JP2008301032A - Video signal processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video signal processor which can reduce external noise from an analog video signal transmitted through a video signal line in good precision, and improve a video S/N ratio. <P>SOLUTION: The video signal processor is provided with: a noise detection line 31 which is prepared in parallel to a video signal line 30 so as to detect noise competent to superimposed external noise when an analog video signal is transmitted through the video signal line 30; and an analog signal processing unit 32 which offsets the external noise superimposed on the analog video signal using the noise detected by the noise detection line 31. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a video signal processing apparatus, and more particularly to a video signal processing apparatus that removes external noise from an analog video signal.

  When an analog video signal is transmitted via a video signal line such as a substrate pattern or a wire, screen noise may appear due to the jumping of external noise, and the video S / N ratio may deteriorate. Although it is fundamental to eliminate the noise source, it may be difficult. Therefore, a video signal processing apparatus that removes external noise from an analog video signal in response to the jumping of external noise into the analog video signal is well known.

For example, Patent Document 1 discloses a noise removing device that removes noise from a signal on which noise in the vicinity of a signal is superimposed, and includes a first mixer unit that selectively outputs a signal using a frequency within the signal band, A second mixer unit that selectively outputs only noise near the signal using an external frequency, a main signal receiving unit that receives a signal from the first mixer unit by the first receiving unit, and noise from the second mixer unit The signal received by subtracting the noise received by the noise detector from the signal received by the main signal receiver from the noise detector received by the receiver by the second receiver having the same reception characteristics as the first receiver There is disclosed a noise removal device that includes a subtraction processing unit that removes noise superimposed on the signal.
JP 2004-254184 A

  However, in the noise removal device disclosed in Patent Document 1, only the noise is selected and detected from the signal on which the noise is already superimposed, and only the noise cannot be accurately detected, and the noise may not be reduced appropriately. was there.

  The present invention has been made in view of the above problems, and its object is to appropriately reduce external noise from an analog video signal transmitted via a video signal line and improve a video S / N ratio. An object of the present invention is to provide a video signal processing apparatus that can perform the above-described processing.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided a video signal processing apparatus for removing external noise from an analog video signal transmitted via a video signal line, wherein the analog video signal is connected to the video signal line. A noise detection line arranged in parallel with the video signal line so as to detect noise corresponding to the external noise superimposed when transmitted via the external video signal, and the external noise superimposed on the analog video signal And providing an analog signal processing unit that cancels using noise detected by the noise detection line.

  In the video signal processing apparatus of the present invention configured as described above, an analog video signal is superimposed when transmitted via the video signal line by a noise detection line arranged in parallel with the video signal line. Noise equivalent to external noise is detected, and the external noise superimposed on the analog video signal by the analog signal processing unit is canceled using the noise detected by the noise detection line. Is obtained. That is, external noise can be appropriately reduced from the analog video signal transmitted through the video signal line. In addition, since the noise detection line is arranged in parallel with the video signal line, the analog signal processing unit can adjust the phase and level of the external noise superimposed on the analog video signal and the noise detected by the noise detection line. No longer needed.

  According to a second aspect of the present invention, in the video signal processing device according to the first aspect, the analog signal processing unit adds a signal obtained by inverting the noise detected by the noise detection line to the analog video signal. There is to do.

  2. The video signal processing apparatus according to claim 1, wherein the analog signal processing unit adds the signal obtained by inverting the noise detected by the noise detection line to the analog video signal. The superimposed external noise can be appropriately canceled using the noise detected by the noise detection line.

  According to a third aspect of the present invention, in the video signal processing device according to the second aspect, the analog signal processing unit performs A / D conversion on the analog video signal and is detected by the noise detection line. The noise is inverted after A / D conversion, and the noise that has been inverted after the A / D conversion is added to the A / D converted analog video signal.

