JPH10164389A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set properly the capacitance of an S-shaped correction capacitor at all times. SOLUTION: The horizontal deflection frequency of an input signal is detected in the step 2. Then a numeral table is retrieved according to the frequency detected in the step 3 and a 1st capacitance CSW of an S-shaped correction capacitor is obtained when a horizontal screen size is at maximum (HSW). Then a numeral table is retrieved according to the frequency detected in the step 4 and a 2nd capacitance C.,. of an S-shaped correction capacitor is obtained when a horizontal screen size is at minimum (HSn ). Then a capacitance CS of an S-shaped correction capacitor is obtained according to a prescribed interpolation calculation formula in the step 5 when a horizontal screen size is Hn . Moreover, data of the capacitance CS calculated in the step 6 are outputted and the S-shaped correction capacitor is controlled based on the data. Thus, a proper capacitance CS of the S-shaped correction capacitor is set at all times according to an input signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device suitable for use in displaying, for example, a television signal or an image signal from a personal computer.

[0002]

2. Description of the Related Art For example, in an image display device for displaying a television signal, a horizontal deflection circuit as shown in FIG. 4 is basically used. That is, in FIG. 4, the power supply terminal 41 to which the power supply Vcc is applied is connected to the choke coil 42.
And the switching transistor 43 are grounded.
A series circuit of a damper diode 44, a resonance capacitor 45, a horizontal deflection coil 46 and a capacitor 47 is connected in parallel with the transistor 43. A terminal 48 to which a horizontal synchronization pulse is supplied is provided at the base of the transistor 43.

In this circuit, when the transistor 43 is turned on by the horizontal synchronization pulse supplied to the terminal 48, the resonance capacitor 45 is short-circuited, and the horizontal deflection coil 46 is kept at a constant voltage from the power supply Vcc applied to the power supply terminal 41. A current having a slope of? Next, transistor 4
When 3 is turned off, the resonance capacitor 45 and the horizontal deflection coil 46 resonate, and the current flowing through the horizontal deflection coil 46 becomes a sine wave.

Further, when this current reaches a negative maximum value, that is, when the potential at both ends of the horizontal deflection coil 46 drops below 0 potential, the diode 44 is turned on. As a result, a current having a constant gradient flows again through the horizontal deflection coil 46, and when the collector voltage of the transistor 43 becomes higher than the ground, the diode 44 is turned off. Therefore, if the transistor 43 is turned on before the diode 44 is turned off, the current flows without interruption in the reverse direction, and the above operation is repeated. This is one cycle of horizontal deflection.

However, when the beam is scanned at a constant speed in one cycle of such horizontal deflection, the images at the left and right ends L and R are extended with respect to the vicinity C of the center of the tube surface as shown in FIG. Therefore, as shown in FIG. 4 described above, a capacitor 47 is connected in series to the horizontal deflection coil 46,
As shown in (1), the waveform A of the deflection current is blunted in an S-shape with respect to the straight line B, so that the scanning speed of the beam at the left and right ends of the horizontal scanning line can be reduced to eliminate the left and right expansion of the image. Is being done. This is “S-shaped correction”, and the above-described capacitor 47 is called an S-shaped correction capacitor.

In recent years, in image display devices,
2. Description of the Related Art A multi-scan monitor that can accurately display a plurality of image signals having different horizontal and vertical deflection frequencies has been implemented. In this case, for image signals having different horizontal deflection frequencies, the appropriate capacitance value of the S-shaped correction capacitor is different. Therefore, for example, a horizontal deflection frequency of a supplied image signal is detected, and an appropriate capacitance value of the S-shaped correction capacitor is set based on the detected horizontal deflection frequency.

That is, the appropriate capacitance value of the S-shaped correction capacitor is determined by the horizontal deflection frequency. Therefore, for example, an S-shaped correction capacitor having an appropriate capacitance value is prepared in advance for each assumed image signal system, the supplied horizontal deflection frequency is determined, and the prepared S-shaped correction capacitor is switched according to this determination.
In this way, an appropriate capacitance value of the S-shaped correction capacitor is set, and for example, even for an image signal having a different horizontal deflection frequency, it is possible to always perform display with accurate S-shaped correction.

[0008]

However, in the above-described image display device, it has been required that the aspect ratio (horizontal deflection width) of the displayed image can be arbitrarily changed. That is, in a television signal, usually 4:
Aspect ratios of 3: or 16: 9 are used, and 4: 3 or 5: 4 aspect ratios are often used in image signals from personal computers.

Therefore, for example, the aspect ratio is 16: 1.
An image display device that prepares a picture tube of 0 and can display image signals of the above-described various aspect ratios is being studied. In this case, for only a certain fixed signal timing, for example, the aspect ratio can be estimated by detecting the above-described horizontal deflection frequency, and the S value of an appropriate fixed capacitance value prepared in advance according to the determined result is obtained.
Switching to a character correction capacitor can be performed.

However, in such an image display device, when the horizontal screen size of a display image is arbitrarily changed, the fixed S-shaped correction capacitor prepared in advance as described above requires an appropriate S-shaped correction capacitor in all cases. It is not character correction.

