones of the second electrodes. The third odd circuits are integrated into at least one chip and the third even circuits are integrated into at least one chip.
In the plasma display device of the present invention, the drive circuit for driving the second (Y) electrodes is divided into the circuit connected to the odd-numbered Y electrodes and the circuit connected to the even-numbered Y electrodes. This leads to improved freedom in wiring. Moreover, when the third odd circuits and third even circuits are formed with ICs, only one kind of sustaining discharge signal is present within one chip. No problem will therefore occur in relation to durability to a high voltage.
For arranging the foregoing circuits, preferably, the chip having the third odd circuits is located near the first circuit, and the chip having the third odd circuits is located near the second circuit.
For matching the orders of output from the chips having the third odd circuits and third even circuits with the order of
Kanazawa Yoshikazu
Koizumi Haruo
Kuwahara Takeshi
Fujitsu Limited
Lesperance Jean
Staas & Halsey , LLP
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