Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1997-12-15
2001-04-03
Saras, Steven (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S182000, C345S085000, C359S295000, C385S019000, C385S901000
Reexamination Certificate
active
06211853
ABSTRACT:
BACKGROUND OF THE INVENTION
1 Field of the Invention
The present invention relates to a display device which consumes less electric power, and which has large screen brightness. In particular, the present invention relates to a display device which is preferable to be used for display units for displaying a picture image corresponding to an image signal on an optical waveguide plate by controlling leakage light at a predetermined position on the optical waveguide plate by controlling the displacement action of an actuator element in a direction to make contact or separation with respect to the optical waveguide plate in accordance with the attribute of the image signal to be inputted.
2. Description of the Related Art
Those hitherto known as the display device include, for example, cathode ray tubes (CRT), liquid crystal display devices, and plasma displays.
Those known as the cathode ray tube include, for example, ordinary television receivers and monitor units for computers. Although the cathode ray tube has a bright screen, it consumes a large amount of electric power. Further, the cathode ray tube involves a problem that the depth of the entire display device is large as compared with the size of the screen. Further, for example, the cathode ray tube involves drawbacks in that the resolution is decreased in the circumferential areas of a display image, the image or the graphic is distorted, there is no memory function, and it is impossible to present a display in a large scale.
The reason for the foregoing phenomenon is as follows. That is, in the case of the cathode ray tube, the electron beam emitted from the electron gun is greatly deflected. Therefore, the light emission point (beam spot) is expanded at portions at which the electron beam reaches the fluorescent screen of the Braun tube in an inclined manner, and thus the image is displayed in an inclined manner. For this reason, strain occurs on the display image. Moreover, there is a limit for the maintenance to keep a large space at the inside of a Braun tube to be in a vacuum.
On the other hand, the liquid crystal display device is advantageous in that the entire device can be miniaturized, and the display device consumes a small amount of electric power. However, the liquid crystal display device involves problems in that it is inferior in screen brightness, and the field angle of the screen is narrow. Further, since gradational expression is made in accordance with the voltage level, there is a drawback that the arrangement of the driving circuit becomes extremely complicated.
For example, when a digital data line is used, its driving circuit comprises a latch circuit for retaining component RGB data (each 8 bit) for a predetermined period, a voltage selector, a multiplexer for making change to provide voltage levels of the type corresponding to the number of gradations, and an output circuit for adding output data from the multiplexer to the digital data line. In this case, when the number of gradations becomes large, it is necessary for the multiplexer to perform the switching operation at an extremely large number of levels, in accordance with which the circuit arrangement becomes complicated.
When an analog data line is used, its driving circuit comprises a shift register for aligning, in the horizontal direction, component RGB data (each 8 bit) inputted successively, a latch circuit for holding parallel data from the shift register for a predetermined period, a level shifter for adjusting the voltage level, a D/A converter for converting output data from the level shifter into an analog signal, and an output circuit for adding the output signal from the D/A converter to the analog data line. In this case, an operational amplifier is used in the D/A converter. Thus, a predetermined voltage corresponding to the gradation is obtained. However, when the range of gradation becomes wide, it is necessary to use an operational amplifier which outputs a highly accurate voltage. Therefore, such a system involves a drawback that the structure becomes complicated, and the price also becomes high.
Since the plasma display has a small volume of its display section in the same manner as the liquid crystal display device the plasma display is advantageous in that it can be miniaturized, and it is easy to recognize the image because it has a flat display screen. Especially, the alternating current type plasma display additionally has an advantage that no refresh memory is required owing to the memory function of the cell.
By the way, in the case of the plasma display described above, in order to allow the cell to possess the memory function, it is necessary that the polarity of applied voltage is changed in an alternating manner so that the discharge is continued. For this reason, it is necessary for the driving circuit to comprise a first pulse generator for generating a sustain pulse in the X direction and a second pulse generator for generating a sustain pulse in the Y direction. For this reason, a problem arises in that the arrangement of the driving circuit is inevitably complicated. Further, it takes a long time to perform row scanning. Therefore, it is difficult to perform high speed scanning, and it is difficult to deal with high quality image display.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of such problems, an object of which is to provide a display device in which the time required to perform row scanning can be shortened drastically, and it is possible to easily deal with high quality image display.
Another object of the present invention is to provide a display device in which, in addition to the foregoing requirement, it is unnecessary to perform, for example, complicated voltage change and voltage selection even when the range of display gradation is widened, it is possible to restrain the number of settings of the use of voltage to the minimum, and it is possible to realize a simplified arrangement of a peripheral circuit system (including a driving circuit).
Still another object of the present invention is to provide a display device in which it is possible to exhibit the function as the display by utilizing, at the maximum, the memory function of a shape-retaining layer (piezoelectric/electrostrictive layer and anti-ferroelectric layer) of an actuator element for constructing a picture element (image pixel), and it is possible to realize stabilization of light emission and stabilization of display brightness (gradation).
Still another object of the present invention is to provide a display device in which the selection period for a picture element is minimized to make it possible to effectively reduce electric power consumption.
According to the present invention, in order to solve the problems as described above, there is provided a display device comprising an optical waveguide plate for introducing light radiated from a light source thereinto, and a driving section for controlling display gradation by changing an entering amount into an evanescent region which exists around a first principal surface of the optical waveguide plate.
According to the present invention, all of the light, which is introduced, for example, from a lateral end of the optical waveguide plate, is totally reflected at the inside of the optical waveguide plate without being transmitted through front and back surfaces thereof (light-off state) by controlling the magnitude of the refractive index of the optical waveguide plate. When any object (for example, a light-scattering object) contacts with the first principal surface of the optical waveguide plate at a distance of not more than the wavelength of light, then the light, which has once arrived at the surface of the object, is reflected by the surface of the object, and it behaves as scattered light. A part of the scattered light is reflected again in the optical waveguide plate. However, almost all of the scattered light is transmitted through the front surface of the optical waveguide plate without being reflected by the optical waveguide p
Akao Takayoshi
Nanataki Tsutomu
Ohwada Iwao
Takeuchi Yukihisa
Bell Paul A.
Burr & Brown
NGK Insulators Ltd.
Saras Steven
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