JP2005026111A - Index color cathode-ray tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an index color cathode-ray tube having high contrast performance and improved in image quality. <P>SOLUTION: A phosphor screen having stripe-like three-color phosphor layers (R, G and B) and shading layers positioned between the phosphor layers are formed on the inside surface of a panel. A metal back is formed by being superposed on the phosphor screen, and first and second index phosphors 14a and 14b are formed on the metal back and superposed on the shading layers. Detection devices 22a and 22b for detecting light emission from the first and second index phosphors are installed; a beam position correction device moves the position of an electron beam according to the light emission from the first and second index phosphors to position the electron beam on a desired one of the phosphor layers, and moves the electron beam so as to position the center of the electron beam on either of the first and second index phosphors in black image display. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color cathode ray tube, and more particularly to an index type color cathode ray tube in which an index phosphor for grasping a beam position is arranged on a phosphor screen.
[0002]
[Prior art]
In general, a color cathode ray tube includes a vacuum envelope including a panel having a substantially rectangular effective portion, a funnel connected to the panel, and a cylindrical neck connected to a small diameter portion of the funnel. Yes. On the inner surface of the effective portion of the panel, there is formed a phosphor screen comprising a dot- or stripe-shaped three-color phosphor layer that emits blue, green, and red, and a light shielding layer. A shadow mask is disposed in the vacuum envelope so as to face the phosphor screen, and a number of apertures functioning as electron beam passage holes are formed in the shadow mask. An electron gun that emits three electron beams is disposed in the neck, and a deflection yoke is mounted from the outer periphery of the neck to the outer peripheral surface of the funnel.
[0003]
In the color cathode ray tube having the above configuration, the three electron beams emitted from the electron gun are deflected horizontally and vertically by the horizontal and vertical deflection magnetic fields generated by the deflection yoke, and the electron beams are selected by the electron beam passage holes of the shadow mask. A color image is displayed by being incident on the phosphor layer of the phosphor screen.
[0004]
The problem of such a color cathode ray tube is energy utilization efficiency. As described above, in the color cathode ray tube, the beam emitted from the electron gun is allowed to pass through a large number of apertures arranged in the shadow mask which is the color selection electrode, and the phosphor screen emits light. However, about 80% of the electron beam emitted from the electron gun collides with the shadow mask, and only the remaining about 20% passes through the aperture of the shadow mask and only emits the phosphor screen. Most of the energy of the electron beam that collided with the shadow mask is changed to heat, which causes thermal expansion of the shadow mask. If the amount of energy that has changed into heat when it collides with the shadow mask can be used for light emission from the phosphor screen, the brightness can be significantly improved, and the range of use can be greatly expanded for dynamic images and outdoor use.
[0005]
As one method for solving such a problem, a color cathode ray tube of a system called an index tube is known. This index tube has substantially the same external shape as a normal color cathode ray tube, and includes a panel, a funnel, and a neck, and an electron gun is disposed in the neck. Striped three-color phosphors of red, green, and blue are arranged on the inner surface of the panel, and the stripes extend in the short axis direction of the screen. A stripe-shaped non-light emitting layer made of a black non-light emitting material is provided between the phosphors of the respective colors. On the electron gun side of the phosphor screen, a metal vapor deposition film called a metal back, usually made of aluminum, is disposed. Since the aluminum film has a metallic luster, it reflects light from the fluorescent material and light from an index fluorescent material, which will be described later, in the respective directions like a mirror.
[0006]
In the case of an index tube, an index phosphor is further formed on the electron gun side of the aluminum layer, and is disposed at a location on the non-light-emitting layer in the stripe shape. In the index tube, a shadow mask that is disposed in a normal color cathode ray tube is not disposed.
[0007]
In such an index tube, the electron beam emitted from the electron gun is deflected by a deflection yoke attached to the funnel and travels toward the phosphor screen. When this electron beam collides with the index phosphor, the index phosphor emits light, and the light is reflected by the aluminum film and does not go on the screen but goes to the funnel side. This light is received by a pickup device constituted by a photodiode or the like provided outside the funnel. The pickup device can detect the current electron beam position in conjunction with other circuits. Based on the detected current electron beam position, it is possible to display various images by emitting an electron beam in accordance with a phosphor to be emitted next. Such vertical stripe type index tubes have been developed for a long time, but are difficult to increase in size and definition, and are not currently mainstream.
