JP2760408B2 - Optical information recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a 2D light source provided with a recording light source and a reproduction light source separately.
The present invention relates to a light source type optical information recording / reproducing apparatus.

2. Description of the Related Art Conventionally, various media such as a disk, a card, and a tape have been known as a medium for recording information using light and reading the recorded information. These optical information recording media include those capable of recording and reproduction,
Some can only be reproduced. In particular, the use of an optical card as a recording medium is expected to be expanded due to features such as ease of manufacturing, portability, and accessibility. Various optical information recording / reproducing apparatuses for this optical card are provided.

In the above optical information recording / reproducing apparatus, recording, while always performing auto tracking and auto focusing control,
Playback is performed. The recording of information on the recording medium is performed by scanning the information track with a light beam that is modulated according to the recording information and narrowed into a minute spot, and the information is recorded as an optically detectable information pit string. You. To reproduce information from a recording medium, a light beam spot having a constant power that does not record on the medium scans an information pit row of an information track and detects reflected light or transmitted light from the medium. It is done by doing.

As a recording / reproducing method of such information, a single light source method and a multiple light source method have been proposed. FIG. 9 shows a typical configuration of the single light source system.

In the apparatus shown in FIG. 9, a collimator lens 102 converts a light beam emitted from a semiconductor laser 101 into a parallel beam,
The light beam is divided into a plurality of light beams, and is condensed on an optical card 107 via a polarizing beam splitter 104, a quarter-wave plate 105, and an objective lens 106. The reflected light from the optical card 107 is
The light enters the photodetector 109 via the 6, 1/4 wavelength plate 105, the polarizing beam splitter 104, and the toric lens. At this time, recording, reproduction, and auto-focusing control (hereinafter, referred to as AF) are performed using the 0th-order diffracted light of the light beams split by the diffraction grating 103, and auto-tracking control (hereinafter, referred to as AT) is performed using ± 1st-order diffracted light. Is called). AF is an astigmatism method, and AT is a three-beam method.

FIG. 10 (A) is a schematic plan view of the optical card. On the optical card 107, a large number of information recording / reproducing tracks are arranged in parallel, and some of them are denoted by T1, T2, and T3. This track is divided by tracking tracks tt1 to tt4. The tracking tracks tt1 to tt4 are formed of a material having a different reflectance from the grooves or the tracks T1 to T3, and are used as a guide for obtaining a tracking signal. Fig. 10 (A) is a truck
An example in which information is recorded or reproduced in T3 is shown. In this example, the 0th-order diffracted light 110 for recording, reproduction, and AF
Above, the ± 1st order diffracted lights for AT 111 and 112 are tracking tt respectively.
Irradiates 3, tt4. Then, a tracking signal described later is obtained from the reflected light from the diffracted lights 111 and 112 so that the zero-order diffracted light 110 scans the track T3 correctly. Each of the diffracted lights 110, 111, 112 scans the optical card 107 left and right on the drawing by a mechanism (not shown) while maintaining the same positional relationship. The scanning method includes a method of moving an optical system and a method of moving an optical card. In any case, since the optical system and the optical card reciprocate relative to each other, portions having non-constant speeds occur at both ends of the optical card.

FIG. 10 (B) shows this state. The horizontal axis in FIG. 10 (B) indicates the left-right direction of the optical card, and the vertical axis indicates the scanning speed. The constant-speed scanning area at the center of the normal optical card 107 is used as a recording area.

FIG. 11 (A) is an enlarged view of a portion of each of the diffracted lights 110 to 112 in FIG. 10 (A). 0th order diffracted light 110 for recording, reproduction, AF
Is located at the center of the ± first-order diffracted lights 111 and 112 for AT and scans the center of the track T3. The hatched portions 113a, b, and c are the zero-order diffracted light
In the recording example by 110, it is generally called a pit. Since the pits 113a, b, and c have different reflectances from the periphery, when the light is scanned again with the weak light spot 110, the reflected light of the zero-order diffracted light 110 is modulated by the pits 113a, b, and c, and a reproduction signal is obtained.

