KR100474331B1 - A Color Image Display Device - Google Patents

Abstract

The present invention provides a panel having a screen formed on its inner surface, a funnel coupled to the panel, an electron gun coupled to a neck portion of the funnel to emit an electron beam toward the screen, and deflecting the electron beam emitted from the electron gun horizontally and vertically on the screen. A color image display device comprising a deflection device for displaying an image, and a color cathode ray tube having a shadow mask arranged at a predetermined distance from a screen, wherein the electron gun is arranged to be adjacent to the cathode, the cathode generating the electron beam, and the cathode; A triode consisting of a grid electrode and an acceleration electrode disposed adjacent to the grid electrode; An image signal voltage is applied to the cathode, and a variable voltage for luminance compensation is applied to the grid electrode or the acceleration electrode.

Therefore, according to the present invention, an image display apparatus having a flat cathode ray tube having a large outer thickness ratio (wedge rate) to a center thickness of a panel has an effect of obtaining uniform luminance over the entire screen.

Description

A color image display device

The present invention relates to improving luminance uniformity over the entire screen in a color image display device, and more particularly in an image display device having a flat color cathode ray tube with a high wedge ratio.

Color image display apparatuses using a color cathode ray tube can be divided into a television receiver mainly displaying a copper screen and a monitor mainly displaying static data.

In the general color cathode ray tube, as shown in FIG. 1, the electron beam emitted from the electron gun 10 is deflected by the deflection yoke 6, passes through the shadow mask, reaches the fluorescent film 7 coated with the phosphor, and emits the phosphor. It is a display element that produces an image by making an image.

The cathode ray tube adjusts the amount of the electron beam by a voltage difference between a heater (2: Heater) for heating the cathode (3) to generate hot electrons, a cathode (3: Cathode) for inputting an image signal, and a cathode (3). An electron gun 10 comprising a triode portion consisting of a grid electrode 4 for grid, an acceleration electrode 5 for accelerating an electron beam passing through the grid electrode, and applying a high pressure to draw the generated electron beam into the phosphor 7 It is composed of anode (9: Anode), deflection yoke (6: DY) for redirecting electron beam to reach the desired phosphor, and phosphor (7) which emits light when the electron beam collides. .

The cathode ray tube operation of this structure accelerates the hot electrons generated by the cathode 3 heated by the heater 2 toward the phosphor 7 by using a high pressure applied to the anode by an amount proportional to the image signal input to the cathode. By colliding with the phosphor, the phosphor emits light and the screen is used to reproduce the screen. In order to reach the phosphor at the specified position, a sawtooth current flows through the deflection yoke (6: DY) to generate a magnetic field. This is achieved by passing this magnetic field and receiving a magnetic force (F = -eVxB).

      The amount of electron beam emitted from the cathode is determined by the difference between the image signal voltage applied to the cathode and the voltage applied to the grid electrode.When the grid electrode voltage is constant (0 V), the proportion of the beam current flows as the cathode voltage decreases. Is in.

In the case of a general curved cathode ray tube, the inner and outer surfaces of the screen have almost similar curvature, but since the curvature of the inner screen of the panel is so large, the moving distance of the electron beam emitted from the electron gun is larger than the center of the screen. The difference in the electron beam movement distance causes a problem in that the luminance of the corner of the screen is lower than that of the center of the screen when the same amount of electron beam is emitted, thereby degrading the overall brightness uniformity (white balance).

In order to solve this problem, as illustrated in FIG. 2, a parabolic signal generator 107 for generating a parabolic signal, and a luminance input voltage for adjusting the brightness of the screen and an image input signal loaded with a black level voltage A first image output signal generator 106 for outputting a first image output signal whose black level voltage is adjusted to the brightness adjustment voltage as an input, and the first image output signal 106 and the parabolic signal are input. There is a screen brightness adjusting unit 101 of the monitor including a signal synthesizing unit 108 for outputting a second image output signal to which the parabolic signal is added to the first image output signal (Korean Patent Publication No. 10-0258982). , July 5, 1999)

In addition, Japanese Patent Application Laid-Open No. 2000-125225 (published on April 28, 2000) shows pixel units by a function of taking an arbitrary pixel reference position and image display pixel position distance with respect to an image luminance signal as shown in FIG. A technique for correcting a luminance level is disclosed.

