JPH07112265B2 - Characteristic correction device - Google Patents

Description

The present invention relates to a signal recording apparatus which automatically corrects distortion caused by non-linearity of a signal processing system at the time of recording and reproduction and correction of a reproduction signal level. The present invention relates to a characteristic correction device.

[Conventional technology]

In a signal recording device such as a VTR, as one method for recording a wideband signal, channel division recording is performed by dividing one signal into a plurality of channels to reduce the bandwidth required for each channel. It is a method.

In such a method, when the signal to be recorded is a television signal, the signal is divided into a plurality of channels by dividing it for each horizontal scanning period, and the divided signal is time-axis expanded and recorded. Is used.

An example of this method is shown in FIG. 9, and in this example, the input video signal is distributed to two channels (A, B). FIG. 3A shows the input signal, and the numbers in the time order are given as H1, H2, H3, ... For each horizontal scanning period. The input signal is distributed to the channel A and the channel B for each horizontal scanning line, and is subjected to the time-axis expansion, as shown in FIG. 9 (b).
It is converted into the form of the recording signal shown in.

When the signal is expanded on the time axis by dividing the channels in this way, the band for each channel decreases, but
Since one signal will be recorded and reproduced in two systems,
If there is a characteristic difference between the channels, in the above example, the reproduction line image quality is deteriorated such that the scanning lines are conspicuous. Therefore, a device that automatically corrects the characteristic difference between channels is required.

VT that records and reproduces by performing the above channel division
An example of the configuration of the characteristic correction device used for R is shown in "Kiyoshi Sasaki et al .: Band compression VTR for HDTV, National Technical Report Vol.32 No.4". FIG. 11 is a block diagram showing the configuration of this device,
In the figure, (10) is a memory for storing a reproduction ramp signal, (11) is an arithmetic mean and a check circuit for performing an arithmetic mean and a check of the reproduction ramp signal, (12) is a level correction table memory, and (13) is a reference lamp. Signal data memory,
(14) is a data processing circuit, (15) is a switch for changing the address of the level correction table memory (12), (16) is a reproduction signal input terminal, (17) is a reproduction lamp signal input terminal,
(18) is a time axis data terminal, and (19) is a correction output terminal.

The conventional characteristic correction device is configured as described above, and records the ramp signal that changes from the black level to the white level within the vertical blanking period of the video signal, and reproduces this to obtain the recording level and the reproduction level. I'm trying to correspond. When the ramp waveform shown in FIG. 10 (a) is recorded, if a distorted waveform as shown in FIG. 10 (b) is obtained as the playback signal, this playback ramp signal is output to the time base collector device (TBC). The input signal level and the reproduction output level are made to correspond to each other by correcting the time axis and matching the timing with the ramp signal at the time of recording.

To explain this operation in detail, the playback ramp signal is first input to the averaging and checking circuit (11), where multiple playback ramp signals are added to improve the S / N, and the playback of the averaging is performed. Check the shape of the ramp signal,
Eliminate the effects of dropouts, etc. The reproduction ramp signal whose arithmetic mean and shape have been checked is stored in the reproduction ramp data memory (10) with the time axis data as an address. Next, the data and address of the reproduction lamp data memory (10) are reversed to each other and the level correction table memory (1
2) Remember it. Reference lamp signal data memory (13)
The shape of the ramp signal at the time of recording is recorded in the, and if the reproduced video signal data is given through the switch (15) as the address of the level correction table memory (12), the address of the reference ramp signal data memory (13) Is determined, and the level-corrected video signal data is obtained at the output of the reference ramp signal data memory (13).

[Problems to be solved by the invention]

Since the conventional characteristic correction device is configured as described above, the timing of the ramp signal at the time of recording and the timing of the ramp signal at the time of reproduction must be perfectly matched. It is necessary, and when there is a time axis fluctuation within one horizontal period called velocity error, it is not possible to completely match the timing during recording and during reproduction in the latter half of one horizontal period.
There is a drawback that the recording level and the reproduction level cannot be correctly associated.

Further, in a signal such as a ramp signal used in a conventional device, in which the video signal level is the same level for a short period, erroneous playback ramp data is taken in if the sampling position is displaced, and correct level correction operation cannot be performed. There was a problem that it did not exist.

