JP2000175209A - Virtual beam index type color picture receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably correct an electronic beam deflection position under any circumstance of an image by preventing occurrence of pseudo color by means of a black zone and using a RAM or the like. SOLUTION: A black zone 14 is provided among R, G, B stripes 13 respectively. A width of the black zone 14 is selected to be larger than a sum of a maximum diameter of an electron beam 1 and twice of a position error of the electron beam to prevent occurrence of a pseudo color. An electron beam deflection position is corrected (18) by correction information stored in a RAM 25 or the like on the basis of signals from index signal generating stripes 11, 12 provided in ach black zone 14 at both ends of a screen. Thus, a color receiver in a stable operation can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a virtual beam index type color picture tube with low power consumption and easy manufacture.

[0002]

2. Description of the Related Art Color picture tubes widely used at present are called a shadow mask system and an aperture grill system, both of which aim to shape an electron beam and regulate a deflection position. Although a shadow mask or an aperture grille is used, the efficiency of use of the electron beam deteriorates as a result, the power consumption increases, and the manufacturing method cannot be said to be easy and efficient.

An electron beam index type color picture tube has long been known as a device which competes with these two systems, and has been studied in various places because it is expected to greatly improve the use efficiency of the electron beam. Until now, it has not been put to practical use because it is difficult to regulate the shape of the electron beam and the detection accuracy of the deflection position of the electron beam is insufficient.

In general, in a shadow mask type color picture tube, as shown in FIG. 1, the shape of an electron beam is circular or rectangular due to a mask effect of a circular hole or a rectangular hole of a shadow mask provided close to a screen surface. Since phosphor dots of R, G, and B colors are previously set on the screen surface at positions corresponding to the positions of the circular holes or the strip-shaped holes of the shadow mask, respectively, the R , G, and B, respectively, are modulated according to the intensity of the signal of each color from the three electron guns, and the emitted electron beam is deflected right and left and up and down by a deflection coil, and applied to a shadow mask. The laser beam passes through the shadow mask while being accelerated by the high voltage, collides with the phosphor dots on the screen, sequentially emits the phosphor, and reproduces a video image. In this method, the transmission efficiency of the electron beam is generally about 10%, which causes an increase in power consumption, and also causes the shadow mask to be deformed by heating, thereby causing a relative displacement between the hole position of the shadow mask and the phosphor dot. This causes a so-called false color phenomenon. In addition, it is unavoidable that so-called convergence is required, in which three electron beams are focused on the same hole on the shadow mask. The influence of geomagnetism on convergence is also considerable. The hole shape of the shadow mask, which is changed to a blind shape, is called an aperture grill system.However, due to the structural necessity, the aperture grill and screen are designed to be spherical in contrast to the shadow mask system. And is designed to be cylindrical. Phosphors are also formed in stripes and aligned. Although the electron beam is restricted only in width, the electron beam efficiency and the like are not much different from the shadow mask method. In addition, a long linear aperture grill may adversely affect vibration resistance and the like, and in order to avoid this, it is necessary to apply strong tension in the vertical direction of the aperture grill.

The electron beam index type color picture tube has been proposed for a long time than the above-mentioned shadow mask type and aperture grill type, and has been studied in various places.
In the electron beam index system, as shown in FIG. 2, a shadow mask is not used, and only one electron beam is used. The screen is formed in an R, G, B stripe shape as in the above-described aperture grill system. Furthermore, R,
Repeated set of G and B stripes (triplet)
For each electron beam position detection, a stripe portion for generating secondary electrons or ultraviolet rays when the electron beam collides is provided. The secondary electrons or ultraviolet rays are captured by a detector, the scanning position of the electron beam is specified, the brightness of the electron beam is modulated according to each of the R, G, and B video signals, and each color is selectively reproduced to reproduce the video. Get an image. In the electron beam index method, since a shadow mask is not required, the utilization efficiency of the electron beam can be made almost 100%, so that the power consumption is reduced, and since only one electron beam is used, convergence is not required, so that the influence of geomagnetism is not required. Can also be reduced. Furthermore, since the structure as a picture tube is simple,
It has been expected to have advantages such as easy production and high mass productivity.

On the other hand, in the electron beam index system, there is a problem 1, since the shadow mask system has no function of limiting the shape of the electron beam, the fluctuation of the electron beam diameter due to the change of the space charge repulsion due to the increase and decrease of the beam current, In other words, in bright scenes, the size of the electron beam increases,
The stripes other than the target phosphor stripe also emit light and the color purity is deteriorated. Problem 2: Since the detection of the position of the electron beam by secondary electrons or ultraviolet rays is based on the detection signal excited by the electron beam including the video signal, the accuracy is low. Is enough
In particular, the beam position detection becomes unstable when the brightness of the scene fluctuates greatly.Problem 3: In order to sufficiently obtain the electron beam position detection signal under any conditions, the electron beam amount is left to some extent even in a dark scene. The problem is that the contrast ratio becomes low, and the problem 4 is that a control circuit having a complicated and wide frequency band is required as compared with the shadow mask method, and the electron beam diameter needs to be reduced to about 1/3. Such a solution was needed.

