JPH10210319A - Raster centering position adjustment circuit and image size adjustment circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically adjust raster centering. SOLUTION: Phosphors 22a, 22b for detecting a raster centering position are provided to each prescribed position at both ends of a color selection device AG, placed in the inner face of a cathode-ray tube 12, and light-detecting means 26, 28 to detect a luminescent output of the phosphor are provided to an outside of a funnel 12c. A time from a reference point (horizontal blanking pulse) until a beam scans out the fluorescent bodies is measured. When both the left and right provided the same scanning time, the centering position is in the center of the CRT. When they are not the same, a horizontal centering correction signal is generated depending on a deviation in the left/right scanning times, and the raster centering is automatically adjusted by using the signal. Since the centering is adjusted independently of the image size, the image quality is considerably improved. Since the adjustment is automatically conducted, adjustment operation may be dispensed with.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a raster centering adjustment circuit and a picture size adjustment circuit for a cathode ray tube. Specifically, a phosphor is applied to the back side of the color selection mechanism, and the position of raster centering and the image size can be automatically adjusted by using the detection output obtained by scanning the electron beam. .

[0002]

2. Description of the Related Art In a cathode ray tube (CRT), FIG.
As shown in the figure, the effective screen frame SV is set as an image frame slightly smaller than the raster image frame SL, and there is a video image frame SS as an image frame smaller than this effective screen frame SV.

[0003] The raster image frame SL is set to be an image frame symmetrical left and right and up and down with respect to the center of the CRT (beam center before deflection), but the raster image frame SL is shifted from its center (raster centering). If there is a deviation, a DC current is passed through an adjustment element (horizontal centering coil HCC) provided in the horizontal deflection circuit to adjust raster centering.

For example, as shown in FIG. 10B, when the raster picture frame SL is shifted to the right (SL ') by ΔL with respect to the raster centering position, the raster picture frame SL is shown by a solid line. The adjustment of the raster centering is performed to the position. This adjustment is usually performed at the factory shipment stage, and is not usually made to be freely adjustable by the user.

On the other hand, the horizontal phase is the raster image frame S
L indicates the relative positional relationship between the image frame SS and
As shown in FIG. 10C, when the video image frame is shifted to the right (SS ′) by ΔL with respect to the raster image frame SL (shown by a broken line), the H.264 image is shifted to the position shown by the video image frame solid line. The phase is adjusted.

[0006] Adjustment of the horizontal phase is usually performed by adjusting the phase of an image based on a video signal for a raster. This adjustment is generally performed using a phase adjustment circuit open to the user.

[0007]

Incidentally, if the circuit elements constituting the horizontal deflection circuit are changed in diameter or affected by temperature characteristics, the raster centering may be shifted due to the change. In this case, the adjustment is performed using a phase adjustment circuit. However, this phase adjustment circuit adjusts the position of the video image frame SS with respect to the raster image frame SL as shown in FIG. 10C. Therefore, a focus error occurs, a convergence deteriorates, or an image distortion occurs due to a shift of the raster centering, and eventually, the image quality deteriorates.

Further, since the phase adjustment for the raster centering must be performed manually, the operation of the user is troublesome and troublesome.

Accordingly, the present invention has been made to solve such a conventional problem, and provides a raster centering adjustment circuit and an image size which are capable of automatically adjusting the raster centering correctly and automatically adjusting the image size. An adjustment circuit is proposed.

[0010]

In order to solve the above-mentioned problems, a raster centering adjustment circuit according to the present invention detects a raster centering position at predetermined positions at both ends of a color selection mechanism disposed on the inner surface of a cathode ray tube. A phosphor is provided, and light detecting means for detecting a light emission output from the phosphor is provided on the outer surface on the funnel portion side of the cathode ray tube, and raster centering is automatically performed based on the output from the light detecting means. It is characterized by being adjusted.

Further, in the image size adjusting circuit according to the present invention, a fluorescent substance for detecting an image size is provided at predetermined positions at both ends of a color selecting mechanism disposed on the inner surface of the cathode ray tube, and a light emission output from the fluorescent substance is provided. Light detecting means for detection is provided on the outer surface on the funnel side of the cathode ray tube, and the image size is automatically adjusted based on the output from the light detecting means.

