JP2002320243A - Video signal processing device - Google Patents

Abstract

(57) [Problem] To provide an easy-to-handle video signal processing device that automatically determines the type of an input signal, performs appropriate signal processing, and outputs the processed signal. SOLUTION: In a video signal processing device which inputs an RGB video signal or a component video signal composed of a luminance signal and a color difference signal as an input signal S1 and performs video signal processing corresponding to the input signal, the input signal S1 is a pedestal level. By determining whether it can always be at a high level or a low level compared to
A video signal discriminating means 2 for discriminating between a GB video signal and a component video signal, and a switching circuit 3 as a processing circuit selecting means for selecting a video signal processing circuit based on the discrimination result of the video signal discriminating means are provided. The video signal is automatically determined and output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention automatically recognizes the type of an input signal when switching and inputting an RGB video signal or a component video signal composed of a luminance signal and a color difference signal, and performs appropriate signal processing. The present invention relates to a video signal processing device for displaying an image.

[0002]

2. Description of the Related Art FIG. 14 shows a conventional video signal output from a video signal processing device which inputs a RGB video signal or a component video signal composed of a luminance signal and a color difference signal and performs appropriate signal processing in accordance with the input signal. It is a principal part block diagram of a display apparatus, such as a liquid crystal projector, which displays a signal. An RGB video signal composed of three primary colors of R (red), G (green) and B (blue) outputted from a personal computer or the like, or a luminance signal (Y) outputted from a BS tuner or the like and two color difference signals Cr (R-
Y) and a component video signal composed of Cb (BY) (in this case, a component video signal composed of a luminance signal and a chrominance signal may be simply referred to as a component video signal) as an input signal S1 and correspond to each of them. The processed signal is processed and displayed on the display unit 7. The input video signal S1 therefore consists of three signals, usually R and Cr,
G and Y, and B and Cb are input using the same signal line.
When the input signal S1 is a component video signal composed of a luminance signal and a color difference signal, these are converted into RGB signals by the matrix circuit 1. Then, the switching circuit 3 switches the output signal of the matrix circuit 1 and outputs the input signal S1 as it is for an RGB signal, and switches the output signal of the matrix circuit 1 for a component signal. In either case, the video signal from the switching circuit 3 that becomes an RGB signal is DC-reproduced by clamping the pedestal level to a predetermined potential by the clamp circuit 4, and is digitized by the A / D conversion circuit 5.
The digitized video signal is supplied to a video signal processing circuit 6.
Then, after performing video signal processing such as gamma correction and resolution correction in accordance with the display characteristics of the display unit 7, an image is displayed on the display unit 7.

However, in such a conventional example, the switching circuit 3 must be switched according to whether the input signal S1 is an RGB signal or a component signal.
Must be input externally or set externally. However, generally, such identification signals are not generated from a video signal source such as a personal computer or a tuner. When a switching device for these signal sources is provided outside, the switching signal of the switching device is determined. It had to be input as signal S2. Further, when there is no external switch and the input signal S1 is directly replaced, it is necessary to provide a switch or the like for setting the discrimination signal S2, and the operator needs to judge and set the type of the signal. There was a problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and automatically determines whether an input signal is switched to an RGB video signal or a component signal including a luminance signal and a color difference signal. It is an object of the present invention to provide a video signal processing device which performs appropriate signal processing and outputs the video signal, which is easy to handle.

[0005]

A video signal processing apparatus which receives a RGB video signal or a component video signal composed of a luminance signal and a color difference signal, performs video signal processing corresponding to the RGB video signal or the component video signal, and outputs the processed video signal. A video signal determining means for determining whether the RGB video signal or the component video signal by determining whether the input signal is always at a high level or a low level as compared with the pedestal level;
A processing circuit selecting means for selecting a video signal processing circuit based on a result of the determination by the video signal determining means is provided, so that a more appropriate video signal processing is performed on the input video signal for display.

[0006] The video signal discriminating means includes an input signal switching detecting means for detecting when an input signal is switched, a clamp circuit for clamping the input signal at a pedestal level, and the clamp level being set at a substantially central value of a dynamic range. An A / D conversion circuit; and a color difference signal detection means for receiving an output signal of the A / D conversion circuit when the input signal is switched, detecting and holding a signal having a level lower than the clamp level, and If no signal is detected, RGB
Processing is performed assuming that a video signal has been input.