[0008]
In recent years, horizontal stripe type index tubes are being developed. In this horizontal stripe type index tube, the red, green and blue stripe phosphors and the stripe non-light emitting layer are arranged so that the direction thereof extends in the horizontal direction (horizontal axis direction) of the screen. A metal back layer is arranged on the electron gun side of the phosphor screen, and an index phosphor is arranged on the electron gun side. The index phosphor is disposed on the striped non-light emitting portion. Therefore, this index phosphor also extends in the horizontal direction of the screen. There are two types of index phosphors, which are alternately arranged.
[0009]
One or three electron beams are emitted from the electron gun and deflected by the deflection yoke in the horizontal direction of the screen. The deflected electron beam is scanned on the red, green, and blue phosphors extending in the lateral direction, and an image is drawn by changing the amount of electron beam current in accordance with the position of the screen.
[0010]
At this time, if the electron beam is positioned on a predetermined phosphor, the two types of index phosphors arranged on the non-light emitting layer collide with almost the same electron beam, and both index phosphors It emits the same amount of light. However, when the position of the electron beam deviates from the position of the predetermined phosphor layer, many electron beams collide with one of the index phosphors. A deviation of the electron beam with respect to a predetermined phosphor is detected according to the amount of light emitted from these two types of index phosphors, and the electron beam position is corrected according to the amount of deviation. The electron beam position can be corrected by a beam position correction device including a coil that generates a magnetic field of a multipole arranged near or in the deflection yoke (for example, see Non-Patent Documents 1, 2, and 3). .
[0011]
[Non-Patent Document 1]
Etch. Bee. Van den Brink, Oh. Etch. Willemsen, “Tracking system of the Fast Intelligent Tracking (FT! Tube)”, Information Display Association, Philips Research Institute, 2002. December, p571-574
[0012]
[Non-Patent Document 2]
A. Etch. A. Bergman, Etch. Bee. Van den Brink, F.V. Pee. M. FP M Budzelaar, P.P. Je. Engeler (PJ Engelaar), A. Etch. M. Holzlag, double. El. E.I. Zerman, M.M. Pee. Sea. M. Klysine (M.P.C.M.Krijn), P.I. Je. Gee. Van Rieshot (PJG van Lieshout), A. A. Notari, Oh. Etch. WH Willemsen, “44.1: Fast Intelligent Tracking (F! T) Tube: CRT Without Shadow Mask (44.1: The Fast Intelligent Tracking (FT) tube: A CRT without a) “Shadow Mask” ”, Eindhoven, The Netherlands, Information Display Association, Philips Research Institute, May 2002, p1210-1213
[0013]
[Non-Patent Document 3]
Remco. Horn (Remko Horne), "44.2: Scaling Up (F! T) CRT Technology (44.2: Scaling-up the F! T CRT Technology"), Eindhoven, Netherlands Association, Elgie. Philips Display, May 2002, p1214-1217
[0014]
[Problems to be solved by the invention]
However, there are the following problems in such an index tube. In the horizontal stripe type index tube described above, in order to know the position of the electron beam, the light of the index phosphor emitted by the beam is required. In general, the diameter of an electron beam emitted from an electron gun and hitting a phosphor screen increases at a high current and decreases at a low current. Therefore, at high current, when the electron beam strikes a predetermined phosphor position, it also strikes the index phosphors above and below the phosphor, and these index phosphors can emit light. However, at a low current, even if the electron beam hits a predetermined phosphor, it is difficult to sufficiently emit the index phosphor. Therefore, in order to accurately detect the position of the electron beam, an electron beam having a certain amount of current must always be emitted.
[0015]
Therefore, even when a black image is expressed, an electron beam having a certain amount of current must be continuously emitted in order to cause the index phosphor to emit light. As a result, in this system, even when a black image is displayed, the phosphor screen emits light slightly, and the contrast is lowered.