The present invention has been made in order to solve the above-mentioned problems of the conventional ones, and an object thereof is to obtain a characteristic correction device capable of correctly performing a level correction operation even in a signal recording device having no time base collector device. And

[Means for solving problems]

A characteristic correction device according to the present invention is a characteristic correction device which corrects the characteristic of a signal processing system when recording and reproducing a video signal, and A / D conversion means for converting an input analog signal into a digital signal, The reference signal generating means for generating a reference signal corresponding to all heights from the black level to the white level of the A / D converted recording video signal, and the height of the reference signal generated by the reference signal generating means A pulse height data generating means for generating the pulse height data to be pointed to, the reference signal and the pulse height data corresponding to the quantization level of the reference signal are time-division multiplexed to blank the recorded video signal. The reference signal and the value of the pulse height data corresponding to the quantization level of the reference signal are sequentially changed in a predetermined period within the period, and the reference signal corresponding to all the quantization levels within a predetermined period, and Reference data inserting means for inserting pulse height data, reference signal and pulse height data selecting means for selecting the reference signal and pulse height data from the reproduced video signal during reproduction, and the reference signal and pulse height data The recording height of the reference signal is detected based on the pulse height data output from the selecting means, and table data for level correction of the reproduced video signal is created using the detection result, and the table data is referred to. And a level correcting means for correcting the level of the reproduced video signal.

[Action]

In the present invention, since the reference pulse has a time width, the pulse height at the time of reproduction can be obtained by sample-holding the vicinity of the center of the reference pulse even if the reproduced video signal includes a time base fluctuation. .

Further, since the pulse height data is quantized data, its value does not change even if it is distorted.

Therefore, each of a plurality of types of pulses having different heights corresponding to the black level to the white level inserted during recording can be accurately associated with each other during recording and reproducing.
Even if the signal recording device does not have the time base collector, the level can be corrected correctly.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
The figure shows a characteristic correction apparatus according to an embodiment of the present invention, and here, it corresponds to the number of quantization levels of an 8-bit reproduction A / D converter.
An example will be described in which 56 sets of reference pulse heights and serial pulse height data are inserted in pairs in the vertical blanking period.

FIG. 1 shows a recording system block of this embodiment. In FIG. 1, (1) is a gate pulse generating means for separating a vertical and horizontal synchronizing signal from a recording video signal to generate a gate pulse, and (2) is a gate pulse. Reference pulse generating means (reference signal generating means) for generating reference pulses having 256 different heights from the black level to the white level according to the output of the generating means (1), and (3) the output of the reference pulse generating means (2). Pulse height data generating means for identifying the pulse height,
Reference numeral (4) is reference data inserting means for inserting a pair of reference pulse and pulse height data into the vertical blanking period of the recording video signal.

Further, FIG. 2 shows a reproduction system block of the present embodiment, in which (5) is a reproduction A / D converter for A / D converting the reproduction video signal, and (6) is a reproduction A / D converter (5 (7) is a pulse height data selecting means for selecting pulse height data from the reproduced video signal, and (8) is a reference pulse selecting means. Level correction means for level-correcting the reproduced video signal using the output data of the means (6) and the output data of the pulse height data selection means (7), and (9) D / A conversion of the level-corrected video signal. This is a playback D / A converter. The gate pulse generating means can also be used for the recording system, but it is of course possible to use another circuit which operates exactly the same.

Next, the operation will be described with reference to FIGS. In FIG. 1, a gate pulse generating means (1) for recording separates a vertical and horizontal synchronizing signal from a recorded video signal (see FIG. 3 (a)), and a vertical synchronizing signal (see FIG. 3 (b)). A gate pulse (see FIG. 3 (c)) which becomes HIGH is generated in one horizontal period after three horizontal periods.

In the first half of the gate pulse (see FIG. 4 (a)), the reference pulse generating means (2) is 256/25 first.
The data of the reference pulse having the high quantization level of 6 is generated by reading the data from the ROM (see FIG. 4 (b)). And pulse height data generating means (3)
Generates pulse height data in serial format indicating the height of the reference pulse (see FIG. 4 (c)). After that, the data of the reference pulse (255/25
6,254 / 256, ..., 2/256, 1/256) is generated for each vertical blanking period (see FIGS. 4 (b) and 4 (c)). When a pair of reference pulse and pulse height data are inserted into the recording video signal by the reference data inserting means (4), an output signal as shown in FIG. 5 is obtained, and this output signal passes through the recording system circuit. Will be recorded.

During reproduction, for example, a reproduced video signal that has been distorted and contracted near the white level is A / D converted by the reproducing A / D converter (5). At the same time, the gate pulse generating means (1) generates a reproduction gate pulse synchronized with the reproduction video signal including the time base fluctuation (see FIG. 6 (a)). According to the reproduction gate pulse, the reference pulse selection means (6) is a reproduction A / D converter (5).
From the output data, the reproduction reference pulse (see FIG. 6 (b)) whose height has been changed by distortion, and the pulse height data selecting means (7) displays the pulse height at the time of recording from the reproduced video signal. Obtain identifiable pulse height data (Fig. 6 (c))
reference).

Next, in the level correction means (8), for example, using the data of all the reproduction reference pulses as addresses, the corresponding pulse height data is written in the memory to create a level correction table. The output data of the converter (5) is used as an address and level correction operation such as reading a value from the level correction table is performed to remove the reference pulse and pulse height data inserted at the time of recording, and then the reproduction is performed.
When the D / A converter (9) performs D / A conversion, a level-corrected reproduced video signal is obtained.

