JPH0750797A - Signal recording and reproducing device and signal reproducing device - Google Patents

Abstract

PURPOSE:To comprise a signal recording and reproducing device capable of always reproducing data recorded at a specific position when fast reproduction is performed. CONSTITUTION:This device is constituted in such a way that an identification code adding circuit 6 for tracking which adds an identification code representing a position on a track on the data to be recorded at the specific position on the track, and a head position judging circuit 12 which judges relative position relation between a reproducing head 10 and the specific position by the identification code added when recording is performed are provided, and the relative positioned relation between the reproducing head 10 and the track of a tape shape recording medium 9 is controlled so that the reproducing head 10 can pass the specific position on the track based on the judged result of the head position judging circuit 12. In this way, it is possible to accurately read out the data recorded on a specific area and to perform the fast reproduction by a compression type VTR that is hard to provide in a conventional device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type signal recording / reproducing apparatus which reproduces at least data at a specific position on a track when the medium speed during reproduction is equal to or higher than the medium speed during recording. The present invention relates to a signal reproducing device and a signal recording / reproducing device that records the signal.

[0002]

2. Description of the Related Art A conventional high speed reproducing method in an analog recording type image signal recording / reproducing apparatus is shown in Home Video Technology (edited by Japan Broadcasting Corporation p.188-p.190). According to this, when reproducing a high-speed reproduction image, the reproduction head crosses and scans a plurality of recording tracks, and an image of one field is composed of images read from a plurality of tracks where the heads intersect. .

An example of a high-speed reproduction method of a conventional image signal recording / reproducing apparatus will be described below with reference to the drawings. FIG. 14 is a conceptual diagram showing a scanner of a conventional helical scan type signal recording / reproducing apparatus. In FIG. 14, 23 is a tape-shaped recording medium, which is obliquely wound around the rotating drum 18 and runs at a predetermined speed. 33,3
A recording / reproducing head 4 obliquely forms tracks on the tape-shaped recording medium 23 during recording.

FIG. 15 shows a recording pattern of a tape-shaped recording medium and a head locus during high-speed reproduction. In FIG. 15, reference numeral 24 represents a track recorded by the recording / reproducing heads 33 and 34. A control track is recorded at the end of the tape.

FIG. 12 is a block diagram of a conventional image signal recording / reproducing apparatus. In this example, an analog recording type processing block is shown. In FIG. 12, 25 is an input terminal to which an analog image signal is input. The input image signal is FM-modulated by the FM modulation circuit 27 and recorded by the recording head 8 on the tape-shaped recording medium 9 by helical scanning. The recording head 8 is the recording / reproducing head 3 of FIG.
3 and 34, the tape-shaped recording medium 9 is the tape-shaped recording medium 2
3 and corresponds to forming the track 24 (FIG. 15) on the medium.

The input image signal is also input to the vertical synchronizing signal separating circuit 26, and the separated synchronizing signal is recorded as a control signal on the control track (FIG. 15) by the fixed head 28. Home VTR
In (VHS etc.), one field of image is recorded on one track, and one pulse of control signal is recorded on each track.

At the time of reproduction, the reproduction head is controlled so that the track is accurately traced based on the control signal. The reproducing heads 10 and 29 reproduce the signals recorded by the recording heads 8 and 28, respectively, but are often shared with the recording heads 8 and 9.

The control signal reproduced by the reproducing head 29 controls the rotation speed and phase of the rotary drum and the tape running speed (servo circuit 30) to obtain a reproduction signal. The obtained reproduction signal is demodulated to the original signal by the FM demodulation circuit 31, and the output signal is output to the output terminal 32.

During high speed reproduction, the reproducing head runs across a plurality of tracks as shown in FIG. Since the azimuths of the adjacent tracks are different from each other and the two heads 33 and 34 shown in FIG. 14 reproduce only the signals of the tracks formed by themselves, the reproducible points are the shaded portions in FIG. 15 on the tracks. Become.

The position of the signal to be recorded on the screen and the position on the track have a one-to-one correspondence. An image of one field is recorded on one track, and each head crosses a plurality of tracks. High-speed replay image by scanning
The image has a noise bar at the position where the head makes a track jump as in 3. The images in the areas above and below the noise bar are images that are one frame apart, but are sufficiently recognizable.