[0016]
The present invention has been made in view of the above points, and an object thereof is to provide an index type color cathode ray tube having high contrast performance and improved image quality.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, an index type color cathode ray tube according to an aspect of the present invention includes a panel having a major axis and a minor axis perpendicular to the axis of the tube, an envelope having a funnel and a neck, and the major axis. The phosphor layers in the form of stripes of red, blue, and green that extend along the direction and have a gap in the minor axis direction, and extend along the major axis direction and are positioned between the phosphor layers A phosphor screen provided on the inner surface of the panel; an electron gun provided in the neck for emitting an electron beam toward the phosphor screen; and the phosphor screen. A metal back formed in an overlapping manner, and provided on the surface of the metal back on the electron gun side, are positioned so as to overlap the light shielding layer and extend along the major axis direction. A first and a second index phosphor; a deflection yoke provided outside the funnel, for deflecting and scanning the electron beam in the major axis direction and the minor axis direction; provided outside the envelope; A detecting device for detecting light emitted from the first and second index phosphors, and moving the position of the electron beam along at least the minor axis direction in accordance with the light emission detected by the detecting device; A beam position correction device that moves the electron beam so that the center of the electron beam is positioned on one of the first and second index phosphors when displaying a black image. It is characterized by having.
[0018]
According to the index type color cathode ray tube having the above configuration, when drawing a black image, the phosphor for drawing the image is not caused to emit light unnecessarily, and the index phosphor is emitted to grasp the position of the electron beam. Is possible. As a result, it is possible to provide an index type color cathode ray tube having good contrast characteristics without impairing the advantages of the index tube.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a color cathode ray tube according to an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIGS. 1 and 2, the color cathode ray tube includes an envelope 10 made of glass. The envelope includes a rectangular panel 1 having a skirt portion 2 at a peripheral edge, and a panel 1. The funnel 3 joined to the skirt portion 2 and the neck 4 extending from the small diameter portion of the funnel 3 are provided. The envelope 10 has a tube axis Z passing through the center of the panel 1 and the center of the neck 4, a long axis (horizontal axis) X extending perpendicular to the tube axis, and extending orthogonal to the tube axis and the long axis. It has a short axis (vertical axis) Y.
[0020]
When a 32-inch wide type color cathode ray tube having a screen aspect ratio of 16: 9 and an effective screen diameter of 76 cm is taken as an example, the outer surface of the panel 1 has a curvature radius of 100,000 mm or more and is substantially flat. An electron gun 8 that emits three electron beams 9R, 9G, and 9B arranged in-line along the long axis X direction is disposed in the neck 4.
[0021]
As shown in FIGS. 3 and 4, a phosphor screen 5 is formed on the inner surface of the panel 1. The phosphor screen 5 includes a phosphor layer of three colors of red (R), green (G), and blue (B) formed in a stripe shape, and a plurality of black light shielding layers 11 formed in a stripe shape. Yes. The phosphor layers R, G, and B extend along the major axis X direction and are arranged with a gap in the minor axis Y direction. Each of the black light shielding layers 11 extends along the long axis direction and is located between the phosphor layers. A metal back 12 made of aluminum, for example, is formed so as to overlap the phosphor screen.
[0022]
A plurality of first and second index phosphors 14 a and 14 b are provided on the surface of the metal back 12 on the electron gun side, that is, on the neck side, respectively. The first and second index phosphors 14a and 14b are each formed in a stripe shape, are positioned so as to overlap the light shielding layer 11, and extend along the major axis X direction. The first and second index phosphors 14a and 14b are alternately provided in the short-axis Y direction, and are located on both sides of each phosphor layer R, G, and B. The first and second index phosphors 14a and 14b are formed so that the length along the major axis X direction is longer than the phosphor layers R, G, and B, and extends outward from both ends of the phosphor layer in the major axis direction. ing. The first and second index phosphors 14a and 14b are formed of phosphor layers having different emission wavelengths.
[0023]
As shown in FIGS. 1 to 3, on the outside of the funnel 3, a deflection yoke 16 that deflects the electron beams 9R, 9G, and 9B emitted from the electron gun 8 in the major axis and minor axis directions, and the position of the electron beam Is provided at least along the minor axis Y direction. In addition, a detection device 20 that detects light from the first and second index phosphors 14a and 14b is provided outside the funnel 3 as will be described later. The detection device includes a pair of first detection units 22a that detect light from the first index phosphor 14a and a second detection unit 22b that detects light from the second index phosphor 14b.