As described above, a method of compensating for the luminance deterioration of the peripheral part of the screen is performed by converting and displaying the video signal according to the screen position. Converting the video signal input in real time through the antenna requires a complicated and expensive luminance compensation circuit. Shall be. In addition, this luminance compensation method is to solve the luminance imbalance caused by the difference in the electron beam moving distance of the cathode ray tube.

However, with the release of cathode ray tubes close to the full plane, the curvature between the inner surface of the cathode ray tube and the outer surface of the screen has been recently released to compensate for the weakening of the strength due to the flatness of the outer surface of the screen. The thickness difference of the outer part became large. This is generally expressed as a wedge ratio. A flat panel with a flat outer surface and curvature on the inside makes a large wedge ratio of 230% and 170%. This difference in thickness causes a difference in luminance with respect to the same signal. In order to overcome such a difference in luminance, generally, a screen panel is manufactured using clear glass having a very high transmittance. Clear glass also has a transmittance of around 80%, so the difference in luminance is caused by the same beam current due to the difference in thickness of each screen glass. We try to obtain a uniform brightness by attaching a film with a different transmittance on the outer surface. Of course, when using tinted glass with a transmittance of 50% to increase the quality of the cathode ray tube or to reduce the manufacturing cost, it is almost impossible to obtain uniform luminance when the wedge ratio is high.

An object of the present invention is to provide a color image display device having a simple and inexpensive peripheral luminance compensation device using an electron gun of a cathode ray tube.

Another object of the present invention is to improve luminance uniformity of an image display device having a flat color cathode ray tube having a glass panel with a high wedge ratio and a low transmittance.

Technical solution of the present invention for achieving the above object is a panel having a screen formed on the inner surface, a funnel coupled to the panel, an electron gun coupled to the neck portion of the funnel emits an electron beam toward the screen, emitted from the electron gun A color image display device comprising: a deflector for displaying an image by deflecting the electron beam horizontally and vertically of a screen; and a cathode ray tube having a shadow mask disposed at a predetermined distance from the screen, wherein the electron gun generates an electron beam. A triode comprising a cathode, a grid electrode disposed adjacent to the cathode, and an acceleration electrode disposed adjacent to the grid electrode; An image signal voltage is applied to the cathode, and a variable voltage for luminance compensation is applied to the grid electrode or the acceleration electrode.

Hereinafter, a planar cathode ray tube according to the present invention will be described in detail with reference to the accompanying drawings.

In order to control the amount of beam current flowing through the cathode ray tube, it is possible to change the voltage between the cathode and the cathode of the cathode ray tube, and within the operating range of the cathode ray tube, a small amount of current flows as the voltage difference between the grid electrode and the cathode increases. No current flows above the voltage (cut off voltage) difference] The smaller the voltage difference is, the more current flows.

In the conventional cathode ray tube, as shown in FIG. 1, the grid electrode is grounded and the cathode is applied with an image signal (white signal) as shown in FIG. 8B, so that a voltage (V _CG ) is applied between the grid electrode and the cathode and the cathode ray tube is applied. The beam current was controlled by allowing a current I to flow in inverse proportion to the voltage. In the waveform of FIG. 8B, the high voltage section of the narrow section is the retrace section, and thus no current flows because the cut-off voltage (the threshold voltage at which the beam does not flow) of the dotted line is higher.

When the amount of current is controlled by the conventional method described above, the same beam current flows at the video signal level of the same voltage, so that the beam current reaching the phosphor at the center of the panel and the beam current reaching the phosphor at the edge are the same, and the light is emitted from the phosphor. Although the amount of light is the same, the thickness of the panel glass is thicker at the edge, so the light transmittance at the edge is lower, resulting in lower luminance than the center.

