JPS58121138A - Recording and reproducing device of optical information - Google Patents

Abstract

PURPOSE:To realize the recording/reproducing of optical information with high recording density, by using together the information read out of a main beam and two secondary beams in order to reduce the crosstalk produced from the adjacent track. CONSTITUTION:A reproduced RF signal V1 is delayed by a variable delaying circuit 11 by a time ta+tb which is required for a beam B1 to move from x1 to x3 on a track T1. While a signal V2 is delayed by a variable delaying circuit 12 by a time tb required for a beam B2 to move from x2 to x3 on a track T2. The signals V1 and V3 are attenuated by attenuators 13 and 14 down to a level equivalent to the crosstalk procuded from the adjacent track that has intervention to the signal V2. The signals V1 and V3 are inverted by polarity inverting circuits 15 and 16 respectively and added with the signal V2 through an adder 17. Thus a signal containing no crosstalk component is delivered.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-beam tracking type optical information recording/reproducing apparatus, and more particularly to means for reducing crosstalk from adjacent trunks.

In general, one of the biggest reasons why recording companies are hindering the increase in the number of recording companies in this type of information recording and reproducing device is that when the track pitch is made small, crosstalk from instantaneous contact tracks increases, making it impossible to obtain a good signal. It is. Therefore, various efforts have been made so far, but overall *a
The problem was that it became complicated and expensive.

By the way, as is well known, in the three-beam tracking type optical information recording/reproducing device, the signal @
In addition to the main beam B2, two sub-beams Bl and BS for tracking are arranged in a predetermined positional relationship. Each beam, which has been modified according to the information recorded on the track, is received by a separate photoreceiver and converted into electrical signals vz, v, t, and va. VJ and vS are shown in Figure 2. After the low frequency component is detected by the level detector 1.2, the subtracter 3 subtracts it to detect the tracking error signal. That is, the low frequency component is not directly related to each piece of information on the track and includes only trunk position information. Thus, for example, for three beams, the track'
I'J, T2. When TJ shifts to the left in FIG. 1, vl increases and vl decreases. If it shifts in the opposite direction, vl will be slightly smaller than vl.
increases. Therefore, by subtracting YJ-Vj, a tracking error signal can be obtained.

It uses two 11" beams and can be changed depending on the recorded information.
Each of the l# beams is individually converted into an electrical signal. Therefore, the crosstalk from the intervening track on the main beam 4 should naturally also intervene on the two sub beams BJ and BJ.

The present invention was developed in light of this point, and its purpose is to use the information read out by the two sub-beams in a three-beam tracking type optical information recording/reproducing device. An object of the present invention is to provide an optical information recording/reproducing device capable of detecting a tracking error according to Fi+ and at the same time reducing crosstalk from adjacent tracks included in a main beam.

An embodiment of the present invention will be described below with reference to the drawings. Third
The figure shows three beams Bl for tracks TI, TI, T3VC.
,B2. It is a diagram showing the @hi ship attendant of Bl. As is clear from the figure,) three beams Bl in the direction perpendicular to the rack,
B2. The BJCD center-to-center distance @, S is set to be slightly smaller than the track pitch P so that when a deviation from the track occurs, the output changes occurring in Vl, Vl are reversed.

Further, the distance between the centers of the three beams Bl, BZ, and B3 in the track direction is a predetermined distance.

Figure 4 shows the three and - modulated by the recorded information on the track.
The signals Vl and Vj are the same as those shown in FIG.

This is a cause indicating the v1 number processing means. Three beams Bl, B
2, BJ (7) Re-iRF signal Vl, V2゜■ Of 3, Vl and vl are low frequency signals detected by level detectors 1 and 2, respectively, as explained in the xJ2 diagram, and subtractor 3 detects Vl. -vl is subtracted, and the tracking error year is detected.

10,000, Vl is beam B1 on track T1 from xl to x
The beam B2 is delayed by the variable delay circuit 11 by the time ta+tb required to move to the track T.
It is delayed by the variable delay circuit 12 by the time tb required to move from xl to xl on 2. Thus VJ.