According to the present invention, a reference phosphor that functions for raster centering detection and image size detection is applied to predetermined positions on the left and right rear sides of the aperture grill that functions as a color selection mechanism, and a beam is scanned when the reference phosphor is scanned. The light emission output is detected by light detection means provided on the funnel side of the CRT. By comparing the detection outputs from the left and right phosphors with reference to the horizontal blanking signal, the shift Δ of raster centering and the image size can be detected.

When a horizontal blanking pulse is used as a reference for beam scanning, a time ta from the horizontal blanking pulse to the first scanning of the phosphor and the time from the last scanning of the phosphor to the horizontal blanking pulse. Is measured time tb. Then, it is determined in which direction and how much the raster centering is shifted from the difference or difference between these times ta and tb. A centering correction signal is generated from the difference and the difference.

The sum of the times ta and tb and the reference value Tref
By detecting the magnitude of the above, it is determined whether the image size is in the standard state, larger or smaller, and an image size correction signal is generated in accordance with that.

Since the detection of the raster centering position and the detection of the image size can be performed by the same phosphor, the detection accuracy is improved. Since the centering correction and the image size correction are automatically performed, a high-quality image can always be displayed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a raster centering adjustment circuit and an image size adjustment circuit according to the present invention will be described in detail with reference to the drawings.

For convenience of explanation, FIG. 2 will be used first. FIG. 2 shows a cathode ray tube (CRT) to which the present invention is applied.
Twelve specific examples are shown. An electron gun (gun) 14 is housed in the neck 12a side of the CRT 12, and a beam (electron beam) emitted from the electron gun (gun) 14 is applied to the face plate 12b side through a color selection mechanism AG to form a striped phosphor (R, G). , B phosphor 16) to emit light.

In this example, the aperture grill AG functions as a color selection mechanism while maintaining a small gap with the phosphor 16.
Is arranged. As shown in FIG. 3, the aperture grill AG has a plurality of linear members 20 formed with a predetermined width and pitch on a frame 18 having the same outer shape as an image frame.
Is stretched in tension. The frame 18 is mounted and fixed in the tube of the CRT 12 by the support plate 21. The linear body 20 matches the stripe direction of the phosphor 16.

On the back side of the aperture grill AG, that is, on the electron gun 14 side, phosphors 22 and 24 that emit light by beam scanning are applied. FIG.
Shows an example of this, and a linear body 20 provided at a predetermined position at both left and right end portions has a phosphor 22 (2
2a, 22b) are applied, and are used both as a phosphor for detecting raster centering and as a phosphor for detecting image size. Of course, the phosphors can be separately applied.

In this example, the linear member 20 is further positioned inside the phosphor 22 at a predetermined position where an underscan is performed.
The phosphors 24 (24a, 24b) are applied with the same width as that of the phosphor 24, and this is used as a phosphor for detecting an underscan state.

Although only one phosphor 22 may be applied, it may be applied to several (3 to 5) linear bodies 20 as shown in FIG. This is because if several phosphors 22 are applied, the emission luminance level when the beam is scanned is increased, and erroneous detection can be avoided. As a result, the detection sensitivity can be improved.

These phosphors 2 for beam scanning position detection
The materials 2 and 24 may be made of the same material as the phosphor 16 or may be made of another material. In this example, the emission wavelength is 600
A phosphor material having a thickness of about nm is used.

When the beam scans these phosphors 22 and 24, it emits light, and the light is emitted as shown in FIG.
The light is detected by light detection means 26 and 28 provided outside the 2c side. For this reason, the light detecting means 26 and 28 are arranged at positions where light emission output can be received, and the detection area is formed as a light detection window by removing the carbon layer 29 applied on the inner surface as shown in FIG. I have.

As shown in FIG. 6, the light detecting means 26 (28) comprises a rectangular parallelepiped light collecting plate 26a and a light detecting element 26b provided on one end side thereof. A pin photodiode (PIN photodiode) or the like is used as the light detection element 26b.

