JP3060003U - Video deck - Google Patents

Abstract

(57) [Summary] To replace a section containing a noise component with a signal of a fixed low level, the low-level signal is displayed as a horizontal line on the screen. SOLUTION: A predetermined scanning line (2) in which demodulation noise has occurred is detected by a head switching signal input from a video head 11, and a video reproduction signal of the scanning line in which demodulation noise has occurred as shown in FIG. By replacing the average value of the video reproduction signals of the scanning lines (1) and (3) with the calculated video reproduction signal, horizontal lines generated on predetermined scanning lines due to noise components due to demodulation noise are removed as shown in FIG. This makes it possible to reproduce a good-looking image even when performing variable-speed reproduction such as search or frame-by-frame reproduction.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a video deck, and more particularly, to a video deck that reduces noise components that occur in a video playback image during variable speed playback of a video tape.

[0002]

[Prior art]

 Conventionally, as this type of video deck, one disclosed in Japanese Patent Application Laid-Open No. Hei 5-110996 is known. In this publication, a video deck is composed of a signal processing circuit, a DOC detection circuit, a signal replacement circuit, a clamp circuit, and a memory. In the above configuration, the signal processing circuit and the DOC detection circuit input a reproduced video signal during variable speed reproduction of a video tape. The DOC detection circuit outputs a timing pulse corresponding to a noise section of the reproduced video signal. Here, based on the timing pulse, the signal replacement circuit replaces the noise section of the reproduced video signal with a low-level signal. The clamp circuit clamps the output video signal of the signal replacement circuit. Then, the memory acquires the output video signal clamped by the clamp circuit, and complements the noise section based on the acquired output video signal.

[0003]

[Problems to be solved by the invention]

 In the above-mentioned conventional video deck, since a noise component is extracted from a reproduced video signal and a timing pulse is output at a timing at which the noise component is included, processing cannot be performed in real time. In addition, since the section containing the noise component is replaced with a constant low-level signal, the noise component can be apparently removed.However, the low-level signal is eventually displayed on the screen. There was a problem that lines would appear on the screen because they would be displayed.

[0004] The present invention has been made in view of the above-described problem. In the variable speed reproduction mode, it is possible to detect a section in which a noise component is included in real time, and to delete a horizontal line generated by the noise component appearing on a screen. The purpose is to provide a VCR that can do this.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the invention according to claim 1 receives a signal from a plurality of video heads in a variable speed playback mode of a video tape and compares the input signals from the plurality of video heads. Video head switching signal output means for switching to an output video head; video reproduction signal storage means for storing a video reproduction signal for forming an image displayed on a predetermined scanning line and scanning lines before and after the predetermined scanning line; A complementary signal calculating means for calculating a complementary signal for complementing the predetermined scanning line based on video reproduction signals of scanning lines before and after the predetermined scanning line stored in the storage means; and Video reproduction signal changing means for changing the video reproduction signal of the predetermined scanning line to the complementary signal in response to the signal. .

In the device according to claim 1 configured as described above, the video head switching signal output means inputs signals from a plurality of video heads in a variable speed playback mode of a video tape, and outputs a plurality of the input signals. The signal from the video head is compared, and a signal for switching to a video head having a larger output is output. A video reproduction signal for forming an image displayed on a predetermined scanning line and scanning lines before and after the predetermined scanning line is stored in the video reproduction signal storage means. On the other hand, in the above-mentioned variable speed reproduction mode of the video tape, a discontinuity point occurs in the reproduced video signal due to the switching of the video head, and this causes noise. That is, the noise causes horizontal lines and the like to appear in the reproduced image in units of scanning lines, causing the image to flicker and deteriorate the appearance. Here, in order to eliminate a horizontal line included in the image, the supplementary signal calculating means performs the predetermined signal based on the video reproduction signals of the scanning lines before and after the predetermined scanning line stored in the video reproduction signal storage means. A complement signal for complementing the scan line is calculated. The video reproduction signal changing means changes the video reproduction signal of the predetermined scanning line to the complementary signal in response to the switching signal output by the video head switching signal output means.

As described above, the video reproduction signals corresponding to the three scanning lines are always stored, and when noise occurs in a predetermined scanning line, this scanning line is referred to while referring to the video reproduction signals of the preceding and following scanning lines. It is possible to obtain an appropriate complementary signal that complements the video signal of this scanning line. Then, when the complementary signal is calculated, the video reproduction signal changing means, when the video head switching signal output means detects a discontinuous point of the video reproduction signal accompanying the switching of the video head, the video reproduction signal changing means. It recognizes that noise has occurred in the scanning line, and changes the video reproduction signal of this predetermined scanning line to the above-mentioned complementary signal. This makes it possible to eliminate horizontal lines generated by noise on the screen.