Further, in order to fix the noise bar generated when the reproducing head straddles the track at a specific position on the screen, the servo between the track and the head is performed by the servo based on the control signal recorded on the fixed track at the tape end. A method of controlling the relative positional relationship has been used. This servo method cannot obtain high accuracy because the track on which the image is recorded and the control track that is the reference of the servo are different tracks, but it is possible to control to the extent that the noise bar is fixed on the screen. .

As described above, in the conventional signal recording / reproducing apparatus, a high-speed reproduced image can be obtained even when the head runs across a plurality of tracks during high-speed reproduction.

[0013]

However, when the recorded image is a compressed digital signal, etc., the position of the compressed image data on the screen and the position on the track have a one-to-one correspondence. In many cases, the conventional high-speed reproduction method cannot compose one screen with data obtained by one head scan.

In this case, data used for high-speed reproduction is recorded in advance in a specific area of the track, and a head is controlled so as to pass over the area to obtain a high-speed reproduction image. With a servo based on the control track, it is very difficult to control the head locus with high accuracy, and it is extremely difficult to accurately position the head at a specific position on the track.

In the conventional analog recording type signal recording / reproducing apparatus, it was sufficient if the positional relationship between the track and the head could be controlled to such an extent that the position of the noise bar did not fluctuate greatly, but for high speed reproduction at a specific position on the track. In the signal recording / reproducing apparatus in which the data of 1) is recorded, a high-speed reproduced image cannot be obtained unless the relative positional relationship between the track and the head is controlled by more precise control.

The present invention is intended to solve the above problems, and an object thereof is to control the relative positional relationship between the track and the head more accurately.

[0017]

In order to achieve the above object, the present invention provides a rotary drum equipped with a recording head,
A signal recording device for recording a signal by forming a plurality of tracks on a tape-shaped recording medium wound obliquely and traveling at a constant speed. A first specific position on the track indicating a position on the track. Means for arranging the identification code group, and a second identification indicating a position ahead of the first specific position at a second specific position located in front of the track from the first specific position. A means for arranging the code group, and a third identification indicating that the code group is located at a third specific position located behind the first specific position and behind the first specific position. At least one of the three means for arranging the code group is provided, and the first
To the third specific position, the identification code is recorded.

On the signal reproducing device side, at least one of the three types of identification codes, that is, the first identification code, the second identification code, and the third identification code added during recording is used. A head position determination circuit that determines the relative positional relationship between the reproduction head and the first specific position based on the identification code, and the reproduction head determines the first specific position on the track based on the determination result of the head position determination circuit determination circuit. The configuration is such that the relative positional relationship between the reproducing head and the track on the tape-shaped recording medium is controlled so as to pass the position of.

Further, the control means varies at least one of the tape running speed or the drum rotation speed or the position of the reproducing head on the rotating drum, so that the reproducing head and the track on the tape-shaped recording medium are changed. It is better to control the relative positional relationship.

When the recording signal is a digital image signal,
If the data recorded or reproduced at the first specific position is data that roughly constitutes an image, a high-speed reproduced image can be easily obtained.

The data that roughly forms an image can be used for high-speed reproduction as long as the data includes at least the DC component of the frequency-separated image signal.

[0022]

According to the present invention, since the code indicating the relative position of the head and the track is included in the recording data, the head position can be accurately determined during reproduction.

Based on the result of this judgment, the head can be controlled so as to accurately trace the target position, so that a signal recording / reproducing apparatus for surely reproducing the data at the specific position on the track can be constructed. By arranging the low-frequency component of the image signal at a specific position, high-speed reproduction with a compression type digital VTR, which has been difficult to achieve in the past, becomes possible.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a signal recording / reproducing apparatus according to an embodiment of the present invention.

In FIG. 1, 1 is an input terminal and 2 is a DCT.
Reference numeral 3 is a quantization circuit, 4 is a variable length coding circuit, 5 is a priority classification circuit, 6 is a tracking identification code addition circuit, 7 is an error correction code addition circuit, 8 is a recording head, and 9 is a tape shape. Recording medium, 10 reproduction head, 11 error correction circuit, 12 head position determination circuit, 13 DCT block reconstruction circuit, 14 variable length code decoding circuit, 15 inverse quantization circuit, 16 inverse DCT circuit, Reference numeral 17 is an output terminal.

