JP2737589B2 - Display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device having an on-screen display circuit, and more particularly to a blanking device for blanking out an electron beam irradiation (overscan) outside the image display area of a cathode ray tube (CRT). The present invention relates to a display device having improved means.

[0002]

2. Description of the Related Art Recently, a display device having a 16: 9 aspect ratio of a CRT has appeared, and accordingly, an image having an aspect ratio of 16: 9 is displayed on a display device having an aspect ratio of 16: 9. Also, a conventional image having an aspect ratio of 4: 3 is displayed. For example, when displaying an image having an aspect ratio of 4: 3 on a display device having an aspect ratio of 16: 9, the central portion of the image having an aspect ratio of 4: 3 is overscanned in the vertical direction by a deflection circuit. Various display modes have been adopted, such as changing the display position even when displaying an enlarged image or displaying an image having an aspect ratio of 16: 9.

In this case, since the electron beam is irradiated outside the image display area of the CRT (so-called overscan),
In some cases, the temperature inside the CRT rises and problems such as CRT damage occur. Therefore, in order to prevent this, CR
It is necessary to blank the video signal supplied to the CRT not only for the retrace time but also for the overscan time so that the portion outside the image display area of T is not irradiated with the electron beam.

FIG. 8 is a block diagram showing an example of a conventional blanking time switching circuit. In this conventional example, when displaying an image on a display device as described above, a plurality of display modes are employed. In this case, three blanking times are switched. In FIG.
A flyback pulse output from a deflection circuit (not shown) is input to an input terminal, and the flyback pulse is selectively supplied to pulse width variable circuits 12 to 14 via a changeover switch 11. The pulse width variable circuits 12 to 14 are configured by, for example, an integrating circuit or a multivibrator, and shape the flyback pulse to output blanking pulses having different pulse widths. The blanking pulse is output from the output terminal and is used for blanking the electron beam (video signal) as described above.

[0005]

On the other hand, a recent display device has an on-screen display circuit for displaying a function selection key and an operation state on a screen by R, G, and B signals, that is, a so-called on-screen display. Often have. FIG. 7 is a block diagram showing a configuration in a case where the above-described conventional blanking time switching circuit is provided in a display device having an on-screen display circuit.

In FIG. 7, a Y (luminance) signal and a C (color) signal supplied from a preceding stage (not shown) are input to a color demodulation circuit 1, and a Y signal and two color difference signals RY and BY are supplied. Is output. These signals are input to the matrix circuit 2 to output R, G, B signals. The R, G, and B signals are supplied to a CRT 4 via an amplifier 3 and are deflected by an electron beam by a deflection circuit 7 to display an image. On the other hand, the control circuit 5 controls, for example, tint by controlling the color demodulation circuit 1, and controls, for example, color temperature by controlling the matrix circuit 2. The control circuit 5 also controls an on-screen display circuit 6 for displaying the above information on the screen of the CRT 4 on-screen. When an on-screen display command is issued from the control circuit 5, the on-screen display circuit 6 outputs R, G, and R for the on-screen display.
A B signal (on-screen display signal) and a first blanking signal (hereinafter, referred to as a Ys signal) for blanking a video signal of the B signal are supplied to the matrix circuit 2. As a result, the on-screen display is performed on the video projected on the CRT 4.

Further, the control circuit 5 controls the deflection circuit 7 to enlarge an image to be displayed on the CRT 4,
The above display mode is controlled. Here, reference numeral 8 in the figure is the blanking time switching circuit shown in FIG. 8, and the blanking time switching circuit 8 blanks the overscan area. The control of each unit by the control circuit 5 is performed by, for example, a serial data bus.

