Shadow mask tube

The Ce -activated cathode-ray phosphors are used in applications where a very short decay time is a requirement [13). Since the emi.ssion is a completely allowed transition (5t/-> 4/, Sect. 3.3.3Ji), the decay time of Ce varies between about 15 and 70 ns, depending on the emission wavelength. One application is in the beam-index tubes which generate color images by means of one electron gun [1,13]. This system could, however, never compete with the above-mentioned shadow-mask tube. The beam-index phosphor indicates the location of the electron beam. Therefore, the emission should have a very short decay time and, in order not to disturbe the image, should be situated in the ultraviolet. A good choice is Y2Si2C>7 rCe with a radiant... 

Electron beam efficiency in a shadow-mask tube is low, relative to a monochrome CRT. Typical beam efficiency is 9% considering the three beams of the color tube, total efficiency is approximately 27%. By comparison, a monochrome tube may easily achieve 80% electron beam efficiency. This restriction leads to a significant reduction in luminance for a given input power for the shadow-mask CRT. 

Elimination of conventional mask transmission loss, which reduces the electron beam-to-luminance efficiency of the shadow mask tube, permits the Trinitron to operate with significantly greater luminance output for a given beam input power. 

An already substantial and rapidly growing market for CRT phosphors and tubes is in the area of data displays, both alphanumeric and graphic, e.g., computer terminals and word processors. In spite of dramatic advances in other technologies, CRT s are still the most cost effective way to present information, and very likely always will be. Most data display tubes do not use rare earth phosphors because of their high cost, rare earth phosphors find use only when there is a compelling need for their special properties. At the present time, this is limited to the use of Eu3+ reds in tricolor tubes that use the same shadow mask principle as conventional color TV. 

In the coating of color picture tubes, the three components red, green, and blue are applied consecutively as dispersions in a photosensitive resin. This is then exposed to light via a shadow mask so that the resin on the exposed areas becomes water-insoluble. The phosphor on the unexposed areas is washed off with water. 

FIGURE 5.103 Basic concept of a shadow-mask color CRT (a) overall mechanical configuration, (b) delta gun arrangement on the tube base, (c) shadow-mask geometry. 

Figure 5.105 illustrates the shadow-mask geometry for a tube at face center using in-line guns and a shadow mask of round holes. As an alternative, the shadow-mask may consist of vertical slots, as shown in Fig. 5.106. The three guns and their undeflected beams lie in the horizontal plane. The beams are...

FIGURE 5.105 Shadow-mask CRT using in-line guns and round mask holes (a) overall tube geometry, (b) detail of... 

Deflection of the electron beams in a color CRT represents a difficult technical exercise. The main problems that occur when the three beams are deflected by a common deflection system are associated with the spot distortions that occur in single-beam tubes. However, the effect is intensified by the need for the three beams to cross over and combine as a spot on the shadow mask. The two most significant effects are curvature of field and astigmatism. 

From the standpoint of television receiver manufacturing simplicity and low cost, packaging of the display device as a single component is attractive. The tube itself is composed of only three basic parts an electron gun, an envelope, and a shadow-mask phosphor screen. The luminance efficiency of the electron optical... 

Cathode Ray Tubes (CRT) contain two elements that are made by means of microlithography the shadow mask and the TV screen. When a TV set operates, electrons emitted from three differently positioned electron guns pass through the holes of the shadow mask and excite the phosphor raster on the TV screen. As three different phosphors are present on the screen (for the colours green, blue and red), a full colour image is produced... 

The shadow mask, which was used to delineate the raster on the screen, is mounted together with the screen in one CRT to obtain a close correlation in each tube between mask and raster. 

ED photoresists are increasingly being successfully applied to photochemical machining processes in the manufacture of products such as colour TV receiver tube aperture masks (shadow masks), integrated circuit lead frames and printing rollers. These resists are used as etch-resists for a variety of metals and alloys, and can withstand the harsh etching conditions used in these processes. 

CPK = Corey, Pauling, and Koltun CRT = cathode ray tube CSM = color shadow mask DOF = degrees-of-freedom. 

In 1976, the number of patents and utility model exhibitions of Japan topped 1,200 cases according to a patent dossier at that time. The reason why many patents were applied for a few-layered device was the electronic companies strong policy for developing LCD TV to their main business. As Dai Nippon Printing had the global top share for shadow masks in cathode-ray tubes their main customers were electronics makers. Since the company could not compete with the customers they decided to withdraw from the LCD market at the end of 1976. 

Shadow masks on cathode-ray tubes that are used for television and... 

The cathode-ray tube is now over 100 years old. In 1880, WiUiam Crookes had demonstrated that cathode-rays, i.e.- an electron beam, would cast sharp shadows on a fluorescent screen if a mask was present within the tube. It remained for Karl Braun to invent the device that changed the world, a working cathode-ray tube (CRT) having internal electrodes which... 

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