In the above embodiment, the reference pulse and the pulse height data are inserted one by one in the horizontal period within the vertical blanking period, starting with the one with the highest pulse height. Insert one by one from the lowest one, or insert only the reference pulse in one horizontal period and the pulse height data in the next one horizontal period as shown in FIG. 7, or as shown in FIG. Any pattern may be used as long as a pair of reference pulse and pulse height data is inserted within the blanking period, such as a pulse height data being inserted first and a reference pulse being inserted later. It has the same effect as the example.

Further, in the above embodiment, the pulse height data corresponding to the reproduction reference pulse data as an address is written in the memory,
In the normal video period, the example of using the level correction method of reading the corrected value using the output data of the reproduction A / D converter (5) as an address has been described. For example, reproduction reference pulse data and pulse height data Difference is written in the memory as correction data, the correction data is read using the output data of the playback A / D converter as an address in the normal video period, and the output data of the playback A / D converter is added to correct the level. Alternatively, another level correction method may be used, such as creating level correction data by software using the method described above or a microcomputer and interpolating the data when a discontinuity occurs in the level correction data.

Further, in the above embodiment, an example using binary pulse height data of HIGH or LOW has been described, but quantized data such as ternary data may be used.

Further, in the above-described embodiment, an example in which the data of the reproduction reference pulse obtained at the time of reproduction is used as it is has been described. Further effects can be expected by combining the means such as not using the reproduction reference pulse data.

〔The invention's effect〕

As described above, according to the characteristic correction device of the present invention,
A / D conversion means for converting an input analog signal into a digital signal in a characteristic correction device for correcting the characteristics of a signal processing system when recording and reproducing a video signal, and the A / D converted recording video signal A reference signal generating means for generating reference signals corresponding to all the heights from the black level to the white level, and a pulse for generating pulse height data indicating the height of the reference signal generated by the reference signal generating means. The height data generating means, the reference signal, and the pulse height data corresponding to the quantization level of the reference signal are time-division multiplexed, and the data are sequentially output in a predetermined period within the blanking period of the recording video signal. A reference signal and a pulse height data value corresponding to the quantization level of the reference signal are changed, and the reference signal corresponding to all the quantization levels and the pulse height data corresponding to all the quantization levels are inserted within a predetermined period. A data inserting means, and the reference signal and the pulse height data selecting means for selecting the said reference signal and the pulse height data from the reproduced video signal during reproduction,
The recording height of the reference signal is detected based on the pulse height data output from the reference signal and the pulse height data selecting means, and the detection result is used to generate table data for level correction of the reproduced video signal. Since it is provided with a level correction means for making a level correction on the reproduced video signal by referring to the table data, the level correction operation can be accurately performed even in a signal recording device having no time base collector device. The characteristic correction device can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a recording system of a characteristic correction device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a configuration of a reproduction system of a characteristic correction device according to an embodiment of the present invention. FIG. 4, FIG. 5, FIG. 5 and FIG. 6 are operation explanatory views of one embodiment of the present invention, FIG. 7 and FIG. 8 are operation explanatory views of another embodiment of the present invention, and FIG. FIG. 10 is a diagram for explaining a channel division recording method in a recording device, FIG. 10 is an operation explanatory diagram of a conventional example, and FIG. 11 is a block diagram showing a configuration of a conventional characteristic correction device. In the figure, (2) is a reference pulse generating means, (3) is a pulse height data generating means, (4) is a reference data inserting means, (5) is a reproduction A / D converter, and (8) is a level correcting means. Is. The same reference numerals in the drawings indicate the same or corresponding parts.

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Claims (2)

[Claims] 1. A characteristic compensating device for compensating the characteristic of a signal processing system when recording and reproducing a video signal, wherein an A /
D conversion means, reference signal generation means for generating reference signals corresponding to all heights from the black level to the white level of the A / D converted recording video signal, and the above-mentioned reference signal generation means Pulse height data generating means for generating pulse height data indicating the height of the reference signal, the reference signal and the pulse height data corresponding to the quantization level of the reference signal are time-division multiplexed, and The reference signal and the value of the pulse height data corresponding to the quantization level of the reference signal are sequentially changed in a predetermined period within the blanking period of the recorded video signal, and the above-mentioned values corresponding to all the quantization levels within the predetermined period are changed. Reference data inserting means for inserting the reference signal and the pulse height data, and a reference signal and pulse height data selecting means for selecting the reference signal and the pulse height data from the reproduced video signal during reproduction. And a table for correcting the level of the reproduced video signal by detecting the recording height of the reference signal on the basis of the pulse height data output from the reference signal and the pulse height data selecting means. A characteristic correction device comprising: level correction means for generating data and correcting the level of the reproduced video signal by referring to the table data. 2. The characteristic correction device according to claim 1, wherein the pulse height data is serial format data.