Here, the variable-speed reproduction mode may be a search operation for performing fast-forward while performing reproduction, or a frame-by-frame reproduction. In other words, this includes the case where the reproduction mode is set and the reproduction is performed at an irregular operation speed. The complementary signal may be generated by referring to the video signals of the scanning lines before and after the scanning line where the noise has occurred. The signal may be used as a complementary signal, or a video signal of a subsequent scanning line may be used as a complementary signal. Further, a predetermined arithmetic processing may be performed on the video signals of the scanning lines before and after this to make a complementary signal.

The arithmetic processing performed by the supplementary signal calculating means mainly takes the video signal of the preceding scanning line into consideration and considers the video signal of the preceding scanning line in consideration of the afterimage effect which is a characteristic of human eyes. A signal may be added at a predetermined rate. In other words, since scanning is performed from the top to the bottom of the screen, when the video signal of the previous scanning line is mainly used to complement the scanning line where noise has occurred, the whole image can be smoothed. Will be possible. As another example of such arithmetic processing, the invention according to claim 2 is the video deck according to claim 1, wherein the complementary signal calculation means includes a video signal of a scanning line before and after the predetermined scanning line. The configuration is such that a supplementary signal is calculated by averaging the reproduced signals. In the invention according to claim 2 configured as described above, the supplementary signal calculation means calculates the supplementary signal by averaging the video reproduction signals of the scanning lines before and after the predetermined scanning line. Therefore, it is possible to complement a scanning line in which noise has occurred by a complementary signal calculated by a simple arithmetic processing.

[0010]

[Effect of the invention]

 As described above, the present invention can detect a section including a noise component in real time in the variable speed playback mode, and can delete a horizontal line generated by the noise component appearing on the screen. Can be provided. Further, according to the invention of the second aspect, it is possible to calculate a complementary signal for complementing noise of a predetermined scanning line by a simple arithmetic processing.

[0011]

[Embodiment of the invention]

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a claim correspondence diagram of a video deck according to an embodiment of the present invention. In this figure, when the video recorded on a video tape is demodulated and played back by this VCR, if a variable speed playback such as a search operation is performed, demodulated noise is generated in the played back video. This demodulation noise occurs in the horizontal direction of the television screen, and specifically occurs in units of scanning lines. This is because when the video is reproduced at a normal reproduction speed, the reproduction of the video reproduction signal is executed in units of the track of the video tape, so that no noise is generated in the scanning lines. On the other hand, during the above-described variable speed playback, a video playback signal that spans a plurality of tracks is played back and output as a video. Will occur. Therefore, in this VCR, while the signals from the plurality of video heads are input to the video head switching signal output means C1 during variable speed reproduction, the signals from the input plurality of video heads are compared and discontinuous. Detect the location.

Then, in order to remove the demodulation noise of the scanning line, the video reproduction signal storage means C2 stores the video reproduction signals of the scanning line to be output to the television and the scanning lines before and after the scanning line. Based on the stored video reproduction signal, the complementary signal calculating means C3 demodulates the video reproduction signal of the scanning line output to the television when the demodulation noise occurs in the video reproduction signal of the scanning line before and after the scanning line. Calculate a complementary signal that complements the video signal of the scanning line where noise has occurred. That is, the video reproduction signal of the scanning line to be output to the television and the video reproduction signals of the scanning lines before and after the television line are stored, and the complementary signal to the video reproduction signal of the scanning line to be output to the television is stored in the video of the scanning line before and after the video. It is calculated based on the reproduction signal. Since the complementary signal is calculated for each video reproduction signal of the scanning line output to the television in this manner, when a discontinuous point is detected, demodulation noise occurs in the video reproduction signal of this scanning line. Then, based on the complementary signal calculated from the video reproduction signals of the preceding and succeeding scanning lines where no demodulation noise is generated, the video reproduction signal of the scanning line where the demodulation noise is generated is changed. This operation is executed in the video reproduction signal changing means C4.

