JPH06141251A - Video signal detector - Google Patents

Abstract

PURPOSE:To reduce a cost, and to simplify a manufacturing process by, detecting a superimposed direct current voltage from an input signal outputted from a changeover switch part, and outputting it as additional video information. CONSTITUTION:A changeover switch part SW1 alternatively selects and outputs the input signal on which the direct current voltage of a prescribed level is superimposed from plural input parts SC1-SC4. At that time, a chrome signal switched at the switch part SW1 by the control signal of a control circuit 15 is outputted to a coupling capacitor C1 and a low pass filter F1. Then, direct current components are removed by the capacitor C1, and only the chroma signal is taken out. And also, the chroma signal is removed from the chroma signal outputted to the filter F1, and only the direct current components are outputted to the non-inversion input of a comparator A1. Then, the comparator A1 detects the presence or absence of the direct current voltage by using a comparison voltage from a power source part E1, and outputs it to the circuit 15 as the video addition information, and outputs it as an aspect rate identification signal A. Thus, the number of parts can be decreased, the cost can be reduced, and the manufacturing process can be simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal detecting device, and more particularly to a detecting device mounted on a monitor device or the like for detecting a video additional information signal superimposed on a chroma signal of S video.

[0002]

2. Description of the Related Art In recent years, with the realization of high-definition broadcasting, a device capable of displaying an image with an aspect ratio of 16: 9 even in a monitor device of a system of 525 scanning lines,
For example, with a built-in MUSE-NTSC converter, 16:
A monitor device having a so-called wide screen corresponding to the aspect ratio of 9 has become widespread. In such a monitor device, it is possible to display video sources having aspect ratios of both 16: 9 and conventional 4: 3.

Further, at present, in an S video signal in which a chroma signal and a luminance signal are separately transmitted, a DC voltage of 0V or 2.5 to 5V is superimposed on the chroma signal of this S video signal, and this is applied. It is known that the aspect ratios of 4: 3 and 16: 9 are associated with the aspect ratio to provide video additional information for identifying the aspect ratio.

Therefore, if a monitor device capable of displaying an image with an aspect ratio of 16: 9 and 4: 3 has a device for detecting the video additional information signal for identifying the aspect ratio, this information can be used. Based on the above, it is possible to automatically switch and control the aspect ratio of the S video displayed on the monitor device.

FIG. 3 is a block circuit diagram of a monitor device capable of controlling the switching of the aspect ratio of the S image. CI ₁ to CI ₄ shown in the figure are composite video input terminals, which are respectively connected to the composite video input changeover switch 1. SI _{1 to} SI ₄ are S-video input terminals, which are respectively connected to the S-video input changeover switch 2.
3 is a Y / C separation circuit that separates the composite video signal into a chroma signal (C signal shown in the figure) and a luminance signal (Y signal shown in the figure). 4 is an S video side or an input of the chroma signal and the luminance signal. It is a composite / S-video selector switch that switches to the composite video side.

Further, 5 is R from the chroma signal and the luminance signal,
Chroma decoder for obtaining G, B signals, 6 is an RGB amplifier for amplifying R, G, B signals and outputting to the CRT 12, 7 is a sync separation circuit for extracting vertical and horizontal sync signals from luminance signals, 8 is a vertical sync signal Vertical deflection circuit for obtaining a vertical deflection current from the horizontal deflection circuit, 9 a horizontal deflection circuit for obtaining a horizontal deflection current from a horizontal synchronizing signal, 10 a vertical deflection coil to which a vertical deflection current is supplied, 11 a horizontal deflection coil to which a horizontal deflection current is supplied Is.

Reference numeral 13 is an operation unit provided on the monitor device for the user to perform various operations such as input switching.
Reference numeral 14 is a light receiving portion of a remote control device (not shown), and both are connected to a control circuit 15 for performing various controls of the monitor device.

Information about a user's input switching operation is input from the operation unit 13 or the light receiving unit 14, and the control circuit 15 switches the composite video input switching switch 1 and the S video input switching switch 2 to display it on the screen. Select the video source. At this time, the aspect ratio identification signal A, which will be described later, is output from the S-video input changeover switch 2 to the control circuit 1520.

Then, the composite / S video selector switch 4 includes the composite video input selector switches 1 to Y.
The chroma signal and the luminance signal of the composite video signal via the A / C separation circuit 3 and the chroma signal and the luminance signal of the S video output from the S video input changeover switch 2 are input, respectively, and the input of the user is switched. Based on the information about the operation, the switch is switched by the control circuit 15 to select either the composite side or the S image side.

