JPH065595B2 - High-speed search system for recording signals - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high-speed search method for a recording signal, and particularly to a high-speed recording signal suitable for reading information at a predetermined position recorded on a disc. It relates to a search method.

[Outline of Invention]

When searching for a target recording track, the frame number inserted for each track at a predetermined track interval and the position information corresponding to the frame number are detected and stored in a memory or the like. When the frame number to be input is input, the moving distance of the pickup is calculated from the data stored in the memory by the linear interpolation method, the pickup is moved to the calculated position at high speed, and then the target frame number is set. It is a search.

[Conventional technology]

As a method for recording video signals and the like on a recording medium formed in a disk shape, a video signal for one frame on a spiral or concentric track so that one image signal can be obtained by one rotation of the disk. Is recorded.

In addition, the video signal recorded by the above-mentioned method,
Various control data are also recorded within the vertical blanking period, and when reproduced, the frame number of the image being reproduced can be known from this control data.

Further, in a device for reproducing such a disc, an arbitrary screen can be reproduced by accessing this frame number by a command inputted from the outside.

In this case, as a conventional search method, a search method in which the input frame number is compared with the currently reproduced frame number, and the pickup is moved at high speed according to the difference has been put into practical use. The recording track pitch is quite different for each disc,
For example, there is a variation of about 1.5 μm to 1.8 μm.

Therefore, the error of the distance to jump the pickup increases, and the time to search for the target recording track after the jump becomes long.

Therefore, as previously proposed by the present application, there is a method of detecting a track pitch of a preset disk by some method and performing a prospective search based on the track pitch information (Japanese Patent Application No. 58-155476).

The “high-speed search method for information signals” described in this prior art is, for example, for 10000 tracks (100 tracks).
The relative movement distance K between the pickup and the disc corresponding to (00 images) is stored in a memory or the like, and the difference between the frame number N ₀ of the recording track position currently being reproduced and the frame number N ₁ to be searched next is calculated. Calculate and N ₀ −N ₁ ×
The target expected moving distance is calculated from K / 10000 to move the pickup at high speed.

[Problems to be solved by the invention]

According to such a method, even for a disc whose track pitch is not standard, for example, 1.67 μm,
Since the pickup can be moved to the vicinity of the target track at high speed with relatively high accuracy, the search time from that point can be shortened.

However, the actual disk has the following problems.

That is, as shown in FIG. 4, when the track pitch is constant for one disc, the frame number N and the distance L from the center of the disc to the frame number are in a proportional relationship as indicated by a straight line A. However, in most discs, the track pitch also slightly varies with the distance L as shown by the line B or C, and the start point and end point of the image program are also uneven.

Therefore, when accessing such a disk at a high speed, even the above-described search method of the prior art may cause a considerable error in the moving distance for performing the track jump, which makes high-speed search difficult.

The present invention has been made in consideration of such circumstances.
The present invention provides a high-speed search method for a recording signal, which enables a target track to be searched in a shorter time even when the track pitch of the disc is uneven.

[Means for solving problems]

In the high-speed search method of the present invention, the number of recording tracks is divided into at least the inner circumference and the outer circumference, and the frame number and the position information of the disk surface are detected at the divided points,
The relationship should be recorded in a memory or the like.

[Action]

Since the position information corresponding to the frame number is detected as data at many points in the radial direction of the disk surface, the position information of the target frame number is accurate by calculating the output of the memory storing the data. Can be calculated.

Therefore, the movement distance to jump the pickup becomes extremely accurate, and the search time after jumping becomes shorter.

〔Example〕

FIG. 1 is a block diagram showing a main part of an optical disk reproducing apparatus which can be adopted in the high speed search system of the present invention, in which M is a spindle motor for rotationally driving a video disk LD,
Reference numeral 1 is a pickup which optically detects a reproduction signal and various servo information from the video disk LD, and can be moved in a radial direction by a sled feed motor 2. A position signal generator 3 outputs the position information of the pickup 1 in the radial direction, and forms the position information from the output signal of the rotary encoder or the pulse generator FG, for example. Reference numeral 4 is a signal reproducing circuit, and 5 is a demodulating circuit.

Various servo signals obtained from the signal reproduction circuit 4 are input to the pickup 1, the thread feed motor 2, and a microprocessor described later via the servo circuit 6,
In addition to applying tracking servo and focus servo, the playback device is set to various drive modes.

