JPH0644926A - Cathode-ray tube display - Google Patents

Abstract

PURPOSE:To substantially attain the flattening of a screen without sacrificing the image quality of a CRT display. CONSTITUTION:A CRT display 1 is constituted of a display front section 2 and a neck section 8. The display front section 2 has an outer surface 3 and an inner tube surface 4. The neck section 8 houses an electron gun or the like, and irradiates an electron beam to the tube surface 4 for image display. While the curvature of the tube surface 4 is maintained at a desired value, the outer surface 3 is flattened. Thus, the thickness of a transparent resin layer 7 positioned between the tube surface 4 and the outer surface 3 is constituted in such a way as gradually increasing along a direction from the center of a screen to the periphery thereof. According to this construction, the peripheral section of the tube surface 4 looks as if remarkably embossed, compared with the center section, due to light refracting action.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to cathode ray tube displays. More specifically, it relates to a technique for flattening a display screen.

[0002]

2. Description of the Related Art The structure and shape of a conventional cathode ray tube display (CRT) will be briefly described with reference to FIG. C
The RT 101 includes a front surface portion 102 and a neck portion 108 that form a display screen. The front part 102 includes a front panel 103 and a safety panel 104 which are transparent resin layers 10
It has a laminated structure of 5. A tube surface 106 is provided inside the front panel 103. The safety panel 104 is used for a relatively large CRT having a size of 20 inches or more, for example, and has a function of explosion proof and antireflection. Therefore, the surface 107 of the safety panel 104 is coated with an antireflection film or an antireflection coating. On the other hand, although not shown, an electron gun and a deflection yoke are attached to the neck portion 108, and the tube surface 10 of the front panel 103 is attached.
An electron beam is deflected and radiated to 6 to display.

[0003]

Generally, the electron beam is raster-scanned in the horizontal and vertical directions of the screen with reference to a predetermined deflection center. Therefore, the tube surface 106 has a convex shape having a predetermined curvature in order to prevent image distortion and the like as much as possible. On the other hand, for the viewer of the display, the screen is preferably as flat as the screen. In particular,
When the CRT is used for a CAD display or the like, it is desired that the straight line be displayed straight as it is, not only in the central portion of the screen but also in the peripheral portion. However, FIG.
In the conventional structure shown in FIG. 2, if the CRT front surface portion 102 is flattened, the curvature of the tube surface 106 must be extremely increased, which causes misconvergence, deterioration of focus, image distortion, and the like in the peripheral portion of the screen, and various CRTs. There is a problem that the characteristics are disadvantageous. Further, when flattening the front surface of the display with a large CRT or the like, the strength of the cathode ray tube itself is reduced. As described above, it is difficult for the conventional structure to achieve both flatness and various characteristics of the CRT.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, it is an object of the present invention to artificially flatten a display screen without sacrificing various characteristics of a CRT.
The following measures have been taken in order to achieve this object. That is,
What is claimed is: 1. A CRT display comprising: a display front part having an outer surface and an inner tube surface; and a neck part for irradiating the tube surface with an electron beam to perform a display, while maintaining a predetermined curvature of the tube surface. The surface is flattened, and the thick layer located between the inner tube surface and the outer surface is configured to be thicker from the center of the display front portion toward the periphery.

Preferably, the display front part has a structure in which a front panel having the tube surface and a safety panel having the surface are laminated with a transparent resin layer. In this laminated structure, the front panel has a convex shape and the safety panel has a flat shape, and the thickness of the transparent resin layer interposed between the two is thin in the central portion of the screen and thick in the peripheral portion of the screen. . Alternatively, the safety panel itself may be formed such that the central portion is thin and the peripheral portion is thick.

Further, in a relatively small household CRT display having a size of 20 inches or less, a safety panel may not always be mounted. In this case, the thickness of the front panel itself, which constitutes a part of the cathode ray tube, may be thinned in the central portion and thicker in the peripheral portion.

[0007]

In the present invention, the thickness of the front surface of the display is set to be thin at the center and thick at the periphery. Therefore, the tube surface located inside the display front portion has a predetermined curvature as in the conventional case, and does not adversely affect various characteristics such as convergence, focus and image distortion. On the other hand, CR
When the screen is observed from the surface of the T-display, the tube surface is lifted up in the peripheral portion of the screen as compared to the central portion of the screen due to the refraction of light, and the tube surface approaches a flat shape. In this way, it is possible to achieve the apparent flatness of the screen.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic sectional view showing a first embodiment of a CRT display according to the present invention, showing a shape cut along the horizontal direction of the screen. The cross-sectional shape when cut in the vertical direction is basically the same. However, when a so-called shadow mask is used to form a cylindrical screen, the cross-sectional shape cut in the vertical direction is originally flat. As shown, the CRT display 1 includes a display front surface portion 2 and a neck portion 8. The display front part 2 has an outer surface 3 and an inner tube surface 4.
On the other hand, although not shown, an electron gun, a deflection yoke, and the like are mounted on the neck portion 8, and the tube surface 4 is deflected and irradiated with an electron beam to perform display.

