Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-12-15
2004-08-03
Bella, Matthew C. (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S204000, C345S096000, C345S208000, C345S209000
Reexamination Certificate
active
06771240
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention generally relates to a method of driving a matrix type display apparatus which suppresses an occurrence of degradation in quality of picture and which reduces the power consumption to an extremely low value, and to such a matrix type display apparatus and electronic equipment.
2. Description of Related Art
In display apparatuses used in portable electronic equipment, such as a hand-portable telephone set, the number of display dots has increased year after year so that more information can be displayed on the screen thereof. On the other hand, the portable electronic equipment is battery driven in principle, and thus required to reduce the power consumption thereof as much as possible. Therefore, the display apparatus used in the portable type electronic equipment is required to have two apparently contradictory features, that is, high resolution and low power consumption. Thus, to solve such a problem, an attempt has been made to adapt the display apparatus to perform a full-screen display operation when a high resolution is required, and to display only a partial region of the screen thereof and put the remaining region into a non-display state.
SUMMARY OF THE INVENTION
However, there has occurred a problem that power consumption is ineffectively reduced against all expectation even when only a partial region of the screen of a display apparatus is indicated in the case that a high resolution is not required. Further, the configuring of the display apparatus in such a way as to display only a part of the screen thereof and to put the remaining region of the screen thereof into a non-display state causes another problem in that the circuit of the apparatus is complex.
The present invention is accomplished in view of the aforementioned problems. An object of the present invention is to provide a method of driving a matrix type display apparatus, which can suppress an occurrence of degradation in the quality of picture, enhance the resolution thereof and reduce the power consumption thereof, and simplify the configuration thereof, and to provide a matrix type display apparatus having a driving circuit for performing this a method and to provide electronic equipment having this display apparatus.
To resolve such problems, according to an aspect of the present invention, there is provided a method of driving a pixel provided corresponding to each of intersections between a plurality of scanning lines and a plurality of data lines by a switching device, wherein when only a first region including a part of the plurality of scanning lines is put into a display state while a second region including the rest of the plurality of scanning lines is put into a non-display state, a non-selection signal, in response to which the switching device is brought into a non-conducting state, is supplied to each of the scanning lines of the second region by inverting a polarity of a signal voltage every one or more vertical scanning time period, by using an intermediate value which is represented by the signal supplied to the data lines as a reference.
It is desirable only from the viewpoint of low power consumption that a signal representing the intermediate value of values represented by signals to be supplied to the data lines is supplied to each of the scanning lines belonging to the second region serving as a non-display region. However, with this configuration, it is necessary to additionally select a signal representing a voltage which corresponds to the intermediate value. Thus, the configurations of the voltage generating circuit and the scanning line driving circuit are complex.
In contrast with this, according to the present invention, the non-selection signal is supplied to each of the scanning lines of the second region by inverting the polarity every one or more vertical scanning time periods, on the basis of the intermediate value. Thus, the effective value of the voltage becomes nearly zero. There is no need for generating and selecting a signal representing the voltage which corresponds to the intermediate value. Consequently, the configuration of the circuit is simplified. Furthermore, the voltage level is changed every one or more vertical scanning time periods, more preferably, every time period, which is longer than the vertical scanning time period. Thus, the frequency of the signal supplied to the scanning line is reduced. Consequently, the power consumption resulting from the voltage level changing operation in the circuit for driving the scanning lines is suppressed. Moreover, the power consumption resulting from the charging and discharging of the associated capacity of the scanning lines and the driving circuit is also suppressed.
Further, according to the present invention, preferably, a selection signal, which puts the switching device into a conducting state, is supplied in one of time periods into which a horizontal scanning time period is divided, and a non-selection signal, which puts the switching device into a non-conducting state, is supplied in the remaining ones of the time periods by inverting the polarity of a signal voltage every predetermined time period, by using the intermediate value which is represented by the signal supplied to the data line as a reference. With this configuration, the signal supplied to each of the scanning lines of the first region used as the display region is not different from a signal in an ordinary state in which all the scanning lines are in the display region. This prevents the configuration of the circuit from being complex by changing the duty ratio. Moreover, this prevents the quality of display of the first region from being deteriorated in comparison with that in the ordinary state.
Furthermore, according to the present invention, preferably, the selection signal is supplied to each of the scanning lines before the second region is put into a non-display state. As described above, each of the pixels of the present invention is driven by the switching device. Thus, in the case that a certain one of the pixels is in the second region, the previously written charge is held as it is according to the non-conducting state of the switching device. Consequently, in the case of a transition from the ordinary state, in which the region including all the scanning lines is used as the display region, to the state in which the second region is put into the non-display region, preferably, the apparatus performs a step at which all the pixels included in the second region are once put into an off display condition. The present invention enables the method to include this step.
Further, to achieve the foregoing object, there is provided a method of driving a matrix type display apparatus for driving a pixel provided corresponding to each of intersections between a plurality of scanning lines and a plurality of data lines by a switching device, wherein in the case that only a first region including a part of the plurality of scanning lines is put into a display state while a second region including the rest of the plurality of scanning lines is put into a non-display state, when a scanning line in the second region is selected, a signal having a positive-side voltage level and a negative-side voltage level, which are determined by using an intermediate value represented by a signal to be supplied to the data lines as a reference, is supplied to each of the scanning lines by inverting a polarity of a signal voltage every one or more vertical scanning time period, by using the intermediate value as a reference.
Only from the viewpoint of limiting the power consumption of each of the data lines at the time of selecting the scanning lines of the second region, which is a non-display region, to a low value, it is preferable that a signal representing the intermediate value of the positive-side voltage level value and the negative-side voltage level value is supplied to each of the data lines. However, with this configuration, it is necessary to additionally select a signa
Inoue Akira
Yamazaki Suguru
Bella Matthew C.
Nguyen Hau
Oliff & Berridg,e PLC
Seiko Epson Corporation
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