The video signal processing device includes a matrix circuit that receives the component video signal and outputs an RGB video signal, and outputs the RGB video signal when the input signal is the RGB video signal, and outputs the RGB video signal when the input signal is the component signal. A switching circuit as the processing circuit selecting means for switching and outputting the RGB video signals output from the matrix circuit, a clamp circuit for performing DC reproduction of the output from the switching circuit, and digitizing the clamped video signal An A / D conversion circuit is built-in, the video signal is digitized, video signal processing is performed, and the video signal is output. The video signal discriminating means includes an input signal switching detecting means for detecting when an input signal is switched. At the time of switching, the clamp level is set to be approximately the center value of the dynamic range of the A / D conversion circuit and switched. Comprising a clamp level conversion circuit for substantially minimum level in the outside, the video signal discrimination means A / D
The conversion circuit also serves as an A / D conversion circuit for digitizing the output video signal.

The color difference signal detection means compares the output of the A / D conversion circuit with the clamp level, and outputs a signal when the output of the A / D conversion circuit is lower than the clamp level. It consists of a latch circuit that clears at the leading edge of time and holds the output of the comparator.

The color difference signal detection means receives the output of the A / D conversion circuit and a signal indicating the time of the switching, and outputs a determination signal when the output of the A / D conversion circuit lower than the clamp level is detected at the time of the switching. Is output from the MPU.

The video signal discriminating means includes an input signal switching detecting means for detecting when an input signal is switched, a clamp circuit for clamping the input signal at a pedestal level, and a clamp level for setting a level slightly lower than the clamp level. A color difference signal including a setting circuit, a comparator that outputs when the clamped input signal is lower than the output of the clamp level setting circuit, and a latch circuit that clears at the leading edge during the switching and holds the output of the comparator It consists of detection means.

The color difference signal detecting means detects a discrimination signal by using one of the two color difference signals.

The color difference signal detecting means detects both of the two color difference signals and determines the discrimination signal by the logical sum of the outputs.

The input signal switching detecting means includes an input frequency detecting means for detecting a frequency of a horizontal synchronizing signal or a vertical synchronizing signal of the input signal, a storing means for holding the detected frequency for a certain period, Comparing means for comparing the frequencies of the input signals and outputting a switching signal when the frequencies are different is provided, and a time when the frequency of the input signal changes is defined as an input signal switching time.

The input frequency detecting means is a counter for inputting a horizontal synchronizing signal or a vertical synchronizing signal of an input signal to be detected and resetting the input signal with a pulse having a frequency lower than that of the synchronizing signal. The latch circuit is a holding circuit, and the comparing means is a comparator that compares the output of the counter with the output of the latch circuit.

The input signal switching detecting means includes an input frequency detecting means for inputting a horizontal synchronizing signal or a vertical synchronizing signal of the input signal to be detected and counting for a predetermined period, a storing means for holding the counted value, The MPU is provided with a comparing means for comparing the value with the new count value.

The input signal switching detecting means includes a synchronizing signal interruption detecting means for detecting that the horizontal synchronizing signal or the vertical synchronizing signal of the input signal is interrupted for a predetermined time or more, and detects when the synchronizing signal of the input signal is interrupted. Assume that the signal is switched.

The synchronizing signal interruption detecting means is a retriggerable monostable multivibrator that outputs a predetermined time by triggering with a horizontal synchronizing signal or a vertical synchronizing signal of an input signal to be detected.

The synchronization signal interruption detecting means includes a timer for measuring and outputting a predetermined time, and an MPU for receiving the output of the timer and the horizontal synchronization signal or the vertical synchronization signal and resetting the timer with the synchronization signal. And the interruption of the synchronization signal is detected by detecting the output from the timer in the same MPU.

The frequency of the horizontal synchronizing signal or the vertical synchronizing signal of the input signal is constant when the input signal is an RGB video signal or a component signal composed of a luminance signal and a color difference signal. The determination unit is an input frequency detection unit that detects the frequency of the horizontal synchronization signal or the vertical synchronization signal of the input signal, a frequency setting unit that sets a predetermined frequency, and compares the set frequency with the frequency of the input signal. A comparison means for outputting a switching signal at the same time is provided, and when the frequency of the input signal becomes a predetermined frequency, it is determined that the input signal is an RGB video signal or a component signal.