FIG. 12 shows details of the photodetector 109 shown in FIG. 9 and a signal processing circuit. The photodetector 109 is a quadrant photosensor 11
4, optical sensors 115 and 116 are provided for a total of six optical sensors. The light spots 110a, 111a, 112a are
Each of the diffracted lights 110, 111, and 112 in FIGS.
Represents reflected light. The light spot 110a is a quadrant light sensor 11
4 and the light spots 111a and 112a are respectively
Focus on 116. Sensor outputs of the four-division sensor 114 in the respective diagonal directions are added by addition circuits 117 and 118, respectively. The outputs of the adders 117 and 118 are similarly added by the adder 121 to produce an information reproduction signal RF. That is, RF corresponds to all of the light spots 110a focused on the four-divided optical sensor 114. Also, the outputs of the adders 117 and 118 are subtracted by the differential circuit 120 to become a focusing control signal Af. That is, Af is the difference between the sums of the four divided optical sensors 114 in the diagonal directions. This astigmatism method is well known in the literature and is not directly related to the present invention, so that the description is omitted. The outputs of the optical sensors 115 and 116 are subtracted by the differential circuit 119 to become a tracking control signal At. Normally, this At is controlled to be zero.

111a and 112a are the ± first-order diffracted light 1 as shown in FIG.
If it is 11,112 reflected light, and each diffracted light 111,112 is applied only to the same part on each tracking track tt3, tt4,
The light spots 111a and 112a have the same light amount. Therefore, if the tracking control signal At is controlled to be zero, the zero-order diffracted light 110 will be located at the center of the tracking tracks tt3 and tt4.

Returning to FIG. 11 (A) again, if the scanning trajectory of the 0th-order diffracted light 110 at the time of recording and at the time of reproduction is different, that is, when the tracking is displaced, the RF contrast and the time width of the pit portion fluctuate, and the information is lost. Playback may not be possible. Such a state is caused by vibration of the device, dust or scratches on the optical card 107. In addition, it also occurs due to a machine difference when performing recording and reproduction by another device. In particular, in the case of the single light source method, since the recording and reproduction are light spots of the same size, information may not be reproduced even if the recording and reproduction tracking are slightly shifted. Therefore, it can be said that the one light source method has a small tracking margin. Also, the power of each of the diffracted lights 110, 111, and 112 is greatly different between pit recording and non-recording, and the light spots 110a, 111a, and 112a change similarly.
It has the disadvantage of affecting AT control.

Compared to these conventional examples, a two-light source method can be considered to increase the tracking margin for recording and reproduction and prevent power fluctuation in the photodetector. The details of the two light source method will be described later, but the operation on the optical card will
This will be described with reference to FIG. In this example, the conventional three light spots are not used for recording information, and the recording light spot 25 is not used.
Is provided separately. The reproduction and AF light spots 26 and the AT light spots 27 and 28 are the same as the diffracted lights 110, 111 and 112 in FIG. 11 (A), respectively. However, the light spots 26, 27, and 28 have the same size, but the light spot 25 is smaller than them.
FIG. 11B shows a state in which information is being recorded in the direction of the arrow on the track T3 by the light spot 25.

Pit 29a in the shaded area recorded by light spot 25,
The width of 29b is smaller than that of the reproducing light spot 26. Therefore, even if the scanning trajectory of the light spot 26 slightly deviates from the scanning trajectory of the light spot 25, the RF signal is not affected as much as in the case of FIG. 11 (A). Increasing the ratio of the light spots 25 and 26 in this way increases the tracking margin, but also reduces the RF contrast.
26 cannot be increased without darkness. Also, light spot
If the 25 light wavelengths are different from the light spots 26, 27, and 28, the reflected light from the light spot 25 can be easily separated by a dichroic mirror and does not enter the photodetector, affecting AF control and AT control. Has no effect.

[Problems to be Solved by the Invention] However, this two-light source system also has a disadvantage. This method is realized by combining light beams from two light sources into the same optical system, but it is difficult to accurately align the respective optical axes.
That is, in FIG. 11 (B), the tracking track tt
It can be said that it is practically almost impossible to accurately position the light spots 25 and 26 on a dashed line (track center) parallel to 3, tt4. Therefore, as shown in FIG. 11 (B), the light spots 25 and 26 of the actual device are shifted by d in the direction perpendicular to the track. That is, as is apparent from the drawing, the light spot 26 scans the dashed line by shifting the pits 29a and 29b recorded on the broken line by the light spot 25 by d.
This means that the tracking margin, which has been increased by making the light spot 26 larger than the light spot 25, is reduced or invalidated. Also a light spot
Since the deviation d between 25 and 26 differs depending on the device, if recording and reproduction are performed by another device, information may not be reproduced at all.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a two-light source capable of effectively correcting a positional deviation between a recording pit and a reproduction light spot and reproducing recorded information accurately. It is an object of the present invention to provide an optical information recording / reproducing apparatus of the type.

