JP2776236B2 - Cathode ray tube and driving method of cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube (hereinafter abbreviated as CRT) equipped with an electron gun using a field emission cathode as an electron source.
And its driving method.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional general CRT. The CRT 1 includes a neck 3 having an electron gun 2,
It has a funnel section 5 provided with a deflection electrode 4 for deflecting the electron beam emitted from the neck section 3, and a panel section 6 on which a phosphor excited and emitted by the electron beam is attached.

FIG. 7 shows a conventional electron gun 2 used in a conventional general CRT 1. The electron gun 2 has an indirectly heated cathode 7 for heating an oxide layer by a heater, an extraction electrode 8, and a focusing electrode 9.

According to the CRT 1 configured as described above, the focused electron beam emitted from the electron gun 2 at the neck is guided to a predetermined position on the panel 6 by the deflection electrode 4 of the funnel 5. As a result, the fluorescent screen is excited to emit light, and a desired display is performed.

[0005] The above-described conventional CRT using an electron gun has the following problems. (1) Since the cathode of the conventional electron gun is of an indirectly heated type, a heater power supply for heating the heater is required. (2) It took some time from when the heater power supply was turned on to when an electron beam was obtained.

(3) Since the life of the heater of the electron gun is short, a long life CR
I couldn't do T. (4) An electron source emitting an electron beam with a high current density could not be obtained.

(5) Since the diameter of the electron generating portion of the electron gun is as large as several millimeters, if the beam is slightly converged to a certain degree or less by the electron lens system, the beam shape is distorted due to aberration, and The electron density is likely to be non-uniform within the beam diameter.

In order to solve the above-mentioned problems, in recent years, a field emission cathode (Field Emi
ssion Cathode, also called FEC. CRT using)
Has also been proposed. This can be said to focus on the advantages of FEC, which is small, does not require a heater, and can obtain a high current density.

[0009]

Some of the conventional CRTs using FEC include different numbers of binary numbers related to F, as described in, for example, Japanese Patent Application Laid-Open No. 4-272826.
In some cases, a plurality of groups each including an EC cell are configured, and these groups are driven in different combinations to realize different brightness.

However, such a structure in which the FEC itself is divided so as to correspond to the number of gradations increases the manufacturing cost,
In addition, it was difficult to control the brightness in stages.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cathode ray tube having an FEC in an electron generating portion of an electron gun, capable of performing excellent brightness control with a simple configuration, and a driving method thereof.

[0012]

According to a first aspect of the present invention, there is provided a cathode ray tube comprising: an electron gun having a field emission cathode having an emitter and a gate as an electron source; and an electron beam emitted from the electron gun. It has a deflecting electrode for the electron beam to be emitted, a panel section on which a phosphor emitting light by the projection of the electron beam is attached, and a brightness control means for controlling the brightness of the panel section.
In the cathode ray tube, the brightness control means has the following structure.
It is characterized by the fact that That is, the brightness
Control means for storing storage means having gradation data;
Said electronic Bee give stairs-shaped deflection electrode control signals to the electrodes
Scans the panel section with the
The addressing signal that changes in synchronization with the control signal is stored in the memory.
Means for inputting the gradation data in the storage means to an address pointer.
CRT controller for setting and the CRT controller
The grayscale data addressed by
Gate voltage-emission current characteristic of emission cathode is in the linear region
In this case, a gradation control signal of a voltage corresponding to the gradation data is transmitted.
The field emission cathode is synchronized with the deflection electrode control signal.
The scanning of the panel section is performed by applying the
Gradation control circuit that controls light emission luminance for each pixel
And consisting of

A method for driving a cathode ray tube according to claim 2.
Uses a field emission cathode with an emitter and a gate as an electron source
And an electron beam emitted from the electron gun
Electrode for deflecting the electron beam
Has a panel part on which phosphors that emit light due to bumps are attached
In the method of driving a cathode ray tube for driving a cathode ray tube,
A stepwise deflection electrode control signal is applied to the deflection electrode to
Scanning the panel section with the sub beam and the deflection
An addressing signal that changes in synchronization with the electrode control signal
Addressing the stored gradation data
The gate voltage-emission current characteristics of the negative
A gradation control signal of a voltage corresponding to the gradation data
The gate of the field emission cathode is synchronized with a deflection electrode control signal.
The panel section is scanned by applying
It is characterized in that the light emission luminance is controlled for each pixel .

