JPS62151083A - Driving method for flat plate type cathode-ray tube - Google Patents

Abstract

PURPOSE:To uniform an electron beam generating in order from all of the electron sources on a picture in a time lapse by detecting a beam current value in a horizontal blanking period,and performing a feedback control so that the beam current value coincides with a prescribed level. CONSTITUTION:A horizontal blanking period beam is cut off with a beam cut off signal 56 impressed on a G4 electrode 16, and flows in an electrode 15', and is taken out as a voltage signal with a current detection part 51, and is inputted to a (-) input terminal in a differential amplifier 52, and a difference between a reference voltage impressed on a (+) input terminal is outputted. The difference against a certain reference in the quantity of the beam current outputted from the differential amplifier 52 is impressed on a G2 electrode 14 as a G2 drive signal 59 through an amplifier 54, and the quantity of the beam current is controlled with the G2 drive signal 59. After an operation is completed, the hold state of a sample holding circuit 53 is generated, and the value of the G2 drive signal 59 is fixed at a certain value, then, a normal picture display can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for driving a flat cathode ray tube used in color vision receivers, computer terminal displays, etc. Some cathode ray tubes have the structure shown in Figure 3.In reality, each electrode is housed in a vacuum envelope (glass container), but in order to make the internal electrodes clear, the vacuum envelope is shown in the figure. is omitted.

In addition, in order to clarify the horizontal and vertical directions of the screen for displaying images, characters, etc., there is a horizontal H9 on the face plate.
A vertical direction V is illustrated.

1o is a linear cathode which is long in the V direction and is made of a tungsten wire whose surface is coated with an oxide cathode material, and a plurality of cathodes are arranged independently at equal intervals in the horizontal direction. Linear cathode 1o
On the opposite side of the face plate portion 2, there are vertical scanning electrodes that are electrically divided and elongated in the horizontal direction on the insulating support 11 in close proximity to the linear cathode 1o. 12 are placed. These vertical scanning power supplies 12 are connected to the number of horizontal scanning lines in the vertical direction (approximately 4 in the case of NTSC system) if normal television images are displayed.
80% of the electrodes are formed as independent electrodes. Next, between the linear cathode 10 and the face plate portion 28, from the linear cathode 10 side, planar electrodes having openings in portions corresponding to the linear cathode 1o and the vertical scanning electrode 12 are installed adjacent to each other. The first grid electrode (hereinafter referred to as G1) 13 is divided between the linear cathodes 10 and performs beam modulation by applying a video signal to each electrode. The undivided second grid electrode (
A third grid (hereinafter referred to as G3) 14 and a third grid (hereinafter referred to as G3) 15 are arranged. The G2 electrode 14 is for generating an electron beam from the linear cathode 10, and the G3 electrode 16 is for shielding the electric field from the subsequent electrode and the beam generating electric field. Next, a fourth grid electrode (hereinafter referred to as G4) 16 is arranged, and its opening is larger in the horizontal direction than in the vertical direction. FIG. 4A shows a horizontal section of FIG. 3, and FIG. 4B shows a vertical section. At the rear of the G4 electrode 16, there are two electrodes 1 having apertures that are sufficiently wider in the horizontal direction than in the vertical direction, similar to the apertures in the G4 electrode 16.
7.18, and vertical deflection electrodes are formed by vertically shifting the axes of the openings of the two electrodes as shown in FIG. 4B. After the vertical deflection electrodes 17 and 18,
A plurality of vertically long electrodes are provided between each of the linear cathodes 10 toward the face plate portion 28 side. FIG. 3 shows an example of a three-stage case, in which each electrode is a first horizontal deflection electrode (hereinafter referred to as DH-1) 19, a second horizontal deflection electrode (hereinafter referred to as DH-2) 20, and a third horizontal deflection electrode (hereinafter referred to as DH-2). Below DH
-3) 21, and each of the horizontal deflection electrodes 19 to 21 is connected to a common bus line 22, 23, 24 at every other horizontal direction.

