JPH05165447A - Display device - Google Patents

Abstract

PURPOSE:To connect one display device to many kinds of computer different by synchronizing signal frequencies of video output signals and to cope with even the video signal of an NTSC signal. CONSTITUTION:The display device in the auto-scan system which automatically follows up the horizontal synchronizing signal frequency of an inputted RGB signal to display a picture indicated by the RGB signal on the screen is provided with an input terminal 7 of the NTSC signal, a converter 3 which converts the NTSC signal to the RGB signal, and a switch circuit 5 which selects either of the RGB signal inputted from an RGB input terminal 8 and the RCB signal outputted from the converter 3 to display the selected RGB signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto-scan type display device connected to a computer or the like, and more particularly to a display device capable of receiving a video signal of an NTSC signal from a VTR or the like and displaying it on a screen.

[0002]

2. Description of the Related Art Due to the spread of computers, many computers have been installed in the same office.
Generally, one CRT display (monitor) device is installed for one computer. As a display device, in order to be compatible with various computers, an auto scan type device that automatically follows the frequency of the horizontal synchronizing signal of the RGB signal has been widely adopted.

[0003]

Conventional display devices connected to a computer usually have no other purpose than to be connected to a computer. For this reason,
When it is necessary to view a video signal from a VTR or the like, another display device (for example, a normal television receiver) capable of displaying the video signal of the NTSC signal as an image must be prepared. However, since the display device takes up a lot of space, it is not possible to install one display device for one computer and another display device in terms of space. It will make the environment worse.

An object of the present invention is to provide an auto-scan type display device capable of displaying an image by an NTSC signal.

[0005]

The above object is to provide an NTSC signal input terminal for an auto-scan display device that automatically follows the horizontal synchronizing signal frequency of an input RGB signal and displays an image represented by the RGB signal on a screen. And NTS
By providing a conversion means for converting the C signal into an RGB signal and a switch means for selecting and displaying on the screen one of the RGB signal input from the RGB input terminal and the RGB signal output from the conversion means, To be achieved.

[0006]

When the display device of the present invention is connected to the computer, the output of the computer is connected to the RGB signal input terminal, the RGB signal input terminal side is selected by the switch means, and the RGB signal from the computer is received. To display. When displaying an NTSC signal from a VTR or the like, the NTSC signal is connected to the NTSC signal input terminal and the switch means selects the NTSC signal input terminal side. As a result, the input NTSC signal is converted into an RGB signal by the conversion means, and this RGB signal is displayed as an image.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a display device according to an exemplary embodiment of the present invention. This display device 1
Includes a converter 3 for converting an NTSC signal into an RGB signal, in addition to a normal CRT display device 2 of the auto scan system,
A receiving circuit 4 for directly receiving RGB signals, an analog switch circuit 5 for selecting one of the converter 3 or the output of the receiving circuit 4 and inputting it to the CRT display device 2, and switching to the analog switch circuit 5 by an operator's manual operation. An NTSC signal input terminal 7 provided with a changeover switch 6 for outputting a command.
NTSC signals from VTR9 etc. connected to
To the RGB from the computer (PC) 10 etc.
The signal is input to the receiving circuit 4.

When the CRT display device 2 is used as a monitor of the computer 10, the operator operates the changeover switch 6 to cause the analog switch circuit 5 to select the receiving circuit 4 side. As a result, the RGB signal output from the computer 10 is input to the CRT display device 2 through the receiving circuit 4 and the analog switch circuit 5.

A CRT display device 2 as a monitor of the VTR 9
When using, the operator operates the changeover switch 6 to cause the analog switch circuit 5 to select the converter 3 side. As a result, the NTSC signal output from the VTR 9 is converted into an RGB signal by the converter 3, the RGB signal is input from the analog switch circuit 5 to the CRT display device 2, and the RGB signal corresponding to the image of the NTSC signal is displayed on the screen. Image is displayed.

