JPH11338400A - Dual electron gun type picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent display by automatically correcting miss- alignment of video on the boundary of split screens even if fluctuation in high voltage due to change of screen pattern or characteristics change in the horizontal deflection system occurs. SOLUTION: A video is displayed by dividing a 1st video signal into two areas in the horizontal direction, also producing 2nd video signals of two systems with the time expanded by two times, supplying these signals to a dual electron guns image receiving tube 100 with two electron guns respectively, scanning electron beams outputted from each electron gun, and connecting the displayed video. In this case, the horizontal scanning positions are detected by index phosphors 110, 111, a photoelectric converting element 109, an LPFs 17, a digital conversion circuit 18, D-type flip-flops 19, 29, etc., and the video position are varied by the subtracters 24, 25 within the horizontal scanning range of the above-mentioned 2nd video signals according to difference between the detection result and a reference value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double electron gun type image display capable of displaying images divided and connected on a screen of a picture tube using a picture tube having a plurality of electron guns. Related to the device.

[0002]

2. Description of the Related Art In recent years, there has been disclosed a technique for connecting divided images on a screen of a picture tube with extremely high accuracy using a picture tube provided with a plurality of electron guns.
In this technique, an electron beam detector is provided outside a video display area within a scanning range, and a picture tube including an electric signal generating means for generating a scanning error signal according to a change in output of the detector is used. Then, the deflection characteristics of the electron beam are changed based on this error signal, so that images can be satisfactorily connected.

In this technique, the use of a digital convergence device as an auxiliary deflection signal generating means for changing the deflection characteristics makes it possible to remove scanning distortion with high accuracy. It is described that good joining is possible.

[0004] However, even if such deflection control is performed satisfactorily and the images are connected, the connection of the images at the boundary portions becomes poor depending on the displayed pattern. this is,
This is due to a change in the screen amplitude caused by the high-voltage fluctuation.

[0005] This phenomenon also occurs in a normal television receiver, and the principle of occurrence will be described with reference to FIG.
FIG. 9 shows a cross section of the picture tube and its periphery. Cathode 5
05 is supplied with a video signal. The cathode 505 is
It is heated by a heater (not shown) on its back. Usually, a cutoff voltage of about 200 V is applied to the cathode terminal. This voltage value is a voltage immediately before the electron beam is emitted from the cathode 505. When a lower voltage is supplied, the electron beam is emitted from the cathode 505. The anode terminal 500 has +
A high voltage of 20 to +30 kV is supplied. The anode terminal 500, the inner conductive film 501 in the tube, the aluminum film 502 deposited as a metal back treatment, the final grid 503, and, in the case of a picture tube having a shadow mask, a shadow mask (not shown) are electrically connected. Which are at the same potential. The electron beam output from the cathode 505 is accelerated by the high pressure supplied to the grid 503 and is emitted toward the display surface 507. A plurality of grids are arranged in a dotted line portion 506,
Focusing of the electron beam is performed, but the description is omitted here.

[0006] Horizontal and vertical deflection signals are supplied to the deflection coil 504, and an image is displayed on a display surface 507. "NHK Television Textbook (above); edited by The Japan Broadcasting Corporation", pages 203 and 204, states that the length of the deflection coil 504 in the tube axis direction is l (cm), the strength of the magnetic field is H (Gauss),
Assuming that the distance from the center of the deflection coil to the fluorescent screen as the display surface is L (cm) and the anode voltage of the picture tube is Eb (V), the deflection amount h (cm) is as follows: It is described that 0.3 × H × 1 × L / √Eb (Expression 1) can be approximated.

[0007] The amount of the electron beam emitted from the cathode 505 changes depending on the brightness of an image to be displayed. When the brightness of an image extremely changes, the anode voltage Eb fluctuates. According to the above formula 1, for example, when Eb becomes small, h becomes large even if other conditions are the same. This means that the screen amplitude increases as Eb decreases.