The input frequency detecting means is a counter for receiving a horizontal synchronizing signal or a vertical synchronizing signal of the input signal and resetting the input signal with a pulse having a lower frequency than the synchronizing signal. , And the comparison circuit comprises a comparator for comparing the value set in the dip switch with the output of the counter.

The input signal discriminating means includes an input frequency detecting means for inputting a horizontal synchronizing signal or a vertical synchronizing signal of an input signal to be detected and counting for a predetermined period, a storage means for holding a predetermined frequency value, It comprises an MPU provided with a comparing means for comparing the value with the output value of the counter.

The video signal processing device is provided with a mute function for setting a video signal output when the input video signal is switched to a black level, and a mute function for setting the output video signal to a black level when the input video signal is switched. ing.

The mute function comprises a multiplexer for switching between an input video signal and a black level signal with a signal indicating when the input signal is switched and outputting the signal.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a main block diagram of a video signal processing device according to an embodiment of the present invention. As described in the conventional example, for example, an RGB video signal composed of three primary colors of R (red), G (green), and B (blue) outputted from a personal computer or the like, or a luminance signal (Y) outputted from a BS tuner or the like. Color difference signals Cr (RY), Cb (B
-Y) to the input signal S1.
And performs signal processing corresponding to each of them to drive the display unit 7 and project and display it on a screen using an optical system (the optical system and the screen are not shown). The input video signal S1 therefore consists of three signals, usually R and Cr,
G and Y, and B and Cb are input using the same signal line.
When the input signal S1 is a component video signal composed of a luminance signal and a color difference signal, these are converted into RGB signals by the matrix circuit 1. Then, the switching circuit 3 is controlled by a discrimination signal S2 indicating whether the signal is an RGB signal or a component signal. When the signal is an RGB signal, the input signal S1 is switched as it is. RGB in both cases
A video signal from the switching circuit 3 serving as a signal is DC-reproduced by clamping a pedestal level to a predetermined potential by a clamp circuit 4, and is digitized by an A / D conversion circuit 5. The digitized video signal is subjected to video signal processing such as gamma correction and resolution correction in accordance with the display characteristics of the display unit 7 by the video signal processing circuit 6, and then the video is displayed on the display unit 7.

The discrimination signal S2 indicating whether the signal is an RGB signal or a component signal is obtained by using one or both of signal lines to which a color difference signal is input, that is, R and Cr or B and Cb signal lines, of the input signal S1. Video signal discriminating means for discriminating between the RGB video signal and the component video signal by determining whether these signals are always at a high level or possibly at a low level as compared with a pedestal level 2 obtained. By switching the switching circuit 3 as a processing circuit selecting means for selecting a video signal processing circuit based on the discrimination signal S2 obtained from the video signal discriminating means 2, a more appropriate video signal processing circuit is selected depending on the input video signal. be able to.

FIG. 2 is a block diagram of a main part of a video signal discriminating section showing an embodiment of a video signal processing device according to the present invention. The above-mentioned video signal discriminating means 2 (FIG. 1) is provided with an input signal switching detecting means 27 for detecting when an input signal is switched.
A clamp circuit 21 for clamping the input signal S1 at a pedestal level, an A / D conversion circuit 22 for setting the clamp level to substantially the center value of the dynamic range, and an output of the A / D conversion circuit 22 when the input signal is switched. A color difference signal detecting means for receiving a signal and detecting and holding a signal having a level lower than the clamp level. FIG.
(A) is a conceptual diagram showing a signal level when the input signal S1 is any of the RGB signals, and the RGB signal is always at a level higher than the pedestal level CL. FIG. 3 (B)
Is a conceptual diagram showing a signal level when the input signal S1 is the color difference signal Cr or Cb.
May be higher or lower than the pedestal level CL. Therefore, R / Cr
If the signal or the B / Cb signal may be lower than the pedestal level, it is determined that the input signal is a component signal.

