JPH0759100A - Convergence correction circuit - Google Patents

Abstract

PURPOSE:To attain correct convergence correction even when a pattern size is hanged. CONSTITUTION:The circuit is provided with a horizontal pattern size detection circuit 60 rectifying a peak horizontal deflection current to detect the picture size and a vertical pattern size detection circuit 90 rectifying a peak vertical deflection current to detect the picture size and the amplitude of the convergence correction signal fed to convergence correction coils 20, 30 is controlled by the detection outputs. Since the amplitude of the convergence correction signal is controlled adaptively by the pattern size, convergence is corrected with a proper quantity based on the pattern size. Over-compensation of the convergence correction is avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a convergence correction circuit suitable for application to a multi-scan compatible image processing monitor or the like.

[0002]

2. Description of the Related Art Recent image processing apparatuses, such as computer graphics monitors, are often supplied with video signals of various horizontal frequencies due to the diversification of input sources. A multi-scan compatible one has been developed.

A monitor capable of freely adjusting the screen size (image size) over a predetermined range has also been developed for this multi-scan monitor.

In such a multi-scan monitor having an image size adjusting function, a deflecting device DY that obtains a uniform magnetic field and a semi-self-convergence type (CFD type) deflecting device DY are used in combination as the deflecting device. There are cases. When the semi-CFD type deflector is used together with the convergence correction circuit system, it is possible to improve the convergence correction with high accuracy and the focus characteristic.

[0005]

SUMMARY OF THE INVENTION In the monitor described above,
The image size can be freely changed from the standard size to an image size of about 1/2 of the standard size. FIG. 3A shows a standard size as an image size, and FIG. 3C shows an image size reduced to about 1/2.

In the case of the standard size, the convergence correction signal applied to the monitor is as shown by the curve Lna in FIG. Since the amplitude of the convergence correction signal does not change from the standard size even when the image size is reduced, the convergence correction signal when the size is reduced is the D curve Lsa in FIG.
become that way.

However, in the case of the reduced size, proper convergence correction cannot be performed unless the amount of convergence correction is reduced as the image size is reduced, resulting in misconvergence. Misconvergence is greatest at the edges of the screen.

When the proper convergence correction amount at both ends of the screen in the standard size is represented by the straight line Lp, the proper correction amount in the reduced size in FIG. Since both have a relationship of Lp> Lp ', if the convergence correction amount is made constant regardless of the size of the image size as in the conventional case, the convergence correction will not be overcompensated.

On the other hand, in the multi-scan type, the input horizontal frequency is configured to cover up to about 24 to 82 KHz, but the convergence correction amount is constant even when the horizontal frequency changes. For example, FIG. 4A
Consider a case where a video signal having a higher horizontal frequency than the horizontal frequency fH of the video signal (for example, B in the same figure) is input.

Assuming that the convergence correction signal for the video signal of FIG. A is Lnb, the amplitude of the convergence correction signal used for the video signal of FIG. B is constant like Lsb. Therefore, also in this case, the convergence correction at both ends of the screen when the horizontal frequency is high exceeds the appropriate amount Lp, so that the convergence tends to be overcompensated.

Therefore, the present invention solves such a conventional problem, and proposes a convergence correction circuit capable of realizing proper convergence correction even when the image size is changed. Similarly, the present invention proposes a convergence correction circuit in which the convergence correction is appropriately performed according to the input horizontal frequency.

[0012]

In order to solve the above problems, in the invention described in claim 1, the amplitude of the convergence correction signal supplied to the convergence correction coil is controlled according to the image size. It is characterized by that.

According to a fifth aspect of the present invention, the amplitude of the convergence correction signal is controlled according to the horizontal deflection frequency.

[0014]

As shown in FIG. 1, the image size detection circuit 60 detects the horizontal image size. The image size in the horizontal direction is detected from the magnitude of the amplitude of the horizontal output signal (FIG. 2B).
The gain control circuit 70 is controlled by the detection output corresponding to the image size, and proper gain adjustment is performed.