In this embodiment, the display front part 2 includes a front panel 5 and a safety panel 6 which form a part of the cathode ray tube.
And a transparent resin layer 7 are laminated. The transparent resin layer 7 is made of, for example, an ultraviolet curable polymer material.

The front panel 5 has a central convex shape facing the observer, and the tube surface 4 has a predetermined curvature as in the conventional case. On the other hand, the safety panel 6 has an extremely large curvature unlike the conventional one, and is made of a substantially flat transparent plate. Therefore, the thickness of the transparent resin layer 7 interposed between the front panel 5 and the safety panel 6 is thin in the central portion and becomes thicker toward the periphery.

FIG. 2 shows a second embodiment of the CRT display according to the present invention, which has basically the same structure as that of the first embodiment shown in FIG. Numbers are attached to facilitate understanding. The difference from the first embodiment is that the safety panel 6 has a flat front surface 3 and a curved back surface 9. Therefore, the safety panel 6 itself has a structure in which the central portion of the screen is thin and the peripheral portion is thick. On the other hand, the transparent resin layer 7 has a substantially uniform thickness and is interposed between the safety panel 6 and the front panel 5. In the first embodiment shown in FIG. 1, it may be difficult to supply and cure the transparent resin layer 7. In particular, the thickness of the transparent resin layer 7 in the peripheral portion of the screen may be considerably increased, and a high technique may be required for moldability and curing treatment. On the other hand, in the second embodiment, the manufacturing process can be simplified by simply adhering the safety panel 6 which is formed in advance to the convex shape of the front panel 5. However, some ingenuity is required to process the different shape of the safety panel 6.

FIG. 3 is a schematic sectional view showing a third embodiment of the CRT display according to the present invention. In order to facilitate understanding, the same parts as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals. In this embodiment, the display front part 2 is composed of the front panel 5 alone, and is not equipped with a safety panel. Such a structure may be adopted in a medium- or small-sized home television receiver of 20 inches or less. The surface 3 of the front panel 5 has an extremely large curvature and is substantially flattened. On the other hand, the tube surface 4 has a predetermined curvature as in the conventional case.
Therefore, the thickness of the front panel 5 itself gradually increases from the central portion of the screen toward the peripheral portion.

According to the present invention, the thickness of the display front portion is thin in the central portion and large in the peripheral portion. Therefore, when observing the screen from the front, it appears as if it goes up toward the periphery due to the refraction of light, and it is as if the tube surface were flattened.

Table 1 below shows the results of calculating the apparent curvature R of the tube surface 4 for the first embodiment of FIG.
In this calculation, the actual curvature of the tube surface is set to 2226 mm and the outer surface curvature of the front panel is set to 3302 mm. Further, the thickness of the central portion is set to 18.3 mm. Furthermore, the central portion thickness of the transparent resin layer 7 is 2.0 mm. The surface 3 of the safety panel (SP) 6 has a curvature of 40,000 mm and is substantially flattened. The thickness of the flat type safety panel 6 is set to 3.0 mm. Finally, the refractive index of the laminated structure including the front panel 5, the safety panel 6 and the transparent resin layer 7 was set to n = 1.5 on average.

[Table 1] As apparent from Table 1 above, when observed at a distance of 50 cm from the screen, the apparent radius of curvature R of the tube surface is 4116.
mm, which is about twice as large as the actual radius of curvature 2226 mm, and a remarkable flattening effect can be obtained. When observed at a distance of 75 cm from the screen, the apparent radius of curvature R of the tube surface becomes slightly smaller. When the distance from the screen is 100 cm, the apparent radius of curvature R of the tube surface further decreases slightly. However, even when observed from an infinite distance, 3
An apparent tube surface curvature radius R of 459 mm is obtained, and a remarkable effect is obtained.

On the other hand, the following Table 2 shows the result of calculating the apparent radius of curvature R of the conventional structure shown in FIG. In performing this calculation, all parameters are shown in Table 1 except for the radius of curvature of the curved safety panel 104.
It is the same as the value used in the calculation. In this conventional example, the radius of curvature of the safety panel (SP) 104 is 33.
02 mm, the radius of curvature 40 in the case of the embodiment shown in FIG.
It is much smaller than 000mm.

[Table 2] As apparent from Table 2, when observed at a position at a distance of 50 cm from the screen, the apparent radius of curvature R of the tube surface is 2758 mm.
Met. Although it is slightly flatter than the actual radius of curvature of 2226 mm, it is much smaller than the numerical value of 4116 mm shown in Table 1.

Finally, the optical theory which is the basis of the above calculation will be described. FIG. 5 is a geometrical optical diagram showing the principle of the present invention. Light emitted from an object located in a medium having a higher refractive index than that of a vacuum reaches an observer after being refracted at the boundary surface. From the observer's side, the light looks as if it were traveling straight, so the object is apparently observed in a raised position.
The present invention utilizes this lifting effect to artificially flatten the tube surface.