The same voltage as the DC voltage applied to the metal back electrode 26 of the face plate section 28 is applied to the DH-s electrode 21, and the DH-1 electrode 19 and the DH-2 electrode 20 are applied with the same voltage as the DC voltage applied to the metal back electrode 26 of the face plate section 28. A voltage is applied. A light emitting layer consisting of a fluorescent surface 27 and a metal back electrode 26 is formed on the inner surface of the face plate portion 28 . On the phosphor surface, during color display, phosphor stripes of light R9, green G, and blue B are sequentially formed in the horizontal direction via a black guard band.

Next, the operation of the color cathode ray tube will be explained. Heat the linear cathode 1o by passing a current through it,
The same voltage as the potential of the cathode 1o is applied to the G1 electrode 13 and the vertical scanning electrode 12. At this time G1. G2 electrode 1
A voltage higher than the potential of the cathode 1o (for example, 100 to 300 V) is applied to the G2 electrode 14 so that the beam advances from the cathode 10 toward the electrodes 3 and 14 and passes through each electrode opening. Here the beam is G1. The amount of light passing through each hole of the G2 electrode is controlled by changing the voltage of the G1 electrode 13. The beam passing through the aperture of the G2 electrode 14 travels from the G3 electrode 1s to the G4 electrode 16 -> vertical deflection electrode 17, 18 - horizontal deflection electrode 19, 20, 21, but these electrodes have electrons on the fluorescent surface 26. A predetermined voltage is applied so that the beam forms a small spot. Here, the beam focus in the vertical direction is performed by an electrostatic lens formed between the G3 electrode 15, the G4 electrode 16, and the vertical deflection electrodes 17, 18, and the beam focus in the horizontal direction is performed by the DH-
1, DH-2, and DH-3. The two electrostatic lenses are formed only in the vertical and horizontal directions, respectively, so that the vertical and horizontal spot sizes of the beam can be adjusted individually.

Also DH-1 (1a), DH-2 (20), DH
-3 (21) is connected to the bus bars 22, 23, and 24 with the same horizontal scanning synchronization sawtooth wave, triangular wave, or staircase wave deflection voltage applied to the buses 22, 23, and 24 to which the electron beam is directed horizontally to a predetermined width. A luminescent image is obtained by scanning the fluorescent surface 26 with the electron beam.

Next, vertical scanning will be explained using FIG. 6.

As described above, by controlling the voltage of the vertical scanning electrode 12 so that the potential of the space surrounding the linear cathode 1o becomes more positive or negative than the potential of the linear cathode 10, the linear cathode 1o The generation of electrons from is controlled. At this time, if the distance between the linear cathode 1o and the vertical scanning electrode 12 is small, a beam is generated from the cathode (hereinafter O
N), the voltage for controlling shutoff (OFF) may be small.

In the case of the current television system that uses an interlace system, a predetermined deflection voltage is applied to the vertical deflection electrodes 18 and 19 for one field in the first field, and a 12A voltage of the vertical scanning power supply 12 is applied to the vertical deflection electrodes 18 and 19. The beam modulation electrode is applied only during one horizontal scanning period (hereinafter referred to as IH), and the beam modulation electrode is applied to the other vertical scanning electrodes 12B to 12Z. After 1H has elapsed, a 1H beam ON voltage is applied only to the vertical scanning electrode 12B, and then a voltage is applied to the vertical scanning electrode to turn the beam ON only for 1H, and when 122 at the bottom of the screen ends, the first 1 field vertical The scan is complete.

In the next second feed, the polarity of the deflection voltage applied to the vertical deflection electrodes 17 and 18 is reversed, and this is applied for one field. The signal voltage applied to the vertical scanning electrode 12 is applied in the same manner as in the first field. At this time, the amplitude of the deflection voltage applied to the vertical deflection electrodes 17 and 18 is adjusted so that the horizontal scanning line of the second field is located between the horizontal scanning line positions of the beam caused by the vertical scanning of the first field.

As described above, the vertical scanning electrode 12 has the first. The same vertical scanning signal voltage is applied to the second field, and by changing the deflection voltage applied to the vertical deflection electrodes 17 and 18 between the first field and the second field, one frame of vertical scanning is completed.

Next, we will explain a generally well-known method for the signal processing system until the video signal is applied to the beam modulation electrode of a cathode ray tube that has a plurality of beam generation sources in the horizontal direction, such as the above-mentioned flat-type cathode ray tube. This will be explained using Figure 6.