Next, the chroma signal and the luminance signal output from the composite / S video selector switch 4 are demodulated into R, G, B signals by the chroma decoder 5, amplified by the RGB amplifier 8 and then supplied to the CRT 12. Driven as an electron beam. And vertical and horizontal deflection coils 10, 11
An image is displayed on the screen by the vertical and horizontal deflection currents supplied to the.

By the way, the inside of the S image input changeover switch 2 is composed of a luminance signal output section for switching and outputting the inputted luminance signal and a chroma signal processing section, and further, this chroma signal processing section is inputted. It comprises a chroma signal output circuit that removes the superimposed DC voltage from the chroma signal and outputs only the chroma signal, and a DC voltage detection circuit that detects the DC voltage and outputs an aspect ratio identification signal.

FIG. 4 is a circuit diagram of a chroma signal processing unit in the S-video input changeover switch 2. The circuit unit surrounded by a broken line is a chroma signal output circuit, and the circuit unit surrounded by a one-dot chain line is a DC voltage detection. A circuit is shown, and each chroma signal from the chroma signal input terminals SC _{1 to} SC _{4 is} input to the chroma signal output circuit and the DC voltage detection circuit as shown in the figure.

In the chroma signal output circuit, coupling capacitors C _{11 to} C ₁₄ for blocking direct current, alternating current termination resistors R _{11 to} R ₁₄ for impedance matching of alternating current signals, and switches to output chroma signals. A chroma signal changeover switch SW ₁₁ is provided.

Further, the DC voltage detecting circuit has a low-pass filter F for removing high frequency components and extracting only DC components.
_{11 to} F ₁₄ , comparators A _{11 to} A ₁₄ that perform comparison processing on input signals, power supply units E _{11 to} E ₁₄ that supply a comparison voltage of a predetermined level to the comparators, and DC termination resistor R ₁₅ that performs impedance matching of DC voltage. R ₁₈ and an aspect ratio identification signal changeover switch SW ₁₂ for switching and outputting the aspect ratio identification signal. The chroma signal input terminals SC _{1 to} SC ₄ are the S video input terminals SI _{1 of} FIG.
～SI ₄ and corresponds, also, chroma signal changeover switch SW ₁₁ and the aspect ratio identification signal changeover switch SW
₁₂ is interlocked and switched by the control signal of the control circuit 15.

For example, when the user selects the video source connected to the S video input terminal SI ₁ by the operation unit 23 or the remote control device, the chroma signal changeover switch SW
The switch a of _{11 and} the switch b of the aspect ratio identification signal changeover switch SW ₁₂ are turned on by the control of the control circuit 15 and the chroma signal input to the chroma signal input terminal SC ₁ is processed. .

The DC signal superimposed on the DC signal output from the chroma signal input terminal SC ₁ to the chroma signal output circuit is removed through the coupling capacitor C ₁₁ , and the chroma signal changeover switch. SW
Only the chroma signal via ₁₁
It is output to the S-picture changeover switch 4.

On the other hand, the chroma signal input terminal SC ₁
The chroma signal superimposed on the DC voltage output from the DC voltage detection circuit to the DC voltage detection circuit is removed by passing through the low-pass filter F _11, and only the DC voltage is input to the non-inverting input of the comparator A _11. It is supposed to be done. The comparator A ₁₁ compares the voltage from the power supply section E ₁₁ supplied to the inverting input with the non-inverting input voltage to detect the presence or absence of the superimposed DC voltage, and uses this as an aspect ratio identification signal. The signal is output to the control circuit 15 via the ratio identification signal changeover switch SW ₁₂ .

Chroma signal input terminals SC _{2 to} SC ₄
The same signal path is used for processing the chroma signal output from the device to output the aspect ratio identification signal and the chroma signal from which the DC voltage has been removed, and the description thereof will be omitted.

By configuring the inside of the S-video input changeover switch 2 in this way, it becomes possible to automatically switch the aspect ratio of the S-video displayed on the screen. That is, FIG.
As shown in, the aspect ratio identification signal A output from the DC voltage detection circuit is output from the S-video input changeover switch 2 to the control circuit 15. According to this aspect ratio identification signal A, the control circuit 15 determines whether the aspect ratio of the S video to be displayed on the screen is 16: 9 or 4:
It is possible to determine whether it is 3.