The light collector 26a is a resin plate made of polycarbonate or the like, and is impregnated with a predetermined amount of an organic fluorescent paint. By impregnating the organic fluorescent paint, the wavelength of the collected light is reduced. Converted to longer wavelength side. In this example, it was confirmed that the wavelength (600 nm) of the received light was shifted to about 700 nm and emitted. The reason for this is to shift the wavelength of the detection light to the wavelength side since the light detection efficiency of the used light detection element 26b is the highest at about 900 nm.

In this example, the detection light condensed by the light collector 26a is emitted from the left end face while being reflected on the inner side wall, and is converted into an electric signal by the light detection element 26b. Here, as shown in FIG.
Based on BLK, the light detection output is as shown in FIG. 7B. The detection output Pa, Pb is such that the beam is the outer phosphor 22a,
The detection outputs Pc and Pd are outputs obtained by scanning the inner phosphors 24a and 24b.

Since the phosphors 22 and 24 are formed at equal distances on the left and right with respect to the center of the CRT, the edge of the horizontal blanking pulse H · BLK is used as a reference time, and the first phosphor 22a is scanned from this time. When the time from scanning the last phosphor 22b to the horizontal blanking pulse H · BLK is denoted by tb, these times ta and tb are measured. When ta = tb, It can be seen that the raster centering is at the center of the CRT 12. However, when ta ≠ tb, it can be determined that the raster centering is shifted.

Thus, comparing the magnitudes of ta and tb,
It can be seen how much the raster is shifted left or right and how much. The arithmetic processing, the magnitude discrimination processing, and the corresponding centering correction signal calculation processing are all performed in the microcomputer, and the calculated centering correction signal is used as a horizontal centering coil (HC) that functions as a centering adjustment unit.
C). At the time of detection, since the light is detected from the index phosphor, the drive state of the electron gun is set to such an extent that the raster shines slightly.

The detection of the raster centering position is performed for each vertical period in which flicker does not occur. Since flicker hardly occurs in a unit of several hundred fields, for example, the light emission output from the beam position detecting phosphor 22 is detected once every 100 fields. The detection timing is performed using an arbitrary scanning line in the vertical cycle. In this example, considering the distortion of the raster and the temperature drift of the horizontal deflecting circuit, it is optimal to detect the signal at a scanning line substantially at the middle of the vertical cycle. Therefore, a program for adjusting the raster centering is set to have such a detection cycle and detection timing.

If the sum of the two times ta and tb at the time of the standard image size is Tref, if T = ta + tb = Tref, it is understood that the image size is the standard image size. However, when T = ta + tb ≠ Tref, it is understood that the image size is shifted from the standard image size.

Then, by comparing the magnitudes of T and Tref, it can be determined whether the image size is larger or smaller than the standard image size. The arithmetic processing, the magnitude discrimination processing, and the corresponding centering correction signal calculation processing are also performed in the microcomputer described above, and the voltage modulation means functioning as the image size adjustment means is modulated by the calculated image size correction signal.

If the beam deflection is smaller than the standard image size, the light does not reach the outer phosphor 22 as shown in FIG. 7C. At this time, light detection outputs Pc and Pd from only the inner phosphor 24 are obtained. Then, when the deflection angle becomes smaller than in the case of FIG. 7C, this inner phosphor 2
4, the light detection outputs Pc and Pd cannot be obtained.
In this case, since the underscan state is detected, appropriate processing can be performed.

In order to realize the above processing, the raster centering adjustment circuit and the image size adjustment circuit according to the present invention are configured as shown in FIG. FIG. 1 shows an embodiment in which both raster centering and image size can be adjusted simultaneously.

In FIG. 1, beam position detection signals detected by a pair of photodetectors 26 and 28 attached to the CRT 12 are amplified by amplifiers 32a and 32b, respectively, and then converted into digital signals by AD converters 34a and 34b. The converted data is supplied to the control unit 40 constituted by a microcomputer. The control program described above is stored in the control unit 40, and the program is started when the power of the apparatus is turned on.