Timing pulse generator 4 based on TV synchronization signal 42
4, a timing pulse is generated to drive a circuit block to be described later. First, the three primary color signals of R, G, and B (Eu, E
a, EB) 41 is converted into a digital signal by an A/D converter 43, and the 1H signal is input to the first line memory circuit 46.

When all the signals for 1H are input, the signals are simultaneously transferred to the second line memory circuit 46, and the next 1H signal is also input to the first line memory circuit 45.

The signal transferred to the second line memory circuit Kiku is stored and retained for 1H, and is sent to the D/A converter (or pulse width converter) 47, where it is converted to the original analog signal (or pulse width modulated signal). signal), which is amplified and applied to the modulation electrode G1 of the cathode ray tube.

Such a line memory circuit is used for time axis conversion.

Problems to be Solved by the Invention As in the above embodiments, the invention has a large number of electron beam generating sources,
In flat cathode ray tubes, in which the electron beams obtained from these sources are deflected horizontally and vertically to form the entire screen, it is extremely difficult to keep the amount of beams obtained from all electron beam sources uniform over time. .

The present invention has been made in view of the above, and it is an object of the present invention to provide a driving method that performs feedback control to keep the amount of beam obtained from all electron beam sources uniform over time with a simple configuration. .

Means for solving the problem: generate a beam under predetermined operating conditions during the horizontal blanking period, and at the same time cut off the beam heading toward the anode;
The beam current value is detected by flowing this into the beam detection electrode, the beam current value is compared with a certain predetermined level, and a voltage corresponding to the difference is applied to the electrode that controls the beam current. Performing feedback control so that the current value matches the predetermined level, and then holding the voltage value applied to the electrode that controls the beam current,
Displays a normal image. The above operation is repeated every 1H for each electron beam source.

Operation Since the generation of electron beams from each electron source is performed sequentially for each 1H period, feedback control is repeated so that the electron beam value matches a predetermined level every 1H. The electron beams sequentially generated from all the electron sources become uniform over time.

Embodiment FIG. 1 is a partial perspective view of a flat plate cathode ray tube and a block diagram of a circuit system for controlling beam current uniformity. G
The first electrode 13, the G2 electrode 14', and the G3 electrode 16' are divided horizontally in correspondence with the cathode 10, but the other parts have the same structure as the conventional example, and therefore the basic structure for displaying images is the same as that of the conventional example. The same action applies. First about the driving method for uniformizing the beam current
This will be explained using the diagram and FIG.

48 is a vertical scanning electrode drive circuit, and a vertical scanning electrode drive signal ss is applied to each electrode 12A, 12B, . . . of the vertical scanning electrode 12 to sequentially turn on the beam for 1H period.
A, ssB... are applied sequentially. A G1 drive circuit 49 generates a G1 drive signal by inserting a pulse 68 having a predetermined time width and a predetermined voltage value into the video signal for beam modulation during the horizontal blanking period, and applies it to the G1 electrode 13. 50 is a G4 drive circuit which generates a beam cutoff signal 56 to cut off the beam irradiated to the anode at the 04 electrode 16 during the horizontal blanking period and applies it to the G4 electrode. Reference numeral 51 denotes a current detection section, which detects the beam current flowing into the G3 electrode 15', and converts the beam current into a voltage signal. 52 is a differential amplifier, and the 10 input terminals are
Input a reference voltage at a certain predetermined level. - A voltage signal corresponding to the beam current value output from the current detection section 51 is input to the input terminal. Reference numeral 53 denotes a sample/hold circuit that samples/holds the output of the differential amplifier 52. The sample/hold control signal 58 switches between the sample state and the hold state, and in the sample state, the output is connected to the input. When in the hold state, the voltage at the time of switching from the sample state to the hold state is held.

Reference numeral 54 denotes an amplifier, which amplifies the output of the sample/hold circuit 53 and applies it to the G2 electrode to control the amount of beam current. Note that the G1 drive circuit 49, the current detection section 51, the differential amplifier 62, and the sample/hold circuit 53
, and amplifier 54 are provided in each block divided in the horizontal direction corresponding to the cathode 10.

The operation of the embodiment of the above configuration will be described below.

