JPH11112892A - Black and white monitor device - Google Patents

Abstract

(57) [Problem] To monitor the color video from an external device by using a relatively simple method, to maintain the resolution of the video and prevent the influence of noise caused by the color signal. It is an object of the present invention to realize a black-and-white monitor device that can be manufactured and that is economical in terms of cost. SOLUTION: In a black and white monitor device for monitoring a color television signal from an external device as a black and white image,
The luminance signal component of the color television signal is input as a black and white video input signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitor device, and more particularly to an improvement in resolution in a black and white monitor device.

[0002]

2. Description of the Related Art In video surveillance in fields such as security and surveillance, a black-and-white camera and a black-and-white monitor are often used because the resolution is higher than that of a color video. However, most of the time-lapse VTRs handle color images, and the S-VHS type having a high resolution is often used.

Accordingly, the output from these VTRs is
A composite signal on which a color signal is superimposed (for example, NTS
C signal, etc.)
Since a composite signal including a color signal balanced-modulated by a subcarrier of about 3.58 MHz is processed as a luminance signal, the color signal becomes noise as it is, and the resolution is significantly reduced. For this reason, a black-and-white monitor or the like for video production is provided with a trap filter of a subcarrier frequency, and a color signal is removed on a circuit in the monitor to secure a resolution.

There is also a time-lapse VTR in which a signal from which a color signal has been removed in advance is produced and output on an internal circuit to ensure the resolution. There is a problem that a certain circuit scale is required and the cost is increased accordingly.

[0005] Here, the NTSC television video signal will be briefly described. The NTSC system is designed so that a color signal can be transmitted in as narrow a frequency band as possible by making full use of the visual characteristics of human colors.
In order to reproduce a color image, three elements of luminance (brightness), hue (hue), and saturation (color density) are required. In the NTSC system, a relatively large area on a screen has a large area. Sends all color information and sends only orange / cyan color components for medium areas. For a finer image portion, a luminance signal representing only the brightness is basically transmitted.

[0006] The video signal is a red CCD of a television camera,
The three primary color signals are extracted from the green CCD and the blue CCD, and a luminance signal (Y signal) representing brightness and two color difference signals are created by a calculation circuit called a matrix circuit. In the color difference signal, a signal representing an orange / cyan color component is represented by ER-EY, and a signal representing a magenta / green color component is represented by EB-EY.

The output level of each CCD is 30%, the output of the red CCD is 30%, and the output level of the green CCD is
Are synthesized by a matrix circuit so that the output of the blue CCD becomes 59% and the output of the blue CCD becomes 11%. That is, EY: a converted voltage value of a luminance signal ER: a converted voltage value of a red signal EG: a converted voltage value of a green signal EB: a converted voltage value of a blue signal, the luminance signal (EY) becomes EY = 0.3ER + 0. .59EG + 0.11EB. Therefore, when the screen is solid white, the size of EY = 1, and the size of EY represents the brightness.

[0008] The luminance signal thus produced has exactly the same structure as that of a black-and-white television signal, so that it can be received by a black-and-white television receiver.

Further, in the NTSC system, in order to save a frequency band, a method called a frequency interpolation method in which a color signal (color signal) is inserted into a luminance signal band and transmitted is adopted.

FIG. 6 shows a frequency spectrum distribution of the NTSC system into which a color signal is inserted. The band of the luminance signal has a band from DC to about 4.2 MHz, and the signal energy of the band is not uniformly distributed in the range from DC to 4.2 MHz. Are distributed around the harmonics, and there is a portion where no energy exists in a portion between the harmonics. By utilizing this, if a chrominance signal is inserted into the gap, it can be transmitted with less interference with the luminance signal.

When the carrier of the chrominance signal is determined so as to satisfy the above conditions, the carrier becomes an odd multiple of 1/2 of the horizontal scanning frequency, and the energy component of the chrominance signal is included between the energy components of the luminance signal. Can be synthesized without interference with This method is called a frequency interpolation method. The carrier modulated by the color signal used at this time is called a color subcarrier.

FIG. 7 shows an energy distribution in the frequency spectrum of a black and white television signal, and FIG.
The energy distribution in the frequency spectrum of the color system is shown.