In FIG. 2, the R / Cr signal is
1 and its pedestal level CL is
The clamp is performed in accordance with substantially the center CT of the dynamic range of the A / D conversion circuit 22 shown in FIG. The clamp is
According to the related art, the synchronization signal superimposed on the G / Y signal is separated by the synchronization signal separation circuit 26, and the separation is performed by a clamp pulse generated using the horizontal synchronization signal in the synchronization signal S3. The clamped R / Cr signal is digitized by an A / D conversion circuit 22 and used as one input of a comparator 24. The other input of the comparator 24 receives, for example, a clamp level set in the DIP switch 23. The R / Cr signal from the comparator 24, which is lower than the clamp level, is latched by a latch circuit 25 as color difference signal detecting means. The latch circuit 25 resets at the leading edge of the switching time signal S4 indicating the switching time of the input signal S1 detected by the input signal switching detection means 27 from the change of the synchronization frequency or the like. Thereby, the input signal S1 is output from the latch circuit 25.
Is 0 when the signal is an RGB signal, and 1 when the signal is a component signal.

FIG. 4 is a main block diagram of a video signal processing apparatus according to another embodiment of the present invention. The same functional portions as those described above are denoted by the same reference numerals and description thereof is partially omitted. The switching circuit 3 is switched by the discrimination signal S2. When the input signal S1 is a component signal, the matrix circuit 1 performs DC reproduction as an RGB signal by the clamp circuit 4, digitizes the signal by the A / D conversion circuit 5, and converts the image signal into a video signal. In step 6, the display unit 7 is driven after the video signal processing.
The video signal discriminating means 2 (FIG. 1) is provided with an input signal switching detecting means 27 for detecting when the input signal is switched, and when the switching is performed, the clamp level is set to substantially the center value of the dynamic range of the A / D conversion circuit. In addition to the above, a clamp level conversion circuit 41 for setting the level to the lowest level is provided, and the A / D conversion circuit 22 of the video signal discriminating means 2 and the A / D conversion circuit 5 for digitizing the video signal to be displayed are also used. Note that the latch circuit 25 is cleared at the leading edge of the switching signal, and a signal that does not pass through the matrix circuit 1 during signal discrimination is A / D.
It is input to the conversion circuit 5. Further, the clamp level conversion circuit 41 can be realized by a conventional technique such as switching the power supply voltage of a switching circuit for generating a clamp pulse by a switching signal.

FIG. 5 is a block diagram of a main part of a video signal discriminating means of a video signal processing device according to another embodiment of the present invention. The same functional portions as those described above are denoted by the same reference numerals and description thereof will be omitted. In this example, the MPU 54 is used as the color difference signal detecting means. MPU
At 54, the output of the A / D conversion circuit 22 and the switching detection means 2
7, a switching signal representing the time of switching is input, and A / A is lower than the clamp level LC stored in the memory 53 or the like at the time of switching.
When the output of the D conversion circuit is detected, a determination signal S2 is output.

FIG. 6 is a block diagram of a main part of a video signal discriminating means of a video signal processing device according to another embodiment of the present invention. The same functional portions as those described above are denoted by the same reference numerals and description thereof will be omitted. R / Cr of input signal S1
Signals or B / Cb signals to the clamp circuits 61a, 61b
To clamp the pedestal level to a predetermined voltage. The clamped input signal is supplied to a comparator 62a,
At 62b, 1 (true) is output when the voltage is lower than the output of the clamp level setting circuit 65 that generates a voltage slightly lower than the clamp level formed by a voltage dividing resistor, a voltage follower, etc. in consideration of noise and the like. Comparators 62a, 6
The output of 2b is latched by latch circuits 63a and 63b that clear the output at the leading edge of the switching signal. Latch circuits 63a, 63
The output of b is ORed by the OR circuit 64, and a determination signal S2 that is 0 for an RGB signal and 1 for a component signal is output. In this color difference signal detecting means, 2
Although both of the two color difference signals Cr and Cb are detected and the discrimination signal is obtained by the logical sum of the outputs, it is also possible to detect the discrimination signal by using one of the two color difference signals Cr or Cb. In this case, the clamp circuit, comparator,
The number of latch circuits is one, and the OR circuit is not required, which simplifies the configuration. On the other hand, the color difference signals Cr, C
When the discrimination signal is detected from both of them, the detection accuracy is increased.