Vl and Vj are synchronized. Also, vl and vl are
Attenuators 11 and 14 each attenuate to a level corresponding to the crosstalk from adjacent tracks intervening in vl. The attenuated vl and {circle around (3)} have their polarities inverted by polarity inverting circuits 15 and 16, respectively, and then are added to vl by an adder 17. As a result adder 17
outputs a signal from which crosstalk components have been removed from vl.

By the way, the times ta and tb are determined by the rotational speed ω of the disk 18 and the read position (position in the radial direction of the disk). Therefore, if ω is constant, the −speed is ωr.
Therefore, the delay time of the delay circuits 11 and 12 is xl-xi xJ-xl.
, tb- ω r ωr.

Therefore, in this device, as shown in FIG. 4, a position signal is obtained by a position detecting potentiometer 20 which is moved by a tracking remoter 19 of a reading optical system, and this is added to a variable delay circuit 11.11. A delay time corresponding to tb is given to Vl and Vl.

In this way, in this device, 3 and 1 are used as the 11th,
Tracking error signals can be detected and crosstalk can be reduced at the same time. In addition, in this device, as a result of performing the beam arrangement as shown in Figure 2, for example, a residual tracking error occurs, and the tracks TJ, T, ', and TJ are replaced by the three beams BJ.
, B2, if it shifts to the right in the figure with respect to BJK,
The degree of influence of the drift stalk on the main beam B2 is greater in track T1 than in track T3, but beam B1 becomes on-track and the level of ■1 increases, so v
The crosstalk caused by l also becomes thicker. For this reason,
There is no deterioration of the crosstalk light enemy effect, and it has the advantage of stably reducing crosstalk.

Note that the present invention is not limited to the one embodiment described above.For example, in the embodiment, the diameters of the three beams B1, Bj, and BJ are the same, and two sub-beams Bl are used for the main beam B2.

By reducing the diameter of BJ, crosstalk from track T2 being reproduced by main beam B2 is transmitted to sub beams Bl and BS.
It may also be possible to prevent intervention. In this way, the effect of reducing crosstalk is one order of magnitude. It goes without saying that the present invention can be implemented in various other ways without departing from the gist of the present invention.

As explained above, according to the present invention, when a tracking error occurs, the tracking error signal is detected by subtracting the low frequency signals reproduced from the two sub beams, and is also included in the main beam for rejection. Crosstalk from adjacent tracks is canceled by a crosstalk component that synchronizes the reproduction RF signals of the two side beams. Therefore, the tracking error signal can be detected as before using the information read out by the two sub-beams, and at the same time the crosstalk from adjacent tracks included in the main beam can be reduced. An optical information recording/reproducing device with a recording density can be provided.

[Brief explanation of the drawing]

1 and 2 show the beam arrangement and tracking error signal correction detection means in a conventional three-beam tracking type optical information recording and reproducing device. Figure 3 is a diagram showing the arrangement of the three beams with respect to the track, and Figure JII!4 is a block diagram showing processing means for signals obtained from the three beams.1. 2...Level detector, 3...Subtractor, 11゜1
2... Variable delay circuit, 11.14... Attenuator, 15
．． 16... Polarity inversion circuit, 11... Adder, 18...
...Disc, 1#...Feed motor, 20...Position detection potentiometer. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 Figure 1 Procedural amendment dated January 1'5, 1982 Director General of the Patent Office Haruki Shimada 1. Indication of the case 1988 patent Ganga No. 2497 2. Name of the invention: Optical information recording/reproducing device 3. Person making the amendment. Relationship to the case. Patent applicant (037) Orin ξ Sukouji Kogyo Co., Ltd. 4. Agent 6. Details subject to amendment. Full text of the book” '11: 'I correct content

Claims (1)

[Claims] In a three-beam tracking type optical information recording/reproducing device, the signal! 51! The two sub-beams for tracking are set to the main beam for tracking, so that the distance between the centers of the beams is slightly smaller than the track pitch in the direction perpendicular to the track, and the distance between the two sub-beams for tracking is slightly smaller than the track pitch in the direction perpendicular to the track. means for receiving each of the beams modulated by information recorded on the disk and converting them into electrical signals; and a low frequency signal reproduced from the two sub-beams converted by the means. means for detecting a tracking error based on the difference between the signals; and means for synchronizing the converted signals;
@! An optical information recording and reproducing device which is advantageous in that it is equipped with a means for subtracting from the number.