In general, the amount of light generated by emitting a phosphor with an electron beam is proportional to the amount of electron beam current as shown in FIGS. 4A to 4C. However, the light emitted from the phosphor passes through the glass and enters our eyes. In the process of passing through the glass, part is absorbed and only the rest passes through the glass. Here, the amount of light passing through the glass is thicker as the distance from the center of deflection increases, as shown in FIG. 4C, when the glass of the same material is used. As shown in FIG. 4B, the transmittance of the glass is the thickness of the glass. The thicker the thickness, the less light passes.

For this reason, when the same beam current strikes the phosphor on the center of the cathode ray tube and the phosphor on the edge, the amount of light emitted from the phosphor is generated equally, but as shown in the left figure of FIG. 5, the center of the panel of the cathode ray tube is shown. Since the glass thicknesses of the portion A and the edge B are different (the portion A is thin and the portion B is thick), the amount of light passing through the glass is smaller than the portion A as shown on the right side of FIG. 5.

The light transmittance (transmitted light / incident light quantity) of light emitted from the glass through the glass by the emission of the phosphor is T, the reflectance is R, the extinction coefficient is k, and the thickness of the glass is t. = (1-R) ² * e ^(-kt), and it becomes a shape like the graph shown in FIG. 4B.

In order to compensate for the luminance that varies according to the difference in the transmittance according to the thickness of the glass, the present invention allows the phosphor of the thin glass to reach a smaller amount of beam current as shown in FIG. 6A, and as shown in FIG. 6B. Use the principle that the amount of light passing through the thick glass glass reaches the amount of beam current so that the amount of light emitted from the phosphor is relatively high in the thick glass glass, even though the light transmittance is low. Doing.

According to the present invention, as shown in FIG. 7, the difference in luminance that changes according to the difference in the thickness of the panel glass in the grid electrode 4, which is one of terminals for controlling the amount of beam current in the electron gun 10 of the cathode ray tube, is shown. In order to correct the error, a luminance compensation circuit 11 for controlling the electron beam current is added.

In order to control the amount of beam current for compensating for the difference in luminance according to the thickness of the glass described above, the present invention is to ground the voltage of the grid electrode (4) of the conventional cathode ray tube as shown in Figure 1 (0V) Instead, the luminance compensation voltage waveform for controlling the current is input to the grid electrode 4 as shown in FIG. 9A.

In order to compensate for such a difference in luminance, the present invention does not apply a constant voltage (generally 0 Volt) to the grid electrode of the cathode ray tube, as shown in FIG. 9A. Is applied to make the potential difference (potential difference between the grid electrode and the cathode: V _CG ) with the image signal (V _C of FIG. 9B) applied to the cathode to have a waveform as shown in FIG. 9C. When a voltage of such a waveform is applied between the grid electrode and the cathode, a small amount of current reaches the cathode ray tube as shown in FIG. 9D and a larger amount of current reaches the edge portion B as shown in FIG. 9D. By calculating the amount of current that can transmit the same light as the center part, the same luminance can be obtained regardless of the position of the panel.

According to the present invention, the luminance compensation voltage applied to the grid electrode is applied by the luminance compensation circuit 11 shown in FIG. 7, and the vertical and horizontal parabola voltages of the dynamic focus circuit of a general cathode ray tube are input to the luminance compensation circuit 11. This parabola input voltage is applied to the grid electrode 4 through an amplifier stage composed of transistors Q1 and resistors R1 and R2.

The same effect can be obtained by applying the parabola voltage to the acceleration electrode 5 adjacent to the grid electrode 5 instead of applying the parabola voltage to the grid electrode 4 by the luminance compensation circuit 11 shown in FIG. The detailed description thereof will be omitted since it is made by the same principle as that applied to the grid electrode 5.

Hereinafter, the relationship between the voltage applied to the grid electrode 4 and the panel wedge ratio and the panel transmittance to the luminance compensation circuit 11 shown in FIG. 7 will be described.