FIG. 7 is a schematic block diagram of an input signal switching detection means of a video signal processing device according to another embodiment of the present invention. The input signal switching detection means 27 (FIG. 2) includes an input frequency detection means for detecting the frequency of a synchronization signal S3 comprising a horizontal synchronization signal or a vertical synchronization signal of the input signal S1, a storage means for holding the detected frequency for a certain period, and A comparison means for comparing the held frequency with the frequency of the synchronizing signal S3 and outputting a switching signal when the frequency is different is provided, and the time when the frequency of the synchronizing signal S3 changes is regarded as the input signal switching time. As the input frequency detecting means, the input signal S1
The counter 71 receives a synchronization signal S3 composed of a horizontal synchronization signal or a vertical synchronization signal separated by the synchronization signal separation circuit 26 (FIG. 2) as a clock, and resets with a pulse having a frequency lower than the clock frequency. When the clock is a horizontal synchronizing signal, a pulse having a lower frequency than the clock frequency can use a vertical synchronizing signal. Or,
An oscillator 72 that oscillates a pulse having a frequency lower than the clock frequency is provided, and the output is reset. Counter 7
The output of 1 is held at a timing immediately before the reset of the counter 71 by a latch circuit 73 as storage means of the count frequency. The output of the latch circuit 73 and the output of the counter 71 are compared by a comparator 74 as comparing means, and when they are different, a switching time signal S4 is output.

FIG. 8 is a schematic block diagram of an input signal switching detecting means of a video signal processing device according to another embodiment of the present invention. Synchronization signal separation circuit 2 from input signal S1
6 (FIG. 2), the synchronization signal S3 composed of the horizontal synchronization signal or the vertical synchronization signal is taken into the MPU 81, counted by the count processing unit 82a for a predetermined period, and synchronized.
The frequency of No. 3 is calculated and stored in the frequency storage processing unit 82b. When the comparison processing unit 82c compares the frequency of the synchronization signal S3 newly counted by the count processing unit 82a with the frequency stored in the frequency storage processing unit 82b and differs, it is determined that the input signal S1 has switched, and the switching time signal S4 Is output.

FIG. 9 is a schematic block diagram of an input signal switching detecting means of a video signal processing device according to another embodiment of the present invention. A retriggerable monostable multivibrator 91 which outputs a predetermined time by inputting, as a trigger, a synchronization signal S3 composed of a horizontal synchronization signal or a vertical synchronization signal of the input signal S1 as an input signal switching detection means.
Is provided. Retriggerable monostable multivibrator 91
Is reset when the trigger is interrupted for a predetermined period or more. Therefore, it can be detected from the negative output that the synchronization signal S3 of the input signal S1 has been interrupted for a predetermined time or more. Therefore, when the synchronization signal of the input signal S1 is interrupted for a predetermined time or more, it is determined that the input signal has been switched, and the negative output of the retriggerable monostable multivibrator 91 is output as the switching time signal S4.

FIG. 10 is a schematic block diagram of an input signal switching detecting means of a video signal processing apparatus according to another embodiment of the present invention. In this case, the synchronization signal interruption detecting means includes a timer 10 for measuring and outputting a predetermined time.
2 and an MPU 101 which inputs a synchronization signal S3 comprising a horizontal synchronization signal or a vertical synchronization signal of the input signal S1 and resets the timer 102 by the input. When the switching signal processing unit 103 receives the time-up signal of the timer 102, the switching signal S4 is output from the MPU 101 on the assumption that the synchronization signal S3 has been interrupted for a predetermined time or more.

FIG. 11 is a block diagram of a main part of a video signal discriminating means of a video signal processing device according to another embodiment of the present invention. The frequency of the synchronizing signal S3 composed of the horizontal synchronizing signal or the vertical synchronizing signal of the input signal S1 often becomes constant when the input signal S1 is an RGB video signal or a component signal composed of a luminance signal and a color difference signal. (For example, when one signal is one type). In this case, the input signal discriminating means includes an input frequency detecting means for detecting a frequency of a synchronizing signal S3 comprising a horizontal synchronizing signal or a vertical synchronizing signal of the input signal S1, and a frequency setting means for setting a predetermined frequency. The frequency of the synchronization signal S3 is compared with the frequency of the input signal S3, and when they are the same, an input signal S1 of that frequency, for example, an RGB signal is input, and the determination signal S2 is output. As the input frequency detecting means, a counter 111 for inputting a synchronization signal S3 of the input signal S1 as a clock and resetting with a pulse having a lower frequency than the clock and an oscillator 112 for transmitting the reset pulse can be used. When the clock of the counter 111 is a horizontal synchronizing signal, the vertical synchronizing signal can be used as a reset pulse, and the oscillator 112 becomes unnecessary. As the frequency setting means, a dip switch 113 for setting a predetermined frequency value can be used, and for the comparison circuit, a comparator 114 for comparing the value set in the dip switch 113 with the output of the counter 111 can be used.