The screen amplitude fluctuation will be further described with reference to FIG. Consider a case where the video source shown in FIG. 10A is displayed on the screen. This is a video source that displays a white stripe and a white horizontal band 450 on a black background. FIG.
(B) shows a case where the image is displayed on a normal television receiver. In this case, by displaying the high-brightness band 450 at the center of the screen, Eb is reduced. As a result, in the high-brightness band 450 portion, the image extends to the left and right, causing distortion.
After the display of the high-brightness band 450, the pattern becomes black again, so that Eb is recovered, and the distortion is gradually recovered. Here, the distortion of the image in the horizontal direction is particularly described, but a change actually appears in the vertical direction. In the vertical direction, the density appears as uneven scanning line density. Since the television receiver has a horizontally long screen, the deflection angle in the vertical direction is small, and the phenomenon appears as a change in the scanning line density, and does not cause a serious problem.

FIG. 10C shows a state in which the same image is projected on a two-division type double electron gun type image display device having two electron guns on the left and right. In this case, the respective screens expand in the left-right direction, and the images overlap at the center of the screens. As a result, the display image becomes discontinuous at the center of the screen, making it very difficult to see.

The above-mentioned invention according to the technology can satisfactorily remove distortion caused by a change in characteristics of an electric circuit due to initial adjustment or temperature change and distortion caused by a change in geomagnetism. Such static distortion correction does not require high speed, and can be implemented by low-speed feedback processing. However, correction of dynamic distortion such as distortion due to high-pressure fluctuation requires extremely high-speed processing, and is difficult to implement with the above-described technology.

As described above, the change in the screen amplitude due to the high-voltage fluctuation can be improved by the invention disclosed in Japanese Patent Application Laid-Open No. Hei 8-102965, "Digital Convergence Device". The present invention detects the fluctuation of the high pressure Eb and adds the E deflection to the horizontal deflection correction signal of the digital convergence device.
This is a technique of adding an amplitude contraction component corresponding to the variation b. This technique reduces the distortion of the picture.

However, in this technique, since the correction is performed after the high-voltage fluctuation occurs, a delay occurs in the correction, and as a result, it is not possible to correct for several lines immediately after the distortion has occurred. Also,
Highly accurate correction cannot be expected.

[0013]

As described above, even when a digital convergence device is used in combination to improve image distortion caused by high-voltage fluctuation, there is a problem that correction is delayed. SUMMARY OF THE INVENTION It is an object of the present invention to provide a multiple electron gun type image display device in which no image shift occurs at a boundary between divided screens.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an n-system in which a first video signal is divided into n regions in the horizontal direction, and each of them is time-expanded n times. Are supplied to the n electron guns of the multiple electron gun picture tube, respectively, and are scanned and projected by the electron beam output from each electron gun. In a multiple electron gun type image display device for displaying all images by connecting individual images, at least one horizontal scanning position is detected, and a second image of the n systems is detected according to a difference between the detected result and a standard value. Any one or one of the signals is changed in the image position within the horizontal scanning range.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. As a first embodiment, a double electron gun type image display device that has the highest effect and is easy to configure and that divides into two in the horizontal direction for display will be described. When displaying a color image, R (red), G (green),
B (blue) video signal processing of three systems is required. Here, for simplicity of description, the video signals are collectively expressed as one system, and the video signal supplied to the picture tube is also described as one system. .

The scanning will be described assuming that the scanning is performed from the center of the screen to the left and right sides in the horizontal direction, and that the scanning is performed from top to bottom in both screens in the vertical direction. FIG. 1 is a configuration diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a double electron gun type picture tube 100 used in the present embodiment. It has a structure in which two picture tubes are arranged side by side, and the boundary between adjacent portions is removed.