[0015]

The gradation data in the storage means is used as a control signal for the deflection electrode.
Addressed synchronously. Gradation control circuit, address
A gray scale control signal of a voltage corresponding to the gray scale data of the storage means designated by the memory is generated . This gradation control signal is a field emission type
When the gate voltage-emission current characteristic of the cathode is in a linear region
Te is supplied to the gate of the field emission cathodes in synchronization with the control signals of the deflection electrodes. The electron emission amount of the field emission cathode is controlled for each pixel to be scanned, and the brightness is adjusted.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The basic configuration of the CRT 10 of the present embodiment is the same as the configuration of the conventional CRT 1 shown in FIG. That is, FIG.
As shown in (1), an electron gun 12 is provided on a neck portion 11a of a glass container 11 included in the CRT 10 of the present embodiment, and an electron beam emitted from the neck portion 11a is deflected by a deflection electrode of a funnel portion. And the electron beam is
The phosphor of the panel portion provided on the inner surface of the front surface of the glass container 11 collides with the phosphor to excite and emit light, thereby displaying a desired image. However, unlike the conventional CRT 1, the electron gun 12 of the CRT 10 according to the present embodiment has a field emission cathode 20 as an electron source, and the electron gun 12 includes the field emission cathode 20 and first and second cathodes. Electron beam focusing electrodes 25 and 28 are provided.

Next, the configuration of the electron gun 12 will be described in detail. On the ceramic substrate 13, a substrate 14 made of an insulating material such as Si or glass is provided. On the substrate 14, a Spindt-type field emission cathode 20 (F
EC20) are formed in a large number in the range of about 0.5 to 0.6 mm in diameter. That is, the cathode conductor 15 is formed of a conductive thin film on the substrate 14, and the insulating layer 16 and the gate 17 are stacked thereon. Holes 1 are formed in the insulating layer 16 and the gate 17 by photolithography.
A cone-shaped emitter 19 is formed on the cathode conductor 15 in the hole 18 by a vapor deposition method. In this embodiment, the emitter 19 is of the Spindt type. However, in addition to the Spindt-type deposition emitter, a vertical field emission emitter by etching may be used, or a plane field emission emitter may be used as long as the directionality is excellent.

The cathode conductor 15 of the FEC 20 is connected to a cathode stem 21 provided on a ceramic substrate 13.
Is drawn out of the neck portion 11a.

The gate 17 of the FEC 20 is connected to a plate-shaped conductor 22 having a hole formed in the center. Both ends of the conductor 22 penetrate the ceramic substrate 13 and are FE
It is connected to one end of each of two gate stems 23 protruding toward the C20 side. The other end of at least one gate stem 23 projects outward through the neck 11a of the glass container 11.

On the ceramic substrate 13, an insulating layer 24 is formed on the conductor 22.
The first electron beam focusing electrode 25 is provided on the first. The first electron beam focusing electrode 25 is a metal plate having a hole 25a having a diameter of 0.5 to 0.6 mm facing the FEC 20 formed on the substrate 14, and a gate 17 of the FEC 20 near the hole 25a. Distance is 0.08 ~
0.1 mm. Both ends of the first electron beam focusing electrode 25 are supported by rod-shaped lead terminals 26, and at least one of them is led out of the glass container 11.

A second electron beam focusing electrode 28 is provided above the first electron beam focusing electrode 25 via a ceramic insulating material 27 of 0.1 to 0.2 mm. The configuration of the second electron beam focusing electrode 28 is the same as that of the first electron beam focusing electrode 25, and at least one of the lead terminals 29 is led out of the glass container 11.

The CRT 10 according to the present embodiment includes the electron gun 12
And a circuit for applying a predetermined voltage to each of the electrodes. In this example, the emitter 19 is grounded, and
50V, 0-150 for the first electron beam focusing electrode 25
V, 200-500 V for the second electron beam focusing electrode 28
Are applied.

Alternatively, the gate 17 may be grounded to give the same potential difference between the electrodes as described above. Although the electron gun 12 of this embodiment has the FEC 20 and the first and second electron beam focusing electrodes 25 and 28, the third and fourth focusing electrodes may be further provided as necessary. Is also good.

Next, the CRT 10 of this embodiment has a brightness control circuit 30 as brightness control means as shown in FIG. In this embodiment, the gradation data of the image to be displayed is given as analog data. The analog data is converted into digital data by an A / D converter (not shown), and is input to an image memory 32 as storage means. The image memory 32 stores the gradation data of the digitized image and outputs it in response to a call from the outside.

The CRT controller 33 outputs a stepwise deflection electrode control signal as shown in FIG. 4 to the deflection electrode 4 of the CRT 10 and scans it. Further, the CRT controller 33 supplies an addressing signal which changes in synchronization with the deflection electrode control signal to the image memory 32.

As shown in FIG. 3, the CRT controller 3
Digital gradation data in the image memory 32 addressed to the D / A conversion circuit 3 is a D / A conversion circuit 3 as a gradation control circuit.
4 is input. The D / A conversion circuit 34 outputs a gradation control signal having a voltage corresponding to the digital gradation data as a video signal. This video signal is an analog signal as shown in FIG. The video signal is applied to the gate 17 of the electron gun 12 of the CRT 10 in synchronization with the deflection electrode control signal being applied to the deflection electrode 4 of the CRT 10.