[Means for Solving the Problems] An object of the present invention is to provide a first light spot for recording information on an optical information recording medium having a plurality of tracks, and reproduction of information from the optical information recording medium. And generating a second light spot or a group of light spots for performing auto-focusing control and auto-tracking control, and scanning the first light spot and the second light spot or the light spot group on a track to obtain information. In an optical information recording / reproducing apparatus for recording and reproducing information, at the time of recording and reproducing information, auto-tracking control is performed using the second light spot or light spot group, and the second light spot or light spot is performed. In order to change the position on the tracks of the group in the direction perpendicular to the track at the time of recording and at the time of reproduction, the automatic tracking servo circuit is turned on at the time of recording and at the time of reproduction. Means for changing the tracking position by changing the offset input signal,
At the time of recording information, the first light spot and the second light spot or the group of light spots are turned on, and an offset is given to the auto tracking servo circuit so that the center of a track is scanned by the first light spot. In reproducing information, the offset given to the auto tracking servo circuit is set to zero, and the center of the track is scanned by the second light spot or the group of light spots without turning on the first light spot. This is achieved by an optical information recording / reproducing device that performs the above-described operations.

Example An example of the present invention will be described below with reference to FIG. In this embodiment, it is assumed that an astigmatism method is used for AF control and a three-beam method is used for AT control.

In FIG. 1, reference numeral 1 denotes a recording semiconductor laser,
The divergent light beam is converted into a parallel light beam by the collimator lens 3, and enters the objective lens 10 through the dichroic prism 7, the polarizing beam splitter 8, and the 波長 wavelength plate 9.
Then, the optical card 11 is irradiated as minute spots on the optical card 11 by the objective lens 10 to form a recording pit on the recording surface of the optical card 11 based on the information. The optical card 11 is the same as the optical card 107 shown in FIG.

The reflected light from the optical card 11 passes through the objective lens 10, the quarter-wave plate 9, and the polarization beam splitter 8 to the photodetector 13 (the ninth
It is reflected to the same side as 109 in the figure). In this case, the reflected light is reflected and absorbed by the toric lens 12 provided with a film that cuts the wavelength of 830 nm, so that the light detector 13
And does not adversely affect the information reproduction system and the AT / AF control system.

Next, the divergent light beam from the reproducing semiconductor laser 2 having a wavelength of 780 mm becomes a parallel light beam by the collimator lens 4, the light beam is restricted by the aperture 5, and is split into a plurality of light beams by the diffraction grating 6. These plural light beams are reflected by the dichroic prism 7 and irradiate the optical card 11 as minute spots along the optical path substantially the same as the optical path of the semiconductor laser 1. The reflected light from the optical card 11 is
After passing through the wave plate 9, the light is reflected by the polarization beam splitter 8 and condensed by the toric lens 12 on the photodetector 13.

Since the aperture of the light beam from the semiconductor laser 2 is controlled by the aperture 5, the light beam forms a light spot group larger than the light spot of the semiconductor laser 1 on the optical card 11. Semiconductor laser 2
Is used for focusing control and tracking control, so that it is always driven by the reproducing laser driver 23 so as to always have a constant weak light amount, regardless of whether it is recording or reproducing. The information generated by the controller 20 including the MPU is modulated by the modulation circuit 21 into a recording code, and the semiconductor laser 1 is driven only during recording by the recording laser driver 22 in accordance with the recording code. In an actual apparatus, recording information is often provided from an external apparatus. In this case, the controller 20 includes an interface with an external apparatus, and the recording information is supplied via this interface. or,
Reproduction information to be described later is also transferred to an external device via this interface.

On the other hand, the photodetector 13 is the same as that in FIG. 9 and the details are the same as those described for the photodetectors 114 to 116 in FIG. The light receiving processing circuit 16 includes the adder circuit 117 shown in FIG.
It has the same configuration as 118 and 121 and the differential circuits 119 and 120, and generates an information reproduction signal RF, a focusing control signal Af, and a tracking control signal At based on a signal received by the photodetector 13. Focusing control signal is AF, AF servo circuit
The focusing coil 14 is driven via 17 to move the objective lens 10 up and down so that the light spot is focused on the optical card 11. The tracking control signal At also drives the tracking coil 15 via the AT servo circuit 18 to move the objective lens 10 in the direction perpendicular to the plane of the drawing to perform tracking. The optical card 11 moves in the direction of the arrow and moves relative to the light spot by means (not shown), and the light spot scans the optical card 11.