Therefore, the control circuit 15 outputs the aspect ratio switching signal B corresponding to the determined aspect ratio to the vertical deflection circuit 8 and the horizontal deflection circuit 9. Then, in accordance with the aspect ratio switching signal B, the vertical deflection circuit 8 changes the synchronization timing of the vertical synchronization signal by a predetermined amount so that the vertical deflection current is changed so that the image display is performed at the aspect ratio of 16: 9 or 4: 3. Is generated. Also in the horizontal deflection circuit 9, the horizontal deflection current is generated by changing the synchronization timing of the horizontal synchronization signal by a predetermined amount according to the aspect ratio switching signal B in accordance with the aspect ratio for image display.

The vertical deflection current and the horizontal deflection current obtained as described above are supplied to the vertical deflection coil 10 and the horizontal deflection coil 11 to control the scanning of the electron beam of the CRT 12 to display 16 on the screen. : 9 or 4:
An image with an aspect ratio of 3 will be displayed.

As described above, by providing a chroma signal processing unit for detecting a DC voltage from the chroma signal in the monitor device or the like, if the aspect ratio identification signal is superimposed on the chroma signal of the S video signal, the S video source The monitor device can be configured to automatically switch the aspect ratio of the display on the screen.

[0023]

However, as shown in FIG. 4, the chroma signal processing unit has a circuit for chroma signal processing of a number corresponding to the input terminals of the chroma signal input terminals SC _{1 to} SC _4. It is provided. That is, one coupling signal, one AC terminating resistor, one low pass filter, one comparator, one power supply unit, and one DC terminating resistor are required for each chroma signal input terminal. This is because the chroma signal changeover switch SW ₁ that switches and outputs the chroma signal uses a switch that allows only the AC component to conduct.

Therefore, in a monitor device or the like having a large number of S video signal input terminals, it is necessary to prepare the above-mentioned components in the number corresponding to the number of inputs, which causes a problem in manufacturing cost. As a result, the manufacturing process is inevitably complicated.

[0025]

Therefore, in order to solve the above-mentioned problems, the present invention selectively selects the chroma signal of the S image on which the DC voltage of a predetermined level is superimposed from a plurality of input sections. Output from the changeover switch section, the chroma signal output section that extracts and outputs only the chroma signal component from the chroma signal on which the DC voltage output from the changeover switch section is superimposed, and the chroma output from the changeover switch section. The video signal detection device, which is configured by a DC voltage detection circuit that detects the presence or absence of the superimposed DC voltage from the signal and outputs the detected DC voltage as an aspect ratio identification signal, is configured as the chroma signal processing unit.

Further, the changeover switch section has a C-MO
It was decided to use an S switch or mechanical relay switch.

[0027]

In the video signal detecting device for detecting the aspect ratio identification signal from the chroma signal of the S video, the chroma signal on which the DC voltage outputted from the plurality of input terminals is superimposed is C
A chroma signal processing unit for performing processing such as detecting a voltage from a chroma signal and outputting an aspect ratio identification signal after switching through a switch capable of conducting both AC and DC such as a MOS switch or a mechanical relay switch. Since the chroma signal output unit, the DC voltage detection circuit, and the like can be shared by configuring the above, it is not necessary to provide components and the like related to these for each input terminal.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram showing an embodiment of a video signal detecting apparatus as a chroma signal processing section of the present invention. It is the second component.

SC ₁ to SC ₄ shown in the figure are chroma signal input terminals to which a chroma signal superimposed with a DC voltage for aspect ratio discrimination is inputted, and SW ₁ is a chroma signal input terminal S.
Changeover switch section for selectively changing and outputting the chroma signal on which the DC voltage from C _{1 to} SC ₄ is superimposed, C ₁ to
C ₅ is a coupling capacitor, F ₁ is a low-pass filter, A ₁ is a comparator, and E ₁ is a power supply section. Also,
R _{1 to} R ₄ are DC terminating resistors each having a resistance value of 100 kΩ, and R _{5 to} R ₈ are AC terminating resistors each having a resistance value of 75 Ω.

To each of the chroma signal input terminals SC _{1 to} SC ₄ , a chroma signal on which a DC voltage for identifying the aspect ratio is superimposed is input. Although the number of chroma signal input terminals is four in the present embodiment, it goes without saying that the number can be changed arbitrarily. In these input signals, the superimposed DC voltage components are impedance-matched by the DC termination resistors R _{1 to} R ₄ , respectively, and the chroma signal components, which are high-frequency signals, are coupled through the coupling capacitors C _{2 to} C ₅ . After that, impedance matching is performed by the AC terminating resistors R _{5 to} R ₈ , respectively, and then input to the changeover switch unit SW ₁ .