Next, referring to FIG. 6, the relationship between the actual wall thickness T of the display front surface portion 2 of the CRT display and the apparent wall thickness t is calculated. When the incident angle of light is θ and the refraction angle is φ, the relationship between the actual wall thickness T and the apparent wall thickness t is given by the following mathematical formula 1 from the geometrical relationship shown.

[Equation 1] When the ratio t / T between the apparent wall thickness and the actual wall thickness is calculated based on Expression 1, it is expressed by Expression 2 below.

[Equation 2]

Next, assuming that the refractive index of the medium constituting the display front part 2 is n and the refractive index of air is 1, Snell's law gives the following formula 3 between the incident angle θ and the refraction angle φ. There is a relationship represented.

[Equation 3] Substituting Equation 3 into Equation 2 to calculate t / T yields Equation 4 below. That is, t / T is represented by a function of the incident angle θ.

[Equation 4] Next, when Equation 4 is modified to obtain the apparent wall thickness t, Equation 5 below is obtained.

[Equation 5] As is clear from Equation 5, when the incident angle θ is constant, the apparent wall thickness t is proportional to the actual wall thickness T. further,
When the amount of uplift (T−t) is calculated using Equation 5, the following Equation 6 is obtained.

[Equation 6] As is clear from Equation 6, the amount of floating is proportional to the actual thickness when the incident angle θ is constant. That is, as the wall thickness increases, the amount of floating increases. Therefore, in the present invention, the thickness of the display front portion is increased toward the periphery as compared with the center of the screen, and the amount of lifting is increased to achieve an apparent flatness.

As explained in Equation 4, t / T depends on the incident angle θ. Numerical value representative of 1.5 in Equation 4 1.5
Was calculated to calculate the relationship between t / T and the incident angle θ. The results are shown in the graph of FIG. As you can see from this graph,
It is understood that the value of t / T becomes smaller and the floating effect becomes more remarkable as the incident angle θ becomes larger.

FIG. 8 is a schematic diagram showing the relationship between the incident angle θ and the observation position. The incident angle θ1 when observed from a position P1 located at a relatively long distance from the CRT screen is relatively short distance P
It is smaller than the incident angle θ2 when observed from 2.
Therefore, as is clear from the graph of FIG. 7, the floating effect decreases as the distance from the CRT screen increases. Therefore, as shown in Table 1, the apparent radius of curvature R of the tube surface when the distance from the screen is 50 cm is 4116 mm, whereas the apparent radius when observed from the position 100 cm from the screen is The radius of curvature R of the tube surface will be reduced to 3624 mm.

[0021]

As described above, according to the present invention, C
The CRT surface was flattened while maintaining the predetermined curvature of the RT tube surface, and the thick layer located between the inner tube surface and the outer surface was thickened from the center of the screen toward the periphery of the screen. Therefore, the peripheral portion of the tube surface is more prominently lifted by the refraction of light and a pseudo flattening effect is obtained. on the other hand,
The actual curvature of the CRT tube surface is set to a desired value and does not adversely affect various CRT characteristics such as convergence, focus and image distortion. Therefore, the present invention has an effect that both flattening and maintenance of image quality can be substantially achieved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a CRT display according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the same.

FIG. 3 is a sectional view showing a third embodiment of the same.

FIG. 4 is a sectional view showing a conventional CRT display.

FIG. 5 is a diagram illustrating the principle of the present invention.

FIG. 6 is a geometrical optical diagram showing the relationship between the actual wall thickness T of the front part of the CRT display and the apparent wall thickness t.

FIG. 7 is a graph showing the incident angle dependence of the ratio of the apparent wall thickness to the actual wall thickness.

FIG. 8 is a geometrical optics diagram showing incident angle dependence.

[Explanation of symbols]

 1 CRT display 2 Display front part 3 Surface 4 Pipe surface 5 Front panel 6 Safety panel 7 Transparent resin layer 8 Neck part

Claims (5)

[Claims] 1. A cathode ray tube display comprising: a display front surface portion having an outer surface and an inner tube surface; and a neck portion for irradiating the tube surface with an electron beam to perform a display. A cathode ray tube characterized in that the surface is flattened while maintaining a curvature, and a thick layer located between the inner tube surface and the outer surface is configured to become thicker from the center of the display front part toward the periphery. display. 2. The cathode ray tube display according to claim 1, wherein the display front part has a structure in which a front panel having the tube surface and a safety panel having the surface are laminated with a transparent resin layer. 3. The cathode ray tube display according to claim 2, wherein the thick layer is made of the transparent resin layer. 4. The cathode ray tube display according to claim 2, wherein the thick layer is a safety panel. 5. The cathode ray tube display according to claim 1, wherein the display front surface portion includes a front panel having the tube surface and the surface.