The other input of the AT servo circuit 18 is an offset input, which is obtained by converting the signal of the controller 20 into an analog signal by the D / A converter 24, and the controller 20 can freely change the tracking offset. ing. The information reproduction signal RF is demodulated from the recording code into the original information by the demodulation circuit 19 and read by the controller 20. or,
This is generally transferred to an external device via the interface in the controller 20 as described above.

Here, the light beams from the semiconductor lasers 1 and 2 are joined to the same optical path by the dichroic prism 7 and
It is difficult to accurately align the optical axis on the above. Normal track pitch, that is, tracking track tt1,
The pitch of each of tt2, tt3, and tt4 is about 12 μm, and the recording light spot and the reproduction light spot need to match on the order of submicron. It is not difficult to optically adjust each optical information recording / reproducing device in such an order.
Rather, it is almost impossible.

In order to solve this, in the present invention, the tracking correction is performed by changing the offset input signal of the AT servo circuit 18 during recording and during reproduction to change the tracking position. FIG. 2 is a diagram for explaining the above operation, and the symbols of the respective parts are the same as those in FIG. 11 (B). FIG. 2A shows a state at the time of recording. In this case, an offset is given to the AT servo circuit 18, and the tracking position (broken line) is shifted to the right on the drawing by δ. Therefore, the light spots 26, 27, 28
Is shifted to the right by δ from the center. δ is the difference between the positions of the light spots 25 and 26 obtained by the position detecting means described later. As a result, the recording light spot 25 scans the center (dot-dash line) of the track T3, and the recording pits 29a, 29b
Is formed at the center of the track T3.

FIG. 2 (B) shows a state in which the information thus recorded is reproduced. In this case, the offset of the AT servo circuit 18 is set to zero, and the light spot 26 scans the center of the track T3.
It takes the same amount to 3, tt4. At this time, the position of the recording light spot 25 (broken line) is shifted to the left by δ, but does not pose a problem because the light spot 25 is not turned on. In this way, the scanning trajectory of the light spot 25 at the time of recording, that is, the scanning trajectory of the recording pit and the light spot 26 at the time of reproduction are almost the same at the center of the track T3, and the feature of the two light source system that the tracking margin is large is sufficiently used. You can enjoy.

The above description will be described in more detail with reference to the tracking signal shown in FIG. FIG. 3 (A) is T S1, TS of FIG.
2 signals, the horizontal axis m is the light spot 111, 112 or
27 and 28 represent the distances when moving in a direction perpendicular to the track. The vertical axis represents the amount of light at the optical sensors 115 and 116. In this case, the light spot is the tracking track tt.
This shows an example in which the amount of received light decreases as much as 3, tt4. If there is no offset in the optical system and electrical system as shown in the figure, the position of m where T S1 and T T2 intersect is the track.
This is the center position of T3, where the light spots 27 and 28 are equally applied to the tracking tracks tt3 and tt4, respectively. FIG. 3B shows At = T S1 −T S2.
As can be seen from this figure, when the offset is zero and tracking control is performed at the center of the track T3, the AT servo pull-in range is symmetrical and the servo characteristics are most stable against disturbances such as vibration. However, as described with reference to FIG. 2, when an offset voltage is applied during recording and the object is shifted by δ in the m direction,
The AT servo pull-in range is symmetrical, and in this example, the right side becomes smaller and becomes weaker to disturbance. Therefore, it is better that the period for forcibly offsetting the AT servo is as short as possible. In particular, the acceleration / deceleration region described with reference to FIG. 10 (B) has a large vibration, and therefore, it is better that the offset is zero here. Since it is necessary to actually apply an offset only to the recording area, it is practical to apply the offset immediately before the recording area and to make the offset zero immediately after the recording area ends. Although this recording area detection is not shown, an optical card
It can be easily realized by providing a position detecting encoder in the mechanism for scanning and moving the position 11. Further, in the above-described embodiment, the case where there is no optical and electrical offset is shown.

Next, the operation of detecting the positional relationship (shift amount) δ between the light spots 25 and 26 shown in FIG. 2 will be described. FIG. 4 shows δ
This is a flowchart of the operation for detecting, and can be realized by the configuration example of FIG.