FIG. 1 will be described. First, the operation of the deflection system will be described. The horizontal synchronization signal HD is supplied to a horizontal deflection signal generation circuit 33 via a terminal 35. Here, a sawtooth wave for performing horizontal scanning is generated. The signal output from the circuit is a double electron gun type picture tube 1
Horizontal deflection coil 1 attached to the left and right necks of 00
01 and 102. Here, it should be noted that, with respect to the right horizontal deflection coil 101, the left horizontal deflection coil 102 is arranged such that a magnetic field generated when the same signal is supplied is generated in the opposite direction. . This is because, as described above, the horizontal scanning is performed from the center of the screen to the left and right sides, that is, only the left screen is scanned in the horizontal direction in the reverse direction.

The vertical synchronizing signal VD is supplied to a vertical deflection signal generating circuit 34 via a terminal 36. Similarly, the vertical deflection signal generation circuit 34 generates a sawtooth wave for performing vertical scanning. The vertical deflection signal output from the circuit is supplied to vertical deflection coils 103 and 104 attached to the left and right neck portions of the double electron gun picture tube 100. In the vertical direction, scanning is performed in the same direction on both screens, and the polarities of the deflection coils are the same.

The horizontal synchronization signal HD is supplied to the phase comparators 26, 2
It is also supplied to the frequency dividing circuit 31. The phase comparator 26, the voltage controlled oscillator (VCO) 27, and the counter 23 include a phase locked loop, so-called PLL (Phase Locked).
Loop). The oscillation frequency of the system clock output from the VCO 27 is subtly changed and controlled by the phase difference voltage output from the phase comparator 26. This system clock is supplied to the counter 23. Counter 23
Resets when a predetermined number of system clocks are counted, and at the same time, sends a signal to the phase comparator 26. With this configuration, a stable system clock locked to the horizontal synchronization signal can be generated.

The divide-by-2 circuit 31 divides HD by two, and
The output is supplied to an index detection image multiplexing circuit 9 for the right image and an index detection image multiplexing circuit 10 for the left image after the polarity is inverted by the inverter 32.

Next, the processing of the video system will be described.
The video signal supplied to the terminal 1 is a low-pass filter (L
PF), the signal is converted into a digital signal by an analog-to-digital (A / D) converter 3,
Supplied to Here, the video signal for one line (first
Are divided into the first half and the second half, and each video signal is time-expanded by a factor of two and output as two new video signals (second video signals). The video start timings of both video signals are equal.

The first half of the video signal is the video on the left screen,
The video signal in the latter half is the video on the right screen. The video signal of the right screen is supplied to the 1H delay circuit 5 and is delayed by one horizontal scanning period. The video signal of the left screen is supplied to the left / right inversion circuit 6. Here, the left / right inversion of the pixel within the horizontal scanning cycle is performed. In the present embodiment, horizontal scanning is performed from right to left only on the left screen, so this processing is necessary. The left-right inversion processing can be realized by writing pixels in one horizontal scanning period to a memory (not shown), and inverting and reading addresses of the memory. In this case, a delay of the horizontal scanning period occurs in the video signal. Therefore, the video on the right screen is delayed by the 1H delay circuit 5, and the delay amounts of the video signals on each screen are made uniform.

The delayed image on the right screen and the image on the left screen subjected to the left-right inversion processing are supplied to variable delay circuits 7 and 8, respectively. Both circuits have a structure in which the delay amount is controlled by the delay amount control data stored in the D-type flip-flops 29 and 30. Here, each video signal is delayed by an appropriate amount of time, and supplied to the index detection video multiplexing circuits 9 and 10, respectively. The two index detection video multiplexing circuits 9 and 10 multiplex the video for index detection on the video signal alternately at the right and left every time horizontal scanning is performed, based on the above-mentioned frequency-divided horizontal synchronizing signal. I do.