Reference numeral 7 is a frame number detection circuit for detecting the frame number of the video signal from the demodulation circuit 5, and the frame number is normally 0.1.2.2.
It is set to a value that increases gradually to 4000.

Reference numeral 8 denotes a microprocessor (CPU) that controls the drive mode of the playback device. For example, the playback device is set to various modes in response to a command from the input device 10, and is shared with the memory 11 as described later. Then, the program for performing the high speed search of the present invention can also be executed.

Reference numeral 11 denotes a memory formed by a RAM, which can store the relationship between the position information output from the position signal generator 3 and the frame number as a table.

The recording signal high-speed search method of the present invention will be described below with reference to the flowchart of FIG.

The reproducing apparatus first sets the interval number Δn of frames to be detected from the type of the loaded disc, and then determines whether or not various servos operate normally to enable reproduction. Then, the table creation mode is set in order to create a relationship (table) between the frame number of the video signal recorded on the disk in the memory 11 and the position information of the position of the pickup 1 when reproducing the frame number.

In this table creation mode, the frame number n _m is m =
A search is performed every 0 _m from the 0th frame interval Δn every n _m = 1 + Δn × m, and the position information _m at this time is _fetched from the position signal generator 3 and written in the memory 11. Then, when a frame number _nm that makes the search impossible occurs, it is determined that the creation of the table for the relevant disc is completed.

Next, after the table is created, when there is a search command from the outside, the target frame number N is input, so at this time, m is sequentially increased from m = 0 and the target frame number N is increased. detecting a frame number n _m which is stored and in the large memory 11 than n, find the position information L of the frame number n of interest.

That is, after having calculated the frame number N is greater than the first frame number n _m of interest as shown in FIG. 3, the frame number n _m and n _m-1 of the position information _m,
read _m-1 from the memory 11, Is calculated to determine the target position information L of the frame number N, and the drive circuit 9 is driven at high speed. When the position information output from the position signal generator 3 becomes L, the high speed operation of the sled feed motor 2 is stopped, and at this point, the search mode is set and the target frame number N is searched.

In this case, the second term of the above equation (1) is the track pitch near the frame number n _m or n _m−1 close to the target frame number N, and the number of frames up to the target frame number N (N -N _m-1 ), the target position information L of the frame number N can be calculated with a considerably high accuracy even when the track pitch of the disc is non-uniform. It becomes accessible.

Needless to say, the larger the number of samples of the frame number _nm, the better the positional information.
The storage capacity of 1 increases, and time is consumed in the first table creation mode. Therefore, this Δ
It is preferable that n can be changed according to the contents of the program recorded on the disc and the usage of the disc.

Although the description has been given to the type (CAV) disk in which the angular velocity is constant, the type with constant linear velocity (CL
It is needless to say that the high speed search method of the present invention can be applied to the disk of V), and when there is a frame number, it can be applied to a recording medium other than the optical disk.

〔The invention's effect〕

As described above, the high-speed search method of the recording signal of the present invention enables the position information of the target recording track to be detected with high accuracy even when the track pitch is non-uniform on one disk. Therefore, the pickup can always be accurately moved to the track position of the target frame number, and the search time can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram of a reproducing apparatus which can be adopted in the high speed search system for recorded signals of the present invention, FIG. 2 is a flow chart showing the operation of the CPU when the high speed search system is performed, and FIG. FIG. 4 is a diagram for explaining the calculation method, and FIG. 4 is a diagram showing variations in the track pitch of the disc. In the figure, 1 is a pickup, 2 is a thread feed motor, 3
Is a position signal generator, 7 is a frame number detection circuit, 8
Is a CPU, 10 is an input device, and 11 is a memory.

Claims (1)

[Claims] 1. A disc reproducing apparatus including a pickup device for reproducing a signal recorded on a disc and a position signal generator for outputting position information of the pickup device, wherein a recording track formed on the disc. Is provided with a storage device for storing the frame number of the recording signal obtained when a multi-point search is performed at predetermined intervals and the position information of the pickup respectively, and the frame number to be searched is input from the input device. when,
Two pieces of position information close to the target frame number are read from the storage device, position information of the target frame number is calculated by a linear interpolation method, and the pickup is moved to the position of the calculated position information at high speed. A high-speed search method for recorded signals characterized by the above.