By the way, as the changeover switch unit SW ₁ , a C-MOS switch or a mechanical relay switch capable of conducting both AC and DC is used. As a result, the chroma signal, which is an AC signal component, can be passed through the changeover switch unit SW ₁ while the DC voltage is still superposed.

Therefore, the chroma signal switched by the control signal of the control circuit 15 by the changeover switch unit SW ₁ is output to the coupling capacitor C ₁ and the low pass filter F ₁ in the state where the DC voltage is superimposed. .

[0033] Although the DC voltage is superimposed on the chroma signal is output to the coupling capacitor C _1, the DC voltage is removed by through the coupling capacitor C _1. That is, only the chroma signal component is extracted by the coupling capacitor C ₁ . This chroma signal is sent from the S-video input selector switch 2 of FIG.
It will be output to the video selector switch 4.

On the other hand, the chroma signal output to the low-pass filter F ₁ is
_The chroma signal is removed by _{1 and} only the DC voltage component is output to the non-inverting input of the comparator A ₁ . In this comparator A ₁ , the power supply unit E ₁
The presence or absence of the DC voltage input to the non-inverting input is determined by using the comparison voltage supplied to the inverting input from the. Then, based on the result of this comparison process, the aspect ratio identification signal A corresponding to 16: 9 or 4: 3 is output from the comparator A ₁ to the control circuit 15.

By configuring the chroma signal processing unit as described above, the coupling capacitor C ₁ as the chroma signal output unit, the low-pass filter F ₁ as the DC voltage detection circuit, the comparator A ₁ , and the power supply unit E _{1 are provided.} It is not necessary to add these parts in accordance with the number of input terminals because the parts such as are common. Further, conventionally, two changeover switch parts were required for the chroma signal and the aspect ratio identification signal,
In this embodiment, the changeover switch unit SW ₁ is integrated.

FIG. 2 is a circuit diagram of a detection device as a chroma signal processing unit showing another embodiment. The same parts as those in FIG. As shown in the figure, a DC terminating resistor R ₉ and an AC terminating resistor R ₁₀ via a coupling capacitor C ₆ are connected to the output of the changeover switch unit SW ₁ , and the chroma signal input terminals SC _{1 to} SC ₄ and the changeover switch unit are connected. Even if SW ₁ is directly connected, the same effect as that of the embodiment of FIG. 1 can be obtained. In this case also, the DC termination resistance R
The resistance value of ₉ is 100 kΩ, and the resistance value of the AC terminating resistor R ₁₀ is 75 Ω.

[0037]

As described above, in the video signal detecting device of the present invention, the changeover switch section uses a switch capable of conducting both AC and DC, and the chroma signal superimposed with the DC voltage is
After the changeover switch section is used, the DC voltage is detected from the chroma signal and the aspect ratio identification signal is output, so that the parts and changeover switch related to these processes are made common. It became possible to. Therefore, even if the number of S video input terminals is increased, the number of parts can be suppressed to a necessary minimum, which is very advantageous in terms of reduction of manufacturing cost and simplification of manufacturing process.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a video signal detecting device according to the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the video signal detecting device according to the present invention.

FIG. 3 is a block circuit diagram of a monitor device in which the video signal detection device of this embodiment is mounted.

FIG. 4 is a circuit diagram showing a conventional video signal detection device.

[Explanation of symbols]

SW ₁ selector switch C ₁ Coupling capacitor F ₁ Low pass filter A ₁ Comparator E ₁ Power supply A Aspect ratio identification signal 2 S video input selector switch 4 Composite / S video selector switch 15 Control circuit

Claims (4)

[Claims] 1. A changeover switch section for selectively selecting and outputting an input signal from a plurality of input sections, on which a DC voltage of a predetermined level is superimposed, and the input signal output from the changeover switch section. Than,
An AC signal output unit that extracts and outputs an AC signal, and from the input signal output from the changeover switch unit,
A video signal detection device comprising: a DC voltage detection unit that detects the superimposed DC voltage and outputs the detected DC voltage as a video additional information signal. 2. The video signal detection device according to claim 1, wherein the input signal is a carrier color signal of an S video signal. 3. The image additional information signal is an aspect ratio identification signal, according to claim 1 or 2.
The video signal detection device described in 1. 4. The video signal detecting device according to claim 1, 2, or 3, wherein a C-MOS switch or a mechanical relay switch is used for the changeover switch section.