Abstract: A tone display method which prevents degradation in image quality of moving images when the subfield method is utilized without an increase in cost. When tone display is performed with 256 tones with respect to one certain color, in each frame, segments 1 to 6 in time are set corresponding to the plural time-shared time bands of the color and each segment includes one or several subfields (sf). In each case, as the tone is increased by 42 (or 43) for segments 1 through 6, sequentially, the subfields in the segment being lit so that the tone is increased continuously.

Abstract: The present invention provides a color wheel assembly comprising a color wheel which is divided into plural color regions, and a motor for rotating the color wheel, in which the position of the color wheel can be detected accurately even at high-speed rotation or at elevated temperatures. A Hall IC 27 as a magnetic sensor is provided inside of a motor 2. Every time a detecting magnet 28 which is provided at a rotor part 6 rotates and passes through the Hall IC 27 as the magnetic sensor, a pulse signal is generated by magnetoelectric conversion characteristics of the Hall IC 27, thereby generating a pulse signal for detecting the position of the color wheel 1 only with the color wheel 1 and the motor 2 for rotating the color wheel.

Abstract: A tone display method is provided that can prevent image quality deterioration of the dynamic image and can avoid a cost increase. When an image with 256 tones is displayed, one field is divided into 37 subfields for one color. Among the 8 bits corresponding to the 256 tones, the six high-order bits from the third bit are displayed by means of time width modulation using 35 subfields SF3-SF37 having weights of ““4” and “8”. The two low-order bits are displayed on a binary base using two subfields SF1 and SF2 whose weights are “'1” and “2”, respectively.

Abstract: In a display panel, a first substrate is opposed to a second substrate and interposing a liquid crystal/resin composite layer. If the display panel is a transmission type display, a film for absorbing light is formed on a black matrix and between pixel electrodes. If the display panel is a reflection type display, a film for absorbing light is formed between reflection electrodes. Further, a counterelectrode is made from a multi-layer film of dielectric films and a transparent electrically conductive film for preventing reflection. The film for absorbing light includes pigments which can absorb light modulated by the liquid crystal/resin composite layer. By using the display panel, a projection display system of high contrast and high brightness can be constructed.

Abstract: In an optical system phase device such as .lambda./2 plate or a .lambda./4 plate is used to convert S polarization to P polarization and vice versa. In the projection display, a white light emitted from a light source is separated by a color separation optical system, including dichroic mirrors or a dichroic prism, into three primary colors which are modulated by optical modulation elements. Then, the modulated lights are synthesized by a color synthesis optical system and projected by a projection element onto a screen. When appropriate plates are inserted appropriately in the optical system of the projection display, the conversion between S and P polarization occurs and an optical bandwidth becomes narrow, and color purity can be improved. A thick transparent plate is preferably adhered to the optical modulation element. A light absorption film is applied to an ineffective plane of the transparent plate.

Abstract: In a light valve, a liquid crystal layer made of liquid crystal/resin composite is interposed between a transparent substrate with a counterelectrode and a reflection substrate with reflection electrodes. The size of the transparent substrate is designed so that the light modulated by the liquid crystal layer is prevented from again entering into the liquid crystal layer after reflected at an interface of the transparent substrate with air. The transparent substrate may be combined with a transparent plate or flat concave lens with a transparent coupling material. Each pixel has a reflection electrode and liquid crystal molecules above the reflection electrode are aligned according to the signals supplied to thin film transistors. The counterelectrode is formed as a multi-layer film of dielectric films and a transparent electrically conductive film. The dielectric films are made of a material having a refractive index of 1.6-1.8, and the optical thickness of the dielectric films is .lambda.

Abstract: A light valve includes a light valve layer for forming an optical image as variations in its ability to scatter light, and two substrates between which the light valve layer is sandwiched and at least one of which is transparent. The light valve satisfies the following condition: ##EQU1## where t denotes a central thickness of the at least one of the substrates, n denotes a refractive index of the at least one of the substrates and d denotes a maximum diameter of an effective display area of the light valve layer. Alternatively, a transparent plate can be optically coupled to one of the substrates by a transparent body. In this case, the same condition is satisfied except that the thickness refers to a central thickness from a face of the transparent plate remote from the transparent body to the light valve layer.

Abstract: A liquid crystal projection device includes a light source, a polymer dispersed liquid crystal panel for forming an optical image as a function of changes in the light scattering condition, a polarizing plate disposed on at lest one of the incident and exit sides of the liquid crystal panel with respect to the direction of travel of the light, and a projection lens for projecting the optical image onto a polarizing screen. The polarizing plate is removably and rotatably supported so that, by rotating the polarizing plate, the direction of the axis of polarization of the polarizing plate can be substantially aligned with the direction of the axis of the polarizing screen. The polarizing screen is utilized when the polarizing plate is mounted, but a non-polarizing screen may be utilized when the polarizing plate is not used, i.e., removed.

