This application claims the benefit of the Korean Patent Application No. 10-2005-0075962, filed on Aug. 18, 2005, which is hereby incorporated by reference as if fully set forth herein.
1. Field of the Invention
The present invention relates to a cathode ray tube, and more particularly, to a cathode ray tube improving an image quality by maximizing velocity modulation (VM) effects. More particularly, the present invention relates to a slim-type cathode ray tube in which electric fields, i.e. dimensions, are decreased in an anteroposterior direction, and comprises a mounting structure where a VM coil portion, a shape and an icon is improved so as to obtain optimum VM effects.
2. Description of the Related Art
A cathode ray tube is an image forming device employed in a TV or a monitor. The image is formed by a light generated when an electron beam emitted from an electron gun hits a fluorescent surface of a panel of the cathode ray tube. Because the cathode ray tube generally has good color quality, little to no afterimage with respect to a moving image, a high brightness and a wide view angle, the cathode ray tube is widely used in a device displaying a moving image such as a TV. However, a general cathode ray tube usually includes an electron gun with a long electric field and a deflection yoke and requires a high vacuum inner space. Thus, the cathode ray tube requires a significant amount of space due to the long length in an anteroposterior direction, that is in a direction from the front of the cathode ray tube to the rear of the same.
Recently, a slim-type cathode ray tube has been suggested by improving the deflection yoke allowing the length of the cathode ray tube to be shortened in the anteroposterior direction. Significant improvements have been made to shorten the length of the cathode ray tube by shortening a length of other goods such as an electron gun in the anteroposterior direction.
First, in general, a cathode ray tube 1 is provided with a shape having a front glass called a panel 2 connected with a funnel 3, and the interior thereof is kept airtight. A fluorescent surface 16 is provided at the rear surface of the panel 2 such that when an electron beam 9 emitted from an electron gun 11 and deflected by a deflection yoke 10 hits a specific position of the fluorescent surface 16, a specific light is emitted to form an image.
Because the interior of the panel 2 and the funnel 3 is in a high vacuum state, constriction by implosion may occur due to an external impact. In order to prevent this, an external contact portion of the panel 2 and the funnel 3 may be made impact-resistant by a reinforcing band 15. A shadow mask 8 performing color classification functions is placed behind the fluorescent surface 16. A frame 6 supporting the shadow mask 8, a spring 5 and a stud pin 4 are also provided in the cathode ray tube 1. Moreover, an inner shield 7 for shielding the effects of geomagnetism during an operation of the cathode ray tube is formed in the frame 6.
The deflection yoke 10 for deflecting the electron beam 9 vertically/laterally is placed outside of a neck portion of the funnel 3 and a color purity magnet 12 CPM for improving a color purity is placed at behind the deflection yoke 10. Here, a rear portion of the funnel 3 is sealed using a material such as a glass and the electron gun 11 is placed within the sealed space. The deflection yoke 10 and the CPM 12 are placed at a rear portion of the sealed funnel 3.
The deflection yoke 10 deflects the electron beam 9 vertically/horizontally toward a specific position on the fluorescent surface 16. The CPM 12 includes a magnet 14 for correcting a convergence of the electron beam and a Velocity Modulation VM coil 13 for improving the image quality.
More particularly, a second differential signal of the image signal is input through a predetermined different circuit in the VM coil 13. The signal input to the VM coil 13 generates electric fields at a circumference portion of the VM coil 13, and the electric fields overlap with a horizontal magnetic field of the deflection yoke 10 to change a horizontal scanning velocity of an image line. The brightness on the screen changes in accordance with the changed velocity. If the deflection velocity is increased, the brightness at the portion is decreased and if the deflection velocity is decreased, the brightness at the portion is increased. Accordingly, since a difference of the brightness at an interface of dark and bright portions on the screen becomes larger than when the VM coil 13 is not included, the interfacial portion becomes clearer resulting in an improved clarity with respect to an outlined portion of the screen. This is called a VM effect.