FIG. 12 is a block diagram of a main part of a video signal discriminating means of a video signal processing device according to another embodiment of the present invention. The synchronization signal S3 of the input signal S1 is input to the MPU 121, and the frequency is counted by the count processing unit 122a. The comparison processing unit 122b determines whether or not the count value matches a predetermined frequency stored in the frequency storage unit 122c in advance. If the count value matches, a video signal having that frequency, for example, an RGB video signal is input. It is determined that the signal S1 has been input, and the determination signal S
2 is output.

FIG. 13 is a block diagram of a main part of a video signal processing apparatus according to another embodiment of the present invention.
The same functional portions as those described above are denoted by the same reference numerals and description thereof will be omitted. When the input signal S1 of the video signal processing device is switched, noise is generally generated on the screen in many cases. In particular, when the A / D conversion circuit for the display signal is also used as the video signal discriminating means, the black level floats when the signal is switched. Therefore, a mute function is provided for setting the video signal displayed when the input video signal is switched to a black level, and the display screen on the screen is set to a black screen when the input video signal is switched. The mute function includes a multiplexer that switches between the input video signal S1 and the black level signal with an input switching signal and outputs the signal. Specifically, the output of the A / D conversion circuit 5 and the set value from the dip switch 132 for setting the black level are input to the multiplexer 131, and are switched by the switching signal S4, and the black level is switched when the input signal S1 is switched. Otherwise, the output from the A / D conversion circuit 5 is sent to the processing circuit 6.

The video processing apparatus according to the present invention is a PDP, LC
It can be applied to a display device using a D, CRT, or the like.

[0039]

As described above, a video signal processing apparatus which receives a RGB video signal or a component video signal composed of a luminance signal and a color difference signal and performs video signal processing corresponding to the RGB video signal or the component video signal. A video signal discriminating means for discriminating between the RGB video signal and the component video signal by determining whether an input signal is always at a high level or a low level as compared with a pedestal level, By providing a processing circuit selection means for selecting a video signal processing circuit according to the determination result of the video signal determination means,
This makes it possible to automatically recognize the type of the input signal and perform appropriate video signal processing.

[Brief description of the drawings]

FIG. 1 is a main block diagram of a video signal processing device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a main part of a video signal discriminating unit showing an embodiment of a video signal processing device according to the present invention.

FIG. 3A is a conceptual diagram illustrating a signal level when the input signal S1 is one of RGB signals, and FIG. 3B is a conceptual diagram illustrating a signal level when the input signal S1 is a color difference signal Cr or Cb. FIG. 3C is a conceptual diagram illustrating a dynamic range of the A / D conversion circuit 22.

FIG. 4 is a main block diagram of a video signal processing device according to another embodiment of the present invention.

FIG. 5 is a block diagram of a main part of a video signal discriminating means of a video signal processing device according to still another embodiment of the present invention.

FIG. 6 is a main block diagram of a video signal discriminating unit of a video signal processing device according to another embodiment of the present invention.

FIG. 7 is a schematic block diagram of an input signal switching detection means of a video signal processing device according to another embodiment of the present invention.

FIG. 8 is a schematic block diagram of an input signal switching detection means of a video signal processing device according to another embodiment of the present invention.

FIG. 9 is a schematic block diagram of an input signal switching detection unit of a video signal processing device according to another embodiment of the present invention.

FIG. 10 is a schematic block diagram of input signal switching detection means of a video signal processing device according to another embodiment of the present invention.

FIG. 11 is a main block diagram of a video signal discriminating means of a video signal processing device according to still another embodiment of the present invention.

FIG. 12 is a main part block diagram of a video signal discriminating means of a video signal processing device according to still another embodiment of the present invention.