However, as described above, when various display modes such as arbitrarily changing the magnification and the display position of an image displayed on the CRT 4 are used, the overscan area is not constant, and a plurality of pulse widths are set. In a display device including a conventional blanking time switching circuit configured to switch a plurality of blanking times by variable circuits (12 to 14), the configuration becomes complicated,
There are problems such as an increase in cost.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention provides an image display section on which an image signal is supplied and an image is displayed, and an electron beam in a horizontal direction and a vertical direction. A deflecting circuit for deflecting, an on-screen display signal for on-screen display of predetermined information on the screen of the image display unit, and a blanking of a video signal in a period during which the on-screen display signal is output. A display device having an on-screen display circuit that outputs a first blanking signal, by outputting a first blanking signal from the on-screen display circuit to an area overscanned by the deflection circuit, Display configured to blank the video signal supplied to the display It is to provide a location.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a display device of the present invention will be described.
This will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of the display device of the present invention, FIG. 2 is a block diagram showing a specific configuration of the control circuit 5 in FIG. 1, and FIG. 3 is an example of a display mode by the display device of the present invention. Diagram,
4 is a timing chart for explaining the display device of the present invention, FIG. 5 is a diagram for explaining a display mode by the display device of the present invention and a Ys signal in that case, and FIG. 6 is an on-screen display in FIG. FIG. 3 is a block diagram illustrating an example of a circuit 6. In FIG. 1, the same parts as those in FIG. 7 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

A display device according to an embodiment of the present invention comprises:
As shown in FIG. 1, a color demodulation circuit 1, a matrix circuit 2,
It comprises an amplifier 3, a CRT 4, a control circuit 5, an on-screen display circuit 6, and a deflection circuit 7. And
The conventional blanking time switching circuit 8 as described above is not provided. In the display device of the present invention, the overscan area is blanked using the Ys signal output from the on-screen display circuit 6, which will be described in detail later.

The control circuit 5 in FIG. 1 has a configuration as shown in FIG. 2, that is, a display selection unit 51, a magnification control unit 52, an overscan area calculation unit 53, a deflection control unit 54, and an on-screen control unit 55. ing. When a display mode selection command is issued by a user selection (instruction of a remote controller or the like), the display selection unit 51 outputs data indicating which of the plurality of display modes is selected and in what format to display the magnification control unit 5.
Feed to 2. The magnification control unit 52 supplies data on the horizontal enlargement ratio ah and the vertical enlargement ratio av corresponding to the designated display format to the overscan area calculation unit 53 and the deflection control unit 54. The deflection control unit 54 sets the horizontal enlargement ratio ah
And the deflection circuit 7 according to the data on the vertical magnification av.
And the amount of deflection by the deflection circuit 7 is increased or decreased. In addition,
To increase the magnification, the amount of deflection is increased. Then, the overscan amount also increases.

On the other hand, the overscan area calculation section 53 calculates an overscan area, that is, an area where the Ys signal is to be output, in the form of coordinates from the data input from the magnification control section 52, as will be described later. The horizontal synchronization pulse (H pulse) and the vertical synchronization pulse (V pulse) are input from the deflection circuit 7 to the on-screen control unit 55, and the Ys signal is output to the overscan area calculated by the overscan area calculation unit 53. The on-screen display circuit 6 is controlled as follows. The on-screen control unit 55 also receives display data for on-screen display selected by the user. Incidentally, the on-screen display circuit 6 is configured as shown in FIG. 6 as an example.

The R, G, B and Ys signals for on-screen display output from the on-screen display circuit 6 and the Ys signal for blanking the overscan area are input to the matrix circuit 2. And
During the period of the on-screen display and the overscan, the video signal is blanked by the Ys signal.

Further, the operation of the overscan area calculation section 53 in the control circuit 5 will be described in detail. In addition,
Here, as an example, as shown in FIG. 3, the display mode on the CRT 4 is a case where an image having an aspect ratio of 4: 3 is vertically enlarged and displayed on a CRT 4 having an aspect ratio of 16: 9. The hatched portion in FIG. 3 is an overscan area, and the upper left coordinate is (0, 0).
The maximum in the horizontal direction (right end) is xmax dots, and the maximum in the vertical direction (bottom end) is ymax dots, and coordinates are set in dot units. The output area (x, y) of the Ys signal when the image is enlarged with the center of the screen fixed is as follows:
This is the portion represented by the equation (4).

0 <x <(1/2) (1-1 / ah) xmax (1) {1- (1/2) (1-1 / ah)} xmax <x <xmax (2) 0 <Y <(1/2) (1-1 / av) ymax (3) {1- (1/2) (1-1 / av)} ymax <y <ymax (4)

The aspect ratio 16: 9 (9/16 = 0.5)
6) CRT 4 with aspect ratio 4: 3 (3/4 =
Since the image of (0.75) is enlarged and displayed in the vertical direction, the vertical enlargement ratio av is 1.333 from 0.75 / 0.56, and the horizontal enlargement ratio is not increased. ah is 1. When these are substituted into the equations (1) to (4), 0 <y <0.125ymax (5) 0.875ymax <y <ymax (6) From the equations (5) and (6), it can be seen that the overscan area is the upper end 12.5% and the lower end 12.5% in the vertical direction, and the Ys signal should be output to this area.