[0024]
The first and second detectors 22a and 22b include a filter that separates the light from the index phosphor according to the wavelength, a wavelength conversion element that amplifies, and a photodiode that converts the received light into an electrical signal according to the amount of light. Etc. The photodiodes constituting the pair of first detection units 22a are provided on the funnel 3 on both sides of the neck 4 and extend along a direction substantially parallel to the long axis X. Similarly, the photodiodes constituting the pair of second detection units 22b are provided on the funnel 3 on both sides of the neck 4 and extend along a direction substantially parallel to the major axis X, respectively.
[0025]
As shown in FIG. 5, the control circuit of the color cathode ray tube includes an image processing circuit 30 that performs image processing in accordance with image input data and detection signals from the first and second detection units 22a and 22b. Connected to the image processing circuit 30 are a current amount control circuit 32 that controls the amount of current applied to the electron gun 8 in accordance with image input data, a deflection yoke 16, and a beam position correction circuit 34. The beam position correction circuit 34 supplies current to the beam position correction coil 18 in accordance with a control signal from the image processing circuit 30 to correct the beam position. The beam position correction circuit 34 and the beam position correction coil 18 constitute a beam position correction device.
[0026]
Next, the operation principle of the horizontal stripe index type color cathode ray tube will be described. As shown in FIG. 3, the electron beam emitted from the electron gun is deflected in the major axis and minor axis directions by the deflection yoke 16, and sequentially scans the phosphor screen from the upper left to the lower right of the screen. The shape of the electron beam projected on the phosphor screen is basically horizontally long, that is, an ellipse that is long in the major axis X direction. When this horizontally long electron beam reaches the phosphor screen, it strikes the first and second index phosphors 14a and 14b arranged on both sides of the phosphor layer in addition to the target phosphor layer. The index phosphor also emits light simultaneously. The light from the three-color phosphor layers R, G, and B for image display draws an image on the screen.
[0027]
The light from the first and second index phosphors 14 a and 14 b is reflected by the metal back and travels in the funnel direction opposite to the panel 1. The first and second index phosphors 14a and 14b emit light with different emission wavelengths, and are taken in by the first and second detectors 22a and 22b disposed outside the funnel 3. The received light is converted into an electrical signal corresponding to the amount of light and sent to the image processing circuit 30. From the viewpoint of the correction operation speed, the two index phosphors 14a and 14b are, for example, Y ₂ Si0 ₅ : Phosphor called registration number P47 made of Ce, Y ₂ Al ₅ 0 ₁₂ It is preferable to use a phosphor having a short afterglow called registration number P46 made of Ce.
[0028]
As shown in FIG. 6, when the electron beam 9G collides with a desired phosphor layer, for example, the green phosphor layer G, at the correct position, the phosphor layer G is excited by the electron beam to emit light, and is displayed on the screen. Draw a green image. At this time, the electron beam 9G also collides with the first and second index phosphors 14a and 14b arranged above and below the phosphor layer G, and these index phosphors emit light at respective wavelengths. If light emission from the first and second index phosphors 14a and 14b is detected by the first and second detectors 22a and 22b, respectively, and these lights are the same as the preset light amount, the position of the electron beam 9G Is on the predetermined phosphor layer G.
[0029]
The first and second index phosphors 14a and 14b desirably form stripes longer than the three-color phosphor layers R, G, and B for image display. By forming the first and second index phosphors 14a and 14b so as to extend longer than the three-color phosphor layers R, G, and B, in particular, to the scanning start side, the electron beam is converted into the phosphor layers R, G, and B. Before hitting B, the position of the electron beam can be estimated and adjusted in accordance with the light emission from the index phosphor. Therefore, an accurate color image can be reproduced on the screen at the scanning start side.
[0030]
As shown in FIG. 7, when the position of the electron beam deviates from a predetermined phosphor layer, for example, when it deviates toward the first index phosphor 14a, the light from the first index phosphor increases, and the second index The light from the phosphor 14b decreases, and the amount of light deviates from a predetermined amount. In this case, the image processing circuit 30 applies a correction current to the beam position correction coil 18 via the beam position correction circuit 34 or applies a correction current to the deflection yoke 16 so that the projecting position of the electron beam is set to the lower side. The beam position is corrected so as to be positioned on a predetermined phosphor layer.