The frequency of the chrominance subcarrier is 4.5
The frequency of the difference between 4.5 MHz and the chrominance subcarrier is also selected to be an odd multiple of 1/2 the horizontal scanning frequency. The value that satisfies these relationships and is closest to the horizontal scanning frequency fH of the monochrome receiver is 4.5 MHz / 286 = 15.734 kHz. From this, the vertical scanning frequency fV becomes fV × 525/2 = for interlaced scanning. From 15.734 kHz, fV = 15.734 kHz / 262.5 = 59.94H
z. Both fH and fV are fH = 1 for black and white TV receivers.
Since it is very close to 5.75 kHz and fV = 60 Hz,
No problem in practical use.

Thus, as can be seen from FIG. 8, the frequency of the color subcarrier is set to 455 times the half of the horizontal scanning frequency from the condition of frequency interpolation. Therefore, the frequency of the color subcarrier (color subcarrier: fsc) is fsc = 15.734 kHz × １ ／ × 455 = 3.57
9545 MHz, which is generally abbreviated or abbreviated to 3.58 MHz.

[0015]

As described above, if a composite signal of a color image is input as it is to a conventional black-and-white monitor, there is a problem that the resolution is significantly reduced, and the color signal is removed by a circuit in the monitor. In the method, there is a problem that a circuit is added correspondingly and the apparatus becomes expensive.

The present invention solves this problem by using a relatively simple method to monitor the color image from an external device while maintaining the image resolution and reducing the influence of noise caused by the color signal. It is an object of the present invention to realize a monochrome monitor which can be prevented and is economical in terms of cost.

[0017]

In order to achieve the above object, the present invention provides a black and white monitor device for monitoring a color television signal from an external device as a black and white image.
The luminance signal component of the color television signal is monitored as a black and white video input signal.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a monitor device according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration of the first exemplary embodiment of the present invention.
In FIG. 1, 1 is an S video output terminal, 2 is an S video input terminal, 3 is a luminance signal, 4 is a color signal, 5 is a video output circuit,
Reference numeral 11 denotes a monochrome CRT, 12 denotes a time lapse VTR, and 13 denotes a monochrome monitor. In this embodiment, the time lapse V
The signal from the S video output terminal 1 provided on the TR 12 is connected to the S video input terminal 2 provided on the monochrome monitor 13,
Only the luminance signal 3 is connected to the video output circuit 5 at the next stage inside the black-and-white monitor 13.
This is a monitor device in which the color signal 4 is removed.

In this way, the luminance signals 3 and the chrominance signals 4 are handled independently in the S video terminals 1 and 2, but the chrominance signals 4 are not used in the black and white monitor 13, so that there is no problem even if they are not connected. On the contrary, it is possible to secure the resolution. Further, since noise mixed in the color signal is also removed at the same time, stable image monitoring is possible. Further, in this embodiment, since there is no need to add a special circuit, an expected effect can be obtained without any cost.

Here, the S signal will be briefly described. S in the S signal is an abbreviation of “separate”, and indicates a state in which a luminance signal and a chrominance signal are separated. The S video terminal transfers the S signal. FIG. 2 shows the signal specifications of the S video terminal. As shown in the figure, a composite video signal (composite video signal, which is usually simply called a video signal) is composed of a synchronizing signal, a luminance signal, and a chrominance signal (a chrominance signal is transmitted to a subcarrier fsc of about 3.58 MHz). And the signals are balanced-modulated).

On the other hand, the S video terminal separates the composite signal of the synchronizing signal and the luminance signal and the chrominance signal and transmits them separately through two lines. As a result, mutual interference between the luminance signal and the chrominance signal can be eliminated, and there is an advantage that image quality degradation is minimized. Specifically, the flow of color signals in the vertical direction, dot crawl, cross color, and the like can be suppressed.

Usually, the most common method for separating a composite signal of a synchronizing signal and a luminance signal and a color signal from a composite video signal is to use a comb filter using a 1H delay line. That is, 3.58 MHz
The chrominance signal is separated by the band-pass filter of the subcarrier fsc, and the synchronizing signal and the luminance signal are separated by the band elimination filter of the subcarrier fsc of 3.58 MHz. The input and output specifications of the S video terminal are 75
At the Ω termination, the luminance + synchronization signal (Y signal) is 1Vp-p,
The color signal (C signal) has a burst level of 286 mV. This is similar to the case of a normal composite signal.

FIG. 3 shows a terminal arrangement of a mini DIN type connector generally used as an S video terminal.
In FIG. 3, 6 is an S video connector, 7 is a luminance signal pin, 8 is a color signal pin, 9 is a luminance signal ground, and 10 is a color signal ground.