Abstract: A light valve projection apparatus includes a light source, a light valve used for forming optical images in response to a change in light scattering conditions in the light valve of light irradiated from the light source, a projection lens for projecting the optical images on a screen, and a shield for shielding the optical images formed at or near a pupil of the projection lens. If the brightness of light exiting from the light valve, which is in a light scattering state, in a direction tilted by .theta. degrees from a normal dissection of the light valve is assumed to be half as bright as the light outgoing in the normal direction at .theta..sub.1/2, .theta..sub.1/2 of the light valve is less than 23.degree.. The light valve may be a polymer dispersion liquid crystal display panel. When the polymer dispersion liquid crystal display panel is in a transparent state, light transmitted through the liquid crystal display panel is shielded by the shield, thus showing a black display on a screen.

Abstract: A liquid crystal display panel includes a first substrate and a second substrate, at least one of which possesses light transmissivity, each having an electrode layer formed thereon, the electrode layers confronting each other, and a liquid crystal layer sandwiched between the first substrate and the second substrate, divided into plural regions, and including liquid crystal molecules. The liquid crystal molecules are oriented in the same direction in each of first regions, and in a different direction in second regions each located between two adjacent first regions. The second regions are spaced at a regular periodicity. Without an electric field applied to the liquid crystal layer, the different orientations of the liquid crystal molecules create differences in the refractive indices at which the light is transmitted so as to serve as a phase grating the diffracts incident light.

Abstract: A viewfinder suited for use in a video camera, wherein rays of light emitted at a large solid angle from a minute light emitting area of a light emitting element are converted by a condenser lens into a bundle of generally parallel rays of light having a narrow directionality before they enter a liquid crystal display. The liquid crystal display modulates the rays of light emerging from the condenser lens according to a video signal to effect an image display. The displayed image is magnified by a magnifying lens. The liquid crystal display is of a type wherein an optical image is formed as a function of a change in state of light scattering and may be a polymer dispersed liquid crystal display, a liquid crystal panel utilizing a dynamic scattering mode, a ferro-electric liquid crystal panel using a scattering mode or a display panel utilizing PLZT.

Abstract: In a liquid crystal light valve apparatus comprising an incident side polarizing plate, a twisted nematic liquid crystal cell of active matrix type and an outgoing side polarizing plate, two phase difference plates are provided between the incident side polarizing plate and the liquid crystal cell. Optical axes of both the phase difference plates are perpendicular with each other, and one of them is slanted by an angle, and thereby, a phase difference which is caused by the liquid crystal cell is compensated by the phase difference caused by two phase difference plates.

Abstract: Pixel electrodes of a liquid crystal panel are made of a transparent conductive material, while a reflection electrode is formed on a counter substrate. A liquid crystal layer made of liquid crystal/resin composite is interposed between the pixel electrodes and the reflection electrode. Incident light is scattered in the liquid crystal layer or transmits the liquid crystal layer and is reflected by the reflection electrode according to the applied voltage to modulate the light. The pixel electrodes consist for example of two layers of a dielectric layer of thickness of .lambda./4 and a transparent conductive layer of thickness of .lambda./2. A grating is formed on the reflection electrode at the interface with the liquid crystal. When a voltage is applied to the liquid crystal layer, the refractive index thereof changes to be equal to that of the grating, and the incident light propagates straightly. Otherwise the incident light is diffracted.

Abstract: A liquid crystal panel includes a liquid crystal/polymer composite between two substrates, one of which having a matrix of pixel electrodes. A mosaic color filter of red, green and blue is provided above counterelectrodes or pixel electrodes. The average pore size of the resin component or of the diameter of liquid crystal droplets in the composite is selected according to the color of the color filter. The average of pore sizes is the largest for red, and the smallest for blue. The average of pore sizes of the resin on the switching elements and on the signal lines is smaller than that on the pixel electrodes. This liquid crystal display panel is used as a light bulb for a projection type television system. This liquid crystal display panel is also used as a viewfinder of a video camera.

Abstract: Pixel electrodes and thin film transistors are arranged in a matrix in a display device, while polymer dispersion liquid crystals are interposed between an opposite electrode and the pixel electrodes on an electrode substrate. A signal is written into each pixel electrode by a pair of drive ICs for outputting signals in positive and negative polarities respectively with respect to an electrical potential at the opposite electrode. Two transistors are provided at each pixel electrode or an analog switch is provided at a signal output terminal of each drive IC so that signals of positive and negative polarities are not simultaneously written into an identical pixel electrode. When no voltage is applied to the pixel electrode, the incident light is reflected so as to be dispersed by the liquid crystal, and when a voltage is applied to the pixel electrode, the state of the liquid crystal is made light-permeable.