EP0680068B1

EP0680068B1 - Flat picture tube

Info

Publication number: EP0680068B1
Application number: EP95104749A
Authority: EP
Inventors: Keum Sik Lee; Byoung Jun Rhee
Original assignee: Youare Electronics Co Ltd
Current assignee: Youare Electronics Co Ltd
Priority date: 1994-04-28
Filing date: 1995-03-30
Publication date: 1998-07-15
Anticipated expiration: 2015-03-30
Also published as: CN1113031A; DE69503427D1; DE69503427T2; JPH0922670A; EP0680068A1; KR950025836A; KR0160322B1

Description

Background of the Invention

The present invention relates to a flat picture tube according to the preamble of claim 1.

Generally, in projecting an image, a cathode ray tube makes a phosphor luminous by using thermoelectrons to be emitted.

Fig. 1 illustrates a conventional color cathode ray tube.

Referring to Fig. 1, there are comprised of an electron gun 1,

deflection yokes

3 and 4, a shadow mask 6, a phosphorous surface 5, and a high-voltage power supply 7.

Electron gun 1, made up of three red, green and blue electron guns, emits red, green and blue electron beams 8.

Deflection yokes

3 and 4 converge red, green and blue electron beams 8 onto one point of shadow mask 6.

Shadow mask 6, formed with a plurality of holes on the inner surface of phosphorous surface 5, passes electron beams 8 emitted from electron gun 1 through one hole, and emits them onto phosphorous surface 5.

Phosphorous surface 5 is made in such a manner that red, green and blue phosphors are coated uniformly on a glass surface 2. Electron beams 8 passing shadow mask 6 make the phosphorous surface luminous.

High-voltage power supply 7 absorbs the electrons used in luminance on phosphorous surface 5, and supplies a highvoltage power to electron gun 1.

When the high-voltage power is fed from high-voltage power supply 7, the red, green and blue electron guns heat a built-in heater (not shown) to emit thermoelectrons. The emitted thermoelectrons are then controlled by a plurality of grids (not shown), and emitted as electron beams 8.

Red, green and blue electron beams 8 emitted from the red, green and blue electron guns converge onto one hole of shadow mask 6 by

deflection yokes

3 and 4, and pass therethrough.

The red, green and blue electron beams 8 passing through one hole of shadow mask 6 collide with the red, green and blue phosphors of phosphorous surface 5 so as to make them luminous.

However, in this conventional color cathode ray tube, electron gun 1 for emitting electron beams 8, and

deflection yokes

3 and 4 are essential to increase the volume. In addition, a high-voltage power must be supplied for the emission of electron beams 8, raising power consumption.
DE-A-3 613 716 discloses a flat picture tube as described in the preamble of claim 1. However, the known flat picture is based on a common anode structure consisting of an anode electrode on which a fluorescent unit is deposited. The object is to prevent mechanical vibrations of a control grid stretched in an envelop. This is achieved by providing spacers (of non conducting material) between the fluorescent units in order to contact with the control grid during its mechanical vibration. No hint is given to a further metal layer being deposited on the fluorescent unit in order to provide a further control electrode in proximity of the anode electrode.

Further, US-A-3 176 184 shows an electron deflection system for image reproduction using a plate cathode for emitting electrons, a control block having a plurality of parallel tunnels therethrough for controlling the electron flow and separate deflection plates in order to focus the electrons emitted from the cathode plate. This known flat picture tube does not even use a matrix arrangement of the control and anode electrodes.

Summary of the Invention

It is an object of the present invention to provide a flat picture tube with improved control and light efficiency.

This object is achieved by a flat picture tube according to claim 1. Further embodiments of the invention are described in the dependent claims.

The flat picture tube according to the present invention comprises a heater for emitting thermoelectrons; a plurality of anodes extending vertically and arranged by a predetermined interval for attracting said thermoelectrons; a plurality of phosphor units arranged in a matrix form on the plurality of anodes and becoming luminous when said thermoelectrons are absorbed; a plurality of grids extending horizontally and arranged by a predetermined interval for controlling the thermoelectrons to be absorbed; and a plurality of metal deposits formed on said phosphor units for controlling the absorption of the thermoelectrons into said phosphor units.

