U.S. Philips Corporation

Philips Electronics North America Corporation

Leendert Vriens

Johannes H Spruit

Johannes C Rijpers

Gerrit B Gerritsen

Cornelis Reinder Ronda

Aart A Van Gorkum

Titus E Brandsma

Dirk Jan Broer

John A Clarke

Willem M Van Alphen

Albert A Comberg

Johannes C Van De Ven

Johannes C Van Nes

Terence Doyle

Henricus M De Vrieze

Robertus A Keijser

Arne L Duwaer

Franciscus A Vollenbroek

Bram Johan Derksema

Matheus J Lammers

Frank Gersmann

Johannes H Roosen

Christaan Hentschel

Johannes H Wilting

Maurits R Smits

Andre Van Der Voort

Antonius P Van De Langenberg

Rene A Stoffels

Barry Singer

Gerard Acket

John A Clark

Alexander R Van Schoonhoven

A display monitor operating under the raster scanning system repeats the line scanning of an electron beam by moving the resulting scanning lines in a direction substantially perpendicular to the line direction. In a cathode ray tube (CRT), the dot pitch of the fluorescent material on the display screen (DS) of the cathode ray tube (CRT) that can emit a fluorescence is determined by the aperture pitch of the shadow mask. Thus, in case of displaying a video pattern (f1h) in which consecutive pixels in a line repeat in an ON and OFF sequence an interference with the aperture pitch of the shadow mask may occur, thereby causing a moir&eacute;. The moir&eacute; phenomenon is reduced with a notch filter (NF) which has a passband for baseband video frequencies (f1h) and which has a notch in the amplitude characteristic at a spatial frequency a) at or near to a spatial frequency of dots (fdh or fhh) on the display screen (DS), or b) at or near to a predetermined spatial higher harmonic (f2h, f4h) of the baseband video (f1h) which is near to said spatial frequency of the dots (fdh or fhh).

Video moire reduction

A display system which comprises a means for changing the s/a.sub.v and/or p/a.sub.h ratio, the scanning-line pitch s and/or the pixel pitch p of incoming signals.

Cathode ray tube, display system incorporating same and computer

By selecting the number of apertures per vertical row in the shadow mask of a color cathode ray tube to be in the range between 615 and 650, such a cathode ray tube can be used both in a PAL, an NTSC system and a MUSE system without the occurrence of disturbing Moire effects. In a second embodiment the number of apertures per row ranges between 425 and 450.

Color cathrode ray tube and display device

A visible light emitting device for use in lighting and/or display applications includes a UV LED, a phosphor layer on the upper, main light emitting surface of the LED, and a short wave pass (SWP) filter between the LED and the phosphor layer to transmit UV light from the LED to the phosphor layer, as well as to reflect visible light from the phosphor layer in a forward direction, thus enhancing the efficiency of the device. Additional optical filters located on the top of the phosphor layer further enhance efficiency and/or spectral characteristics of the emitted light.

UV/blue LED-phosphor device with short wave pass, long wave pass band

A light emitting device for use in lighting and/or display applications includes a UV/blue LED located in a depression having reflecting sidewalls, a light transmitting material surrounding the LED and filling the depression, and a phosphor in the form of particles either dispersed in the light transmitting material or adhered to the surface of the LED. The sidewalls reflect UV as well as visible light, thus enhancing the efficiency of the device. Optical filters located on the top of the LED and/or the bottom of a UV absorbing glass plate covering the depression further enhance efficiency and/or spectral characteristics of the emitted light.

UV/blue led-phosphor device with efficient conversion of UV/blues light

A display device having a cathode ray tube which comprises a display window. The radius of curvature of the inside of the display window along the diagonal (R.sub.diag) is greater than 1.6.times.1.767.times.D and smaller than 3.0.times.1.767.times.D, where D is the length of the diagonal of the display window. For the inside surface it holds that the quotient of the sagittal height at the end of the diagonal (21) and the sum of the sagittal heights at the end of the long axis (22) and at the end of the short axis (23) ranges between 0.75 and 0.95. In embodiments, the inside surface also complies with the formula 1.5&lt;R.sub.x (0,0)/R.sub.x (x.sub.max, O)&lt;4, where R.sub.x (0,0) and R.sub.x (x.sub.max, 0) are the radii of curvature along the long axis in the centre of the display window and at the end of the long axis, respectively. By virtue thereof, an improved picture display as regards reflection, local doming and raster distortion can be obtained.

Display device having a display window

By selecting the number of apertures in the shadow mask of a color cathode ray tube system to be such that the s/a.sub.v ratio, where s is the scan pitch for the entire frame and a.sub.v is the vertical mask pitch, is between 5.8/8 and 6.4/8 (5.8/8.ltoreq.s/a.sub.v .ltoreq.6.4/8) or between 9.4/8 and 10.6/8 where the lines are progressively scanned or, where the lines are scanned in an interlace mode with a frequency higher than 70 Hz, the s/a.sub.v ratio is between 5.8/8 and 6.4/8 (5.8/8.ltoreq.s/a.sub.v .ltoreq.6.4/8) or between 9.4/8 and 10.6/8, a cathode ray tube system is provided with a reduced occurence of disturbing Moire effects.