Further, for example, when a 4: 3 signal in which the same vertical screen size is set at the same horizontal deflection frequency and a 16: 9 signal is input to a 16:10 picture tube, a suitable horizontal The screen size will be very different.
Therefore, if the capacitance value of the S-shaped correction capacitor determined by the horizontal deflection frequency as described above is used, it is difficult to provide an appropriate capacitance value for all horizontal screen sizes.

The present invention has been made in view of such a point, and a problem to be solved is that in the conventional apparatus, when the horizontal screen size of the display image can be arbitrarily changed, This is because the appropriate S-shaped correction value has changed.

[0013]

For this reason, in the present invention, the required capacitance value of the S-shaped correction capacitor is calculated based on the horizontal deflection frequency and the horizontal screen size, and the S-shape is calculated so as to be the calculated value. The capacitance value of the correction capacitor is adjusted. According to this, the capacitance value of the S-shaped correction capacitor can always be appropriately adjusted with a very simple configuration.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS That is, according to the present invention, in an image display device capable of arbitrarily changing the horizontal screen size of a display image, a required capacitance value of an S-shaped correction capacitor is calculated based on a horizontal deflection frequency and a horizontal screen size. And an adjusting means for adjusting the capacitance value of the S-shaped correction capacitor so as to obtain the calculated value. Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an example of an image display device to which the present invention is applied.

In FIG. 1, a power supply terminal 1 to which a power supply Vcc is applied is grounded through a choke coil 2 and a switching transistor 3. A damper diode 4 and a resonance capacitor 5 are connected in parallel with the transistor 3.
And a series circuit of the horizontal deflection coil 6 and the capacitor 7 are connected. A terminal 8 to which a horizontal synchronization pulse is supplied is provided at the base of the transistor 3. With it
The capacitors 91, 92,... 9n each having a predetermined capacitance value are connected in parallel with the above-described capacitor 7 to the selector 1.
0 is connected.

In FIG. 1, a terminal 8 to which a horizontal synchronizing pulse is supplied is connected to a microcomputer 20. In this microcomputer 20, the frequency of the horizontal synchronizing pulse supplied from the terminal 8 is
1 and a numerical value table 22 according to the detection result.
Is searched.

Accordingly, from the numerical value table 22, for example, the first capacitance value Csw of the S-shape correction capacitor of Hsw when the horizontal screen size at the horizontal deflection frequency is the maximum, and the S-shape correction of Hsn when the horizontal screen size is the minimum. The second capacitance value Csn of the capacitor is read. Then, the read first and second capacitance values are supplied to the calculating means 23.

The preset data table 2 is stored in accordance with the horizontal frequency determined by the frequency determining means 21 described above.
4, a preset basic horizontal screen size Hs is read. Then, the read basic horizontal screen size Hs is supplied to the calculating means 23. Alternatively, the horizontal screen size Hs set by the setting input means 25 is supplied to the calculating means 23.

As a result, the calculating means 23 calculates an appropriate capacitance value Cs of the S-shaped correction capacitor in accordance with, for example, the following equation (1).

(Equation 1)

The data is supplied to the selector 10 in accordance with the calculated data of the capacitance value Cs of the S-shaped correction capacitor. Thereby, for example, the above-mentioned capacitor 7
And the capacitors 91 and 92 selected by the selector 10.
Control of the selector 10 is performed so that the total capacitance value of 9n is equal to the calculated capacitance value Cs.

Further, in this apparatus, the microcomputer 20 operates according to, for example, the flowcharts of FIGS. 2 and 3 described below.

That is, in FIG. 2, the capacitance value Cs of the S-shaped correction capacitor is set based on the basic horizontal screen size Hs. In FIG. 2, when the input signal changes, this flowchart is started. In step [1], the screen is muted. Next, in step [2], the horizontal deflection frequency of the input signal is detected, and various processing of the signal system according to the change in the frequency is performed.

Further, the numerical value table is searched according to the frequency determined in step [3], and the above-mentioned first capacitance value Csw is obtained. Further, a numerical value table is searched according to the frequency determined in step [4], and a second capacitance value Csn is obtained. Then, in step [5], the required capacitance value Cs of the S-shaped correction capacitor is calculated according to the above [Equation 1].

Then, data of the capacitance value Cs calculated in step [6] is output, and the selector 10 is controlled based on this data. Step [7]
To release the muting of the screen and end the operation. Thus, for example, when the input signal is changed, the capacitance value Cs of the S-shaped correction capacitor is set according to the basic horizontal screen size Hs of the system determined by the horizontal deflection frequency of the new input signal.

Further, in FIG. 3, the capacitance value Cs of the S-shaped correction capacitor is set according to the horizontal screen size Hs set by the user, for example. When the operation is started in FIG. 3, it is first determined at step [11] whether or not a key has been pressed. If the key is not depressed in this step [11] (No), the operation is terminated as it is.