Brief Description of the Attached Drawings

Fig. 1 illustrates a conventional color cathode ray tube;

Fig. 2 is a side sectional view of a flat picture tube of the present invention;

Fig. 3 is a front view of the flat picture tube of the present invention;

Fig. 4 is a diagram of an operation state of the flat picture tube of the present invention;

Fig. 5 is a diagram of input signal waveforms of the grid electrode of the present invention;

Fig. 6 is a diagram of input signal waveforms of the anode electrode of the present invention; and

Fig. 7 illustrates another embodiment of the flat picture tube of the present invention.

Detailed Description of the Invention

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings.

Referring to Figs. 2 and 3, there are provided a heater 17, a plurality of anodes 15, phosphor units 12, a plurality of grids 18, and a plurality of target electrodes 20.

Heater 17 is to emit thermoelectrons (also called "thermions"), being composed of 40 vertical heater lines H1-H40 in order to uniformly distribute the theroelectrons. The distance between lines is about 10 mm.

The power supplied to heater 17 is available from 3V to 250V for both DC and AC, not requiring a high-voltage power.

Anodes 15 are to attract the thermoelectrons emitted from heater 17 for luminance. Positive power is supplied thereto. The anodes 15 are made so that they extend vertically and are coated with vertical transparent metal lines by predetermined intervals on a plane glass surface 11.

A black dielectric 13 is formed between anodes 15 of vertical transparent metal lines for the purpose of light insulation. The width of the vertical transparent metal lines, that is, anodes 15, is 0.11 mm. The width of the black dielectric 13 between anodes 15 is 0.08 mm.

For instance, for a 19-inch picture tube, anodes 15 are made up of 2100 vertical transparent metal lines, increasing the resolution, as compared with that of a conventional picture tube of 600 lines.

Phosphor units 12 are arranged in a matrix form on anodes 15, and become luminous by the thermoelectrons attracted by anodes 15. The phosphor is made in a manner that red, green and blue phosphor units are alternately printed horizontally by using a silk screen. Here, in order to form phosphor units 12 as many as the number of grids 18, that is, the number of vertical scan lines, vertically, said black dielectric 13 is arranged by predetermined intervals. The black dielectric 13 is for light insulation.

For instance, for the 19-inch picture tube, the phosphor 12 is formed by 0.46 mm vertically, with the black dielectric 13 being formed by 0.11 mm. The number of vertical scan lines is predetermined by a broadcasting station. In the NTSC method, it is 525.

An aluminum layer is deposited on the red, green and blue phosphor units 12 to form a metal deposit (metal back) 14. An dielectric screen 16 is attached to the metal deposit 14.

Grid 18 is installed on dielectric screen 16 to thereby control the thermoelectrons emitted from heater 17 to be absorbed into the phosphor units 12. The grid extends horizontally, and is arranged by predetermined intervals.

Grid 18 is arranged as many as the number of the vertical scan lines, for instance, 525 (G1-G525), horizontally. They are arranged vertically by predetermined intervals, and attached to the dielectric screen 16.

Target electrodes 20 are installed near the upper and lower ends of the phosphor units 12 between the heater 17 and the grid 18, that is, near the black dielectric units 13. Negative power is applied to the target electrodes 20 so that the thermoelectrons emitted from heater 17 are absorbed to the phosphor units 12 of corresponding anodes 15, whereby not being emitted to sides. For this reason, the phosphor units 12 becomes luminous. The number of target electrodes 20 is twice the number of the vertical scan lines, that is, the number of grids 18.

The operation will be described with reference to Figs. 4, 5 and 6.

The red, green and blue phosphors of anode 15 operate as one, according to one anode input signal A1', A2',..., or A700', and grid input signal G1, G2 ,..., or G525.

For instance, when anode input signal A1' and grid input signal G1 both are positive and synchronized, the first red, green and blue phosphors become luminous. The brightness of the red, green and blue phosphors is controlled by an input image signal. Here, the theroelectrons emitted from heater 17 are converged to the respective phosphor units 12 by target electrodes 20 to which negative power is applied, and then incident on anode 15 according to synchronized anode 15 and grid 18.

This operation will be explained in the case of the 19-inch flat picture tube.