In the case of glass having different transmittances, the amount of change in the beam current due to the change in thickness must be adjusted differently. For example, in the case of a cathode ray tube glass commonly known as a clear glass, the glass thickness at the center is 12.5 to 14.5 mm, When the thickness is set to 25.5 ~ 29.6mm and has a wedge ratio of 204%, if the same level of beam current is used at the center of the screen glass and the corner of the screen glass, the difference in luminance is 6.6%. In the case of cathode ray tube glass, which is known as glass, the glass has the same thickness and wedge rate of 204%, the difference in luminance is 23.2% when the same beam current is used at the center of the screen glass and the corner of the screen glass. .

In the case of flat cathode ray tube glass, also known as dark tint glass, when the glass thickness at the center is set to 12.5 to 14.5 mm and the thickness at the periphery is set to 25.5 to 29.6 mm, the wedge ratio of 204% is achieved. If the same level of beam current is used at the corners of, the difference in luminance is 22.4%.

Of course, if the curvature is set smaller in order to improve the shadowing and howling characteristics of the shadow mask, the wedge ratio can be set larger, and accordingly, the beam current adjustment range should be increased. In case of raising the bay unilaterally, it is difficult to double the focusing ability. Therefore, if the current limiting range is about 50% for the cathode ray tube for television and about 70% for the cathode ray tube for monitor, The above characteristics can be obtained economically without taking an action to adjust the focus of the electron gun.

The panel employed in the planar cathode ray tube has a shape where the outer surface is almost flat and the inner surface has a constant curvature, and the thickness ratio (wedge rate) of the outer to the thickness of the center of the panel is about 170% to 230%. The panel is composed of clear glass (absorption coefficient k = 0.00578) with a transmittance of 75% or more, a tint glass (absorption coefficient of k = 0.04626) of 45% or more and less than 75%, and a dark tint of less than 45%. Tint) It is divided into glass (absorption coefficient k = 0.06737), and tint glass or dark tint glass is mainly used in high-quality cathode ray tubes to improve contrast.

When the wedge rate of the panel is 170% to 230%, the thickness of the portion _A is 1.7d _{B when} the thickness of the portion _A is d _A in FIG. Therefore, the transmittance (T _A ) of the A portion is T _A = (1-R) ² * e ^(-kdA), and the transmittance (T _B ) of the A portion is T _B = (1-R) ² * e ^{(- kdB)} . That is, T _B = (1-R) ² * e ^{-k (1.7dA)} to (1-R) ² * e ^{-k (2.3dA)} .

If the amounts of light emitted from the phosphors of the A and B portions are L _A and L _B , respectively, the amount of light passing through the glass is L _A × T _A and L _{B ×} T _B. Therefore, in order to be L _A x T _A = L _B x T _B , the following must be satisfied.

L _B = L _A × (T _A / T _B )

= L _A × [(1-R) ² * e ^(-kdA) / (1-R) ² * e ^(-kdB) ]

= L _A × [e ^(-kdA) / * e ^(-kdB) ]

= L _A × e ^{k (dB-dA)} ]

Considering the range of wedge ratio is as follows.

^{_{L B = L A × e k}} (1.7dA-dA) ~L A × e k (2.3dA-dA)

= L _A × e ^{k (0.7dA) to} L _A × e ^{k (1.3dA)}

Here, when the absorbance coefficient k of the clear glass is 0.00578 and the thickness d _A of the A portion is 12.5 mm to 14.5 mm, L _B should have the following value.

L _A x e ^{0.00578 x 0.7 x (12.5 to 14.5)} ≤ L _B ≤ L _A x e ^{0.00578 x 1.3 x (12.5 to 14.5)}

⇒ (1.052 to 1.060) L _A ≤ L _B ≤ (1.098 to 1.115) L _A

Further, when the absorption coefficient k of the tint glass is 0.04626 and the thickness d _A of the A portion is 12.5 mm to 14.5 mm, L _B should have the following value.

L _A × e ^{0.04626 × 0.7 × (12.5 ~ 14.5)} ≤ L _B ≤ L _A × e ^{0.04626 × 1.3 × (12.5 ~ 14.5)}

⇒ (1.499 to 1.599) L _A ≤ L _B ≤ (2.121 to 2.392) L _A

Further, when the absorption coefficient k of the dark tint glass is 0.06737 and the thickness d _A of the A portion is 12.5 mm to 14.5 mm, L _B should have the following value.