  3. The video signal processing apparatus according to claim 2, configured as described above, wherein the analog video signal and noise detected by the noise detection line are A / D converted by the analog signal processing unit and superimposed on the analog video signal. Noise is appropriately canceled by digital processing using the noise detected by the noise detection line.

  According to a fourth aspect of the present invention, in the video signal processing device according to any one of the first to third aspects, the analog video signal is a video signal input from an external device to an external input terminal.

  4. The video signal processing apparatus according to claim 1, wherein the external noise superimposed when the video signal input from the external device to the external input terminal is transmitted is detected as noise. The noise detected by the line is appropriately canceled out.

  According to a fifth aspect of the present invention, in the video signal processing device according to the fourth aspect, the external input terminal is provided in a thin television device, and the external noise is generated by the thin television device. The analog signal processing unit is a signal processing IC provided in the thin television device, and the video signal line is a signal transmission line from the external input terminal to the signal processing IC. The noise detection line has one end connected to the signal processing IC and the other end grounded via a resistor.

  5. The video signal processing device according to claim 4, configured as described above, wherein an analog video signal input via an external input terminal provided in the thin television device is provided in the thin television device. A noise detection line is arranged in parallel with the video signal line to be transmitted to the signal processing IC, and one end of the noise detection line is connected to the signal processing IC and the other end is grounded through a resistor. Therefore, the noise detection line can function as an antenna to properly detect the noise equivalent to the in-flight noise of a thin television device superimposed on an analog video signal input from an external device via an external input terminal. The in-machine noise superimposed on the video signal is appropriately canceled using the noise detected by the noise detection line.

  As described above, according to the first aspect of the present invention, the external noise is appropriately reduced from the analog video signal transmitted through the video signal line, so that the video S / N ratio can be improved. it can. In addition, the analog signal processing unit eliminates the need for phase alignment and level adjustment between the external noise superimposed on the analog video signal and the noise detected by the noise detection line. Noise is easily reduced.

  According to the second aspect of the present invention, since the external noise superimposed on the analog video signal is appropriately canceled using the noise detected by the noise detection line, the analog signal transmitted through the video signal line External noise is appropriately reduced from the video signal.

  According to the third aspect of the present invention, since the external noise superimposed on the analog video signal by digital processing is appropriately canceled using the noise detected by the noise detection line, it is transmitted via the video signal line. External noise is easily reduced from the analog video signal.

  According to the fourth aspect of the present invention, the external noise superimposed when the video signal input from the external device to the external input terminal is transmitted is appropriately detected using the noise detected by the noise detection line. Since it is canceled out, the video S / N ratio can be improved in the video based on the video signal from the external device.

  According to the invention described in claim 5, the noise detection line serves as an antenna, and the noise corresponds to the in-machine noise of the thin television device superimposed on the analog video signal input from the external device via the external input terminal. Is appropriately detected, and the in-flight noise superimposed on the analog video signal is appropriately canceled using the noise detected by the noise detection line, so that the video S / N in the video based on the video signal from the external device The ratio can be improved. Further, for example, even if the video signal line becomes longer due to an increase in the size of the thin television device, the external noise is appropriately reduced from the analog video signal transmitted through the video signal line.

Hereinafter, embodiments of the present invention will be described with reference to the drawings according to the following items.
(1) Schematic configuration of liquid crystal television device (2) Configuration of video signal processing device (3) Summary

(1) Schematic Configuration of Liquid Crystal Television Device Hereinafter, a schematic configuration of a liquid crystal television device 10 to which the present invention is applied will be described with reference to FIGS. FIG. 1 is a perspective view showing a liquid crystal television device 10, and FIG. 2 is a block configuration diagram of the liquid crystal television device 10. In the present embodiment, a liquid crystal television apparatus is exemplified as an apparatus to which the present invention is applied. However, the present invention is not limited to this embodiment, and an image subjected to various processes for displaying an image based on an analog image signal. The present invention can be applied if a signal processing device is provided. The present invention will be described by taking a liquid crystal television device as an example, but a thin television device such as a plasma television, a rear projection television, an organic EL television, etc., as long as it is a display device capable of displaying an image based on an analog video signal. If the projector is a thin display such as a liquid crystal display or plasma display that does not have a television function, or a projector device that projects an image on a screen, various modifications can be made without departing from the gist of the present invention.