525 grid input signals G1, G2, G3,..., and G525 stay HIGH for 59 µs sequentially for one period of a vertical sync signal VS. Anode input signals A1', A2',... and A700' stay HIGH for 75ns sequentially for one period of a horizontal sync signal HS. Here, red, green and blue phosphors in which the grid input signal and anode input signal both are HIGH, become luminous. According to horizontal sync signal HS and vertical sync signal VS, the red, green and blue phosphors become luminous horizontally and sequentially, and then a next row of red, green and blue phosphors becomes luminous, making all of the phosphors of the flat picture tube luminous for one period of vertical sync signal VS.

Here, a grid input signal and anode input signal corresponding to a phosphor unit not to become luminous stay LOW. This state indicates a standby. The brightness of red, green and blue phosphors is determined by an input image signal.

Referring to Fig. 7, an electrode is connected to the metal deposit 14, and is integrally formed with the grid 18. By doing so, the metal deposit 14 deposited on phosphor 12 can be used as a grid, without having a separate grid.

In other words, the electrode is connected to metal deposit 14 to control the thermoelectrons emitted from heater 17 to be absorbed to phosphor 12 of anode 15.

As described above, the present invention operates in a matrix digital method, not requiring an electron gun and deflection yoke. This reduces the volume. For a 20-inch picture tube, the thickness is 4 cm at maximum so that the picture tube can be used as wallmounted TV. In addition, the present invention does not need a high-voltage power supply, reducing power consumption. For a 19-inch color picture tube, the number of horizontal lines is 2100, increasing the resolution, as compared with 600 lines in the conventional color cathode ray tube.

Claims

A flat picture tube comprising:

a heater (17) for emitting thermoelectrons;

a plurality of anodes (15) extended in a first direction in the plane of the picture tube and arranged in a predetermined interval for attracting said thermoelectrons:

a plurality of grids (18) extended in a second direction in the plane of the picture tube perpendicular to said first direction and arranged in a predetermined interval for controlling the amount of thermoelectrons;

a plurality of phosphor units (12) disposed on said anodes for emitting radiation when said thermoelectrons are absorbed;

characterized in that,

said phosphor units (12) are disposed in a matrix-like manner on said anodes (15) ; and

a plurality of metal deposits (14) is formed on said phosphor units (12) for controlling the absorption of the thermoelectrons into said phosphor units (12).
A flat picture tube as claimed in claim 1, further comprising a plurality of target electrodes (20) installed near the upper and lower ends of said plurality of phosphor units (12) between said heater (17) and said grids (18) for converging said thermoelectrons onto said phosphor units (12).
A flat picture tube as claimed in claim 1, wherein a dielectric screen (16) is arranged between said grids (18) and said metal deposits (14).
A flat picture tube as claimed in claim 1, wherein an aluminum layer is deposited to form said metal deposits (14).
A flat picture tube as claimed in claim 1, wherein said heater (17) is made up of 40 heater lines extending in the first direction.
A flat picture tube as claimed in claim 1, wherein said anodes (15) are made up of transparent metal lines extending in the first direction and coated by a predetermined interval on a plane glass surface (11).
A flat picture tube as claimed in claim 1, wherein black dielectrics (13) are arranged in the first direction by a predetermined interval in order to dispose said phosphor units (12) in a matrix form.
A flat picture tube as claimed in claim 1, wherein said phosphor units (12) are made up of the same number as that of said grids (18).
A flat picture tube as claimed in claim 1, wherein said phosphor units (12) are made in a manner that red, green and blue phosphors are sequentially and printed in the second direction on said plurality of anodes (15).
A flat picture tube as claimed in claim 1, wherein said grids (18) are made up of the same number as that of scan lines extending in the first direction.
A flat picture tube as claimed in claim 2, wherein said target electrodes (20) are made up of twice the number of said grids.
A flat picture tube as claimed in claim 2, wherein black dielectrics (13) are arranged in the first direction by a predetermined interval in order to dispose said phosphor units (12) in a matrix form and said electrodes (20) are installed on said black dielectrics (13).
A flat picture tube as claimed in claim 5, wherein said heater lines are formed by the interval of 10 mm.
A flat picture tube as claimed in claim 6, wherein a black dielectric (13) is formed between said transparent metal lines.
A flat picture tube as claimed in claim 6, wherein said transparent metal line is 0.11 mm in width.
A flat picture tube as claimed in claim 6, wherein said transparent metal lines are coated by the interval of 0.08 mm.
A flat picture tube as claimed in claim 7, wherein said black dielectrics (13) are arranged by a predetermined interval so that said phosphor units (12) are the same number as that of scan lines extending in the first direction.