Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2002-09-30
2004-09-07
Vo, Tuyet T. (Department: 2821)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S082000, C345S087000, C345S100000, C315S169200
Reexamination Certificate
active
06788277
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a drive unit of a display panel for active driving light-emitting elements constituting pixels, and more particularly, to a drive unit and a drive method of a light-emitting display panel for realizing low power consumption by selecting a partial display mode for controlling light emission making use of a part of the effective light-emitting elements disposed in a display panel.
2. Description of the Related Art
Displays using a display panel composed of light-emitting elements disposed in a matrix shape are under extensive development. Attention is given to organic electroluminescence (EL) elements using, for example, an organic material in the light emitting layers thereof as the light-emitting elements used in the display panel. This is because the efficiency and life of the organic display panel have been improved to a practically usable level by using an organic compound promising good light emitting characteristics in the light-emitting layers of the EL elements.
There have been proposed, as the display panel using the organic EL elements, a simple matrix type display panel in which EL elements are simply disposed in a matrix shape and an active matrix type display panel in which drive elements composed of, for example, TFTs (Thin Film Transistors) are added to the respective EL elements disposed in the matrix shape. The latter active matrix type display panel is suitable for a high-definition display because the latter display panel has such characteristics that it can realize lower power consumption than the former simple matrix type display panel and that it has a less amount of crosstalk between pixels.
In particular, nowadays, the application of the self-emitting type displays described above to hand-held type terminal equipment, and the like, which are typically represented by portable phones, has been partly realized, and the equipment more and more requires low power consumption. To realize the low power consumption, it is effective, in an example of, for example, the portable phones, to select a partial display mode for controlling light emission making use of only a part of the effective light-emitting elements of a display in a waiting mode.
Incidentally, in the active matrix type display panel described above, a data driver and a scan driver are designed so as to be arranged on, for example, a glass substrate, on which a display pixel section is formed, so that the number of signal lines connected between the display panel and external circuits is reduced as much as possible. When it is intended to realize the partial display described above in the above circumstances, it is necessary to add a partial drive circuit to the scan driver.
FIG. 1
schematically shows an example of a display screen, in which a display region is formed, for example, between a scan start position (START) and a scan end position (END), when the partial display is executed. When the partial display is executed, it is necessary to input a start signal at the START position and to clear a shift register in the scan driver at the END position.
To permit a scan to be started from an arbitrary line on an effective display screen as shown in
FIG. 1
, a register for setting a scan start position, a decoder for enabling the value of the register to respective scan lines, and the like are necessary. When it is assumed that the total number of the scan lines is, for example, 240, a decoder for making conversion from 8 bits to 240 bits is necessary, and the scale of the decoder is made very large. Further, gates and the wirings thereof are necessary to reset the shift resister.
When the wirings described above are added to the active matrix type display panel, it is anticipated that the number of TFTs constituting the scan driver will be at least quadrupled. According to this arrangement, it is contemplated that the ratio of the glass substrate occupied by the scan driver increases from, for example, 5% to 20%. As a result, an active area is forced to be reduced by about 15% and thus an opening ratio is reduced, which requires to increase the instant luminance of light-emitting elements in order to obtain predetermined luminance.
Accordingly, when it is intended to realize the partial drive in the conventional active matrix type display panel, there is a technical problem in that low power consumption cannot be realized as a whole due to an increase in the electric power consumed by the circuits added as described above and to an increase in the electric power consumed to increase the instant luminance of the EL elements.
SUMMARY OF THE INVENTION
An object of the present invention, which was made based on the technical point of view described above, is to provide a drive unit and a drive method of a light-emitting display panel capable of realizing a partial drive without the addition of a complex control circuit added thereto and reducing power consumption thereby in an active matrix type display panel in which a data driver and a scan driver are arranged on the same substrate constituting the display panel.
In a drive unit of an active matrix type display panel according to a first embodiment of the present invention, which was made to solve the problems described above, having a plurality of light-emitting elements which are disposed at the intersecting positions where a plurality of data electrode lines and a plurality of scan electrode lines intersect and the light emission of which is controlled by drive circuits, respectively, the drive unit is characterized by including a data driver for supplying image data to the respective data electrode lines, a scan driver for sequentially supplying a scan signal to the respective scan electrode lines, and control means for stopping the operation of the data driver when a partial display drive for controlling the light emission of a part of the effective light-emitting elements in the display panel is executed and when the scan driver scans a non-display region.
In this case, it is preferable that the data driver and the scan driver be disposed on the same substrate constituting the display panel together with the respective drive circuits and the respective light-emitting elements corresponding thereto. Further, the drive circuits are preferably composed of control transistors for transmitting image data supplied from the data driver based on a scan signal supplied from the scan driver and drive transistors for supplying a drive current to the light-emitting elements based on the image data transmitted by the control transistors.
Then, in a preferable embodiment, the data driver may include a shift register for capturing serial image data as parallel image data by sequentially shifting up the serial image data based on a clock signal and a latch circuit for outputting pixel unit image data to the respective data electrode lines by latching the image data captured by the shift resister based on a latch signal. Further, the scan driver may include a shift register for outputting a scan signal to the respective scan electrode lines by sequentially shifting up it based on a clock signal.
Then, it is preferable that the drive unit include a black data set means for capturing black data for controlling the light-emitting elements in a non-lighting state for at least one horizontal period when a scan is executed from a display region to a non-display region while the partial display drive is being executed to control the light emission of a part of the effective light-emitting elements in the display panel.
In contrast, in a drive method of the active matrix type display panel according to the first embodiment of the present invention having a plurality of light-emitting elements which are disposed at the intersecting positions where a plurality of data electrode lines and a plurality of scan electrode lines intersect and the light emission of which is controlled by drive circuits, respectively, a data driver for supplying image data to the respective data electrode li
Kanauchi Katsuhiro
Seki Shuichi
Tohoku Pioneer Corporation
Vo Tuyet T.
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