To obtain the maximum VM effects, it is preferable that the VM coil is positioned at a focus electrode of the electron gun 11, i.e., outside of a G4 electrode of the electron gun. However, if the cathode ray tube is shortened in the anteroposterior direction such as with the slim-type cathode ray tube 1, a position where the CPM 12 can be mounted is limited by the deflection yoke 10, and thus, a position where the VM coil 13 can be placed is also limited. Therefore, the VM desirable effects cannot be obtained. In other words, the slim-type cathode ray tube has a shape so that the length of a neck portion of the electron gun 11 and the funnel 3 is shortened, and the CPM 12 is not placed at the focus electrode position of the electron gun 11 and instead, applies electric fields to other electrodes of the electron gun 11. For example, the VM coil 13 is positioned outside close to G1, G2 and G3 electrodes. In this case, the VM effects are reduced or non-existent.
In order to mitigate the above problems, a current applied to the VM coil may be increased. However, this increases power consumption which is undesirable. It is also possible to shorten the electric field of the deflection yoke by installing the VM coil more towards the front of the cathode ray tube. But in this case, a moving characteristic of the image and a sensitivity characteristic are decreased undesirably.
Another method to form an opening of a main electrode so as to increase the VM effects is suggested in Korean Patent Laid-open Publication No. 10-2003-0005605. However, in this case, the electric effects of an electrode is degraded, an integration of the electron beam is reduced even though the VM effects can be improved. Also, this presents a problem in the manufacturing process.
In order to mitigate the above-noted problems, it is an object of the present invention to provide a cathode ray tube capable of maximizing the VM effects by applying electric fields to an exact position of an electron gun by the VM coils.
In addition, it is another object of the present invention to provide with a cathode ray tube capable of improving the image quality by maximizing the VM effects.
Furthermore, it is an object of the present invention to provide a cathode ray tube capable of obtaining the maximum VM effects even if an electric field of an electron gun is shortened.
In order to obtain these and other advantages, an embodiment of a cathode ray tube comprises: a panel having a fluorescent surface provided to the inside to raise colors; a shadow mask provided behind the fluorescent surface; a funnel provided to a rear portion of the panel to provide with an inner portion as an airtight space; an electron gun formed at a rear portion of the funnel for emitting an electron beam; a deflection yoke equipped outside of at least a neck portion of the funnel to deflect the electron beam; and a VM coil portion of which at least a portion is inserted in an interval between the deflection yoke and the funnel to apply an electric field to the electron beam.
In accordance with another object of the present invention, an embodiment of a cathode ray tube comprises: a panel having a fluorescent surface provided to the inside to raise colors; a shadow mask provided behind the fluorescent surface; a funnel connected with the rear portion of the panel to provide with an inner portion as an airtight space; an electron gun sealed in the funnel for emitting an electron beam; a deflection yoke equipped outside of a neck portion of at least the funnel to deflect the electron beam; a magnet placed behind the deflection yoke; and a VM coil portion placed outside of the G4 electrode of the electron gun as other goods separated from the magnet.
In accordance with another aspect, an embodiment of a cathode ray tube comprises: a panel having a fluorescent surface provided to the inside to raise colors; a funnel connected with a rear portion of the panel to provide with an inner portion as an airtight space; an electron gun placed to a rear portion of the funnel for emitting an electron beam; a deflection yoke placed outside of the funnel to deflect the electron beam; a magnet placed behind the deflection yoke; and a VM coil portion of which at least a portion is inserted at an interval between the deflection yoke and the electron gun as a plate to generate the VM effects.
Even if the electric field of the cathode ray tube in anteroposterior direction is shortened, the cathode ray tube is stably placed and the maximum VM effects can be obtained. Furthermore, even if the length of electric fields is shortened further in the anteroposterior direction, a position of a VM coil can be changed. The embodiments of the present invention are advantageous in that high resolution image quality can be obtained without sacrificing the VM effects.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
Referring to
The inner space of the panel 52 and the funnel 53 is in a high vacuum state. As such, an implosion can occur due to an external impact. To minimize or to prevent the implosion, a contact portion of the panel 52 and the funnel 53 is reinforced by a reinforcing band 65 to maximize an impact resistant capacity.
