Computer graphics processing and selective visual display system – Computer graphics processing – Attributes
Reexamination Certificate
2000-05-10
2002-04-30
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Computer graphics processing
Attributes
C345S591000, C345S600000, C345S604000
Reexamination Certificate
active
06380943
ABSTRACT:
TECHNICAL FIELD
The present invention relates to display apparatuses such as plasma displays, electroluminescence displays, and light emitting diode displays.
BACKGROUND ART
Conventionally, a light-emitting type display apparatus such as a plasma display, an electroluminescence display or a light emitting diode display generally emits light to display when it has some amount of information that should be displayed. The display apparatus inevitably involves large power consumption as the amount of information to be displayed becomes large. Therefore, it has been studied to restrict power consumption when the amount of display data has become large. In Japanese Patent Laid-Open Publication No. H08-65607, it is disclosed that depending on average luminance signal level of images, an automatic power control (APC) section adjusts the light emission amount per unit area (luminance) of a display in response to variations in the average luminance signal level so that the power consumption is controlled so as not to increase excessively.
FIG. 11
is a block diagram showing the configuration of the display apparatus according to the prior art disclosed in the publication. R, G and B signals as picture signals are fed into their corresponding terminals. The R, G and B signals via their corresponding terminals are fed into a Y-encode circuit
61
which encodes the R, G and B signals into a luminance signal (hereinafter, referred to as Y signal) to output. A digital luminance integrating circuit
62
inputs and integrates the Y signal from the Y-encode circuit
61
to output an average luminance.
Taking as a parameter the average luminance outputted from the digital luminance integrating circuit
62
, a memory controller
63
receives data corresponding to the average luminance from a memory
64
to output the data to an automatic power controller
66
of a plasma display apparatus
68
. The automatic power controller
66
outputs to a PDP (plasma display panel) display section
67
a control signal for adjusting the light emission amount per unit area (luminance) of the PDP display section
67
in response to the data from the memory control section
63
, thereby power consumption is controlled.
However, the power consumption at the PDP display section
67
is not proportional to the luminance signal. For example, with a common transform equation, Y=0.3R+0.59G+0.11B, used in the Y-encode circuit
61
, the ratio among their respective luminance signals (YR, a luminance signal for display of single red; YG, a luminance signal for display of single green; and YB, a luminance signal for display of single blue) is YR: YG: YB =0.3:0.59:0.11 when single color of red (hereinafter, expressed as R), green (hereinafter, expressed as G) and blue (hereinafter, expressed as B) are displayed,. Here, the luminance signal YG for the display of G is the largest and the luminance signal YB for the display of B is the smallest so that different control processes are performed by the automatic power controller
66
for the respective cases of the display of the single color depending on the average luminance. Ratio among respective coefficients (0.3, 0.59,0.11) for obtaining luminance signals in the transform equation equals to a ratio at which human eyes feel the brightness with each three primary colors (R, G, B), and do not show any power consumption ratio. Therefore, it may cause inappropriate control to be performed.
As shown above, in the technique of the prior art, with average luminance used as a parameter for the power consumption control of a display apparatus, light emission amount (luminance) of the display section
67
would be recognized as less than required amount in the case of an image in which green components occupy a larger portion than the other colors, and power consumption would be recognized as more than the performance of the power supply
65
in the case of an image in which blue components occupy a larger portion than the other colors. Thus, it has been a problem of the prior art technique that an accurate automatic control of power consumption or light emission amount cannot be achieved.
DISCLOSURE OF THE INVENTION
In order to solve the above problem, a display apparatus of the present invention is characterized in that the light emission amount (luminance) or power consumption is controlled based on a power prediction signal obtained by weighted average levels of individual colors with coefficients representing ratios of power consumptions involved in data display when the three primary colors of red, green and blue are displayed in single colors, respectively, or representing ratios of phosphor areas of the individual colors, and by then summing up the weighted average levels.
According to the present invention, since the power consumption or light emission amount (luminance) is controlled based on a power prediction signal computed with coefficients representing power consumption ratios or phosphor area ratios, it becomes possible to control the power consumption or light emission amount (luminance) independently of the hue of input picture signals.
In a first aspect of the invention, a display apparatus comprises an emission unit, integrating circuits, three multiplying circuits, a power consumption prediction circuit, a controller and a brightness control circuit.
The emission unit emits light to display images. The integrating circuits integrate input picture signals of R (red), G (green) and B (blue) for each predetermined period to output an average level of R signal, an average level of G signal and an average level of B signal, respectively. The first, second and third multiplying circuits multiplies the R average level, the G average level and the B average level by their respective parameters KR, KG and KB, respectively. The power prediction circuit adds output signals from those multiplying circuits together to obtain and output a power prediction signal. The signal indicates amount of power predicted or expected to be consumed on the emission unit. The controller receives the power prediction signal to output a control signal based on a value of the received signal. The brightness control circuit controls light emission amount per unit area according to the control signal.
In the display apparatus, a ratio of parameters KR, KG and KB may be determined to be equal to a ratio of powers consumed for display each color of red, green and blue with same brightness. In this case, the display apparatus can control the power consumption or light emission amount (luminance) more accurately, as compared with the prior art technique in which power consumption of the display apparatus is controlled with average luminance.
In a second aspect of the invention, a display apparatus comprises an emission unit, integrating circuits, first, second and third multiplying circuits, a power consumption prediction circuit, a controller, a delay circuit and a first, second and third multiplying circuits.
The emission unit emits light to display images. The integrating circuits integrates input picture signals of R, G and B for each predetermined period to output an average level of R signal, an average level of G signal and an average level of B signal, respectively. The first, second and third multiplying circuits multiplies the R average level, the G average level and the B average level by their respective parameters KR, KG and KB, respectively. The ratio of parameters KR, KG and KB is determined to be equal to a ratio of powers consumed for display each color of red, green and blue with same brightness. The power consumption prediction circuit adds output signals from the multiplying circuits together to obtain and output a power prediction signal. The signal indicates amount of power expected to be consumed on the emission unit. The controller receives the power prediction signal to output a multiplying coefficient based on a value of the received signal. The delay circuit delays the input picture signals of R, G and B to output the delayed picture signals DR, DG
Ishikawa Yuichi
Kasahara Mitsuhiro
Morita Tomoko
Greenblum & Bernstein P.L.C.
Hjerpe Richard
Lesperance Jean
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