The above-mentioned predetermined timing is a timing at which the electron beam passes through the index phosphors 110 and 111 by the electron beam scanning described below. The video signal for which index detection is performed may be a fixed value at an appropriate level. The reason why the video signals for index detection are alternately multiplexed on the left and right is that the light emitted from each index phosphor is taken in by one system of the photoelectric conversion element 109. The delay correction of the second video signal based on the index detection signal is performed alternately on the left and right in the horizontal scanning cycle. However, the photoelectric conversion element 109 can be shared, and the cost can be reduced. After multiplexing the index detection video signals, the index detection video multiplexing circuits 9 and 10 perform D-type flip-flops 29 and 30.
, And the output of the subtractor 22 is held.

From the subtracters 24 and 25, data corresponding to the amount of deviation from the reference position in the horizontal scanning is output alternately left and right in the horizontal scanning cycle. Hold the deviation amount. The delay amount of the variable delay circuits 7 and 8 is controlled by the value of the shift amount.

The video signals of the left and right screens on which the index detection video signals are multiplexed are digital analog (D / D
A) The signals are converted into analog signals by the converters 11 and 12, harmonics are removed by low-pass filters (LPF) 13 and 14, and supplied to the video drive circuits 15 and 16. Furthermore,
Here, the signal is amplified and supplied to the cathodes 105 and 106 of the double electron gun type picture tube 100. Cathode 10
5, 106 emits an electron beam in an amount corresponding to the magnitude of the video signal. The electron beam is applied to a plurality of grid groups 10
The beam is focused and accelerated by 7 and 108, scanned by the above-described deflection system, and an image is projected on the face plate 113.

A range 115 indicates a horizontal scanning range of the electron beam, and a range 116 indicates a range of image display. In the center of the screen, if the left and right video display ranges 116 are properly matched, the left and right screens are connected. Horizontal scanning range 11
Regions within 5 and outside the range 116 of the video display exist on both sides of each screen. Index phosphors 110 and 11 for detecting a horizontal scanning position are provided in this area.
Lay 1 The shape of the phosphor may be a vertical line substantially equal to the screen height.

FIG. 3 shows index phosphors 111 and 11.
It is a drawing of the shadow mask 112 where 0 is laid. In this example, the two index phosphors are
12 is laid directly, but with one,
You may make it use shared. In this case, boundary 1
14 is unnecessary. Further, in this example, the index phosphor is laid on the shadow mask, but other laying methods are conceivable. For example, a fluorescent paint is applied to a rod-shaped or linear structure such as a hard wire or a thin metal wire under the condition that the horizontal scan range 115 is out of the image display range 116 and the fluorescent paint is vertically applied to the area. It may be arranged. When an electron beam hits an index phosphor laid as a detector for such an electron beam, the index phosphors 110 and 111 emit light. This light is converted into an electric signal by the photoelectric conversion element 109 and taken in, and is examined as a signal generation time, whereby a horizontal scanning position can be detected. In detecting the index, a boundary 114 is provided so that the index phosphor on the adjacent screen is not caused to emit light. This boundary 11
By providing 4, the right (left) index phosphor does not respond to the left (right) electron beam.

The index signal output from the photoelectric conversion element 109 has its noise component removed by the LPF 17 and is converted into a digital signal by the digital conversion circuit 18. This signal is input to the D-type flip-flop 19, the polarity is inverted through the inverter 28, and the inverted signal is supplied to the clock terminal of the D-type flip-flop 20. The counter 23 is configured to make one round in the horizontal synchronization cycle, and the count value can be used for time measurement. By supplying the counter value of the counter 23 to the D-type flip-flops 19 and 20 as it is, the D-type flip-flop 19 stores the count value at the rising edge of the index signal output from the digital conversion circuit 18.
The D-type flip-flop 20 holds the falling count value. By inputting both outputs to the averaging circuit 21 and taking the average, a count value at a time substantially at the center of the index signal can be obtained. Hereinafter, this value is referred to as index detection timing.