The cathode ray tube 51 includes a shadow mask 58 configured to perform a color distinction function positioned behind the fluorescent surface 66, a frame 56 supporting the shadow mask 58, a spring 55 and a stud pin 54. The frame 56 is connected with an inner shield 57 configured to shield the cathode ray tube 51 from the effects of terrestrial magnetism during an operation of the cathode ray tube.
In addition, the deflection yoke 60 configured to deflect the electron beam 59 vertically/horizontally is placed outside of a neck portion and toward a rear of the funnel 53. The electron beam 59 is deflected vertically/horizontally by the deflection yoke 60 to hit an appropriate position on the fluorescent surface 66.
Moreover, a magnet 29 is installed behind the deflection yoke 60 to perform a function of correcting a convergence. The magnet 29 may be in contact with the rear surface of the deflection yoke 60, or may be spaced apart with a predetermined interval. The position of the magnet 29 may be changed as necessary in accordance with a shape and length of the funnel 53, an installation position of the deflection yoke 60, placement of the electron gun 28, etc.
A VM coil portion 21 may be inserted in an interval between the deflection yoke 60 and the neck portion of the funnel 53, in other words, outside of the funnel 53 and in an inner space of the deflection yoke 60. The VM coil portion 21 position can be conveniently changed. For example, depending on position of the deflection yoke 60 with respect to the funnel 53, the depth with which VM coil portion 21 inserted within the interval can be changed and adjusted.
The VM coil portion 21 is preferred to be positioned near the G4 electrode 114 of the electron gun 28, which also includes a G1 electrode 111, a G2 electrode 112, a G3 electrode 113, and a G5 electrode 115 in addition to the G4 electrode 114. In other words, the VM coil portion 21 can be positioned outside and close to the focus electrode to maximize the VM effects.
Since the position of the VM coil portion 21 can be easily changed, the VM coil portion 21 can be placed at an appropriate place, e.g. outside of the G4 electrode 114, to obtain the desirable VM effects even though an electric field of the electron gun 28 is shortened. The brightness with respect to the outlined portion of the image is also corrected by the VM coil portion 21 to improve the image quality.
The VM coil portion 21 is illustrated as being entirely inserted in the interval between the deflection yoke 60 and the funnel 53 in
Referring to
The VM coils 23 and 24 are wound so that the electric fields formed are oriented in the same direction. Moreover, it is preferred that the VM coils 23 and 24 are wound so that substantially uniform electric fields are applied to the focus electrode. This may be achieved, for example, by winding the coils in a square manner as illustrated. If the VM coils 23 and 24 are inserted in the interval between the deflection yoke 60 and the funnel 53 in a winding shape, the VM coils 23 and 24 are arranged in a saddle shape to apply substantially equal electric fields to an entire region of the focus electrode G4. As illustrated in
The flexible substrate 25 has a planar shape shown in
In another embodiment, the flexible substrate 25 of the VM coil portion 21 may be a substrate of a plane type or a circularly winding type. Also, if the substrate is the circular type, a hard substrate may be used instead of the flexible substrate 25.
Referring to
The VM coil portion 21 may rotate or otherwise move within the interval. Thus, a shaking preventing portion may be provided to prevent such movement. The shaking preventing portion may be implemented as a contact portion 100 so that the VM coil portion 21 contacts with a side of the deflection yoke 60 and/or the funnel 53. For example, the shaking preventing portion may include a first guide (not shown) formed at the VM coil portion 21 or a second guide (not shown) formed at the deflection yoke 60 and/or the funnel 53, and a connecting portion connecting the connecting terminal 22 with the deflection yoke 60 and/or the funnel 53 at a predetermined position. The shaking preventing portion can be embodied in various ways, and the detailed description is omitted.