L _A ^{xe 0.06737 x 0.7 x (12.5 to 14.5)} ≤ L _B ≤ L _A ^{xe 0.06737 x 1.3 x (12.5 to 14.5)}

⇒ (1.803-1.981) L _A ≤ L _B ≤ (2.988-3.561) L _A

Since the brightness of the phosphor is proportional to the beam current, when the thickness of the part A is 12.5 mm, the clear glass is 1.052 to 1.098 according to the wedge ratio of the beam current I _B of the part B rather than the beam current I _A of the A part. When the voltage is applied to the grid electrode 4 so that the double and the tint glass can flow 1.499 to 2.121 times and the dark tint glass to 1.803 to 2.988 times, the overall brightness becomes the same.

Similarly, when the thickness of the portion A is 14.5 mm, the beam current I B of the portion _B is 1.060 to 1.115 times higher than the beam current I _A of the portion _A depending on the wedge ratio. 2.392 times and dark tint glass is the same brightness as the voltage applied to the grid electrode 4 to flow 1.981 ~ 3.561 times more.

If the cutoff voltage (V _cut ) is set to 180V and the white level voltage is set to 70V, the gamma coefficient of the electron gun is 3.04. Therefore, the signal level applied to the cathode is set to I = (180-V _CG ) ^γ × 10 ^-3.

= (180-V _CG ) ^3.04 × 10 ^-6 (kPa). Therefore, it can be seen that the current I in the white signal is (180-70) ^3.04 × 10 ⁻⁶ = 1.61 mA.

As a result, in the case of clear glass, when the thickness of the A portion is 12.5 to 14.5 mm, and the wedge ratio is 170%, the current I _B to be flowed to the B portion is 1.61 ㎃ × (1.052 to 1.060) = (1.69 to 1.71) If the wedge rate is 230%, the current I _B to be flowed to the portion _B is 1.61 ㎃ x (1.098 to 1.115) = (1.77 to 1.80) ㎃.

In the case of tinted glass, when the thickness of the A portion is 12.5 to 14.5 mm, and the wedge ratio is 170%, the current I _B to be flowed to the B portion is 1.61 ㎃ × (1.499 to 1.599) = (2.41 to 2.57) 웨 and the wedge rate is 230%, the current I _B to be flowed to the B portion is 1.61 ㎃ × (2.121 to 2.392) = (3.41 to 3.85) ㎃.

In the case of dark tint glass, when the thickness of the A part is 12.5 to 14.5 mm, and the wedge ratio is 170%, the current I _B to be flowed to the B part is 1.61 ㎃ × (1.803 to 1.981) = (2.90 to 3.19) ㎃ If the wedge rate is 230%, the current I _B to be flowed to the portion _B is 1.61 ㎃ × (2.988 to 3.561) = (4.81 to 5.73) ㎃.

As described above, the voltage required to flow a current in the portion B according to the wedge ratio is V _CG = 180- (3.04 × 10 ⁶ ) ^{1 / 3.04} at I = (180-V _CG ) ^3.04 × 10 ^-6 (㎃). .

Therefore, in the case of clear glass, when the thickness of the A portion is 12.5 to 14.5 mm and the wedge ratio is 170%,

V _CG = 180-{(1.69∼1.71) × 10 ⁶ } ^{1 / (3.04)} = (68.2∼67.8) V,

In the case of clear glass, when the thickness of the A portion is 12.5 to 14.5 mm and the wedge ratio is 230%,

V _CG = 180-{(1.77-1.80) × 10 ⁶ } ^{1 / (3.04)} = (66.5-65.9) V,

In the case of tinted glass, when the thickness of the A portion is 12.5 to 14.5 mm and the wedge ratio is 170%,

V _CG = 180-{(2.41-2.57) x 10 ⁶ } ^{1 / (3.04)} = (54.3-51.7) V,

In the case of tinted glass, when the thickness of the A portion is 12.5 to 14.5 mm and the wedge ratio is 230%,

V _CG = 180-{(3.41-3.85) x 10 ⁶ } ^{1 / (3.04)} = (39.1-33.4) V,

In the case of dark tint glass, when the thickness of the A portion is 12.5 to 14.5 mm and the wedge ratio is 170%,

V _CG = 180-{(2.90-3.19) x 10 ⁶ } ^{1 / (3.04)} = (46.5-42.2) V,

In the case of dark tint glass, when the thickness of the A portion is 12.5 to 14.5 mm and the wedge ratio is 230%,

V _CG = 180-{(4.81 to 5.73) × 10 ⁶ } ^{1 / (3.04)} = (22.3 to 12.9) V.