[0031]
On the other hand, in the index type color cathode ray tube, the position of the electron beam is grasped by the light from the index phosphor. Therefore, if there is no light emission from the index phosphor, the position of the electron beam will not be known. For example, as shown in FIG. 8, when most of the screen is a black image A and a part of a normal light-emitting image B is present, the black portion can be expressed if the electron beam is not emitted in the black image portion. During that time, the position of the electron beam cannot be grasped. For this reason, the position of the electron beam cannot be accurately detected at the boundary from the black image A to the light emission image B, and it is difficult to express an image of a predetermined color at this boundary portion. Actually, it is possible to estimate the electron beam position to some extent by storing the electron beam position information in the display image up to the previous time in a memory or the like. Therefore, the electron beam position up to the previous screen does not always match the current amount of the deflection yoke and the control input to the beam position correction device.
[0032]
Therefore, according to the index-type color cathode ray tube according to the present embodiment, when a black image is expressed, the electron beam is emitted from the electron gun 8, and the projection position of the electron beam is obtained by the deflection yoke 16 or the beam position correction device. Is slightly moved up or down along the minor axis Y direction to correct the electron beam to be positioned on the first or second index phosphor 14a, 14b. As shown in FIG. 9, here, the electron beam 9G is slightly moved upward.
[0033]
That is, when displaying a normal image, the light from the first and second index phosphors 14a and 14b above and below a predetermined phosphor layer is received by the first and second detectors 22a and 22b and converted into an electrical signal. Convert. The image processing circuit 30 grasps the position of the electron beam based on the detection signals from the first and second detection units 22a and 22b. In the case of black screen display, at least the deflection yoke 16 and the beam position correcting device are arranged so that the electron beam is positioned on the first or second index phosphors 14a and 14b above or below from the current electron beam position. One side adjusts the electron beam position.
[0034]
10 (a) and 10 (b) show image signals applied to one scanning line (C) in the major axis X direction crossing the circular effective portion B when the image shown in FIG. 8 is displayed. The relationship with the correction current is shown. In FIG. 10A, the horizontal axis indicates the horizontal position (position in the long axis direction) of the screen, and the vertical axis indicates the cathode voltage (cathode current) that controls the amount of the electron beam. In FIG. 10B, the horizontal axis indicates the horizontal position (position in the long axis direction) of the screen, and the vertical axis indicates the correction current amount for correcting the electron beam position.
[0035]
As can be seen from these figures, when displaying the area of the black image A, the cathode voltage is adjusted so that the cathode current becomes almost zero, and at that time, the position correction current is changed from the initial value to a predetermined value on the + side. Then, the projecting position of the electron beam is slightly moved upward and adjusted on the second index phosphor 14b. Further, in the region of the luminescent image B, the cathode voltage is adjusted so that the cathode current becomes a value corresponding to the image input data, the position correction current is returned to the initial value at the normal display, and the electron beam projecting position is changed to the fluorescence. Return to body layer G. As described above, the electron beam position can be controlled by adjusting the beam correction current amount in synchronization with the level of the cathode voltage.
[0036]
According to the index type color cathode ray tube configured as described above, the index phosphor emits light even when the electron beam is continuously emitted during black image display, but the phosphor layer for image display does not emit light. Therefore, it is possible to reproduce almost the same state on the display screen as the screen state where the electron beam is not emitted. At this time, it can be determined by the image processing circuit 30 that the image is displayed on the black screen, and the vertical position of the electron beam can be grasped without any problem by emitting a predetermined amount of electron beam and receiving the corresponding index light. can do. That is, light emission from the index phosphor is detected while emitting a predetermined amount of electron beam, and when the amount of light is less than a predetermined value, it can be detected that the position of the electron beam is deviated from the index phosphor. In this case, the electron beam position may be corrected upward or downward by the beam position correction device.
[0037]
Thus, according to the index type color cathode ray tube, the position of the electron beam can be detected without lowering the contrast when displaying a black image. The switching from the black image display to the normal light emission image display can be smoothly switched by correcting the position of the electron beam corrected for the black image display to the normal position.
