U.S. Philips Corporation

Martinus V Stroomer

Karel E Kuijk

Henricus F De Leeuw

John A Clarke

Adrianus J De Vaan

Ties S Te Velde

Jean H Lorteije

Jacobus H Neijzen

Wilhelmus A Timmers

Frederick M Boekhorst

Allan Carmichael

Louis M Cobben

A presentation system comprising an image projection screen and an overhead projector is described. The overhead projector comprises an illumination system, a support for supporting an image record carrier and a projection head for projecting the image present in the image record carrier on the image projection screen. The image projection screen is a polarizing screen which transmits radiation having a well-defined direction of transmission polarization, and the overhead projector is adapted to supply light having this direction of polarization. In this way, the quantity of radiation used for forming the image is considerably increased and substantially half the quantity of ambient light incident on the screen is suppressed, so that images having a considerably enhanced contrast and brightness are obtained.

Presentation system with overhead projector

In a color liquid crystal projection display in which three differently-colored illuminating beams (R,G,B) are incident from mutually different directions on an LC panel (20) having an array of display elements (40) with a microlens array (21) at the input side of the panel end of whose elements (42) overlies a respective group of three adjacent display elements in row or delta configuration and through each of which light of the three colours (R,G,B) is directed at different angles respectively and converged towards respective ones of the display elements in its associated group, a deflecting element array (25), comprising, for example, microlens element (44) or microprisms (46) formed in a glass substrate of the panel, is positioned close to the plane of the display elements to deflect the directions of light of at least two of the three colours from each microlens element (42) to bring the directions of light of the three colours at the output side of the panel towards a common direction, and preferably substantially parallel to one another. A significant reduction in the amount of spread of light if the output side is thereby achieved, such that, inter alia, a comparatively small aperture projection lens (30) can be used.

Color liquid crystal projection display systems

A picture display device is disclosed having an illumination system and a picture display panel which is provided with a matrix of n panels and has a pitch p.sub.p. The device further has a projection lens system for projecting light modulated by the picture display panel to form an image. The illumination side of the picture display panel is provided with a microlens array having m microlenses and a pitch p.sub.m. The illumination system includes N illumination elements which are arranged in an array and have pitch p.sub.1. The illumination elements generate light simultaneously. Moreover, N&lt;&lt;m,n and p.sub.1 &gt;&gt;p.sub.m, p.sub.p.

Picture display device

The invention relates to an image projection device. This device comprises an illumination system having a lamp for supplying an illumination beam, at least one image display panel for modulating the illumination beam in accordance with an image to be projected to a signal beam, and a projection lens system for projecting the image on a projection screen. To suppress Moire interference between the structure of the image projection screen and the image display panel, an optically transparent beam-displacing element is arranged at an angle with respect to the signal beam axis in at least a portion of the signal beam in the light path between the image display panel and the projection screen at a position where a lamp image is present.

Image projection device with suppressed moire

A multi-standard display device having a liquid crystal display screen has so far only been realized by using all kinds of interpolation techniques. To make the number of rows and columns of the display screen independent of the incoming video signal and yet provide the possibility of displaying the various television standards without any disturbing errors, the incoming video signal is applied to the display screen via a scan-conversion circuit. The scan-conversion circuit reads in the video information in a first direction and subsequently reads it out in a second direction perpendicular to the first direction, for example, with storage in a memory. The video information is subsequently applied in the second direction to the row driver of the display screen, which row driver applies the video information to the display screen per column and under the control of the column driver.

Multi-standard display device with scan conversion circuit

A low-throughput illumination system is described, comprising a radiation source (1), a plurality of condensors (2, 14; 3, 15) for forming a plurality of beams (b.sub.1, b.sub.2) from the radiation supplied by the source and a first reflector (4, 5) for each beam, which reflectors direct the beam towards the principal axis (00'). The system comprises second reflectors (6, 7) which deflect the beams in the direction of the principal axis so that the beams have their narrowest constrictions (8, 9) in the exit plane (10) and are located close together.

Illumination system

In a picture display device driven with an active matrix the voltage across the picture elements (12) is accurately adjusted by discharging or charging the associated capacitances, if necessary, first to beyond the transition range (17) in the transmission/voltage characteristic.

Display device and method of driving such a device

In a color display device color elements (17, 18, 19, 21, 22, 23) are built up with the aid of picture cells (2) from juxtaposed rows of picture cells which are driven by line electrodes (3). The resolving power in the horizontal sense is increased by building up the color elements from picture cells of different rows of picture cells. The period t.sub.1 which is required for driving a color element is split up into sub-periods 1/2t.sub.1 during which period samples of the signal to be displayed (length t.sub.o) are presented to the column electrodes (4). Since notably for LCD-TV there applies that t.sub.1 &gt;t.sub.o, these samples can be presented during a period which is longer than 1/2t.sub.o.

Color display device

Such a device comprises display elements (RC) arranged, for example, in matrix form in rows and columns with, each display element comprising a first (E1) and a second electrode (E2) and an intermediate, movable, third electrode (E3). The first electrode (E1) is used in common by the elements (RC) with, the second electrode (E2) forming part of a strip-shaped row electrode and the third electrodes (E3) having an electrical through-connection in the column direction. Depending on the polarities of information pulses applied to the electrodes by a control voltage source, the third electrode is positioned adjacent the first or second electrode to achieve a bright or a dark picture element on display. With picture element-selective drive by a row selection with, a change being made for the selected picture element from the bright to the dark state, a non-energized state occurs at the other bright and dark picture elements in the column. To counteract the possibility of picture disturbance, a pulse (CT2) is simultaneously applied, in addition to the information pulses (CT1), to each electrode with a polarity which is the same for the first and the second electrodes and is the opposite for the third electrode. This results in a reset with a memory state.

Electroscopic picture display device having selective display of local

The display arrangement is provided with display elements which comprise a first and a second electrode, between which each a displaceable third electrode is present, and with a control voltage source, for selectively situating the third electrode near the first or second electrode, depending upon a voltage difference with the first or second electrode. In order to obtain a minimum or no cross-talk from selected display elements to adjacent selected or non-selected display elements, the display elements being arranged in a matrix in rows and columns, the voltage source supplies at least during the period (DT) of the information supply to the display elements (R1C1, R1C2, . . . R3C3) three values of control voltage (SC1, SC2, SC3) to at least one of the three electrodes.

Electroscopic picture display arrangement

A line synchronizing circuit for a picture display device comprising a voltage-controlled oscillator for generating a signal whose frequency is higher than the line frequency, a frequency dividing circuit for dividing the frequency of the oscillator signals and a phase comparison stage for generating a control voltage in dependence on the phase deviation between the signals applied thereto, more specifically a received line synchronizing signal and a locally generated reference signal. The elements of the line phase control loop, are part of an integrated circuit which functions as a frequency synthesizing circuit. The reference-frequency dividing circuit incorporated in the integrated circuit is programmed to operate with a constant divisor.

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Eindhoven, Netherlands

Martinus V Stroomer