  1 and 2, a liquid crystal television device 10 includes a tuner 11, a front end 12, a decoder 13, an OSD circuit 14, an audio output unit 15, an image display unit 16, a remote control receiving unit 17, A microcomputer 18, a power supply circuit 19, an external input terminal 20, an external input signal processing unit 21, and a switch circuit 22 are provided.

  The tuner 11 is connected to, for example, the antenna 23, and is set to one channel (for example, a channel selected by the user) from the television broadcast signals received by the antenna 23 in accordance with a control signal input from the microcomputer 18. A corresponding television broadcast signal is acquired and output to the front end 12.

  The front end 12 converts the television broadcast signal output from the tuner 11 into an intermediate frequency signal according to a control signal input from the microcomputer 18, for example, and outputs the intermediate frequency signal to the decoder 13.

  The decoder 13 performs a process according to a predetermined file format (for example, a well-known MPEG-2 format) on the intermediate frequency signal output from the front end 12 in accordance with, for example, a control signal input from the microcomputer 18. Thus, the intermediate frequency signal is separated into an audio signal and a video signal and decoded. Then, the decoded audio signal is output to the audio output unit 15 via the switch circuit 22 and the video signal is output to the image display unit 16.

  The external input terminal 20 is a terminal for inputting an analog video signal and an analog audio signal output from the external device 24. Terminals for inputting analog video signals are, for example, composite terminals, S terminals, component terminals, and the like. The external device 24 is a DVD player or a video tape player that can output a composite video signal, an S video signal, and a component video signal.

  The external input signal processing unit 21 performs predetermined processing on the analog video signal and the analog audio signal output from the external device 24 and converts them into digital signals, respectively. Then, the converted audio signal is output to the audio output unit 15 via the switch circuit 22 and the video signal is output to the image display unit 16.

  For example, according to a control signal from the microcomputer 18, the switch circuit 22 sends the audio signal and video signal from the decoder 13 or the audio signal and video signal from the external input signal processing unit 21 to the audio output unit 15 and the image display unit 16, respectively. Output.

  The OSD circuit 14 outputs an OSD display signal for causing the image display unit 16 to perform a predetermined OSD display (on-screen display display) from the switch circuit 22 to the image display unit 16 in accordance with, for example, a control signal input from the microcomputer 18. Is synthesized with the video signal to be recorded.

  The audio output unit 15 includes, for example, an audio output amplifier IC (D-AMP) 15a, a speaker 15b, and the like, and performs predetermined processing such as power amplification on the audio signal input from the switch circuit 22 by the audio output amplifier IC 15a. The sound corresponding to the sound data based on the sound signal is output from the speaker 15b.

  The image display unit 16 includes, for example, a panel drive circuit 16a, a liquid crystal panel 16b, and the like. An image corresponding to image data based on the video signal output from the switch circuit 22 and an image output from the switch circuit 22 and output from the OSD circuit 14 An image corresponding to the image data based on the video signal combined with the OSD display signal is displayed.

  The remote control receiving unit 17 receives various infrared signals (control commands) transmitted from the remote control 25, for example, and outputs various data based on these various signals to the microcomputer 18.

  The remote controller 25 is operated by a user, for example, and transmits an infrared signal corresponding to the operation to the remote control receiver 17.

  The microcomputer 18 includes, for example, a CPU 18a, a RAM 18b, a ROM 18c, and the like, and controls the operation of the liquid crystal television device 10. For example, the microcomputer 18 controls channel switching, volume up / down, and the like based on a control command received by the remote control receiver 17.

