JPS6035785B2 - Index type color picture tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an index type color picture tube, and more particularly to the structure of a video screen of the picture tube.

Indexing color picture tubes detect index signals related to the position of the electron beam on the video screen;
This color picture tube reproduces colors by modulating and switching the color video signal in relation to the electron beam position using this signal.

In general, index type color picture tubes (hereinafter referred to as index tubes), as shown in Figure 1, have crab photoreceptor stripes 2, 3, and 4 that generate three colors of red, green, and blue, and the light sandwiched between them. A panel consisting of an absorption strip 1 and a metal back layer 5 formed thereon; and a video screen consisting of a crab light strip 6 for detecting an index signal (hereinafter referred to as index strip) formed thereon; It consists of an electron gun 7 provided opposite to these, and the index strip 6 is accurately arranged in a fixed relationship with respect to the position and arrangement pitch of the tricolor light strips 2, 3, and 4.

The electron beam 8 emitted from the electron gun 7 is deflected by a deflection device 9, scans the video screen, and causes the index strip 6 to emit light together with the three color nectar strips 2, 3, and 4.

At this time, a continuous light panel obtained from the index stripes is received by a photoelectric conversion device 10 provided outside the index tube, and converted into electric pulses. By switching the video signal with an electric pulse having an appropriate time interval in synchronization with this electric pulse, the electron beam 8 is modulated with a predetermined color video signal when the electron beam 8 reaches a predetermined position of the crab photoresis. This means that color reproduction can be performed. Furthermore, as is well known, the amount of beam current in the index tube is at a minimum, and even when the video signal is zero, it is necessary to always emit a constant electron beam in order to prevent the index signal from being interrupted. The amount of current is determined on the condition that it must be of an amount that does not impede a reduction in the contrast of the image.

The maximum value is determined under the conditions of obtaining high brightness, high color saturation, and high contrast ratio. Specifically, since the operating current of the index tube has a wide dynamic range from several amps to mA, a corresponding dynamic range is also imposed on the detector (photoelectric conversion device). Particularly during high current operation, the saturation and response characteristics of the photoelectric conversion device (usually a photomultiplier tube) cause a phase error, making it difficult to extract an accurate index signal, resulting in desirable color reproduction. becomes impossible. The present invention has been made in view of the above-mentioned drawbacks, and particularly relates to the structure of the image screen of the index tube. Next, one embodiment of the index tube of the present invention will be explained with reference to FIGS. 2 and 3. In other words, a panel is formed with a film surface consisting of crab light strips 12, 13, and 14 that emit light in three colors and a light absorption strip 11 interposed therebetween, and these backlight strips are placed on the electron gun side surface of this panel. A video screen is constituted by index stripes 16 arranged in a certain positional relationship with the index strips and light absorption strips, and a metal back layer 15 formed on the surface of the panel facing the electron gun, including the index strips 16 thereon.

In the figure, 17 is an electron gun, 18 is an electron beam, 19 is a deflection device, and 20 is a photoelectric conversion device. FIG. 3 is an enlarged view of the above video screen structure. For example, the AI particles forming the metal back layer deposited on the surface of the index strip 16 on the electron gun side are extremely small compared to the crab photon particles for the index strip. Therefore, it is arranged so that it penetrates into the surface layer of the index strip and has a sufficient metal back effect on the tricolor light strips 12, 13, and 14. Therefore, when the beam current IK is small (left side of the figure), the index light pulse is emitted only from the index stripe surface,
Furthermore, when the beam current IK is large (see the right in the same figure), the entire index strip emits light, but the light emitted from the part near the screen face 21 is scattered by the mountain particles or absorbed by the black light absorption light, resulting in As a result, a relative decrease in the received light input occurs,
As a result, the output of the index light pulse has a relative selection characteristic (sublinear characteristic) with respect to the magnitude of the beam current.
will be obtained. To explain this relationship using Figure 4, curve a is a normal index tube, that is, one in which an index strip is arranged on the back of the AI membrane, and the light emitting output of the stripe is almost linear with respect to the beam electric firewood 5K. Therefore, when the beam current IK is large, the photoelectric conversion device (photomultiplier tube) operates in the saturation region, which not only causes the above-mentioned phase error but also shortens its life. Curve b shows an index tube according to the present invention, that is, a metal back layer is placed on the surface of the index strip on the electron gun side. (characteristics), the above-mentioned phase error does not occur, and the life of the photoelectric conversion device can be improved. Further, the present invention not only has the above-mentioned advantages, but also has the advantage that defects in the video screen such as blistering and seepage of the deposited film can be prevented during the manufacturing process. As described above, the present invention has extremely great industrial value.

In the above embodiment, the metal back layer on the electron gun side side of the panel consisting of the three-color light stripes and the light absorption strips was omitted, but the formation of this metal back layer, i.e. By forming two metal back layers sandwiching the index stripes, in addition to increasing the stability of the panel surface during filming, which is necessary after forming the three-color light strips, color image reception is improved. Needless to say, the brightness of the tube can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of a conventional index type color picture tube, FIG. 2 is a partially cutaway side view of an embodiment of the index type color picture tube of the present invention, and FIG. 3 is a partially cutaway side view of a conventional index type color picture tube. FIG. 4 is a curve diagram showing the relationship between the optical output of the index stripe and the beam current in the index type color picture tube of the conventional and the present invention. 1, 11... Light absorption strip, 2, 3, 4, 12, 1
4... Crab light body stripe, 6, 16... Index stripe, 5, 15... Metal back layer. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. A panel having a film surface formed on the inner surface consisting of phosphor stripes of three colors and light-absorbing stripes interposed between the phosphor strips, and a metal back layer coated thereon. , a phosphor strip for detecting an index signal formed on the surface of the metal back layer on the electron gun side in a certain positional relationship with respect to the phosphor strip and the light absorption strip; and the phosphor strip for detecting an index signal. An index type color picture tube characterized in that it has a metal back layer formed on the surface of the panel facing the electron gun, including the top surface of the panel. 2 A panel with a film surface formed on the inner surface consisting of phosphor strips of three colors and light absorption strips interposed between the phosphor strips, and a panel with the phosphor strips on the electron gun side of the film surface. and a phosphor strip for detecting an index signal formed to have a certain positional relationship with respect to the light absorption strip, and a metal back formed on the electron gun side surface of the panel including above the phosphor strip for detecting the index signal. An index method color picture tube characterized in that it has a layer.