As indicated above, according to an embodiment of the present invention, the VM coil portion may be separated from a magnet so that the positions are adjusted, and the position of the VM coils can be easily adjusted to maximize the VM effects. Therefore, the position of VM coils can be changed when the detailed specification of the cathode ray tube, such as the electron gun, is changed to conveniently move the VM coil into a proper position. Especially, even when a space for installing the VM coils such as in the slim-type cathode ray tube is relatively small, the VM coils can be positioned in the narrow interval between the deflection yoke and the funnel. Accordingly, the clarity of the image can be improved.
In addition, the positions installing the VM coils are not limited by other goods, and the VM coils can be placed at a desired position of the narrow and long interval between the deflection yoke and the funnel. Therefore, if an electric field of the G4 electrode 114 is long, an electric field due to a VM coil can be affected. Accordingly, it is advantageous that the VM effects can be realized at a low current state requiring less power consumption.
The second embodiment of the present invention is substantially similar to the first embodiment except that the configuration and the shape of the VM coil portion are changed. Therefore, the portions which have not been described in the descriptions of the first embodiment and the changed portions are described in the present embodiment in detail.
Referring to
As described above, the VM coils 33 and 34 maintain a predetermined shape by winding the conductive line having a regular intensity itself to obtain an advantage of reducing manufacturing costs. In addition, as the thickness of the conductive line increases, a conductive amount also increases. Each conductive line can be wound a plurality of times around the center of a specific position and the conductive pattern is formed on a curved plane which is different from the first embodiment. The second embodiment is advantageous that a uniformity of electric fields is increased and the intensity of the electric fields is strengthened.
The functions and the operations of the VM coils 33 and 34 are generally similar to those described in the first embodiment.
The third embodiment of the present invention is similar to the second embodiment except that the VM coils are protected in a film.
Referring to
The VM coils 43 and 44, maintained in their original state by the film 46, also prevents electric leakage by preventing the coils 43 and 44 from contacting with other goods.
The fourth embodiment of the present invention is similar to the first, the second and the third embodiments except that the shape of the electron gun is changed to precisely control the positions of the electron beam by the VM coils.
Referring to
When the VM gap 119 is present, i.e. the G4 electrode is divided, an eddy current degrading a velocity modulation due to the VM coils is minimized and an interval of an electron beam affected by an electric field due to the VM coil is increased. Accordingly, the VM effects can be improved even though a current flowing in the VM coil is relatively small. The present embodiment is possible in a slim-type cathode ray tube, because the VM coils of the present invention can be installed regardless of the shape and the position of the deflection yoke 60. Therefore, the embodiments of the VM coil of the present invention can be formed to have a length as long as possible. For example, if the deflection yoke 60 is not provided at a position where it is overlapped with the VM coil, the VM coil can be placed behind the deflection yoke 60.
The present embodiments have an advantage in that the VM effects are optimized.
With the embodiments of the present invention, at least a part of the VM coil portion can be arranged with the deflection yoke to conveniently change the position of installing VM coils, thereby maximizing the VM effects. The VM coils can be placed in the inner portion of the panel or can be placed in a single body with the neck portion and outside of the neck portion as the need arises and as other technical problems are addressed.
According to the embodiments of the present invention, the magnetic fields are applied to a precise electrode position of the electron gun by the VM coil to maximize the VM effects.
In addition, the VM effects are maximized at a low current state to improve the image quality, which has an advantage to reduce power consumption.
Furthermore, even if the magnetic field of a cathode ray tube is shortened due to the slimming of the cathode ray tube, the VM coil can be placed at an exact G4 electrode position of the electron gun, resulting in obtaining the maximum VM effects. In addition, since a scaffold to slim the cathode ray tube is provided, there is an advantage that the cathode ray tube can be slimmed further.
Number | Date | Country | Kind |
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10-2005-0075962 | Aug 2005 | KR | national |