FIG. 13 is a main block diagram of a video signal processing device according to another embodiment of the present invention.

FIG. 14 is a block diagram of a main part of a conventional display device which inputs and displays a component video signal composed of an RGB video signal or a luminance signal and a color difference signal.

[Explanation of symbols]

 S1 input signal S2 determination signal S3 synchronization signal S4 switching signal 1 matrix circuit 2 video signal determination means 3 switching circuit 4 clamp circuit 5 A / D conversion circuit 6 video signal processing circuit 7 display unit 21 clamp circuit 22 A / D conversion circuit Reference Signs List 23 DIP switch 24 Comparator 25 Latch circuit 26 Synchronous signal separation circuit 27 Input signal switching detection means 41 Clamp level conversion circuit 53 Memory 54 MPU 61a, 61b Clamp circuit 62a, 62b Comparator 63a, 63b Latch circuit 64 OR circuit 65 Clamp level setting Circuit 71 Counter 72 Oscillator 73 Latch circuit 74 Comparator 81 MPU 82a Count processing unit 82b Frequency storage unit 82c Comparison processing unit 91 Retriggerable monostable multivibrator 101 MPU 1 2 timer 103 changeover signal processing unit 111 the counter 112 oscillator 113 dip switch 114 comparator 121 MPU 122a counting section 122b comparison processing section 122c frequency storage unit 131 multiplexer 132 dip switch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/04 G09G 5/00 520W

Claims (19)