The control unit 40 is further supplied with a horizontal blanking pulse H · BLK, so that the scanning time t until the beam reaches the above-mentioned phosphors 22 and 24 is reached.
a and tb (tc and td as necessary) are calculated, and the arithmetic processing shown in the above equation is performed, and a centering correction signal and an image size correction signal are generated according to the magnitude.

The generated centering correction signal and image size correction signal are converted back into analog signals by the DA converters 36a and 36b, respectively.
Is controlled, and a horizontal deflection current flowing through a horizontal deflection coil (HDY) 52 mounted on the CRT 12 is controlled based on the output.

FIG. 8 shows a specific example of the horizontal deflection circuit 50. The figure shows the horizontal output circuit 6 of the horizontal deflection circuit 50 in particular.
The figure is centered on the 0 part. A horizontal linearity coil (HLC) 56 and a capacitor 58 for S-shaped correction are connected to the horizontal deflection coil 52 in series as is well known. The horizontal output transistor Q is driven by the horizontal drive pulse HD, and a sawtooth horizontal deflection signal (current) flows through the horizontal deflection coil 52. Capacitor 6
Reference numeral 2 denotes a charge / discharge capacitor, and diode 64 denotes a damper diode.

The power supply terminal 6 is connected to the collector of the transistor Q.
6 is connected, and a horizontal output transformer (HO)
T) 68 and a voltage modulation circuit 70 for controlling the power supply voltage + B. An image size control signal is supplied from a terminal 72 to a voltage modulation circuit 70 configured as a part of the image size adjusting means 90 via an amplifier 74 and applied to the horizontal deflection coil 52 based on the image size control signal. The voltage is adjusted.

As is well known, the image size control signal can be manually adjusted from outside the set.
Since the peak value of the horizontal deflection voltage changes according to the applied voltage value, the image size can be adjusted accordingly.

In the present invention, an adder 76 is further provided before the amplifier 74, and the image size correction signal generated by the control unit 40 is supplied to the terminal 78. As a result, the image size correction signal is added to the image size control signal, so that the voltage applied to the horizontal deflection coil 52 is finely adjusted, so that the image size can be automatically finely adjusted.

The horizontal centering control signal from the horizontal centering adjusting means 100 is supplied to the connection point p between the horizontal linear retaining coil 56 and the capacitor 58 described above. Therefore, a horizontal centering control signal is supplied to the terminal 80, and is supplied to the connection point p via the current amplifier 82 and the horizontal centering coil 84. As a result, the value of the DC deflection current flowing through the horizontal deflection coil 56 is adjusted, and adjustment of raster centering is performed. The horizontal centering control signal is adjusted at the factory shipment stage, but after that the value cannot be adjusted unless the set is opened.

In the present invention, an adder 86 is further provided, and the above-mentioned centering correction signal is added to the terminal 88. Therefore, when the semi-fixed horizontal centering control signal and the automatically generated centering correction signal are simultaneously supplied to the connection point p, the centering of the raster is automatically finely adjusted.

As described above, according to the present invention, when the horizontal blanking pulse H.BLK is used as a reference, the phosphors 22, 24 are used.
By measuring the time until scanning, it is possible to detect raster centering deviation and image size, and automatically adjust raster centering and image size, so that adjustment work can be abolished,
Also, the image quality can be improved.

Since the raster centering and the image size can be detected by using the common phosphor 22, variations in detection accuracy are reduced, and the work of applying the phosphor can be simplified. Since both the raster centering adjustment and the image size adjustment are automatic, stable and high-quality images can always be displayed.

Although only the adjustment of the raster centering in the horizontal direction has been described above, the present invention can be applied to the raster centering in the vertical direction. In this case, the beam scanning position in the vertical direction is also detected.
As described above, the position detecting phosphor applied to the back side of the aperture grill AG is applied separately at three locations, that is, the left and right upper and lower ends and the center.

The central phosphor 22 is used for raster centering detection in the horizontal direction, and the upper and lower phosphors 102 (one or both of 102a and 102b) and 104 (one of 104a and 104b or Both are used to detect raster centering in the vertical direction. Then, similarly to the detection of the raster centering in the horizontal direction, by measuring the time required to scan the upper and lower phosphors 102 and 104 with reference to the vertical blanking pulse, the raster centering in the vertical direction can be detected.