The digital image signal input from the input terminal 1 is first subjected to discrete cosine transform (DCT) by the DCT circuit 2. In the DCT circuit 2, as shown in FIG. 2, the screen is divided into M × N blocks (B11 to BNM), and each block is a type of orthogonal transformation 2
Perform dimension DCT. The size of each block is 8x8
Is often used.

Data after DCT (DC, A12 to A88, FIG.
a) has been transformed into a two-dimensional orthogonal basis component. The orthogonal basis components in the two-dimensional DCT correspond to almost two-dimensional frequency components. The upper left of the transform coefficient is DC (direct current component), the right is a horizontal high-frequency component, and the lower is a vertical high-frequency component. You can think of it as representing.

Each block converted into a two-dimensional frequency component in this manner is then quantized by the quantization circuit 3. Quantization is an operation that divides each transform coefficient by a certain numerical value and rounds the number after the decimal point to assign an appropriate fixed-length bit to each coefficient.

FIG. 3b shows an example of a quantization table used for quantization. Numerical value in the quantization table,
Fig. 3b represents dividing the coefficient at the same position in Fig. 3a. For example, the DC component is divided by 8 and the A88 component is divided by 83. This operation is performed for all DCT blocks.

An appropriate code is assigned to each quantized coefficient in the variable length coding circuit 4 according to the frequency of occurrence of the quantized coefficient. Variable length coding is performed in the order of zigzag scanning as shown in FIG. A Huffman code, which is one of entropy coding, is often used as the code. The Huffman code classifies data by two parameters, which are a continuous amount of 0 and a numerical value following it. A short code is assigned to data with high occurrence frequency, and a long code is assigned to data with low occurrence frequency. It is often used as a so-called two-dimensional Huffman code.

By this processing, the statistical redundancy of the quantized DCT coefficient is removed. The variable length code does not necessarily have to be assigned to all the data in the block, and only a part may be variable length coded and the rest may be fixed length coded. For example, since the DC component has no statistical bias, it is often processed with a fixed length. Here, the DC component has a fixed length, and the AC component is divided into a set of high-order bits of the low-frequency component and a set of other AC components, and then variable length coding processing is performed in each set unit. Be present.

The variable length coded DCT coefficients are then
The classification circuit 5 for each priority classifies the screens according to their importance. In the importance level classification circuit 5, each coefficient inside the DCT block is given priority. For example,
As shown in FIG. 5, it is preferable to prioritize the low-frequency upper bits and the low-priority of the low-frequency lower bits and the high-frequency components. The codes classified by priority are then added with tracking identification codes by the tracking identification code addition circuit 6.

The high-order low-frequency component upper bits are recorded, for example, in the area 1 at the center of the track in FIG. Other low priority data are recorded in areas 2 and 3 at the bottom and top of the track. At this time, the data recorded in each area includes the above-mentioned tracking identification code adding circuit 6
In the above description, different identification codes are added to the signals, and the error correction code adding circuit 7 adds the error correction codes.

The identification code added to area 1 is a code indicating that the reproducing head is traveling in the correct position, and the code added to area 2 or 3 is such that the head is displaced to the front or the rear of the track. It is a code indicating that there is. This tracking identification code may be shared with another identification code representing the content of the data, or may be newly added.

The rotary drum equipped with the recording head is the same as the conventional example and is shown in FIG. The head loci when the tape-shaped recording medium thus recorded is reproduced at high speed are shown by arrows in FIGS. 7 and 8.

When the medium is made to travel at a speed higher than that at the time of recording during reproduction, the head travels across a plurality of tracks. In FIGS. 7 and 8, a wavy arrow indicates a case where the head has not traveled in the area 1 in which data used for high-speed reproduction is written (off tracking state), and a solid line indicates a case where the head has traveled in the area 1 (on tracking state). ) Is represented. When the head is off track, the data in area 2 or area 3 should be reproduced.

In this area, a code indicating which of the heads is displaced is recorded, so that the head can be used to perform servo control so that the head is on-tracked in area 1. Actually, after the reproduced signal is error-corrected by the error correction circuit 11, the head position judgment circuit 12 judges the head position by the identification code, and the servo is performed by the control means such as a servo circuit (not shown). Will be applied.