[Claims] An RGB video signal or a component video signal composed of a luminance signal and a color difference signal is input, and the RGB video signal is input.
In a video signal processing device that performs video signal processing corresponding to a video signal or a component video signal, by determining whether an input signal is always at a high level or a low level as compared with a pedestal level, A video signal discriminating means for discriminating between an RGB video signal and a component video signal, and a processing circuit selecting means for selecting a video signal processing circuit based on the discrimination result of the video signal discriminating means are provided. A video signal processing device for performing video signal processing. 2. The image signal discriminating means includes: an input signal switching detecting means for detecting when an input signal is switched; a clamp circuit for clamping the input signal at a pedestal level; An A / D conversion circuit, and a color difference signal detection means for inputting an output signal of the A / D conversion circuit when switching an input signal, detecting a signal having a level lower than the clamp level, and outputting a determination signal. 2. The method according to claim 1, wherein
2. The video signal processing device according to 1. 3. A video signal processing apparatus comprising: a matrix circuit for inputting the component video signal and outputting an RGB video signal; and outputting the RGB video signal when the input signal is the RGB video signal; A switching circuit as the processing circuit selecting means for switching and outputting the RGB video signals output from the matrix circuit, a clamp circuit for performing DC reproduction of the output from the switching circuit, and digitizing the clamped video signal A / D conversion circuit for converting the video signal into a digital signal and performing video signal processing, wherein the video signal discriminating means includes an input signal switching detecting means for detecting when the input signal is switched, Sometimes, the clamp level is set to approximately the center value of the dynamic range of the A / D conversion circuit, except when switching. 3. The apparatus according to claim 2, further comprising a clamp level conversion circuit for setting the level substantially to the lowest level, wherein the A / D conversion circuit of the video signal discrimination means and the A / D conversion circuit for digitizing the video signal to be displayed are used. Video signal processing device. 4. The color difference signal detecting means compares the output of the A / D conversion circuit with the clamp level and outputs the A / D signal.
4. The circuit according to claim 2, further comprising a comparator that outputs when the output of the D conversion circuit is lower than the clamp level, and a latch circuit that clears the leading edge during the switching and holds the output of the comparator. 2. The video signal processing device according to 1. 5. The color difference signal detection means receives an output of the A / D conversion circuit and a switching time signal indicating the time of switching and detects an output of the A / D conversion circuit lower than the clamp level at the time of switching. 4. The video signal processing device according to claim 2, wherein the video signal processing device comprises an MPU that outputs a discrimination signal when necessary. 6. The video signal discriminating means includes an input signal switching detecting means for detecting when an input signal is switched, a clamp circuit for clamping the input signal at a pedestal level, and setting a level slightly lower than the clamp level. It comprises a clamp level setting circuit, a comparator that outputs when the clamped input signal is lower than the output of the clamp level setting circuit, and a latch circuit that clears at the leading edge during switching and holds the output of the comparator. 2. The video signal processing apparatus according to claim 1, comprising a color difference signal detection unit. 7. The color difference signal detection unit according to claim 2, wherein the color difference signal detection unit detects a color difference signal using one of two color difference signals. The video signal processing device according to claim 6. 8. The color difference signal detecting means according to claim 2, wherein said color difference signal detecting means detects both of the two color difference signals and generates a color difference signal by a logical sum of the outputs. The video signal processing device according to claim 5 or 6. 9. The input signal switching detection means includes: an input frequency detection means for detecting a frequency of a horizontal synchronization signal or a vertical synchronization signal of an input signal; a storage means for holding the detected frequency for a predetermined period; And comparing means for comparing the frequency of the input signal and outputting a switching signal when the frequency of the input signal is different, wherein a time when the frequency of the input signal changes is regarded as a switching time of the input signal. The video signal processing device according to claim 3 or claim 6. 10. The input frequency detecting means is a counter which inputs a horizontal synchronizing signal or a vertical synchronizing signal of an input signal to be detected as a clock and resets it with a pulse having a lower frequency than the synchronizing signal. 10. The video signal processing device according to claim 9, wherein the latch circuit holds an output, and the comparing means is a comparator that compares the output of the counter with the output of the latch circuit. 11. The input signal switching detecting means, comprising: an input frequency detecting means for inputting a horizontal synchronizing signal or a vertical synchronizing signal of an input signal to be detected and counting for a predetermined period; a storing means for holding the counted value; Provided with comparing means for comparing the set count value with the new count value
10. The video signal processing device according to claim 9, comprising a PU. 12. A synchronizing signal interruption detecting means for detecting that a horizontal synchronizing signal or a vertical synchronizing signal of an input signal is interrupted for a predetermined time or more as said input signal switching detecting means. 7. The video signal processing device according to claim 2, wherein input signal switching is performed. 13. A retriggerable monostable multivibrator for outputting a predetermined time by triggering the synchronization signal interruption detecting means with a horizontal synchronization signal or a vertical synchronization signal of an input signal to be detected.
2. The video signal processing device according to 1. 14. The synchronization signal interruption detection means, a timer for measuring and outputting a predetermined time, and receiving the output of the timer and the horizontal synchronization signal or the vertical synchronization signal and resetting the timer by the synchronization signal. 13. The video signal processing device according to claim 12, wherein the video signal processing device comprises an MPU for detecting interruption of the synchronization signal by detecting an output from a timer. 15. The frequency of a horizontal synchronizing signal or a vertical synchronizing signal of the input signal is constant when the input signal is an RGB video signal or a component signal composed of a luminance signal and a color difference signal. The input signal discriminating means includes an input frequency detecting means for detecting a frequency of a horizontal synchronizing signal or a vertical synchronizing signal of the input signal, a frequency setting means for setting a predetermined frequency, and comparing the set frequency with the frequency of the input signal. 2. A comparison means for outputting a switching signal at the same time, and when the frequency of the input signal becomes a predetermined frequency, the input signal is determined to be an RGB video signal or a component signal. Video signal processing device. 16. The input frequency detecting means is a counter for receiving a horizontal synchronizing signal or a vertical synchronizing signal of the input signal and resetting the input signal with a pulse having a lower frequency than the synchronizing signal. 13. The video signal processing device according to claim 12, wherein a dip switch for setting the value of the dip switch is set, and the comparison circuit includes a comparator for comparing the value set in the dip switch with the output of the counter. 17. The input signal discriminating means, an input frequency detecting means for inputting a horizontal synchronizing signal or a vertical synchronizing signal of an input signal to be detected and counting for a predetermined period, a memory means for holding a predetermined frequency value, 13. The video signal processing apparatus according to claim 12, comprising an MPU including a comparison unit that compares the frequency value obtained and the output value of the counter. 18. The video signal processing device according to claim 2, further comprising a mute function for setting a video signal output when the input video signal is switched to a black level.
Alternatively, the video signal processing device according to claim 6. 19. The apparatus according to claim 18, wherein the mute function comprises a multiplexer that switches between an input video signal and a black level signal with an input switching signal and outputs the selected signal.
2. The video signal processing device according to 1.