[0047]

As described above, according to the present invention, it is possible to detect the deviation of the raster centering and the image size by measuring the time until the phosphor is scanned based on the horizontal blanking pulse. Things.

According to this, when the deviation of the raster centering is detected, the centering correction signal is automatically added to the centering adjusting means, so that the automatic correction can be realized. Since a centering correction signal can be added to the centering adjustment means itself, the correction accuracy is high. Since it is automatic correction, troublesome adjustment work such as manual adjustment can be completely eliminated.

Similarly, since the image size can be detected, if the image size is different from the standard size, an image size correction signal is added to the corresponding image size adjusting means, so that the image size can be automatically corrected. From the above, the present invention can realize a CRT without image quality deterioration. Therefore, the present invention is extremely suitable for application to a cathode ray tube device or the like incorporating a color selection mechanism such as an aperture grill.

[Brief description of the drawings]

FIG. 1 is a system diagram of a main part showing an embodiment of a raster centering adjustment circuit and an image size adjustment circuit according to the present invention.

FIG. 2 is a sectional view of a cathode ray tube to which the present invention is applied.

FIG. 3 is a perspective view of an aperture grill.

FIG. 4 is a rear view of the aperture grill.

FIG. 5 is a sectional view showing a relationship between an aperture grill and a flat panel.

FIG. 6 is a diagram of a light detection unit.

FIG. 7 is a waveform chart showing a relationship between a horizontal blanking pulse and a photodetection output.

FIG. 8 is a connection diagram of a main part of a horizontal deflection circuit to which the present invention is applied.

FIG. 9 is a rear view of an aperture grill showing another embodiment of the present invention.

FIG. 10 is a diagram illustrating a relationship between raster centering, an image size, and a video image frame.

[Explanation of symbols]

12 ・ ・ ・ CRT, AG ・ ・ ・ Aperture grill, 2
2, 24... Phosphor for scanning position detection, 26, 28,.
Light detection means, 50 horizontal deflection circuit, 52 horizontal deflection coil, 90 image size adjustment means, 100
..Horizontal centering adjustment means (raster centering adjustment means)

Claims (7)

[Claims] 1. A phosphor for detecting a raster centering position is provided at predetermined positions at both ends of a color selection mechanism disposed on an inner surface of a cathode ray tube, and light detecting means for detecting a light emission output from the phosphor is provided by the cathode ray tube. A raster centering adjustment circuit, which is provided on the outer surface of the tube on the funnel side and wherein the raster centering is automatically adjusted based on the output from the light detecting means. 2. The time ta, tb until the phosphor is scanned from the horizontal blanking pulse is measured with reference to the horizontal blanking pulse, and the time t between the left and right phosphors and the horizontal blanking pulse is measured.
2. The raster centering adjustment circuit according to claim 1, wherein the raster centering is adjusted based on the difference between a and tb. 3. The raster centering adjustment circuit according to claim 1, wherein the detection of the raster centering position is performed for each vertical cycle in which flicker does not occur. 4. A phosphor for detecting an image size is provided at predetermined positions at both ends of a color selection mechanism disposed on the inner surface of the cathode ray tube, and the light detecting means for detecting a light emission output from the phosphor is a cathode ray tube. An image size adjusting circuit provided on the outer surface on the side of the funnel section and automatically adjusting the image size based on the output from the light detecting means. 5. The time ta, tb from when the phosphor is scanned by the horizontal blanking pulse is measured with reference to a horizontal blanking pulse, and the sum of the times ta and tb is compared with a reference value. 5. The image size adjustment circuit according to claim 4, wherein the size of the image size is determined, and the image size is adjusted based on the output. 6. A phosphor for detecting an underscan state is provided inside the phosphor in the color selection mechanism, and when a light detection output from the phosphor is obtained, it is determined that the apparatus is in the underscan state. 5. The image size adjusting circuit according to claim 4, wherein: 7. The image size adjustment circuit according to claim 4, wherein the detection of the image size is performed for each vertical period in which flicker does not occur.