An NTSC signal from a VTR or the like has a luminance signal representing light and dark, a color signal representing color, and a sync signal as information for transmitting a position and timing of a screen, which are superimposed on one cable. On the other hand, the display device of the auto scan system is compatible with analog RGB, and the synchronization signal (SYNC) is a signal superimposed on the G (green) signal. Therefore, when the NTSC signal is converted into the RGB signal, the sync signal SYNC is superimposed on the G signal. FIG. 2 is a detailed configuration diagram of the NTSC signal / RGB signal converter 3 shown in FIG. The NTSC signal / RGB signal converter according to this embodiment includes a Y / C separation circuit 20 that separates an NTSC signal into a luminance signal Y and a color signal C, a synchronization circuit 21 that extracts a synchronization signal SYNC from the luminance signal Y, A circuit 22 for adjusting the image quality and contrast of the luminance signal Y,
A circuit 23 for clamping the output signal of the circuit 22 and a circuit 24 for adjusting the luminance after clamping are provided. Also, Y /
The ACC circuit 25, which keeps the level of the color signal C separated by the C separation circuit 20 constant, the APC circuit 26, and the VCO.
A circuit 27, a dint control circuit 28, a color control circuit 29, a color killer circuit 30, a color demodulation circuit 31, an output signal of the circuit 24 and a color demodulation circuit 31.
An RGB matrix circuit 32 that outputs an RGB signal from the output signal of 1 and a synthesis circuit 33 that superimposes the synchronization signal SYNC output from the synchronization circuit 21 on the G signal output from the matrix circuit 32.

The NTSC signal has the characteristics as shown in FIG. 3, and by using a comb-shaped filter suitable for this characteristic, it is possible to leave a high-frequency luminance component. Also, since the color signals have an opposite phase relationship, they cancel each other out,
On the contrary, by using the subtraction circuit, only the in-phase luminance signal can be erased. The Y / C separation circuit 20 uses these relationships to separate the luminance signal Y and the color signal C.
The separated chrominance signal is controlled in amplitude variation of the burst signal by the ACC circuit 25, and its level is always kept constant. Then, the APC circuit 26 at the next stage is connected to the ACC circuit 25.
And the VCO circuit 27 whose level has become constant due to
The oscillation output of the VCO circuit 27 is controlled to control the oscillation operation of the VCO circuit 27. This VCO circuit 27 has 90
Two reference phase signals having a phase difference of 1 degree are output.
It should be noted that the dint control circuit 28 adjusts the hue by operating the phases of the color subcarrier and the burst.

On the other hand, the color control circuit 29 controls the amplitude of the color signal output from the ACC circuit 25, and adjusts the color density. The color killer circuit 30
Is provided in order to prevent the color control circuit 29 from malfunctioning and output unpleasant color noise when a black and white signal is input. It operates so as not to output a signal.

The color demodulation circuit 31 detects a color signal necessary for a CRT (picture tube) from the two reference phase signals output from the VCO circuit 27 and the color signal output from the color control circuit 29. The output of the color demodulation circuit 31 and the luminance signal output from the circuit 24 are input to the RGB matrix circuit 32, and the R matrix signal, G signal, and B signal are output from the RGB matrix circuit 32. In this embodiment, this R
Signal and B signal are directly input to the CRT display device 2,
A signal obtained by superimposing the synchronization signal SYNC signal on the G signal by the combining circuit 33 is input to the CRT display device 2.

As described above, it is possible to display an image by an NTSC signal on an auto-scan type display device which automatically follows the frequency of the horizontal synchronizing signal of the input signal and displays an appropriate image only by switching the screen size. It is no longer necessary to manufacture display devices separately for business use, government office use, education use, and home use, and the user side also uses various computers and VRs in one display device.
It becomes possible to connect T etc., which reduces facility costs and is advantageous in terms of space.

[0015]

According to the present invention, one display device can be applied to various kinds of computers having different synchronizing signal frequencies of video output signals, and can also be applied to video signals of NTSC signals. effective.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a display device according to an exemplary embodiment of the present invention.

FIG. 2 is a detailed configuration diagram of the NTSC signal / RGB signal converter shown in FIG.

FIG. 3 is a characteristic diagram of an NTSC signal.

[Explanation of symbols]

1 ... Display device, 2 ... Auto scan CRT
Display device, 3 ... NTSC signal / RGB signal converter, 4 ...
Receiving circuit, 5 ... Analog switch circuit, 6 ... Changeover switch, 7 ... NTSC signal input terminal, 8 ... RGB signal input terminal, 9 ... VTR, 10 ... Computer.

Claims (1)

[Claims] 1. An auto-scan type display device for automatically tracking the horizontal synchronizing signal frequency of an input RGB signal and displaying an image represented by the RGB signal on a screen.
An input terminal for the TSC signal, a conversion means for converting the NTSC signal into an RGB signal, and an R input from the RGB input terminal
A display device comprising: a switch unit for selecting and displaying on the screen one of a GB signal and an RGB signal output from the converting unit.