Next, FIG. 2 shows a schematic block diagram of a reproduction system circuit for reproducing a video signal recorded on a video tape in the video deck, which is connected to a television for displaying reproduced video and the like. In the figure, in a video deck 10, a signal reproduced by a video head 11 is amplified and high-frequency compensated by a head amplifier 12, only an FM signal is extracted by a high-pass filter 13, and an original luminance signal is extracted by an FM demodulation circuit 14. Demodulate. The low-pass filter 15 extracts only the low-frequency-converted carrier color signal, and the frequency demodulation circuit 16 returns the carrier color signal to a 3.58 MHz carrier color signal. Here, the FM demodulation circuit 14 and the frequency demodulation circuit 16 constitute a demodulation circuit 40 integrally. The luminance signal and the carrier color signal demodulated by the FM demodulation circuit 14 and the frequency demodulation circuit 16 are output to the S video output terminal 17 and input to the S video input terminal 33.

The demodulated luminance signal and carrier chrominance signal are mixed by a YC mixing circuit 18 to form a composite video signal. The composite video signal is output to the video output terminal 19 and to the video input terminal 32. Further, the signal is converted into VHF 1ch or 2ch in the RF converter circuit 20 and output from the U / V output terminal 21 to the U / V antenna terminal 31. Therefore, the S video signal, the composite video signal, and the RF 1ch or 2ch signal demodulated by the video deck 10 are supplied to the television 30. By switching, it is possible to select whether to display an image based on any of the signals.

The video reproduction signal reproduced by the video head 11 can be viewed on the television 30. Here, usually, the playback of the video playback signal is performed in units of video tracks recorded on a video tape while the rotating reel is driven at a predetermined speed. However, in a so-called variable speed playback mode in which a search operation by fast forward or rewind is performed during playback, or in a so-called variable speed playback mode, demodulation noise occurs in the video as shown in FIG. I will. This is because the number of discontinuous points is generated because the feed speed of the rotating reel becomes high or low, and the video reproduction signal to be reproduced extends over a plurality of video tracks.

The horizontal line formed in the video by the noise component of the demodulation noise is generated for each scanning line as shown in FIG. In the figure, it is shown that demodulation noise is generated in the scanning line (2) in the scanning lines (1) to (3). In the present embodiment, it is obvious that the image of the scanning line (2) in which the demodulation noise occurs has a strong correlation with the image formed by the scanning lines (1) and (3), Making use of the fact that (1) and scan line (3) will averagely correlate to scan line (2), using the video playback signals on scan lines (1) and (3), A configuration for modifying the video reproduction signal of the scanning line (2) is employed. For the discontinuous point, the switching of the video track can be detected by the switching of the head in the video head 11, so that it is connected to the video head 11 and a head switching signal can be input.

Next, FIG. 5 shows a block diagram of a demodulation circuit 40 for correcting the video reproduction signal of the scanning line in which the above-mentioned demodulation noise has occurred based on the video reproduction signals of the scanning lines before and after the scanning line. The demodulation circuit 40 inputs the signals output from the high-pass filter 13 and the low-pass filter 15 by the analog / digital conversion circuit 41 for each scanning line, and converts the analog signal into a digital signal. Then, the input signals are sequentially stored in the line memories 42 and 43. Therefore, the first input signal is stored in the line memories 42a and 43a, and when a video reproduction signal for the next scanning line is input, the signal stored in the line memories 42a and 43a is transferred to the line memories 42b and 43b. Then, the data is input to the line memories 42a and 43a. Similarly, when a video playback signal is input again, the signals stored in the line memories 42b and 43b are transferred to the line memories 42c and 43c, and the signals stored in the line memories 42a and 43a are transferred to the line memories 42b and 43b. The process proceeds to 43b. Then, the data is input to the line memory 42a43a.

As described above, the video reproduction signals of the scanning lines to be displayed at present are stored in the line memories 42b and 43b, and the video reproduction signals of the scanning lines before and after that are stored in the line memories 42a, 42c and 43a and 43c. Then, the video reproduction signals stored in the line memories 42a and 42c and 43a and 43c are input to the arithmetic circuits 44 and 45, and the average value of the signal components of each video reproduction signal is calculated. Here, the calculated average value and the video reproduction signal of the currently displayed scanning line stored in the line memories 42b and 43b are input to the switching circuits 46 and 47.