  The CPU 18a performs various control operations in accordance with various processing programs for the liquid crystal television device 10 stored in the ROM 18c.

  The RAM 18b includes a program storage area for expanding a processing program executed by the CPU 18a, a data storage area for storing input data, a processing result generated when the processing program is executed, and the like.

  The ROM 18c is a system program that can be executed by the liquid crystal television device 10, various processing programs that can be executed by the system program, data that is used when these various processing programs are executed, and various results that are arithmetically processed by the CPU 18a. Memorize etc. Note that the program is stored in the ROM 18c in the form of a computer readable program code.

  The power supply circuit 19 is, for example, a partial resonance power supply circuit, converts commercial AC power into a plurality of types of predetermined voltages, and outputs an operating power supply voltage to each part of the liquid crystal television device 10.

(2) Configuration of Video Signal Processing Device Hereinafter, the external input signal processing unit 21 will be described in detail with reference to FIG. FIG. 3 is a block diagram illustrating an example of the configuration of the external input signal processing unit 21. In FIG. 3, the external input signal processing unit 21 includes a video signal line 30, a noise detection line 31, and an analog signal processing unit 32, and is input to the external input terminal 20 from the external device 24 to display the video signal line 30. It also functions as a video signal processing device that removes external noise from the analog video signal transmitted through the network. This external noise is in-machine noise of the liquid crystal television device 10 such as noise from a transformer provided in the power supply circuit 19 and noise from an inverter for driving a backlight that emits light from the back of the liquid crystal panel 16b.

  One of the video signal lines 30 is connected to the external input terminal 20 and the other is connected to the analog signal processing unit 32, and the analog video signal input to the external input terminal 20 is transmitted from the external input terminal 20 to the analog signal processing unit 32. This is a signal transmission line. The video signal line 30 includes, for example, a capacitor C1 connected in series to the signal transmission line, and a resistor R1 that is connected to the external input terminal 20 and grounded to the other.

  The noise detection line 31 is arranged in parallel with the video signal line 30 and is superimposed when the analog video signal input to the external input terminal 20 is transmitted to the analog signal processing unit 32 via the video signal line 30. Detects noise equivalent to external noise. In other words, by providing the noise detection line 31 along substantially the same path as the video signal line 30, it is substantially the same as external noise that jumps into the analog video signal when the analog video signal is transmitted through the video signal line 30. The noise detection line 31 is made to function as an antenna capable of detecting the same noise. For example, one end of the noise detection line 31 is connected to the analog signal processing unit 32, and the other end is grounded near the external input terminal 20 via the resistor R2.

  The analog signal processing unit 32 cancels the external noise superimposed on the analog video signal input to the external input terminal 20 using the noise detected by the noise detection line 31. The analog signal processing unit 32 is configured by a signal processing IC having a function of adding a signal obtained by inverting the noise detected by the noise detection line 31 to the analog video signal transmitted through the video signal line 30, for example. . More specifically, the analog signal processing unit 32 includes a first A / D conversion unit 33 that A / D converts an analog video signal transmitted via the video signal line 30, and noise detected by the noise detection line 31. A / D conversion by a second A / D conversion unit 34, an inversion processing unit 35 for inverting the noise A / D converted by the second A / D conversion unit 34, and an inversion processing unit 35 after A / D conversion This is a one-chip IC that includes an arithmetic processing unit 36 that adds the inverted noise to the analog video signal A / D converted by the first A / D conversion unit 33.