On the other hand, if the key is pressed in step [11] (Yes), it is determined in next step [12] whether the pressed key is a key for adjusting the horizontal screen size. If the key pressed in step [12] is the horizontal screen size adjustment key (Yes), the horizontal screen size Hs is recalculated in step [13].

Further, based on the recalculated horizontal screen size Hs and the first and second capacitance values Csw and Csn in step [14], the S-shaped correction capacitor required in accordance with the above [Equation 1] is obtained. Is calculated. Then, the data of the capacitance value Cs calculated in step [15] is output, and based on this data, the above-described control of the selector 10 is performed, and the operation is completed.

Thus, for example, when the horizontal screen size adjustment key is operated by the user, the capacitance value Cs of the S-shaped correction capacitor is set in accordance with the newly adjusted horizontal screen size Hs. Step [1
If the key pressed in 2] is a key other than the adjustment of the horizontal screen size (No), the process associated with the other keys is performed in step [16], and the operation ends.

In this way, in this apparatus, when the input signal is changed or when the user operates the horizontal screen size adjustment key, the required capacitance value of the S-shaped correction capacitor is calculated according to the horizontal screen size Hs. , The capacitance value C of the S-shaped correction capacitor so as to become the calculated value.
s is set.

Therefore, in this apparatus, the required capacitance value of the S-shaped correction capacitor is calculated based on the horizontal deflection frequency and the horizontal screen size, and the capacitance value of the S-shaped correction capacitor is adjusted to the calculated value. Thus, the capacitance value of the S-shaped correction capacitor can always be appropriately adjusted with a very simple configuration.

Thus, in the conventional apparatus, when the horizontal screen size of the display image can be arbitrarily changed, it is impossible to properly adjust the capacitance value of the S-shaped correction capacitor. According to the extremely simple configuration, S
The capacitance value of the character correction capacitor can always be properly adjusted.

In the above-described apparatus, the resolution of the horizontal screen size is adjusted to 10 bits and the resolution of the adjustment of the capacitance value of the S-shape correction capacitor is set to 6 bits. Experiments have shown that adjustments can be made.

According to the image display apparatus described above, in the image display apparatus capable of arbitrarily changing the horizontal screen size of the display image, the necessary capacitance value of the S-shaped correction capacitor is determined based on the horizontal deflection frequency and the horizontal screen size. By providing a calculating means for calculating and an adjusting means for adjusting the capacitance value of the S-shaped correction capacitor so as to have the calculated value,
With an extremely simple configuration, the capacitance value of the S-shaped correction capacitor can always be properly adjusted.

[0034]

According to the present invention, the required capacitance value of the S-shaped correction capacitor is calculated based on the horizontal deflection frequency and the horizontal screen size, and the capacitance value of the S-shaped correction capacitor is calculated so as to be the calculated value. , The capacitance value of the S-shaped correction capacitor can always be properly adjusted with a very simple configuration.

Thus, in the conventional apparatus, when the horizontal screen size of the display image can be arbitrarily changed, it is impossible to properly adjust the capacitance value of the S-shaped correction capacitor. According to the extremely simple configuration, S
The capacitance value of the character correction capacitor can always be properly adjusted.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an example of a main part of an image display device to which the present invention is applied.

FIG. 2 is a flowchart for explaining the operation.

FIG. 3 is a flowchart for explaining the operation.

FIG. 4 is a configuration diagram of a main part of a conventional image display device.

FIG. 5 is a diagram for explaining this.

FIG. 6 is a diagram for explaining S-shaped correction.

[Explanation of symbols]

Reference Signs List 1 power supply terminal, 2 choke coil, 3 switching transistor, 4 damper diode, 5 resonance capacitor, 6 horizontal deflection coil, 7 capacitor, 8 horizontal synchronization pulse supply terminal, 91, 92... 9n capacitor, 10 selector, 20 microcomputer ,
21 frequency discriminating means, 22 numerical value table, 23 calculating means, 24 preset data table, 25 setting input means

Claims (3)

[Claims] 1. An image display device capable of arbitrarily changing a horizontal screen size of a display image, comprising: an arithmetic unit for calculating a necessary capacitance value of an S-shaped correction capacitor based on a horizontal deflection frequency and the horizontal screen size; An image display device comprising: an adjustment unit that adjusts a capacitance value of the S-shaped correction capacitor so as to have a calculated value. 2. The image display device according to claim 1, wherein said horizontal deflection frequency of the supplied image signal is detected, and said S when said horizontal screen size is a maximum based on the detected horizontal deflection frequency. A first capacitance value of the character correction capacitor and a second capacitance value of the S-character correction capacitor when the horizontal screen size is minimum are obtained from a preset numerical table, and based on the set horizontal screen size. An image display device for calculating the necessary capacitance value of the S-shaped correction capacitor by interpolation calculation between the maximum and minimum horizontal screen sizes and the first and second capacitance values. 3. The image display device according to claim 1, wherein the necessary capacitance value of the S-shaped correction capacitor is calculated based on the horizontal deflection frequency and the arbitrarily set horizontal screen size. Image display device.