In the electron gun 12 in which the video signal is supplied to the gate 17, the emission current of electrons, that is, the emission amount of electrons, is controlled for each scanned pixel of the panel section to adjust the brightness. Controlling the amount of emitted electrons for each pixel scanned in this manner is impossible with a conventional electron gun using a filament as an electron source.

As described above, when the emission current from the FEC is controlled by the video signal (gradation control signal) which is an analog signal, the gate voltage of the FEC shown in FIG.
In the emission current characteristics, a linear region is used. For example, if the range A of the gate voltage in FIG. 5 is set as the control range, the voltage level of the video signal and the amount of electron emission of the FEC can be made proportional. To turn off the light, the voltage of the video signal applied to the gate is set to be equal to or lower than the threshold level voltage (V _TH ) (including 0 V).

[0029]

According to the present invention, in a CRT using a field emission cathode as an electron source of an electron gun, an analog signal having a voltage corresponding to gradation data is supplied to a gate voltage of the field emission cathode.
- in the region of the emission current characteristic straight line, supplied to the gate of the field emission cathodes in synchronism with the deflection electrode control signal, the panel
The brightness is controlled by controlling the amount of emitted electrons for each pixel being scanned in the pixel section . Therefore, according to the present invention, the brightness control of an arbitrary number of gradations which is resistant to noise and excellent in linearity can be realized by an extremely simple configuration, and the convenience in applying a field emission cathode to an electron gun of a CRT is improved. CR
An industrially remarkable effect of improving the functionality of T can be obtained.

Further, according to the present invention, since a field emission cathode is used as an electron source, an electron beam having a small aberration and a uniform electron density in the beam can be obtained only by providing a simple electrostatic lens. Since the emission of the electron beam can be controlled by controlling between the emitters, a compact electron gun can be obtained without having to provide a new control electrode.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an electron gun according to one embodiment.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a block diagram illustrating a configuration of a luminance control circuit according to one embodiment.

FIG. 4 is a drive timing chart of a luminance control circuit in one embodiment.

FIG. 5 is a graph showing a relationship between a gate voltage and an emission current in the FEC of one example.

FIG. 6 is a sectional view showing a structure of a general cathode ray tube.

FIG. 7 is a sectional view of a conventional electron gun.

[Explanation of symbols]

 Reference Signs List 4 deflection electrode 6 panel unit 10 cathode ray tube (CRT) 12 electron gun 17 gate 19 emitter 20 field emission cathode (FEC) 30 luminance control circuit as luminance control means 32 image memory as storage means 33 CRT controller 34 gradation control D / A conversion circuit as a circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-272638 (JP, A) JP-A-63-37543 (JP, A) JP-A-7-220646 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H01J 29 / 48,29 / 04 G09G 1/00 H04N 5/68

Claims (2)

(57) [Claims] 1. An electron gun having a field emission cathode having an emitter and a gate as an electron source, an electron beam deflection electrode for deflecting an electron beam emitted from the electron gun, and emitting light by projecting the electron beam. A panel portion on which a phosphor is applied, and a brightness control means for controlling the brightness of the panel portion.
In cathode ray tube having the brightness control means, giving a storage unit having a tone data, a stepped deflection electrode control signals to the deflection electrode and the
While scanning the panel section with an electron beam,
An addressing signal that changes in synchronization with the counter electrode control signal
The gradation data in the storage means is given to the storage means and stored in the storage means.
A CRT controller to specify a dress, and a gray scale addressed by the CRT controller
Data is input and gate voltage of field emission cathode-emission
In the region where the current characteristic is a straight line, according to the gradation data
The voltage control signal is synchronized with the deflection electrode control signal.
And applying it to the gate of the field emission cathode.
The light emission luminance for each scanned pixel of the panel unit.
And a gradation control circuit for controlling the operation of the cathode ray tube. 2. A field emission shade having an emitter and a gate.
An electron gun having a pole as an electron source, and an electron gun emitted from the electron gun.
An electron beam deflection electrode for deflecting the electron beam;
A panel with a phosphor that emits light when the beam strikes
Method for driving a cathode ray tube driving a cathode ray tube having a
A stepwise deflection electrode control signal is given to the deflection electrode,
While scanning the panel section with an electron beam,
Addressing signal that changes in synchronization with the counter electrode control signal
Thus, the stored gradation data is addressed and
The gate voltage-emission current characteristics of the output cathode are in the linear region.
A grayscale control signal of a voltage corresponding to the grayscale data
The field emission cathode is synchronized with the deflection electrode control signal.
By applying to the gate, the panel section is scanned
The feature is to control the light emission brightness for each pixel
How to drive a cathode ray tube.