With such a configuration, even if the light of the index phosphors 110 and 111 is weak or the level is unstable, the center time of the signal can be accurately obtained. The output of the averaging circuit 21 is supplied to one end of the subtracters 21 and 24, and the other end is used as a standard value for the index detection timing in a state where images are well connected in the center of the screen by adjusting the deflection system. In a state where the images are connected well, 0 is output to the subtracters 21 and 24. However,
If there is a change in the horizontal deflection system, or if there is a change in the electron beam trajectory due to a change in high voltage even if there is no change in the horizontal deflection system, the index detection timing will increase or decrease according to the change in the trajectory, and as a result subtraction The shift amount of the index detection timing according to the change of the trajectory of the electron beam is output to the devices 21 and 24.

The index detection video signal is multiplexed alternately on the left and right sides in the horizontal scanning period as described above, and the shift amount of each screen is determined by the D-type flip-flop 2.
9 and 30 are alternately held. Then, the delay amounts of the left and right variable delay circuits 7 and 8 are adjusted during the blanking period based on this shift amount, so that the image is connected well.

The correction principle for connecting images will be described with reference to FIG. In FIG. 4, a circle indicates one pixel. Assuming that the total number of display pixels in the horizontal direction is 2n, an image of n pixels, which is そ の of the left and right screens, is displayed. FIG.
(A) shows a case where the left and right images 301 and 302 can be displayed in each screen in a small amount, and the images appear to be connected. FIG. 4B shows a state in which the horizontal amplitude is increased due to a factor such as a high-voltage fluctuation and the pixels protrude one pixel on both sides. Since the left and right images 303 and 304 protrude from each screen, the continuity of pixels is lost at the center of the screen, and a screen shift occurs. In this example, the horizontal scanning is performed from the center to the outer side of each screen, and in such a state, the index detection timing is advanced by exactly one pixel. Therefore, if the delay time of the left and right video signals is increased by one pixel, the left and right video images 305 and 306 are connected well in the center of the screen as shown in FIG. However, the left end of the image 305 on the left screen, the image 3 on the right screen
Although the image at the right end of 06 is partially missing, this is not a big problem compared to the case where the image continuity at the center of the screen is disrupted. FIG. 4D shows a state in which the left image 307 is shifted by one pixel to the right and the right image 308 is shifted by two pixels to the left.
In such a state, the index detection timing of the left screen is advanced by a time corresponding to one pixel, and the index detection timing of the right screen is advanced by a time corresponding to two pixels.
Therefore, the delay time of the left video signal is increased by one pixel,
The delay time of the right video signal is increased by two pixels. Then
As shown in FIG. 4E, the left and right images 309 and 310 are well connected at the center of the screen. In this way, since the index detection timing is alternately monitored on the left and right screens,
Even if there is a change in the characteristics of the deflection system as well as a change in amplitude due to a high-voltage fluctuation or the like, an image is satisfactorily connected at the center of the screen.

In the above embodiment, the horizontal scanning direction for forming the left and right screens is the direction in which the scanning is performed from the center to the left and right. However, the scanning directions for the left and right screens may be the same.

In the above example, the electron beam detector is laid at the center of the left and right screens. However, depending on the design of the double electron gun type picture tube, it may be difficult to lay it at this position. In such a case, the electron beam detectors may be laid out in portions outside the video display area within the scanning ranges on the left side of the left screen and the right side of the right screen, respectively. In this case, the number of photoelectric conversion elements is doubled,
The present invention can be implemented.

Next, as a second embodiment, a double electron gun type image display device which performs display by dividing the image into three parts in the horizontal direction will be described. FIG. 5 is a block diagram showing a second embodiment of the present invention, and FIG. 6 shows a shadow mask in a picture tube.

Regarding scanning, it is assumed that horizontal scanning is performed from left to right on all the right, center, and left screens, and vertical scanning is performed from top to bottom on all of the screens. The basic configuration is almost the same as that of the first embodiment, and the components having the same operations as those of the first embodiment have the same numbers.
Description is omitted.