As a result, when the image size becomes smaller than the standard, the amplitude of the convergence correction signal in the horizontal direction is controlled accordingly, so that the amplitude is controlled.
The convergence correction signal at this time is as shown by the curves Lsa 'in FIGS. 2C and 3D, and thus the proper convergence correction is made at both ends of the screen. Similar processing is performed on the convergence correction signal in the vertical direction.

When the input horizontal frequency changes, this is detected by the frequency / voltage conversion circuit 72 shown in FIG. 1 and the amplitude of the horizontal deflection frequency is similarly adjusted. When the horizontal deflection frequency is high, the adjustment is performed as shown by the curve Lsb ′ in FIG. 4D. As a result, the convergence correction in the horizontal direction is optimized in this case as well.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a case where an example of the convergence correction circuit according to the present invention is applied to the deflection system of the computer graphic monitor described above will be described in detail with reference to the drawings.

According to the present invention, when the image size is changed, the optimization control of the convergence correction is performed along with the change of the image size. Even when the horizontal deflection frequency changes, the convergence correction optimization control is performed. Figure 1
Is an embodiment including a control system for both of them.

The horizontal blanking pulse HBLK supplied to the terminal 12 is supplied to a sawtooth wave signal generating circuit 14 to generate a sawtooth wave signal. The sawtooth wave signal is supplied to a horizontal convergence correction coil (HCY) 20 via a gain control circuit 16 for fine adjustment and an amplifier 18 to perform convergence correction.

The gain control circuit 16 is for fine adjustment for absorbing the deviation of the convergence correction due to the variation of the CRT. In this example, the gain is adjusted from both the horizontal sawtooth wave signal and the vertical sawtooth wave signal. I have to.

A vertical blanking pulse VB is applied to the terminal 22.
LK is supplied, and this is converted into a sawtooth wave signal having a vertical cycle in the sawtooth wave signal generation circuit 24. The converted sawtooth wave signal is supplied to a vertical convergence correction coil (VCY) 30 via a gain control circuit 26 for fine adjustment and an amplifier 28 to be subjected to vertical convergence correction.

In the present invention, with respect to the horizontal convergence correction system, a gain control circuit 70 is provided after the sawtooth wave signal generation circuit 14, and gain adjustment (amplitude adjustment) is performed here according to the size of the image size. Gain adjustment is also controlled by the horizontal deflection frequency.

The image size will be described first. A horizontal drive signal PH having a horizontal cycle is supplied to the terminal 40, and this is supplied to the horizontal output circuit 44 via the horizontal drive circuit 42. As is well known, the horizontal output circuit 44 includes a horizontal output transistor 46.
And a horizontal deflection coil (HDY) 50 is connected to the collector side thereof. Reference numeral 52 is a capacitor for S-shaped correction.

By applying a horizontal output pulse to the horizontal deflection coil 50, a sawtooth-shaped horizontal deflection current as shown in FIG. 2B flows through the horizontal deflection coil 50.

The horizontal output pulse obtained at the collector of the horizontal output transistor 46 is further supplied to a voltage dividing circuit 54 composed of capacitors 54a and 54b connected in series to divide the peak-to-peak value of the horizontal output pulse. To be done.

The divided output is the horizontal image size detection circuit 6
Supplied to zero. In this example, a peak value detection circuit is used. In the figure, it is composed of two rectifying diodes 62 and 64 and smoothing capacitors 66 and 68.

The peak value of the horizontal output pulse corresponds to the image size. When the image size becomes smaller than the standard, the peak value becomes smaller accordingly. Since the size of the image size can be known from the peak value of the horizontal output pulse thus divided,
This rectified and smoothed detection output is supplied to the gain control circuit 70 as an image size detection output.

The gain control circuit 70 adjusts the gain so that the amplitude of the sawtooth wave signal becomes smaller as the image size becomes smaller. Now, as shown in FIG. 2B, the horizontal convergence correction signal when the horizontal deflection current at the standard image size is the curve Id is the curve Lsa in FIG.