FIG. 4 shows a wiring according to a second embodiment of the present invention, in which the same connection as that of the first embodiment is connected between such S-video connectors. This is realized by operating on the connection cable. In FIG. 4, the same numbers are assigned to those having the same functions as those in FIG. In this embodiment, among the luminance signal pins 7, the color signal pins 8, the luminance signal grounds 9, and the color signal grounds 10 of the S video connector 6, the wiring connection of the color signal pins 8 is not performed. In this case, there is no need to make special work on the monitor side, and a normal monitor can be used as it is.

FIG. 5 shows the wiring according to the third embodiment of the present invention. The same connection as that of the first embodiment is made between the S-video connector and the input terminal of the composite signal. This is realized by connection. In FIG. 5, the same functions as those in FIGS. 3 and 4 are designated by the same reference numerals. In this embodiment, the luminance signal pin 7 of the S video output connector 6 on the VTR side is connected to the composite signal input terminal 20 on the monitor side, and the luminance signal ground 9 and the chrominance signal ground 10 are connected to the ground terminal 21. The wiring connection of the color signal pin 8 is not performed. Also in this case, there is no need to make any special work on the monitor side, and a normal monitor having no S-video input connector can be used as it is.

[0026]

As described above, according to the first aspect of the present invention, in a black-and-white monitor apparatus for monitoring a color television signal from an external device as a black-and-white image, the luminance signal component of the color television signal is converted to a black-and-white image. It is characterized by comprising input means for inputting as an input signal. This makes it possible to monitor a color image from an external device in a simple manner while maintaining the resolution of the image and preventing the screen from being disturbed by the influence of noise caused by the color signal. It is possible to realize a black-and-white monitor device which is possible and economical in price.

According to a second aspect of the present invention, a luminance signal component is obtained from a Y signal pin of an S video output terminal of an external device. Accordingly, it is possible to perform monitoring that maintains the resolution and has little influence of noise due to the color signal without providing any special means.

According to a third aspect of the present invention, the input means is S
It has a video input terminal, and only the Y signal pin and the ground pin are connected between the S video input terminal and the S video output terminal of the external device. As a result, the color signal can be automatically removed without providing any special means, so that the resolution can be maintained and monitoring can be performed with less influence of noise caused by the color signal.

According to a fourth aspect of the present invention, the input means has a composite video input terminal, and the composite video input pin of the composite video input terminal is connected to the Y signal pin of the S video output terminal of the external device. It is characterized by. As a result, even with a monitor device having no S-video input terminal, it is possible to perform monitoring with stable black-and-white video having an excellent resolution without providing any special means.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of signal specifications of an S video terminal.

FIG. 3 is an explanatory diagram showing a terminal arrangement of a mini DIN type connector used as an S video terminal.

FIG. 4 is a block diagram showing a wiring according to another embodiment of the present invention.

FIG. 5 is a block diagram showing wiring according to still another embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a frequency spectrum distribution of the NTSC system into which a color signal is inserted.

FIG. 7 is an explanatory diagram showing an energy distribution in a frequency spectrum of a black and white television signal.

FIG. 8 is an explanatory diagram showing an energy distribution in a frequency spectrum of the NTSC color system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... S video output terminal, 2 ... S video input terminal, 3 ... luminance signal, 4 ... color signal, 5 ... video output circuit, 6 ... S video connector, 7 ... luminance signal pin, 8 ... color signal pin, 9 ... Luminance signal ground, 10: color signal ground 11, black and white CRT,
12: time-lapse VTR, 13: monochrome monitor, 20 ...
Composite signal input terminal, 21... Ground terminal.

Claims (4)

[Claims] 1. A black-and-white monitor device for monitoring a color television signal from an external device as a black-and-white image, comprising input means for inputting a luminance signal component of the color television signal as a black-and-white image input signal. Black and white monitor device. 2. The monochrome monitor device according to claim 1, wherein the luminance signal component is obtained from a Y signal pin of an S video output terminal of the external device. 3. The input means has an S video input terminal,
The monochrome monitor device according to claim 2, wherein only the Y signal pin and the ground pin are connected between the S video input terminal and the S video output terminal of the external device. 4. The input means has a composite video input terminal, and a composite video input pin of the composite video input terminal is connected to the Y signal pin of an S video output terminal of the external device. 3. The black-and-white monitor device according to 2.