Area 2 and area 3 do not have to be on the same track as the track in which area 1 is included. For example, the track including area 2 may be a track ahead of the track including area 1, and the track including area 3 may be a track behind the track including area 1.

The servo is usually performed by controlling any or all of the medium traveling speed, the drum rotation speed, and the head position on the drum. The head position on the drum is often controlled in a direction perpendicular to the drum rotation direction, but it may be in the same direction as the drum rotation direction or in an oblique direction.

FIG. 10 shows an example of the identification code. a
Is similar to the method described above, but if the identification code indicating the center is recorded in the center of the area 1, the servo can be applied with higher accuracy. The method will be described.

FIG. 11 is a conceptual diagram showing a reproduction envelope during high speed reproduction. The playback envelope during high-speed playback is
Since the head runs across a plurality of tracks, the amplitude changes periodically. The minimum envelope is when the head jumps the track. Even if the head passes through the area 1 during high-speed reproduction but does not pass through the center of the area 1, the center identification code is displaced from the maximum amplitude position of the envelope as shown in FIG. 11A. Detected in.

As described above, by checking the relative positional relationship between the amplitude of the envelope and the center identification code, it can be determined whether the head passes through the center of the area 1 or the end thereof. To determine the amplitude of the envelope, the envelope may be monitored directly, but a method of checking the error rate of the reproduced data or a method of recording another code before and after the code for identifying the central part in area 1 is there. If it is possible to detect which position the head is passing in area 1, control the head trajectory by the method described above,
As shown in FIG. 11B, accurate servo can be performed so that the central identification code is located at the central position of the envelope.

FIG. 10B shows an example in which the identification area is further increased. FIG. 10D is an example in which the identification code is not assigned to each area but is sequentially assigned from the lower end to the upper end of the track. In the examples of (b) and (d), it is possible to know in detail which position on the track the head is passing, so the distance between the position where the head should pass and the current head position is grasped, and It is possible to apply the optimum servo according to the situation. (C) is area 1
The same control can be performed when the is located outside the center of the track.

FIG. 6 shows an example in which two pairs of heads are provided instead of one pair. At this time, since two pair tracks can be simultaneously scanned, even if an error occurs in the data of one track and the identification code cannot be obtained, the identification code of the other track can be used. The structure can be strong against data errors.

FIG. 9 shows an area where the head can acquire data at this time. It shows that two tracks can be simultaneously scanned. Also, the scannable area changes depending on the speed of the medium, and the area increases in the track length direction as the speed becomes lower. Therefore, the priority classification circuit 5 classifies and arranges the data into a plurality of priorities. As a result, it is possible to realize high-speed reproduction in which an image having a large amount of information is reproduced as the reproduction speed becomes low. Even in this case, the control of the head may be the same as that described above.

The data thus obtained is D
It is passed to the CT block reconstruction circuit 13. The DCT block reconstructing process performs a completely opposite operation to the classification process according to priority at the time of recording, and DCT is performed from each code recorded in a distributed manner.
This is a process of reconfiguring a block. The code returned to the DCT block is variable-length coded at the time of recording by the variable-length code decoding circuit 14, and is returned to the fixed-length code.

The code returned to the fixed length code is then quantized by the inverse quantization circuit 15. Inverse quantization is to multiply the values in the quantization table during recording. The inversely quantized code is finally processed by the inverse DCT circuit 16 by the inverse DC.
Then, the reproduced image is obtained at the output terminal 17.

At the time of high speed reproduction, the image data is restored only by using the data in the specific area (data having a high priority).

As described above, according to the present embodiment, different identification codes are added to the data forming the image and other data during high speed reproduction, and the head locus is controlled by reproducing the same, so that the specific area can be accurately defined. Can be played.

[0050]

As described above, according to the present invention, different codes can be added to the data to be reproduced at the time of high-speed reproduction and other data, and the head can be accurately controlled to a specific area based on the code, so that compression is possible. High-speed reproduction of a digital VTR or the like becomes easy.

[Brief description of drawings]

FIG. 1 is a processing block diagram showing an image signal recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a process of dividing a screen into a plurality of DCT blocks.

FIG. 3 is a conceptual diagram showing a DCT coefficient and a quantization table.

FIG. 4 is a conceptual diagram showing a zigzag scan.