In this state, when the horizontal deflection current is controlled so that its amplitude becomes small like Id ', the horizontal convergence correction signal also appears at the both ends of the screen as shown by the curve Lsa' (see FIGS. 3C and D) in FIG. Since the amplitude of is smaller, the amount of convergence correction is smaller than that of the standard image size. Therefore, the amplitude of the horizontal deflection current Id 'is controlled by the image size detection output so that an appropriate convergence correction amount is obtained when the horizontal convergence correction signal of the curve Lsa' is obtained.

If the amplitude (peak value) of the convergence correction signal at both ends of the screen is controlled, the amount of convergence correction from both ends of the screen to the center of the screen is also controlled according to the peak value control as shown in FIG. 3C or 4D. Is done,
An appropriate correction amount can be obtained not only at the both ends of the screen but also up to the center of the screen where the convergence correction amount is the smallest.

Of course, the convergence correction value may be controlled by positively dividing the screen from both ends to the center of the screen in several steps.

A similar control is applied to vertical convergence. Therefore, the sawtooth wave signal generation circuit 24
The gain control circuit 100 is provided in the subsequent stage.
Further, the vertical drive signal PV supplied to the terminal 80 is supplied to the vertical deflection signal generation circuit 82 to form a sawtooth wave signal having a vertical cycle.

The sawtooth wave signal is supplied to a vertical deflection coil (VDY) 86 through an amplifier 84. The vertical deflection coil 86 is provided with a resistor 88 for current / voltage conversion in series with the vertical deflection coil 86, and vertical deflection is performed. Current is converted to voltage. The converted voltage is supplied to the vertical image size detection circuit 90.

The detection circuit 90 is a horizontal image size detection circuit 60.
A peak value detection circuit is used as in. The configuration is the same, and has smoothing capacitors 92 and 94 and rectifying diodes 96 and 98.

If the image size becomes smaller, the vertical drive signal PV
Since the peak value becomes smaller, the image size is reflected in the peak value of the vertical deflection current, and this is reflected in the magnitude of the rectified output (detection output) of the detection circuit 90. The gain of the wave signal is adjusted appropriately. With this, an appropriate correction amount can be obtained for vertical convergence as well.

Next, the horizontal deflection frequency will be described.
As the horizontal deflection frequency becomes higher, the cycle of the video signal becomes shorter as shown in FIG. 4A to FIG. 4B, so that the cycle of the horizontal deflection current also changes as shown in FIG.

When the horizontal deflection current for the video signal Sx is the curve Lx, the horizontal deflection current for the video signal Sy is as shown by the curve Ly. If the convergence correction signal is Lnb for the horizontal deflection current of the curve Lx, the curve Ly
When the horizontal deflection current is, the convergence correction signal must have a correction amount as shown by the curve Lsb '. This is because the appropriate correction amount at both ends of the screen is given by the adjustment Lp.

In the present invention, as shown in FIG. 1, the horizontal drive pulse obtained from the horizontal drive circuit 42 is supplied to the frequency / voltage conversion circuit 72. Since the cycle of the horizontal drive pulse corresponds to the horizontal deflection frequency, the conversion voltage also rises and falls in proportion to the level of the horizontal deflection frequency.

This converted voltage is supplied to the horizontal gain control circuit 70 as a gain control signal, and is controlled so that the gain of the horizontal sawtooth signal becomes smaller when the horizontal deflection frequency becomes higher. As a result, the amplitude-corrected convergence correction signal Lsb 'shown in FIG. 4D is obtained, and the convergence correction amount becomes appropriate even when the horizontal deflection frequency changes.

In this example, only the horizontal convergence correction signal is controlled according to the horizontal deflection frequency. If the input horizontal deflection frequency changes, the input vertical deflection frequency also changes. Therefore, the amplitude of the vertical convergence correction signal can be controlled according to the vertical deflection frequency of the input video signal. However, vertical convergence is not as affected as horizontal convergence.

In FIG. 1, only the amplitude of the convergence correction signal is controlled according to the image size information to optimize the correction at both ends of the screen. At the same time, an appropriate correction is made from the both ends of the screen to the center of the screen. The value of the convergence correction signal may be controlled in several steps so as to perform.