As a result, the difference between the above-described voltage and the signal voltage is the edge correction waveform voltage of the parabola voltage.

That is, as shown in FIGS. 10A to 10F, the edge correction waveform voltage V _V of the parabola voltage is a voltage that should be applied to the grid electrode 4 to display the B portion when the white signal is used.

When the wedge rate of the clear glass is 170%, 70 V-(68.2 to 67.8) V = (1.8 to 2.2) V,

When the wedge rate of clear glass is 230%, 70 V-(66.5 to 65.9) V = (3.5 to 4.1) V,

When the wedge rate of the tinted glass is 170%, 70 V-(54.3 to 51.7) V = (25.7 to 28.3) V, depending on the thickness of the A portion.

When the wedge rate of the tinted glass is 230%, 70V- (39.1-33.4) V = (30.9-36.6) V,

When the wedge rate of dark tint glass is 170%, 70V- (46.5 ~ 42.2) V = (23.5 ~ 27.8) V,

When the wedge rate of dark tint glass is 230%, 70 V-(22.3-12.9) V = (47.7-57.1) V depending on the thickness of the A portion.

As described above, according to one embodiment of the present invention, the vertical and horizontal parabola voltages of the dynamic focus circuit of the general cathode ray tube are input to the grid electrode 4 of the luminance compensator 11 shown in FIG. The input voltage is applied to the grid electrode 4 through an amplifier stage composed of transistors Q1 and resistors R1 and R2.

However, since the luminance compensator 11 always applies a constant parabola voltage to the grid electrode 4, there is a problem that an unnecessary luminance image occurs when displaying a black level or a white level on the entire screen. In other words, when the black level is displayed, the background luminance is deteriorated by applying the luminance compensation voltage, thereby degrading the contrast.

FIG. 11 is a diagram illustrating a luminance compensator according to another exemplary embodiment of the present invention, a voltage controller for inputting vertical and horizontal parabola voltages of a dynamic focus circuit of a cathode ray tube driving circuit and receiving and amplifying a voltage according to a beam current. The grid electrode of the electron gun by amplifying the vertical and horizontal parabola voltages controlled according to the output voltage of the first amplifier Q1 and the first amplifier Q1 that input the amplified voltage as the control voltage of the voltage controller. It consists of the 2nd amplifier part Q2 applied to (4).

The voltage controller comprises a volume control IC, and the vertical and horizontal parabola voltages are input to the voltage controller through resistors R1 and R2, respectively, and the first amplifier and the second amplifier are transistors Q1 and Q2, respectively. It consists of.

In this way, the mixed parabolic voltage of the vertical horizontal period is connected to the resistors R1 and R2 by connecting vertical and horizontal parabola voltages having a magnitude of several tens of volts in front of the second amplifier in the circuit generating the dynamic focus voltage. By dividing by R1 and R2, adjust the size of vertical and horizontal parabolic waveform. This voltage is input to the voltage control unit (Volume Control IC) and the voltage of the ABL terminal is connected to the control voltage of the voltage control unit to detect the change in voltage according to the beam current.

The voltage of the ABL terminal is amplified by changing the polarity by the first amplifier (transistor Q1) and then input to the control voltage of the voltage controller, and the output of the voltage controller is varied according to the magnitude of the control voltage. When the voltage increases, the voltage decreases when the beam current is small. In addition, the voltage of the voltage control unit is very small and amplified by the second amplifier (transistor Q2) and input to the grid electrode of the electron gun.