Color cathode ray tube and display device with reduced moire

A display device having a rectangular display window with a major and a minor dimension, and a deflection unit producing a scanning line raster on a display screen on the inner surface of the display window, the scan lines extending in the minor direction. The inside surface of the display window has a major radius of curvature (R.sub.cmajor), a minor radius of curvature (R.sub.cminor), a diagonal dimension (D) and an aspect ration (A), which parameters are related by the formulas 1.1&lt;R.sub.cminor /D&lt;2.5, also 2.5&lt;R.sub.cmajor /D, also R.sub.cmajor &gt;A*R.sub.cminor. The display window is thereby very flat and scanning line raster distortion is reduced so that it is easily correctible by the deflection fields produced by the deflection unit.

Color picture tube with reduced raster distortion and flat appearing

Method of vapor-depositing an interference filter layer on the inside of a display window, a display window, a projection cathode ray tube and a projection television apparatus. A method of manufacturing a projection cathode ray tube comprising an interference filter on an inwardly directed surface of a display window, the method comprising as a process step the vapor deposition of at least one layer of the interference filter. It has been found that the edges of a display window during the vapor deposition of an interference filter layer detrimentally influence the thickness of the vapor deposited layer, the thickness increases more towards the edges than follows from geometrical computations. In the method according to the invention vapor deposition is performed on a display window for which the height of the edge is less than 1/5 of the minor axis. The display screen preferably comprises a recessive edge.

Method of vapor depositing an interference filter layer on the inside of

Device for projecting television pictures by means of an assembly of three television picture tubes with associated lens systems arranged in each other's proximity, including an integrated cooling system. The integrated cooling system has a liquid circuit comprising a first duct extending below the television picture tubes, which duct is in direct communication via passages with the lower ends of the flow spaces, and a second duct extending above the television picture tubes, which duct is in direct communication via passages with the upper ends of the flow spaces. The first and the second duct are connected via at least one connection duct which extends along an end the assembly constituted by the three television picture tubes.

Television projection system having frame with integral cooling

Picture display device comprising an in-line color display tube of the shadow mask type having an elongate display screen with a short axis and a long axis, and comprising a deflection system. The plane in which the undeflected electron beams are located is parallel to the short axis of the display screen. The shadow mask has elongate apertures with longitudinal axes extending transversely to the short axis of the display screen. This configuration renders the picture display device less sensitive to unwanted displacements of the shadow mask in the direction transverse to the display screen, which is advantageous, particularly for display screen aspect ratios of more than 4:3.

Shadow mask color display tube

A cathode ray tube, such as a projection cathode ray tube, having a multilayer interference filter disposed between the cathodoluminescent screen and the interior side of the faceplate, the interference filter comprising alternate layers having high (H) and low (L) refractive indices, the high refractive index material being niobium pentoxide and the low refractive index material being either silicon oxide or magnesium fluoride. These filters are substantially free from the crazing which occurs in known filters when subjected to the normal thermal processing of cathode ray tubes.

Cathode ray tube having multilayer interference filter

Projection television display device includes three monochrome projection television display tubes (20, 21, 22) each having a display screen (24, 25, 26) which is provided on the inside of the display window (23) and luminesces in a different color. Each tube has an optical axis extending perpendicularly from the center of the display screen, the optical axes (33, 34, 35) of the three display screens being co-planar. The axes (34, 33) of the display screens of the first and second tubes (20, 22) coincide and the axis (35) of the display window of the third tube (21) constitutes the main axis of the device, the axis being perpendicular to the two coincident axes (33, 34). Two flat dichroic intersecting reflective mirrors (27, 29) extend perpendicularly of the plane and through the point of intersection of the axes, each at an angle of 45.degree. with the main axis. The first mirror (27) reflects the image of the first display screen and the second mirror (29) reflects the image of the second display screen into the direction of the main axis and away from the third display screen, interference filters being disposed between the display screens and mirrors for passing the desired color of light. With interference filters disposed between the luminescent material of the display screens and the display windows, the reflection greatly increases for light rays constituting an angle of more than 20.degree. to 35.degree. with the normal of the filter. When there is substantially no transmission up to 90.degree., there is a gain in brightness by a factor of 1.5 to 2, a gain in contrast by more than a factor of 2 and also a considerable color improvement and reduction of color errors when the conventional green and blue phosphors are used.

Projection television display device

A color cathode ray tube of the shadow mask or beam index type in which the screen structure applied to the faceplate has a plurality of triplets of optical interference filter stripes which are adapted to pass red (R), green (G) and blue (B) light produced by a homogeneous cathodoluminescent screen layer. The usual aluminium layer may be applied to the screen layer. The optical interference filter stripes may have short wave pass filters, band pass filters or a combination of both types. The short wave pass filter stripes may have modified quarter wavelength multilayer dielectric filters and the bandpass filter may have a Fabry-Perot filter.

Color cathode ray tube having interference filter with different pass

In a device for measuring the cut-off wavelength of an interference filter for a projection television display tube, the interference filter and a bandpass filter are arranged one behind the other. The bandpass filter has a transmission characteristic with a cut-off wavelength which approximately coincides with the desired cut-off wavelength of the interference filter, but with a slope varying in the opposite direction. A white light beam generated in a light source is incident through the two filters. The intensity, which is measured by a detector on the other side of the filters, is a measure of the cut-off wavelength of the interference filter. The device may have a second measuring system for measuring the absorption of the interference filter.

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Eindhoven, Netherlands

Leendert Vriens