FIG. 4 is a timing chart in this case. 4A shows a video signal, FIG. 4B shows a V pulse, FIG. 4C shows a Ys signal, and FIG. 4D shows an input signal to the CRT 4. In the video signal shown in (A), a hatched portion is an overscan area. Since the blanking time is blanked including this area, the area where the Ys signal is to be output is in a period of 0.875ymax to 0.125ymax. As a result, the input signal to the CRT 4 becomes as shown in (D).

FIG. 5 shows a case where the reception channel "1" is displayed on the CRT 4 as an on-screen display.
The output period of the s signal is shown. In FIG. 5, a hatched portion is an overscan area as described above. The upper and lower A portions, which are areas of this overscan, are CR
The Ys signal is output from the left end to the right end of T4 (one horizontal period excluding the horizontal retrace time). During the period B, the Ys signal is not output. Then, during the period C in which the reception channel "1" is displayed, the Ys signal is output only in that portion.

In this embodiment described above, a case where an image having an aspect ratio of 4: 3 is enlarged and displayed in the vertical direction on a CRT 4 having an aspect ratio of 16: 9 is described as an example. It goes without saying that blanking can also be performed in the event of a failure. Although the preferred embodiment of the present invention has been described, various modifications can be made without departing from the spirit of the present invention.

[0021]

As described in detail above, the display device of the present invention blanks the video signal supplied to the CRT by outputting the first blanking signal from the on-screen display circuit in the overscan area. With this configuration, it is not necessary to provide another circuit for blanking the overscan area.
Even in the case where the overscan area is not constant due to various display modes, the blanking can be accurately performed at an arbitrary position in the horizontal and vertical directions without complicating the configuration or increasing the cost. It has the feature that it can perform.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a display device of the present invention.

FIG. 2 is a block diagram showing a specific configuration of a control circuit 5 in FIG.

FIG. 3 is a diagram showing an example of a display mode by the display device of the present invention.

FIG. 4 is a timing chart for explaining the display device of the present invention.

FIG. 5 is a diagram for explaining a display mode by a display device of the present invention and a Ys signal in that case.

FIG. 6 is a block diagram showing an example of an on-screen display circuit 6 in FIG.

FIG. 7 is a block diagram showing a conventional display device.

FIG. 8 is a block diagram showing an example of a conventional blanking time switching circuit.

[Explanation of symbols]

 Reference Signs List 1 color demodulation circuit 2 matrix circuit 3 amplifier 4 CRT (image display section) 5 control circuit 6 on-screen display circuit 7 deflection circuit 52 magnification control section 53 overscan area calculation section 54 deflection control section 55 on-screen control section

Claims (2)

(57) [Claims] An image display unit to which a video signal is supplied to display an image, a deflection circuit for deflecting an electron beam in a horizontal direction and a vertical direction, and predetermined information on a screen of the image display unit. A display device comprising: an on-screen display signal for on-screen display; and an on-screen display circuit that outputs a first blanking signal for blanking a video signal in a period during which the on-screen display signal is output. A display device configured to blank a video signal supplied to the image display unit by outputting a first blanking signal from the on-screen display circuit to an area overscanned by the deflection circuit. . 2. An image display unit to which a video signal is supplied to display an image, a deflection circuit for deflecting an electron beam in a horizontal direction and a vertical direction, and predetermined information on a screen of the image display unit. A display device comprising: an on-screen display signal for on-screen display; and an on-screen display circuit for outputting a first blanking signal for blanking a video signal during a period during which the on-screen display signal is output, A magnification control unit that outputs data relating to an enlargement ratio of an image displayed on the screen of the image display unit based on the displayed display format; and an area that is overscanned from the data relating to the enlargement ratio output from the magnification control unit. An overscan area calculation unit that calculates the magnification, and a data related to the magnification output from the magnification control unit. A deflection control unit that controls the amount of deflection by the deflection circuit based on data, and an on-off unit that blanks a video signal supplied to the image display unit by a first blanking signal in the overscan area. A display device comprising: an on-screen control unit that controls a screen display circuit.