The operation of the deflection system is not much different from that of the first embodiment. The sawtooth wave generated by the horizontal deflection signal generation circuit 33 is supplied to horizontal deflection coils 201, 202, and 203 attached to the neck of the double electron gun type picture tube 200. As for the vertical, the vertical deflection signal generation circuit 34
The sawtooth wave generated by the vertical deflection coils 204 and 2
05, 206. Since the scanning directions are the same in both the horizontal and vertical directions, the polarities of the coils are all the same.

The video signal is supplied to a video division processing circuit 50. Here, a video signal for one line is divided into three, and each video signal is time-expanded three times and output as a new video signal of three systems. The video start timings of the video signals are equal. The first video signal is the left screen, the center video signal is the center screen, and the last video signal is the right screen video. The video signals of the right and left screens are supplied to variable delay circuits 51 and 52, respectively. The video signal of the center screen is supplied to an index detection video multiplexing circuit 55.
In this example, index detection is performed only on the center screen. Index phosphors 210, 21
No. 1 is laid on the shadow mask 219 shown in FIG. 6, and two are laid, one on each of the left and right sides of the central screen area. The index detection video multiplexing circuit 55 multiplexes the video for index detection before and after the video portion of the video signal of the center screen with reference to the horizontal synchronization signal HD. A clock is output to the D-type flip-flop 54 after multiplexing the detected video signal before the video portion, and a clock is output to the D-type flip-flop 53 after multiplexing the detected video signal later.

As a result, the D-type flip-flop 54
Holds the difference between the index detection timing of the index signal captured on the left side of the center screen and its standard value. The shift amount is provided from the subtractor 24. Also,
The D-type flip-flop 53 holds the difference between the index detection timing of the index signal captured on the right side of the center screen and its standard value. The shift amount is provided from the subtractor 25. D type flip-flop 5
4 to control the delay amount of the video signal of the left screen and the delay amount of the video signal of the right screen by the shift amount held in the D-type flip-flop 53, thereby controlling the delay amount of the video signal at the screen boundary. Screens can be connected well.

The correction principle of this example will be described with reference to FIG. In FIG. 7, assuming that the total number of display pixels in the horizontal direction is 3n, an image of n pixels, which is 1/3 of the left and right screens, is displayed. FIG. 7A shows left, center, and right images 3.
When the images 11, 312, and 313 are successfully displayed in the respective screens, the images appear to be connected. FIG. 7 (b)
In the figure, the horizontal amplitude is increased due to a factor such as a high-voltage fluctuation, and the pixels protrude one pixel on both sides. The left, center, and right images 311, 312, and 313 protrude from the respective screens, so that the continuity of pixels is lost at the screen boundary, and the screen is shifted. In the center screen, index detection is performed. In such a state, the index detection timing of the left index is advanced by exactly one pixel, and the index detection timing of the left index is exactly one pixel. Become slow. Therefore, by increasing the delay time of the video signal of the left screen by two pixels and reducing the delay amount of the video signal of the right screen by two pixels, as shown in FIG. Video 31
7, 318 and 319 are connected well at the boundary.

In the above example, the scanning directions of all the screens are the same, but the scanning direction of any of the screens may be in the opposite direction as in the first embodiment. For example, the scanning directions of the left and right screens may be reversed. The system for multiplexing the index detection video signal and the position where the index fluorescent substance is provided are not limited to this, and various embodiments are possible.

FIG. 8 shows the principle of correction when the image is further divided into four parts in the horizontal direction. Assuming that the total number of display pixels in the horizontal direction is 4n, an image of n pixels, which is ４ of the left and right screens, is displayed. FIG. 8A shows left, center left, center right,
In the case where the right images 321, 322, 323, and 324 have been successfully displayed in the respective screens, the images appear to be connected. FIG. 8B illustrates a state in which the horizontal amplitude is increased due to a factor such as a high-voltage fluctuation and the pixels protrude one pixel on both sides.
Left, center left, center right, right images 325, 326, 32
Since pixels 7 and 328 protrude from the respective screens, the continuity of pixels is lost at the screen boundary, and the screen is shifted. For example, index detection is performed on the center screen. In such a state, the index detection timing of the left index is advanced by exactly one pixel, and the index detection timing of the left index is delayed by exactly one pixel. Therefore, by shifting the delay time of the video signals of the left and right screens by three pixels and the delay time of the video signals of the center left and center right by one pixel, as shown in FIG. Center left, center right, right images 329, 330, 33
1, 332 lead well at each boundary.

