JP2801289B2 - Information signal reproduction device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information signal reproducing apparatus, and more particularly to an information signal reproducing apparatus that corrects characteristics of a reproduced information signal in accordance with a reference signal in a reproduced information signal.

[Conventional technology]

As this type of device, a video tape recorder (VTR) that records and reproduces a video signal including a reference signal for one line in each frame, and processes the reference signal to have a predetermined waveform during reproduction is known.

In recent years, with the increase in the amount of information (recording band) due to higher definition and higher quality of video signals, it is conceivable to record and reproduce video signals as signals of a plurality of channels.
In particular, in this type of device, it is difficult to make the recording and reproducing characteristics of each channel uniform. That is, a difference occurs in the characteristics of the reproduced signal between the respective channels, and this difference appears as a stripe pattern on the reproduced image. Therefore, in this type of apparatus, it is desirable to perform correction for reducing the difference in the reproduction signal between the respective channels at the time of reproduction using the reference signal.

FIG. 2 is a diagram showing a schematic configuration of a conventional reproduction system of this type of VTR. In FIG. 2, reference numerals 100 and 101 denote reproduction heads for A channel (A-CH) and B channel (B-CH), respectively.
102 and 103 are reproduction amplifiers, 104 and 105 are FM demodulators, 106 and 107 are analog-digital (A / D) converters, 118 is a memory, 119
Is a digital signal processing circuit, 112 is a digital-analog (D
/ A) Transducer, 401 is Look-Up Table (LUT), 402
Is a microprocessor (hereinafter referred to as CPU), and 403 is a timing controller.

The signals reproduced from the heads 100 and 101 are the reproduction amplifiers 102 and 1
Amplified by 03 and FM demodulated by FM demodulators 104 and 105, then A / D
The data is digitized by the converters 106 and 107 and written into the memory 118.

Here, heads 100 and 101 of A-CH and B-CH, reproduction amplifier 1
It is very difficult to make the characteristics of analog circuits such as 02, 103 and FM demodulators 104, 105 the same. For this reason, FM demodulators 104, 10
The reproduced signal obtained from 5 has different characteristics among the channels.

The CPU 402 accesses the memory 118 and fetches data corresponding to the reference signal included in one line in one frame of the video signal for each of A-CH and B-CH. CP
The U402 operates in accordance with the distortion of the acquired A-CH and B-CH reproduction reference signals to eliminate A-CH and B-CH reproduction signal characteristic differences.
The correction data for CH and B-CH is calculated, and the correction data is written to the LUT 401 during the vertical or horizontal blanking period. Here, assuming that the reproduction data digitized by the A / D converters 106 and 107 is 8 bits, about 10 bits of correction value data is required to properly correct the characteristics. Therefore, CP
The U402 writes the 10-bit correction data D into the LUT 401 according to the 8-bit addressing data A.

On the other hand, in the memory 118, when the playback video data is shuffled under the timing control of the timing controller 403, the original data array is restored, and when the time axis is converted, the time axis expansion, compression, etc. After processing, the playback video data is sent to the LUT 401.

In the LUT 401, the video data reproduced from the A-CH is corrected according to the correction data for the A-CH, and the video data reproduced from the B-CH is corrected for the B-CH. The characteristic difference between the reproduced video signals of CH and B-CH is removed.

The data corrected by the LUT 401 is sent to a digital signal processing circuit 119, subjected to digital signal processing such as filtering and de-emphasis, and supplied to a D / A converter 112. The analog video signal output from the D / A converter 112 is output from the output terminal 113.

[Problems to be solved by the invention]

However, in the above configuration, if the reproduced video data is quantized by 8 bits as described above, it is necessary to expand the data by about 2 bits in order to perform correction with appropriate definition when performing correction by the LUT 401. Yes, the reproduced video data after correction becomes 10 bits. Along with this, there is a problem that the digital signal processing thereafter must be performed at 10 bits, and the scale of the hardware of the digital signal processing different circuit 119 becomes large.

Under such a background, an object of the present invention is to provide an information signal reproducing apparatus capable of minimizing the scale of hardware as a whole of the reproducing apparatus and performing fine correction of reproduction characteristics.