  In the external input signal processing unit 21 configured in this way, as shown in the signal waveform of FIG. 3, a noise detection line 31 corresponding to the external noise from the waveform of the analog video signal of the video signal line 30 on which the external noise is superimposed. The analog signal processing unit 32 subtracts the noise waveform to obtain a signal close to the original signal of the analog video signal input from the external device 24 to the external input terminal 20. Further, since the noise detection line 31 is arranged in parallel with the video signal line 30, the phase and level of the external noise and the noise detected by the noise detection line 31 are substantially the same, and the external noise is detected as the noise detection line. When canceling out using the noise detected by 31, phase alignment and level alignment are not necessary. Further, for example, even if the video signal line 30 is lengthened with an increase in the size of the liquid crystal television device 10, noise corresponding to external noise that jumps in when the video signal line 30 is transmitted is appropriately detected by the noise detection line 31. Can be detected.

(4) Summary As described above, according to the present embodiment, analog signal processing is performed using the noise detected by the noise detection line 31 as external noise superimposed on the analog video signal transmitted via the video signal line 30. Since the external noise is appropriately reduced from the analog video signal by being appropriately canceled out by the digital processing in the unit 32, the video S / N ratio can be improved. In addition, the analog signal processing unit 32 has a simple configuration because the analog signal processing unit 32 does not require phase alignment or level adjustment between the external noise superimposed on the analog video signal and the noise detected by the noise detection line 31. In addition, external noise can be easily reduced from the analog video signal transmitted through the video signal line 30.

  Further, according to the present embodiment, the noise detection line 31 serves as an antenna, and the noise corresponding to the in-machine noise of the liquid crystal television device 10 superimposed on the analog video signal input from the external device 24 via the external input terminal 20. Is appropriately detected, and the in-flight noise superimposed on the analog video signal is appropriately canceled using the noise detected by the noise detection line 31, so that the video in the video based on the analog video signal from the external device 24 is displayed. The S / N ratio can be improved. Further, for example, even if the video signal line 30 is lengthened with the increase in size of the liquid crystal television device 10, noise corresponding to the external noise jumping in when the video signal line 30 is transmitted is appropriately detected by the noise detection line 31. Since it can be detected, the external noise is appropriately reduced from the analog video signal transmitted through the video signal line 30.

  As mentioned above, although the Example of this invention was described in detail based on drawing, what was mentioned above is one embodiment to the last, and this invention is implemented in the aspect which added various change and improvement based on the knowledge of those skilled in the art. can do.

It is a perspective view which shows an example of the liquid crystal television apparatus with which this invention is applied. It is a block block diagram of a liquid crystal television apparatus. It is a block diagram which shows an example of a structure of an external input signal processing part.

Explanation of symbols

10: Liquid crystal television device (flat-screen television device)
20: External input terminal 21: External input signal processing unit (video signal processing device)
24: External device 30: Video signal line 31: Noise detection line 32: Analog signal processing unit (signal processing IC)
R2: Resistance

Claims (5)

In a video signal processing apparatus that removes external noise from an analog video signal transmitted via a video signal line,
A noise detection line arranged in parallel with the video signal line so as to detect noise corresponding to external noise superimposed when the analog video signal is transmitted through the video signal line;
A video signal processing apparatus comprising: an analog signal processing unit that cancels out external noise superimposed on the analog video signal using noise detected by the noise detection line.   2. The video signal processing apparatus according to claim 1, wherein the analog signal processing unit adds a signal obtained by inverting noise detected by the noise detection line to the analog video signal.   The analog signal processing unit performs A / D conversion on the analog video signal, reverses the noise detected by the noise detection line after A / D conversion, and performs reverse processing after the A / D conversion. 3. The video signal processing apparatus according to claim 2, wherein the noise is added to the analog video signal obtained by A / D conversion.   4. The video signal processing apparatus according to claim 1, wherein the analog video signal is a video signal input from an external device to an external input terminal. The external input terminal is provided in a thin television device,
The external noise is in-flight noise of the thin television device,
The analog signal processing unit is a signal processing IC provided in the thin television device,
The video signal line is a signal transmission line from the external input terminal to the signal processing IC,
5. The video signal processing apparatus according to claim 4, wherein one end of the noise detection line is connected to the signal processing IC, and the other end is grounded via a resistor.

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