The switching circuits 46 and 47 are connected to the video head 11 so that the switching of the head in the video head 11 and the level of a signal output from the video head can be detected. Further, the switching circuits 46 and 47 are connected to a mode selection circuit 50, and input a mode selection signal output from the mode selection circuit 50. The mode selection signal is a signal indicating a mode selected by the user of the VCR, such as a reproduction mode, a search mode, and a frame feed mode. Therefore, when the normal reproduction mode is input, the switching circuits 46 and 47 execute the switching so as to output the video reproduction signals stored in the line memories 42b and 43b, and perform the search mode and the frame feed. When a variable speed reproduction mode such as a mode is input, switching is performed so as to output video reproduction signals output from the arithmetic circuits 44 and 45. The video reproduction signal selected by the switching by the switching circuits 46 and 47 is converted to an analog signal by the digital / analog circuit 48 and output to the next stage circuit.

The present embodiment employs a configuration in which the detection of a discontinuous point is detected by a head switching signal in the video head 11. Of course, the method of detecting a discontinuous point is as described above. The configuration is not limited to the one directly detecting by the switching signal, and may be a configuration in which a noise component is detected as a discontinuous point by a noise component detection circuit that detects a noise component.

FIG. 6 is a time chart showing the operation of the switching process executed in the switching circuits 46 and 47 described above. A head switching signal is output from the video head 11 every time the head is switched, and the switching circuits 46 and 47 receive the head switching signal. At this time, when the ON of the variable speed reproduction mode signal is input from the mode selection circuit 50 at the time t1, the output of the video reproduction signal of the normal scanning line stored in the line memories 42b and 43b is stopped, and the arithmetic circuit 44 , 45 so as to output a video reproduction signal composed of an average value of the line memories 42a, 42c and 43a, 43c. When the variable speed reproduction mode signal is turned off at time t2, the output of the video reproduction signal composed of the average values of the line memories 42a, 42c and 43a, 43c output from the arithmetic circuits 44, 45 is stopped. Then, switching is performed so that video reproduction signals of normal scanning lines stored in the line memories 42b and 43b are output.

As described above, by switching the video reproduction signals to be output to the scanning lines by the switching circuits 46 and 47, a predetermined scanning line (2) shown in FIGS. When the demodulation noise is generated, the predetermined scanning line (2) where the demodulation noise is generated is detected by the head switching signal input from the video head 11, and the scanning line in which the demodulation noise is generated as shown in FIG. By replacing the video reproduction signal of the line with the video reproduction signal obtained by calculating the average value of the video reproduction signals of the preceding and following scanning lines (1) and (3), the noise component due to the demodulation noise as shown in FIG. It is possible to remove horizontal lines that occur in a given scanning line, so that a good-looking image can be reproduced even when performing variable-speed playback such as search or frame-by-frame playback. become.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to a claim of a video deck according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a connection form of a television connected to the video deck.

FIG. 3 is a diagram illustrating a state where demodulation noise occurs in a video output from a television.

FIG. 4 is an enlarged view of a portion where demodulation noise occurs.

FIG. 5 is a block diagram of a demodulation circuit of the video deck.

FIG. 6 is a timing chart of a switching process performed by a switching circuit included in the demodulation circuit.

FIG. 7 is a diagram showing a specific image in which demodulation noise has occurred.

FIG. 8 is an enlarged view of a portion where demodulation noise occurs.

FIG. 9 is a diagram illustrating a case where a scanning line in which demodulation noise has occurred is replaced with an average value calculated by an arithmetic circuit.

FIG. 10 is a diagram showing an image from which demodulation noise has been removed by the processing performed by the demodulation circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Video head 13 ... High-pass filter 14 ... Low-pass filter 40 ... Demodulation circuit 41 ... Analog / digital conversion circuit 42, 43 ... Line memory 44, 45 ... Arithmetic circuit 46, 47 ... Switching circuit 48 ... Digital / analog conversion circuit 50 ... Mode selection circuit

Claims (2)

[Utility model registration claims] 1. A video head switching signal for inputting signals from a plurality of video heads in a variable speed playback mode of a video tape, comparing the input signals from the plurality of video heads, and switching to a video head having a larger output. An output unit, a video reproduction signal storage unit that stores a video reproduction signal that forms an image displayed on a predetermined scanning line and the scanning lines before and after the predetermined scanning line, and a predetermined scanning line stored in the video reproduction signal storage unit. A complementary signal calculating means for calculating a complementary signal for complementing the predetermined scanning line based on video reproduction signals of preceding and succeeding scanning lines; and the predetermined scanning line in response to a signal from the video head switching signal output means. A video reproduction signal changing means for changing the video reproduction signal to the complementary signal. 2. The video deck according to claim 1, wherein said complementary signal calculating means calculates the complementary signal by averaging video reproduction signals of scanning lines before and after said predetermined scanning line. VCR featuring.