[Means for solving the problem]

For this purpose, according to the present invention, there is provided a reproducing unit that reproduces an information signal including a reference signal from a recording medium, and a correction unit that generates correction data according to the reference signal in the information signal reproduced by the reproducing unit. A data processing unit, a digital signal processing unit that converts the information signal reproduced by the reproduction unit into a digital signal and performs a predetermined process on the digital information signal obtained by the conversion, and a digital signal processing unit. Correction means for correcting the characteristics of the processed digital information signal in accordance with the correction data generated by the correction data generation means.

[Action]

With the above configuration, even when the accuracy of the correction by the correction means is improved, the number of bits of the digital reproduction information signal processed by the digital signal processing means does not increase. Therefore, the circuit scale of the digital signal processing means can be significantly reduced, and the reproduction signal can be corrected with high accuracy.

〔Example〕

FIG. 1 shows a reproducing apparatus according to an embodiment of the present invention. In the figure, the elements having the same functions as those of the apparatus of FIG. 2 are given the same numbers.

 Hereinafter, only differences from the apparatus of FIG. 2 will be described.

108 is a memory for writing A-CH and B-CH reproduction signals, 1
Reference numeral 19 denotes a digital signal processing circuit for correcting video data stored in the memory 108 such as filtering.

The CPU 402 accesses the memory 108 storing the reproduced signals from the A-CH and the B-CH, and reads data corresponding to the reference signals of the A-CH and the B-CH. Next, the CPU 109 calculates a correction value from the distortion of the read reference signal data, and calculates a correction value for the A-CH reproduced video data and a B-CH
And the correction value for the video data reproduced from the LUT 401 is written to the LUT 401 in accordance with the 8-bit addressing data.

Memory 108 which stores reproduction signals from A-CH and B-CH
Returns the reproduced video data divided into A-CH and B-CH to the original state by the timing control of the timing controller 403, and sends the reproduced video data to the digital signal processing circuit 109 at 8 bits. The digital signal processing circuit 109 subjects the reproduced video data to digital signal processing such as filtering and, if it is a color signal, synchronizing color difference lines and the like, and sends it to the LUT 401 at 8 bits. The LUT 401 corrects the characteristics according to the correction data for the A-CH to the reproduced video data from the A-CH by the timing control from the timing controller 403,
The reproduction video data from the CH is corrected according to the correction data for B-CH, expanded to 10 bits, and transmitted to the D / A converter 112.

As described above, by providing the LUT 401 for correcting the reproduction characteristic immediately before the D / A converter 112, all other digital signal processing can be performed with 8 bits, and the hardware scale of various digital signal processing circuits can be reduced. It became possible to make it smaller.

As described above, in the VTR of this embodiment, a look-up table is provided immediately before the D / A converter, digital signal processing is performed before the look-up table, and bit expansion is performed last. Various data processing in the system can all be performed in 8 bits, and the hardware scale can be reduced.

In the present embodiment, the description is made on the assumption that the characteristic difference between the channels is corrected by the LUT 401. However, the present invention can be applied to a one-channel reproducing apparatus that only corrects the linearity of the reproducing characteristic.

〔The invention's effect〕

As described above, according to the information signal reproducing apparatus of the present invention, it is possible to minimize the scale of hardware as a whole and to perform fine correction of reproduction characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a VTR reproduction system as one embodiment of the present invention, and FIG. 2 is a diagram showing a configuration example of a conventional VTR reproduction system. In the figure, 100 and 101 are playback heads, 102 and 103 are playback amplifiers, 104 and
105 is an FM demodulator, 106 and 107 are A / D converters, 108 is a memory, 10
9 is a digital signal processing circuit, 112 is a D / A converter, 113 is an output terminal, 401 is a look-up table, 402 is a microprocessor, and 403 is a timing controller.

Claims (3)

(57) [Claims] A reproducing means for reproducing an information signal including a reference signal from a recording medium; a correction data processing means for generating correction data according to the reference signal in the information signal reproduced by the reproducing means; Digital signal processing means for converting the information signal reproduced by the digital signal into a digital signal and performing a predetermined process on the digital information signal obtained by the conversion, and the digital information signal processed by the digital signal processing means. An information signal reproducing device comprising: a correction unit configured to correct characteristics according to the correction data generated by the correction data generation unit. 2. The apparatus according to claim 1, wherein said reproducing means reproduces said information signal of a plurality of channels, and said correcting means corrects a difference in characteristics of said reproduced information signal between said plurality of channels. The information signal reproducing device according to the item 1). 3. The information according to claim 1, wherein said correction means converts the n-bit digital information signal into an m-bit (n <m) digital signal and outputs the converted signal. Signal playback device.