[0007]

The problems to be solved are the problem 1 of the electron beam index type color picture tube, the deterioration of the color purity due to the fluctuation of the electron beam diameter caused by the increase and decrease of the beam current, the problem 2 and the like. Image reproduction instability when the brightness of the scene changes due to insufficient electron beam position detection accuracy due to ultraviolet rays, etc., problem 3, the contrast ratio decreases to sufficiently obtain an electron beam position detection signal. 3 points. (Prior Art) Section (0006)
The problem 4 mentioned above can be sufficiently solved by the recent improvement of the circuit technology, and the reason will be described as a specific example in (0012) of (0012).

[0008]

The present invention solves the problem 1 by providing a black band having a width sufficient for the electron beam diameter between the R, G, and B phosphor stripes. In order to prevent color purity deterioration and solve problems 2 and 3, electron beam position detection is performed at a constant beam intensity only at the left and right end positions of the screen, and the middle position of the left and right electron beam position detection signals is At the time of start-up of the apparatus or at any time requiring readjustment, position correction information over the entire screen area stored in the RAM or the like is stored for each triplet of R, G, and B stripes and for each scanning line order. By using this, the position detection signal for each triplet in the middle becomes unnecessary, and as a result, conventionally, the detected electron beam cannot be controlled at a constant value. Sufficiently and it becomes, and the image becomes unstable problem when brightness change, the problem of the contrast ratio is lowered in order to obtain a sufficient electron beam position detection signal, and simultaneously addressed.

[0009]

FIG. 3 is a developed view of an embodiment of the screen of the apparatus of the present invention, in which a black band narrower than each stripe is inserted between each of the R, G, and B stripes. Color purity is prevented from deteriorating by preliminarily restricting a value obtained by adding twice the position error to the electron beam diameter at the time of the maximum beam current so as not to always be larger than the width of the black band.

As shown in FIG. 4, for large correction, the deflection current is controlled based on the output from the PLL circuit by a beam detection signal so that the error becomes zero at the two indices at both ends. Means for correcting the deflection position for each triplet are as follows. Means 1, R, G, B stripes are arranged in accordance with the deflection distortion. Means 2, the deflection current is adjusted so that the electron beam always strikes the correct deflection position.
Correction is performed based on the correction information stored in the AM, and control is performed. Means 3 corrects and controls the delay time of the video signal based on the correction information stored in the RAM, and causes the electron beam to strike the correct deflection position. FIG. 5 is a system diagram for correcting the deflection position of the apparatus of the present invention. The deflection output is deflected at both ends to match the beam index each time, and small errors in the middle are corrected for each stripe triplet according to the correction information of the RAM. Fires. After this,
This is called a virtual beam index type color image receiving apparatus.

As a practical operation, the following conditions can be considered. (Conditions) R, G, B stripe width 80 micron meter Black band width between stripes 70 micron meter Screen display width 30 centimeters (corresponding to 17 "CRT) Horizontal frequency 15.75 kHz (1), where the horizontal resolution is It is in the practical range because it can take more than 600 triplets (2), beam spot diameter 50 microns or less (3), control error ± 10 microns or less Beam spot diameter is 20 microns in a flying spot tube etc. The control error of ± 10 μm is less than 50 μm in the practical range.
5.75 kilohertz, effective width 30 centimeters,
It is about ± 2.2 nanoseconds.

Incidentally, in the study of the conventional electron beam index type color image receiving apparatus, a complicated and wide band control circuit has been required. However, with the recent spread of the high definition display, a high precision and wide band circuit has been required. , And can be easily applied to realize the electron beam index method. In order to stably synchronize the PLL, it is necessary to add a time base correction function.

[0013]

As described above, in the virtual beam index type color image receiving apparatus according to the present invention, a black band is provided between the phosphor stripes to eliminate the generation of a pseudo color and to maintain a constant value in the non-emission bands at both ends. The detection of the index signal by the electron beam current and the correction of the electron beam scanning position by the value stored in the RAM, etc., caused a problem in the conventional index method. It is possible to eliminate the instability of the electron beam position detection signal due to an excessive change in the electron beam index, and to realize an electron beam index type color picture tube that can be sufficiently used practically.

[Brief description of the drawings]

FIG. 1 is an operation principle diagram of a shadow mask type color picture tube.

FIG. 2 is a diagram illustrating the operation principle of a conventional electron beam index tube.

FIG. 3 is an explanatory diagram of a beam index tube provided with a black band.

FIG. 4 is a principle diagram of position correction.

FIG. 5 is a block diagram of a deflection position correction circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron beam 2 3 electron guns 3 Shadow mask 4 Phosphor dot on screen 5 Phosphor 6 Aluminum film 7 Glass panel 8 UV light 9 Photomultiplier tube 10 UV light emitter 11 Start index 12 End index 13 Light emission band 14 Black band 15 Start electrode position 16 End electrode position 17 Theoretical position 18 Actual position 19 Frame memory 20 Time base correction 21 Interpolation PLL 22 Deflection circuit 23 Variable delay circuit 24 D / A converter 25 Error prediction value storage

Claims (2)

[Claims] In an electron beam index type color image receiving apparatus, a black band having a necessary and sufficient width is inserted between each of R, G, and B stripes, and the maximum diameter of the electron beam is twice as large as the electron beam position error. Is a color image receiving apparatus provided with a means for restricting a value obtained by adding a value so as not to be larger than a width of a black band. 2. An electron beam index type color image receiving apparatus, wherein a correction information storage device for correcting an electron beam position is provided, and R, R and R are output according to the correction information and output signals of position signal generating electrodes provided at both left and right ends of a screen. A color image receiving apparatus provided with means for performing position correction for each triplet of each of G and B stripes.