First, in step S (step) 31, the offset mi is made zero by the controller 20, the D / A converter 24, and the AT servo circuit 18, and in step S32, predetermined information is written by the controller 20, the modulation circuit 21, and the recording laser driver 22 into the optical card 11. Test record on track T3. FIG. 5 shows the positional relationship between recording pits and tracks at this time. Light spot as in the example of FIG.
If 25 and 26 are shifted by d, recording pits 29a, 29b, 29c
Is recorded at a position (dashed line) shifted by d from the center of the track T3 (dashed line). The two-dot chain lines m ₁ and m ₂ indicate the track T3
Are symmetrical with respect to the center and are separated from the center by a distance sufficiently larger than d. Next, offset mi in S33
Is set to m ₁ and the recording pit is reproduced in S34. The reproduced signal reaches the controller 20 via the light receiving processing circuit 16 and the demodulation circuit 19, and is collated with the predetermined information recorded in the collation determination in S35. Next, compare the current offset mi and m ₂ at S36, m
If i has not reached m ₂ , the offset value is shifted right by a small amount Δ in S37, and the information is reproduced again in S34. Thus the offset value mi within which repeated to gradually move to the right offset S34~37 reaches m _2, exits the loop. An offset value l ₁ collation determination operation in collation result S35 is consisted not in a good out of this loop, stores the offset values l ₂ became not good to, at S38 [delta] = (l ₁ + l ₂ ) /
Exit as 2. Then, as described with reference to FIGS. 2 and 3, at the time of recording, an offset is applied by δ in the direction opposite to the direction at the time of position detection. In the above description, the positive and negative signs of mi are omitted. The δ thus measured may not exactly correspond to d. However, it is practically sufficient to correct the offset by δ measured by this method. In the above embodiment, the information reproduction is performed by m ₁
It beginning ended in m _2, but may be terminated with m ₁ and to the m ₁ and m ₂ in the reverse start with m _2.

In the embodiment of FIG. 4, the number of times of information reproduction, that is, S34 to S38
The number of repetitions of the loop is fixed and (m ₂ −m ₁ ) / Δ. However, according to this method, even if l ₁ and l ₂ can be detected early, it takes as much time as when the detection is performed late. FIG. 6 shows another embodiment in which this is improved. Note that the same step numbers as those in FIG. 4 represent the same operations, and a description thereof will be omitted.

In this example, a good flag is used in S40 when the collation determination in S35 is good from bad. Offset starting at m ₁ and S
If the collation result is negative at 35, the good flag is determined at S40, and S41
Then, the good flag set of S42 is bypassed, and the offset value is shifted to the right to go around the loop of S41 and S42. Further, the offset value reaches l _1, the verification is good, the process proceeds from S41 turn to S42, and one set in a good flag and returns to the subsequent S34 through S37.

Next, since the good flag is 1, S43 is passed through S35 and S40.
If the offset has not reached l ₂ ,
Continue turning around the loop from S37 to S34. If the offset exceeds l _2, the process proceeds from S43 to S38, and ends by calculating the [delta].

In this embodiment, the number of loop iterations is (l ₂ −m ₁ )
/ Δ, which is smaller than in the example of FIG. 4, so that the position detection time can be shortened. Note that there are various other procedures for changing the offset value in the position detection as described above, and the present invention is not limited to the above-described embodiment.

FIGS. 4 and 6 show an example in which a positional relationship is indirectly estimated, that is, a determination is made by collating predetermined recording information with its reproduction information.

FIG. 7 shows another embodiment in which the position of the reproduced signal is detected by judging the reproduced signal itself. This utilizes the fact that the amplitude of the reproduction signal RF becomes maximum when the recording pit and the reproduction light spot coincide. In this embodiment, the demodulation circuit shown in FIG.
Instead of 19, the information reproduction signal RF is rectified by the rectifier circuit 44, the maximum value of one information reproduction is held by the peak hold circuit 45, and the digital value is converted by the A / D converter 46 to be compared by the controller 20. Make a decision. FIG. 8 shows this operation procedure. Note that the same step numbers as those in FIGS. 4 and 6 represent the same operations, and therefore description thereof will be omitted. FIG. 4,
An offset value similar to the Figure 6 and from m _1, performs information playback S34. Then, in S47, the peak of the amplitude of the information reproduction signal RF described with reference to FIG. 7 is detected. Next, in S48, the previous peak value P _i-1 is compared with the current peak value P _i, and if P _i is large, the offset value is shifted to the right by Δ in S37, and S37 to
Go around the loop of 34. Of course, the initial value of Pi _-1 is set to zero so that a loop is reliably established. Then, P _i in S48
When ≦ P _i−1 , the process exits the loop and ends in δ with the offset value mi at that time in S49.