In FIG. 1, the image size information is obtained from the amplitude information of the horizontal output pulse or the vertical sawtooth wave signal. However, the horizontal convergence control information may be taken out from the inside of the horizontal drive circuit 42, or the vertical convergence control may be performed. The signal may be obtained from the vertical sawtooth wave signal generation circuit 24.

In the above description, the image size information is obtained from the horizontal output pulse or the amplitude information of the vertical sawtooth wave signal.
Since this information is input to the control unit (not shown) that is composed of the microcomputer installed in the monitor, the image size information is extracted from this control unit by software processing and the detected output is used. The gain control circuits 70 and 100 can also be controlled. The same applies to the horizontal deflection frequency or the vertical deflection frequency.

In the case of a multi-scan type monitor whose image size cannot be changed, the convergence correction amount may be controlled depending only on the input horizontal deflection frequency.

[0045]

As described above, the convergence correction circuit according to the first aspect of the present invention controls the amount of convergence correction according to the image size.

According to this, since the convergence correction is optimized at least at both ends of the screen, it is particularly applicable to a monitor using a semi-self-convergence type CRT capable of correcting the convergence with high accuracy by using a convergence correction circuit system together. And is very suitable.

In the convergence correction circuit according to the fifth aspect of the present invention, the convergence correction amount is controlled according to the input horizontal deflection frequency.

According to this, the convergence correction is optimized at least at both ends of the screen regardless of the input of the video signal of any horizontal deflection frequency, and thus the convergence correction circuit system is also used in the same manner as described above. It is extremely suitable to be applied to a monitor using a semi-self-convergence type CRT capable of highly accurately correcting.

[Brief description of drawings]

FIG. 1 is a system diagram of a main part showing an example of a convergence correction circuit according to the present invention.

FIG. 2 is a waveform chart showing the relationship between image size and convergence correction amount.

FIG. 3 is an explanatory diagram showing a change state of a convergence correction signal depending on an image size.

FIG. 4 is a waveform diagram showing a relationship between a horizontal deflection frequency and a convergence correction signal.

[Explanation of symbols]

 10 Convergence correction circuit 20, 30 Convergence correction coil 42 Horizontal drive circuit 50 Horizontal deflection coil 54 Voltage dividing circuit 60, 90 Image size detection circuit 70, 100 Gain control circuit 72 Frequency / voltage conversion circuit

Claims (8)

[Claims] 1. A convergence correction circuit, wherein the amplitude of the convergence correction signal supplied to the convergence correction coil is controlled according to the image size. 2. The convergence correction circuit according to claim 1, wherein both the amplitudes of the convergence correction signals of the horizontal period and the vertical period are controlled according to the image size. 3. A horizontal image size detection circuit for rectifying the peak value of the horizontal deflection current to detect the size of the image size, and a vertical image size detection circuit for rectifying the peak value of the vertical deflection current to detect the size of the image size. 2. A convergence correction circuit according to claim 1, further comprising a size detection circuit, wherein the amplitude of the convergence correction signal is controlled by each detection output. 4. The image size change information is supplied to a control unit composed of a microcomputer, and the detection output obtained from the control unit controls the amplitude of the convergence correction signal. 1. The convergence correction circuit according to 1. 5. A convergence correction circuit, wherein the amplitude of the convergence correction signal is controlled according to the horizontal deflection frequency. 6. A horizontal output pulse from a horizontal drive circuit is supplied to a frequency / voltage conversion circuit to detect an output corresponding to a horizontal deflection frequency, and the output controls the amplitude of the convergence correction signal. Claim 5
Convergence correction circuit described. 7. The input horizontal frequency information is supplied to a control section composed of a microcomputer, and the amplitude of the convergence correction signal is controlled by a detection output obtained from the control section. Item 5. The convergence correction circuit according to item 5. 8. The convergence correction circuit according to claim 1, wherein the amplitude of the convergence correction signal is controlled according to the image size and the horizontal frequency of the input video signal.