Patent Grant
7309952
The present invention relates to a flat panel for use in a cathode ray tube; and, more particularly, to a flat panel whose weight is reduced by improving the shape of a blend round portion thereof.
As well known, a glass bulb employed in a cathode ray tube for use in color television sets, computer monitors, or the like basically includes three parts, namely a panel for displaying images, a conic funnel joined to a rear portion of the panel and a cylindrical neck joined to an apex portion of the conic funnel. The panel, the funnel and the neck are made of glass, and particularly the panel and the funnel are formed by press-forming a charge of molten glass called a glass gob into predetermined sizes and shapes. After press-formed, the panel is subjected to a pin sealing process for sealing stud pins, an annealing process performed in an annealing lehr for removing residual stress from the panel by heat-treatment, a lapping process and an inspection process in order, so that a finished panel product is obtained.
Referring to
A funnel 30 has a body portion 32, which is provided with a seal edge 31 connected to the seal edge 22 of the panel 20, and a yoke portion 33 extending backward from the body portion 32. Further, a neck 40 is connected to the yoke portion 33 of the funnel 30.
Recently, an increasing number of active researches are in progress to reduce the thickness and the weight of the panel, to thereby cut costs in manufacturing the panel for use in the cathode ray tube.
Conventionally, in order to reduce the weight of the panel, the faceplate portion has been designed to have a reduced thickness or the skirt portion has been configured to have a reduced height. However, there has been reported no method for changing the shape of the blend round portion for the purpose of realizing the weight reduction of the panel.
It is, therefore, an object of the present invention to provide a flat panel for use in a cathode ray tube, which has a blend round portion which is capable of reducing a gross weight of the panel while, at the same time, satisfying the IEC (International Electrotechnical Commission) standard for implosion resistance and guaranteeing formability in press-forming.
In accordance with the present invention, there is provided a flat panel for use in a cathode ray tube, including: a faceplate portion for displaying images; a skirt portion extended backward from a perimeter of the faceplate portion; and a blend round portion joining the faceplate portion with the skirt portion, wherein, looking at a cross section of the panel, a point formed by an external contour of the faceplate portion and an external blend round contour of the blend round portion is defined as a first point and a point formed by an external contour of the skirt portion and the external blend round contour of the blend round portion is defined as a second point, wherein the external blend round contour is formed between an imaginary arc whose two opposite end points coincide with the first and the second point, respectively and a line segment whose two opposite end points coincide with the first and the second point, respectively, or is the line segment whose two opposite end points coincide with the first and the second point, and wherein the imaginary arc is smoothly connected to the external contours of the faceplate portion and the skirt portion at the first and the second point, respectively.
The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Referring to
As shown in
Referring to
Next, a first point A where an external contour 51b of the faceplate portion 51 meets the imaginary round contour 54c and a second point B where an external contour 53b of the skirt portion 53 meets the imaginary round contour 54c are obtained. The first point A does not go into the useful screen 59 and the second point B does not go beyond the mold match line 55 from the blend round portion 54. Further, the imaginary round contour 54c is smoothly connected to the external contour 51b of the faceplate portion 51 and the external contour 53b of the skirt portion 53. That is to say, a graph formed by the external contour 51b of the faceplate portion 51, the imaginary round contour 54c and the external contour 53b of the skirt portion 53 has differential values at the first and the second point A and B. Then, a first straight line L1 connecting the first and the second point A and B is drawn, and a second straight line L2 having the same gradient as that of the straight line L1 is then obtained. At this time, the second straight line L2 locates between the first straight line L1 and the apex C of the imaginary round contour 54c. Once the second straight line L2 is obtained, the blend round portion 54, which has the external blend round contour 54b which connects the first and the second point A and B and is tangent to the second straight line L2, is formed.
Furthermore, as shown in
R2≧1 Eq. 1
The rounds 54d having such radius of curvature R2 allow the external contour 51b of the faceplate portion 51 and the external contour 53b of the skirt portion 53 to be smoothly connected to the external blend round contour 54b, thereby contributing to the formability of press-forming and avoiding breakage, such as cracks, due to the concentration of stress.
As shown in
ρ=D1/D2 Eq. 2
wherein D1 represents a distance between the base a-b of a cone Co and the apex d of the conic section Cs; and D2 represents a distance between the base a-b of the cone Co and the top c of the cone Co. Further, oblique sides a-c and b-c of the cone Co are parts of tangent lines that are tangent to the conic section Cs at points a and b, respectively.