As described above, the present invention considers the scanning direction and the positional relationship between the screens as described above, and takes into account the difference between the standard value of the index detection timing and the actually measured value to determine the video signal to be displayed on each screen. This is an invention of controlling a delay time to maintain continuity of an image at a boundary portion. Therefore, it does not depend on the number of divisions.

In practicing the present invention, if the deflection coil characteristics and picture tube accuracy of each screen are high, only one screen is required for index detection. On the basis of the detected index detection timing shift amount, the delay amount of the video of the entire screen can also be obtained by an arithmetic expression obtained from the relationship between the screen arrangement and the scanning direction of each screen. Also,
If the deflection coil characteristics and picture tube accuracy for each screen are low,
The index detection may be performed individually.

The electron beam detection is provided outside the image display area in the scanning area. This detector can be shared by adjacent screens. Of course, a photoelectric conversion element that converts detection information into an electric signal can be shared.

Further, in practicing the present invention, the correction accuracy can be improved by setting the oscillation frequency of the VCO 27 high. The resolution of the index detection timing and the video signal delay amount increases, and the correction accuracy increases.

In the above-described embodiment, a variable delay circuit is provided for delaying a video signal, and a left / right inversion circuit is provided for left / right inversion of an image. In actually practicing the present invention, it is possible to incorporate these functions into a video division circuit. To realize a function equivalent to video delay, an equivalent function can be obtained by controlling the timing of writing or reading of a memory included in the video division circuit. Further, when performing left-right inversion, it can be realized by inverting the read address of the same memory. With such a configuration, cost can be reduced.

According to the present invention, more advanced functions can be realized. In the above-described embodiment, the standard value of the index detection timing has been described as being constant. However, if this value can be set from the outside, the adjustment work for connecting the images becomes very easy. Furthermore, according to the configuration in which this standard value can be set to a different value for each scanning line, there are restrictions on the laying conditions of the electron beam detector, and the standard value is set for each location (the center of the screen, the upper and lower ends of the screen, etc.). ) Can be satisfactorily corrected even when the need arises.

[0049]

As described above, according to the present invention,
In a double electron gun type image display device, even if a high voltage fluctuation caused by a change in a picture occurs or a characteristic change occurs in a horizontal deflection system, an image shift occurs at a boundary of the divided screen. A double electron gun type image display device without any problem can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of a double electron gun type image display device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a double electron gun type picture tube used in the first embodiment.

FIG. 3 is a schematic view of a shadow mask in a double electron gun type picture tube used in the first embodiment.

FIG. 4 is a diagram illustrating a principle of a correction operation according to the first embodiment;

FIG. 5 is a block diagram of a double electron gun type image display device according to a second embodiment of the present invention.

FIG. 6 is a schematic diagram of a shadow mask in a double electron gun type picture tube used in the second embodiment.

FIG. 7 is a principle diagram of a correction operation according to the second embodiment.

FIG. 8 is a principle diagram of a correcting operation of the four-split double electron gun type image display device according to the present invention.

FIG. 9 is a sectional view of a picture tube.

FIG. 10 is a principle diagram of an image amplitude change caused by a high voltage fluctuation.