FIG. 5 is a conceptual diagram showing an example of priority of each DCT block in a screen.

FIG. 6 is a conceptual diagram showing an embodiment of a scanner used in the present invention.

FIG. 7 is a conceptual diagram showing a tape pattern and a head locus according to an embodiment of the present invention.

FIG. 8 is a conceptual diagram showing a tape pattern and another head locus according to an embodiment of the present invention.

FIG. 9 is a conceptual diagram showing a tape pattern and a head locus according to an embodiment of the present invention.

FIG. 10 is a conceptual diagram showing an identification code recording area according to an embodiment of the present invention.

FIG. 11 is a schematic diagram showing a central identification code and a reproduction envelope according to an embodiment of the present invention.

FIG. 12 is a block diagram showing a conventional image signal recording / reproducing apparatus.

FIG. 13 is a conceptual diagram showing a conventional high-speed playback image.

FIG. 14 is a conceptual diagram showing an example of a conventional scanner.

FIG. 15 is a conceptual diagram showing a head locus and a reproduction area during conventional high-speed reproduction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input terminal 2 DCT circuit 3 Quantization circuit 4 Variable length coding circuit 5 Priority classification circuit 6 Tracking identification code addition circuit 7 Error correction code addition circuit 8 Recording head 9 Tape-shaped recording medium 10 Reproduction head 11 Error correction circuit 12 head position determination circuit 13 DCT block reconstruction circuit 14 variable length code decoding circuit 15 inverse quantization circuit 16 inverse DCT circuit 17 output terminal 18 rotating drum 19, 20, 21, 22 recording head or reproducing head

Claims (8)

[Claims] 1. An apparatus for recording a signal by forming a plurality of tracks on a tape-shaped recording medium which is obliquely wound around a rotating drum equipped with a recording head and which runs at a constant speed. Means for arranging a first identification code group indicating a position on the track at a first specific position of the second and a second position located in front of the track from the first specific position.
Means for arranging a second identification code group indicating that it is ahead of the first specific position at a specific position of
And a means for arranging a third identification code group indicating that it is behind the track from the first specific position at a third specific position located behind the track from the specific position Among them, a signal recording / reproducing apparatus comprising at least one means for recording an identification code in at least one of the first to third specific positions. 2. The signal recording / reproducing apparatus according to claim 1, wherein the first to third specific positions are located on the same track. 3. The second specific position and the third specific position are tracks different from the track containing the first specific position, and the second specific position is the first specific position. Located on the track ahead of the track that contains the specific position,
The signal recording / reproducing apparatus according to claim 1, wherein the third specific position is located on a track rearward of a track including the first specific position. 4. At least one data group of first to third data groups corresponding to each of the first to third at least specific positions is recorded at each position. 4. The signal recording / reproducing device according to claim 1, wherein the signal recording / reproducing device is recorded in addition to the identification code or recorded in a data group alone. 5. The recording signal is a digital image signal, and at least one data group among the first to third data groups is a data group that roughly forms an image. Signal recording and reproducing device. 6. The signal recording / reproducing apparatus according to claim 5, wherein the data group which roughly forms the image is a data group which includes at least a DC component of the frequency-separated image signal. 7. A part or all of a signal recorded on a tape-shaped recording medium which is wound obliquely around a rotary drum equipped with a reproducing head and which runs at a speed higher than the tape running speed at the time of recording. A signal reproducing device for reproducing,
7. A first identification code group reproduced from a first specific position according to claim 1, a second identification code group reproduced from a second specific position, or a third specific code group. The relative positional relationship between the reproducing head and the first to third specific positions is determined by at least one type of identification code group among the three types of identification code groups reproduced from the position. Head position determining circuit and the reproducing head and the tape-shaped recording so that the reproducing head can accurately pass any one of the first to third specific positions based on the determination result of the head position determining circuit. A control means for controlling a relative positional relationship with a track on the medium, and reproducing a part or all of the signals recorded at at least first to third specific positions on the tape-shaped recording medium. Signal reproduction characterized by Location. 8. The control means varies at least one of the tape running speed, the drum rotation speed, and the position of the reproducing head on the rotating drum, so that the reproducing head and the track on the tape recording medium are changed. The signal reproducing device according to claim 7, wherein the relative positional relationship is controlled.