[0038]
In the embodiment described above, the green electron beam 9G out of the three electron beams emitted from the electron gun has been described for the sake of simplicity. However, the same applies to the other electron beams 9R and 9B. The position can be corrected. That is, unnecessary light emission does not occur on the screen by simultaneously adjusting the positions of the three electron beams on the first or second index phosphor by the beam position correcting device. At this time, the three electron beams may be adjusted to be positioned on the same index phosphor, or may be adjusted to be positioned on different index phosphors. In any case, the positions of the three electron beams can be detected by determining the amount of each electron beam current in advance and detecting whether or not the index light corresponding to the amount is received. it can.
[0039]
The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
[0040]
【The invention's effect】
As described above in detail, according to the present invention, the position of the electron beam can be accurately detected to display a high-quality image, and a good black image can be drawn and an index with improved contrast performance. Type color cathode ray tube can be provided.
[Brief description of the drawings]
FIG. 1 is a sectional view including a major axis of an index type color cathode ray tube according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a back side of the index type color cathode ray tube.
FIG. 3 is a perspective view schematically showing a phosphor screen, an index phosphor, a deflection yoke, a beam position correction coil, and a detector in the index type color cathode ray tube.
FIG. 4 is a sectional view showing the phosphor screen and the index phosphor.
FIG. 5 is a block diagram showing a control circuit of the index type color cathode ray tube.
FIG. 6 is a diagram schematically showing a positional relationship between the phosphor screen, the index phosphor, and an electron beam that has hit a normal position.
FIG. 7 is a diagram schematically showing a positional relationship among the phosphor screen, the index phosphor, and an electron beam that has been projected to a shifted position.
FIG. 8 is a front view schematically showing an example of a black screen display.
FIG. 9 is a diagram schematically showing a correction state of an electron beam position when a black screen is displayed.
10 is a diagram showing a relationship between a card voltage and a beam position correction current when the black screen shown in FIG. 8 is displayed.
[Explanation of symbols]
1 ... Panel, 3 ... Funnel, 5 ... Phosphor screen,
8 ... electron gun, 9B, 9G, 9R ... electron beam,
12 ... metal back, 14a ... first index phosphor,
14b ... second index phosphor, 16 ... deflection yoke,
18 ... Beam position correction coil, 22a ... First detector, 22b ... Second detector,
30 ... Image processing circuit 34 ... Beam position correction circuit

Claims (4)

An envelope comprising a panel having a major axis and a minor axis perpendicular to the tube axis, a funnel and a neck;
Each of the phosphor layers in the form of red, blue, and green stripes extending along the major axis direction and spaced apart in the minor axis direction, and the phosphor layers extending along the major axis direction, respectively. A plurality of light shielding layers located between the layers, and a phosphor screen provided on the inner surface of the panel;
An electron gun provided in the neck and emitting an electron beam toward the phosphor screen;
A metal back formed over the phosphor screen;
First and second index phosphors provided on a surface of the metal back on the electron gun side, each positioned overlapping the light shielding layer and extending along the major axis direction;
A deflection yoke provided on the outside of the funnel for deflecting and scanning the electron beam in the major axis direction and the minor axis direction;
A detection device provided outside the envelope and detecting light emitted from the first and second index phosphors;
The position of the electron beam is moved along at least the minor axis direction according to the light emission detected by the detection device, the electron beam is positioned on the desired phosphor layer, and the electron beam is displayed when displaying a black image. A beam position correcting device for moving the electron beam so that the center of the beam is positioned on any of the first and second index phosphors;
An index type color cathode ray tube characterized by comprising: 2. The index type color cathode ray tube according to claim 1, wherein the first and second index phosphors have emission wavelengths different from each other and are provided on both sides of each phosphor layer. The detection device includes a first detection unit that detects light emission from the first index phosphor, and a second detection unit that detects light emission from the second index phosphor. 3. The index type color cathode ray tube according to 1 or 2. The first and second index phosphors are formed such that a length along the major axis direction is longer than the phosphor layer, and extends outward from a major axis direction end of the phosphor layer. The index type color cathode ray tube according to any one of claims 1 to 3.

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