1 for each electrode 12A, 12B of the vertical scanning electrode.
Each electrode 12A of the vertical scanning electrode is driven by a vertical scanning electrode drive signal that is sequentially applied for each H period.

A beam is sequentially irradiated toward the anode from each portion of the cathode 10 corresponding to 12B, and the amount of beam current is controlled by the G1 drive signal 57 and the G2 voltage. The beam during the horizontal blanking period is cut off by the beam cutoff signal 56 applied to the G4 electrode 16, flows into the electrode 16', is taken out as a voltage signal by the current detection section 51, and is inputted to one input terminal of the differential amplifier 52, where it is input into ten input terminals. The difference from the reference voltage applied to the terminal is output.

In this state, the G1 drive signal 67 is fixed at a constant voltage value during the pulse 58, and the sample/hold circuit 63 further outputs the sample/hold control signal 58.
sample state (i.e. output follows input)
Thus, the difference in the amount of beam current output from the differential amplifier 52 with respect to a certain reference is applied to the G2 electrode 14 as a G2 drive signal 69 through the amplifier 64, and the amount of beam current is controlled by this G2 drive signal 59. Become. That is, a feedback loop is formed by the current detection section 51, differential amplifier 62, sample/hold circuit 63, amplifier 64, and electron beam control system whose input is the 02 voltage and output is the G3 current, and the beam current is transferred to the differential amplifier 52. The value corresponds to the reference voltage applied to the terminal.

Such an operation is performed during the horizontal blanking period, and after the operation is completed, the sample/hold circuit 53 enters a hold state, fixes the G2 drive signal 69 to a certain value, and performs normal image display. By repeating the above operation every 1HK, each electrode 12A, 12B of the vertical scanning electrode...
The beam from each position in the vertical direction corresponding to The beam current value is adjusted to correspond to the reference level input to the human power terminal. The same applies to each block divided horizontally corresponding to the cathode 1o, so by applying the same reference voltage to the differential amplifier of each block, the beam current value can be made uniform with the entire screen beam current value. be able to.

Effects of the Invention According to the present invention, feedback control can be performed to keep the electron beams from all the electron beam sources of a flat plate cathode ray tube having a large number of electron beam sources uniform over time, which is very practical. It is valid.

[Brief explanation of drawings]

Fig. 1 is a partial perspective view of a flat cathode ray tube according to an embodiment of the present invention and a block diagram showing a circuit system for feedback control of beam current, and Fig. 2 is a shape of a signal in the first section. FIG. 3 is a perspective view of a conventional flat cathode ray tube, FIG. 4 is a horizontal and vertical sectional view of a conventional flat cathode ray tube, and FIG. 5 is an explanatory diagram of vertical scanning. , FIG. 6 is a signal system diagram for driving a flat cathode ray tube. 48... Vertical scanning electrode drive circuit, 49...
...G1 drive circuit, 50...G4 drive circuit, 51...Current detection section, 52...
... Differential amplifier, 63 ... Sample/hold circuit, 64 ... Amplifier. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure ~ (Dito e-, + or 4N Figure 4 Figure 5 f3 flc/ /2Y Zz

Claims (3)

[Claims] (1) Cut off the beam heading towards the anode for a predetermined period,
A beam current is detected by a beam current detection means, and a voltage corresponding to the difference between the beam current value and a predetermined level is applied to an electrode for controlling the beam current, so that the beam current value matches the predetermined level. 1. A method for driving a flat cathode ray tube, characterized in that feedback control is performed to ensure that the beam current is controlled, and thereafter, a voltage value of an electrode that controls the beam current is held, and an image is displayed. (2) Generate a beam under predetermined operating conditions during the horizontal blanking period, simultaneously cut it off by applying a negative pulse voltage to the beam cutoff electrode, and then reduce the amount of beam current by letting it flow into the beam detection electrode. 2. A method for driving a flat cathode ray tube according to claim 1, further comprising the step of: (3) Input a signal corresponding to the detected beam current to the − input terminal of the differential amplifier, input a signal at a predetermined level to the + input terminal, and control the current through the output of the sample/hold circuit. The flat cathode ray according to claim 1 or 2, wherein the sample/hold circuit is placed in a sample state (tracking state) and in a hold state during an image display period during a horizontal blanking period. How to drive the tube.