Especially, the characteristic value of an arc can be expressed as follows:
ρ=cos(θ/2)/(1+cos(θ/2)) Eq. 3
wherein θ represents a central angle corresponding to the arc, namely, an angle formed by a straight line connecting a start point of the arc and a center of a circle including the arc and another straight line connecting an end point of the arc and the center of the circle.
With regard to the flat panel 50 in accordance with the present invention, it is preferred to design the external blend round contour 54b of the blend round portion 54 for connecting the faceplate portion 51 and the skirt portion 53 to become a conic section having a characteristic value (ρ) as follows:
0.44≦ρ≦0.5 Eq. 4
If the characteristic value (ρ) of the conic section for the external blend round contour 54b is smaller than a minimum value of 0.44, the effect of reducing the weight of the panel is very low. That is, the rate of weight reduction is less than 0.9%. Meanwhile, if the characteristic value (ρ) of the conic section for the external blend round contour 54b is greater than a maximum value of 0.5, the external blend round contour 54b becomes a concave curve rendering the first and the second point A and B sharpened, thereby increasing the probability of breakage of the flat panel 50 when the flat panel 50 is transferred or when an implosion-proof band (not shown) is installed around the skirt portion 53, while deteriorating the implosion resistance due to the concentration of vacuum stress. Moreover, if the characteristic value of the conic section for the external blend round contour 54b is equal to 0.5, the contour 54b becomes almost straight.
Experiments were conducted in order to illustrate the weight reduction rates of panels in accordance with the first preferred embodiment of the present invention, and Table 1 shows results of the experiments. In Table 1, panels of comparative examples 1 to 8 were conventional panels of 17 to 32 inch having the same configurations as those of the panels in accordance with the present invention except the configuration of the blend round portion 54 shown in
As indicated in Table 1, in each of the comparative examples 1 to 8, a characteristic value ρ of a conic section for an external blend round contour is found to be less than 0.44 with respect to a shorter axis, a longer axis and a diagonal axis, respectively. Further, each of the panels of 17 to 32 inch of the examples 1 to 8 is fabricated such that their characteristic values (ρ) of conic sections for external blend round contours are 0.499. In comparison with the weights of the panels of the comparative examples 1 to 8, the weights of the panels of the examples 1 to 8 are reduced by 0.9 to 2.1%. Furthermore, the respective panels of 17 to 32 inch of the examples 1 to 8 each of which has an external blend round contour for which the characteristic value of conic section ranges from 0.44 to 0.5 satisfies the IEC (international Electrotechnical Commission) standard for the implosion resistance and guarantees the formability of press-forming.
Referring to
Further, as in the first embodiment, edge portions at the first and the second point A and B are rounded to become rounds 54d each having a radius of curvature equal to or greater than 1 mm, as shown in
Moreover, the external blend round contour 54b may be a line segment between two points where the second straight line L2 (see
Moreover, as in the first embodiment, edge portions at the first and the second point A and B are preferably rounded to become rounds 54d each having a radius of curvature equal to or greater than 1 mm. In addition, it is preferred that an edge portion created by the two line segments is rounded to become a round 54e having a radius of curvature equal to or greater than 1 mm.
Furthermore, the external blend round contour 54b can be formed with at least one curve or at least two line segments connecting the first and the third point A and D and at least one curve or at least two line segments connecting the second and the third point B and D. Moreover, the external blend round contour 54b may be formed with a combination of curves and line segments.
The flat panel in accordance with the present invention described above is designed to have a blend round portion whose external blend round contour is formed more inside than that of the conventional flat panel. Therefore, the weight of the flat panel can be reduced. Particularly, since the external blend round contour is formed such that its conic section has a characteristic value ranging from 0.44 to 0.5, the weight reduction of the flat panel can be effectively achieved while, at the same time, satisfying the IEC standard for implosion resistance and guaranteeing the formability in press-forming.
Furthermore, since an edge portion created by the external blend round contour and the external contour of the faceplate portion and an edge portion created by the external blend round contour and the external contour of the skirt portion are rounded to become rounds each having a radius of curvature equal to or greater than 1 mm, the probability of breakage of the panel due to the stress concentration can be greatly reduced.
Moreover, since the locations of the point where the external blend round contour meets the external contour of the faceplate portion and the point where the external blend round contour meets the external contour of the skirt portion can be set at identical locations of those of the conventional flat panel, a conventional installation area for the implosion-proof band is still available in manufacturing a cathode ray tube even though the external blend round contour differs from that of the conventional flat panel, and, further, a conventional casing can be still used in manufacturing TV sets or monitors.
While the invention has been shown and described for the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the sprit and scope of the invention as defined in the following claims.
| Number | Date | Country | Kind |
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| 10-2003-0060422 | Aug 2003 | KR | national |
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| Number | Date | Country | |
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