Therefore, by sensing the amount of beam current emitted from the cathode through the ABL stage and adjusting the parabola voltage input to the grid electrode 4 of the electron gun according to the sensed value, it is possible to prevent excessive luminance or lack of compensation.

In the above description, the luminance compensation voltage is applied to the grid electrode 4, but similar effects can be obtained by applying the acceleration compensation voltage 5 adjacent to the grid electrode 4.

Recently, with the release of cathode ray tubes whose outer surface is nearly flat, the difference in curvature between the inner surface of the cathode ray tube and the outer surface of the screen causes a great difference in thickness between the middle portion of the screen and the outside portion of the screen. In general, this is expressed as wedge ratio. When using a conventional form mask, the wedge ratio is 230% smaller and 170% smaller, and the difference in luminance due to the thickness difference is obtained. In order to overcome this problem, the screen panel is manufactured by using clear glass having a very high transmittance. Clear glass also has a transmittance of 75% or more, so the difference in luminance is caused by the same beam current due to the difference in thickness, so that the transmittance on the outer surface of the screen varies depending on the position of the screen. This other film is attached to the outer surface to obtain uniform luminance. Of course, when tint glass having a transmittance of 45% or more and less than 75% is used to increase the quality of the cathode ray tube or to reduce the production cost, it is almost impossible to obtain uniform luminance at high wedge ratios.

The present invention can be solved by simply and easily varying the intensity of the electron beam, the difference in luminance due to the distribution of glass thickness by using the characteristics of the relevant portion.

In addition, as a method for overcoming the difference in luminance between the middle and outer portions of the screen caused by an increase in the wedge ratio due to the difference in curvature between the inner surface and the outer surface of the CRT, the current of the beam is obtained by using the voltage of the ABL stage. By varying the degree of compensation according to the change of, the luminance of the middle and outer portions of the screen can be kept uniform or the ratio is constant regardless of whether the luminance of the screen is high or low.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.

1 is a view showing the operation principle of a conventional color cathode ray tube,

2 is a block diagram showing the configuration of a conventional luminance compensation device;

3 is a block diagram showing the structure of another conventional luminance compensation device;

4A to 4C are graphs showing the glass current relationship according to the beam current and the luminance relationship, the glass thickness and the light transmittance relationship, and the screen position, respectively;

5 is a view showing a light transmittance difference according to the panel thickness;

6 is a diagram illustrating a principle of luminance compensation according to glass thickness;

7 is a diagram illustrating a luminance compensation principle according to an embodiment of the present invention;

8A to 8D are waveforms showing voltage waveforms in a conventional electron gun triode;

9A to 9D are waveforms showing voltage waveforms at the three-pole portion of the electron gun of the present invention;

10A to 10F are waveforms showing compensation voltage waveforms according to glass transmittance and wedge ratio, and

11 is a diagram illustrating a luminance compensation principle according to another embodiment of the present invention.

*** Explanation of symbols for the main parts of the drawing ***

1: color cathode ray tube 2: heater

3: cathode 4: grid electrode

5: acceleration electrode 6: deflection yoke

7: phosphor 8: panel

10: electron gun 11: luminance compensation circuit

Claims (18)