[Explanation of symbols]

2: low-pass filter, 3: analog-to-digital converter,
4 video division processing circuit, 5 1H delay circuit, 6 left / right inversion circuit, 7, 8 variable delay circuit, 9, 10 index detection video multiplexing circuit, 11, 12 digital / analog converter, 13, 14 ... Low-pass filter, 15, 16 drive circuit, 17 low-pass filter, 18 digital conversion circuit, 19, 20 D-type flip-flop, 2
1 ... Averaging circuit, 24, 25 ... Subtractor, 26 ... Phase comparator, 27 ... Voltage controlled oscillator, 28 ... Inverter, 29,
Numeral 30: D-type flip-flop, 33: horizontal deflection signal generation circuit, 34: vertical deflection signal generation circuit, 100: double electron gun picture tube, 101, 102: horizontal deflection coil, 10
3, 104: vertical deflection coil, 105, 106: cathode, 107, 108: grid group, 109: photoelectric conversion element, 110, 111: index phosphor, 113: face plate, 114: boundary.

Claims (10)

[Claims] 1. A first video signal is divided into n regions in the horizontal direction, and a second video signal of n systems, each of which is time-expanded by n times, is generated, and the second video signal is generated. Double electron gun type image display that supplies each of the n electron guns of the multiple electron gun picture tube, scans the electron beam output from each electron gun, and combines the individual images projected to project all the images. In the device, at least one horizontal scanning position is detected, and any one or one of the n-system second video signals is shifted to a video position within a horizontal scanning range according to a difference between the detection result and a standard value. A double electron gun type image display device characterized by giving a change. 2. A detecting means for detecting the horizontal scanning position, comprising: laying an electron beam detector on one of right and left sides of a scanning area and an area where no image is displayed; and detecting the electron beam detector. 2. The double electron gun according to claim 1, further comprising: an electric signal generating means for outputting the passage of the electron beam as an electric signal; and a measuring means for measuring a time at which the electric signal is generated by the electric signal generating means. Image display device. 3. The detecting means for detecting the horizontal scanning position comprises laying a vertical phosphor fine line having a length substantially equal to the screen height on one of the right and left sides of the scanning area and the area where no image is displayed. A test signal for causing the phosphor fine lines to emit light is multiplexed in a specific period within a horizontal blanking of a desired signal of the second video signal and outside a retrace period, and the fluorescent light emitted by scanning is emitted. 2. The double electron gun type image display device according to claim 1, wherein the light of the body thin line is converted into an electric signal by a photoelectric conversion element, and the result is a detection result of a time when the change of the electric signal occurs. 4. A detecting means for detecting the horizontal scanning position, wherein an electron beam detector is laid on both left and right sides of a scanning area and an area where no image is displayed, and an electron beam is irradiated on the electron beam detector. 2. The double electron gun according to claim 1, further comprising: an electric signal generating means for outputting the passage of the electric signal as an electric signal; and a measuring means for measuring a time interval between generation times of the electric signal by the electric signal generating means. Image display device. 5. A detecting means for detecting the horizontal scanning position comprises laying a vertical phosphor fine line having substantially the same length as the screen height on both left and right sides of a scanning area and an area where no image is displayed,
In addition, a test signal for causing the phosphor fine lines to emit light is multiplexed in horizontal blanking of the second video signal and in specific periods on both sides of a retrace period, and the phosphor emitted by scanning is multiplexed. 2. The double electron gun type image display device according to claim 1, wherein the light of the thin line is converted into an electric signal by a photoelectric conversion element, and a value obtained by measuring a time interval of the change of the electric signal is used as a detection result. 6. The double electron gun type image display device according to claim 1, wherein said detecting means for detecting said horizontal position shares a part or all of said detecting means in adjacent areas. 7. A detection means for detecting the horizontal position, the number of which is smaller than the number of screen divisions, and an area not provided with the horizontal scanning position detection means determines an expected change in a phase of an image in each area according to a result of the detection means. 2. The double electron gun type image display device according to claim 1, wherein the amount is obtained by calculation. 8. The double electron gun type image display device according to claim 1, wherein said standard value can be set externally. 9. The double electron gun type image display device according to claim 2, wherein said detector comprises a shadow mask and a phosphor substantially equal to a screen height laid thereon. 10. The double-electron gun type image display device according to claim 2, wherein the detection body is a rod-shaped structure coated with a phosphor.