4 and 6 can be implemented with the configuration example of FIG. 1. Since the configuration of FIG. 1 is necessary for an optical information recording / reproducing apparatus, in this case, a position detecting means may be incorporated. . However,
If the software that implements this is large, it is better to separate it. In addition, since the example shown in FIG. 7 is not usually required for an optical information recording / reproducing apparatus, it is disadvantageous in terms of cost and size to incorporate it. Since the optical positional relationship does not fluctuate after it has been created once, in this example, when the adjustment is made, the apparatus shown in FIG. 7 is coupled to the optical information recording / reproducing apparatus to perform position detection. It is practical to store only the information in the optical recording / reproducing apparatus or set it by other means.

In the two light source system described above, three light spots for reproduction control are used, but the present invention is not limited to this. Various methods have been proposed for focusing control and tracking control, and it is also possible to realize information reproduction, focusing control, and tracking control with one light spot. Also, the method of performing reproduction and control with one light spot is in the same state as in the present embodiment with respect to tracking, and the present invention is effective.

[Effects of the Invention] As described above, according to the present invention, in a two-light source system in which a light spot for recording and a light spot for reproduction control are used as separate light sources, pits are recorded by offsetting tracking during recording, and offset is performed during reproduction. And zero, the positional deviation between the recording pits and the reproduction light spot caused by the positional relationship between the light spots on the recording medium by the two light sources can be corrected, and the advantage of the two light source system can be enjoyed to the maximum. effective. Further, according to the present invention, the positional relationship between the light spots from the two light sources on the recording medium can be easily measured, and the measurement and the above correction can be realized without increasing the cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an optical information recording / reproducing apparatus according to the present invention, and FIGS. 2 (A) and 2 (B) are views showing the positional relationship of light spots on an optical card. FIGS. 3 (A) and 3 (B) are explanatory diagrams showing a tracking control signal, FIG. 4 is a flowchart showing an operation for detecting a positional relationship between two light spots in the embodiment, FIG. FIG. 4 is an explanatory diagram showing the positional relationship between recording pits on the optical card in the detecting operation of FIG. 4, FIG. 6 is a flowchart showing the positional relationship detecting operation of a light spot in another embodiment, and FIG. FIG. 8 is a block diagram showing another embodiment of the spot position detecting means, FIG. 8 is a flowchart showing the detecting operation of the embodiment of FIG. 7, FIG. Figure (A) is a schematic plan view of an optical card. FIG. 10 (B) is an explanatory diagram showing the relationship between the area of the optical card and the scanning speed, and FIG. 11 (A) is an explanatory diagram showing the positional relationship between light spots on the optical card in the conventional one light source system. FIG. 11 (B) is an explanatory view showing the positional relationship of light spots on an optical card in a conventional two light source system, and FIG. 12 is a diagram showing the photodetector of FIG. 9 and a signal processing circuit for processing its light receiving signal. It is a block diagram shown in detail. 1: Semiconductor laser for recording 2: Semiconductor laser for reproduction 11: Optical card, 13: Photodetector 16: Light receiving processing circuit, 17: AF servo circuit 18: AT servo circuit 20: MPU controller

Claims (1)

(57) [Claims] 1. A first light spot for recording information on an optical information recording medium having a plurality of tracks, and a first light spot for reproducing information on the optical information recording medium and performing auto-focusing control and auto-tracking control. An optical information recording / reproducing apparatus that generates two light spots or light spot groups, scans the first light spot and the second light spot or light spot group on a track, and records and reproduces information. At the time of recording information, at the time of reproduction, perform auto-tracking control using the second light spot or light spot group,
In order to change the position of the second light spot or light spot group on the track in the direction perpendicular to the track at the time of recording and at the time of reproduction, the offset is changed by changing the offset input signal of the auto-tracking servo circuit at the time of recording and at the time of reproduction. Means for changing the position, when information is recorded, the first light spot and the second light spot or a group of light spots are turned on, and the center of a track is scanned by the first light spot. An offset is given to the auto-tracking servo circuit, and at the time of reproducing information, the offset given to the auto-tracking servo circuit is set to zero, the first light spot is not turned on, and the track is shifted by the second light spot or the light spot group. An optical information recording / reproducing device which scans the center.