A panel having a screen formed therein, a funnel coupled to the panel, an electron gun coupled to a neck portion of the funnel to emit an electron beam toward the screen, and an image of the electron beam emitted from the electron gun deflected horizontally and vertically to display an image. A color image display device comprising: a cathode ray tube having a deflection device; and a shadow mask disposed at a predetermined distance from a screen. The electron gun includes a triode consisting of a cathode generating an electron beam, a grid electrode disposed adjacent to the cathode, and an acceleration electrode disposed adjacent to the grid electrode, A variable voltage is applied to the grid electrode or the acceleration electrode, When the transmittance of the panel is 75% or more, the following formula (1) is satisfied, (1.052 to 1.098) I _A ≤ I _B ≤ (1.060 to 1.115) I _A. (One) When the transmittance of the panel is greater than 45% and 75% Mimin, the following formula (2) is satisfied, (1.499-2.121) I _A ≤ I _B ≤ (1.599-2.392) I _A. (2) And the following formula (3) is satisfied when the transmittance of the panel is 45%. (1.803 to 2.988) I _A ≤ I _B ≤ (1.981 to 3.561) I _A. (3) (I _B : Beam current when displaying the part corresponding to the outermost part of the display screen, I _A : Beam current when displaying the part corresponding to the center of display screen) The method of claim 1, The cathode ray tube is a planar cathode ray tube having a substantially flat outer surface and a constant curvature on its inner surface; And a variable voltage applied to the grid electrode or the acceleration electrode is a parabola waveform voltage gradually increasing from the center of the screen to the outside. delete delete delete The method of claim 1, In the case of the white signal, the beam current when displaying the part corresponding to the outermost part of the display screen is referred to as I _B , and the beam current when displaying the part corresponding to the center of the display screen is referred to as I _A. A color image display apparatus, characterized by the following. (1.69-1.71) I 1 _B (1.77-1.80) (4) The method according to claim 1 or 2, And a voltage (V _V ) applied to a grid electrode or an acceleration electrode when displaying a portion corresponding to the outermost portion of the display screen when the white signal is displayed, satisfying the following expression (5). (1.8 to 2.2) V? V _V ? (3.5 to 4.1) V. (5) The method of claim 1, In the case of the white signal, the beam current when displaying the part corresponding to the outermost part of the display screen is referred to as I _B , and the beam current when displaying the part corresponding to the center of the display screen is referred to as I _A. A color image display apparatus, characterized by the following. (2.41 to 2.57) ≤ I _B ≤ (3.41 to 3.85) (6) The method according to claim 1 or 2, The color image display device characterized in that the voltage V _V applied to the grid electrode or the acceleration electrode when displaying a portion corresponding to the outermost portion of the display screen when the white signal is satisfied satisfies the following expression (7). (25.7 to 28.3) V ≤ V _V ≤ (30.9 to 36.6) V... (7) The method of claim 1, In the case of a white signal, the beam current when displaying the part corresponding to the outermost part of the display screen is referred to as I _B , and the beam current when displaying the part corresponding to the center of the display screen is referred to as I _A. A color image display apparatus, characterized by the following. (2.90-3.19) ≤ I _B ≤ (4.81 to 5.73) (8) The method of claim 1, And a voltage (V _V ) applied to a grid electrode or an acceleration electrode when displaying a portion corresponding to the outermost part of the display screen when the white signal is displayed, satisfying the following expression (9). (23.5 to 27.8) V? V _V ? (47.7 to 57.1) V (9) A panel having a screen formed therein, a funnel coupled to the panel, an electron gun coupled to a neck portion of the funnel to emit an electron beam toward the screen, and an image of the electron beam emitted from the electron gun deflected horizontally and vertically to display an image. A color image display device comprising a cathode ray tube having a deflection device and a shadow mask arranged at a predetermined distance from a screen, The electron gun includes a triode comprising a cathode for generating an electron beam according to an input image signal voltage, a grid electrode disposed adjacent to the cathode, and an acceleration electrode disposed adjacent to the grid electrode; A luminance compensation device for applying a luminance compensation voltage to the grid electrode or the acceleration electrode of the electron gun to compensate for the luminance difference according to the panel glass thickness; And the luminance compensation voltage is changed according to a beam current emitted from the cathode. The method of claim 12, The luminance compensator includes a voltage controller for adjusting vertical and horizontal parabola voltages input according to a detected beam current value, a first amplifier for amplifying a voltage according to beam current, and a second amplifier for amplifying an output of the voltage controller. A color image display apparatus comprising an amplifier section. The method of claim 12, And the detected beam current is detected from an ABL output terminal. The method of claim 13, And said vertical and horizontal parabola voltages are output voltages of a dynamic focus circuit. The method of claim 13, And the voltage control unit is a volume control IC. The method according to any one of claims 1, 2, and 12, And a wedge ratio (thickness ratio of the outermost portion to the center thickness of the panel) of the panel is 170% to 230%. The method according to any one of claims 1, 2, and 12, And a center portion thickness of the panel is 12.5 to 14.5 mm.