JPH0973638A - Optical information recording / reproducing device - Google Patents

Abstract

(57) [Summary] [Problem] In conventional land / groove recording, the amount of data that can be continuously processed at one time is the same as in the conventional case, and high-speed recording / reproducing of data is impaired. SOLUTION: An optical system 22 for irradiating a land and a groove with a light beam, AT error signal generating circuits 23, 24 for generating an AT error signal of the land light beam and the groove light beam, and any one AT Equipped with a tracking servo loop that performs tracking control with an error signal, the phase difference between the AT error signals of the land and groove light beams is set to 0, and the servo polarity of the land and groove light beams is switched to reverse the servo polarity. Do without letting. Further, an adder 25 for adding the AT error signals of the light beams of the land and the groove is provided, and tracking control of the two light beams of the land and the groove is performed using the added signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for optically recording or reproducing information, and more particularly to a track guide groove (groove) of an information track of an information recording medium and a space between guide grooves (land). The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information on / from both.

[0002]

2. Description of the Related Art Conventionally, as a technique for optically recording or reproducing information, when classified by a recording and reproducing system, R is
Three types are known: an OM (reproduction only) type, a WORM (additional write) type, and an R / W (rewritable) type. The recording media in such three types of recording / reproducing technologies all use a transparent material such as glass or polycarbonate as a substrate,
The types are classified according to the difference in the material to be coated and film-formed on this substrate. That is, if a material having a high reflectance and a high thermal stability such as aluminum is used, a ROM type recording medium is used, and if a material that causes an irreversible reaction by heat such as an organic dye is used, a WORM type recording medium or a magnetic material is used. An R / W type recording medium is obtained by using a material that magnetically and thermally causes a reversible reaction such as a phase change material (which can be in a crystalline or amorphous state). Further, when classifying such recording media according to their shapes, they are mainly classified into a disk type, a card type and a tape type. Each of these recording media has its own characteristics and is used depending on the intended use. Among them, the disk-type recording media are popular as the most general recording media because of their excellent high-speed information transfer.

FIG. 9 is a diagram showing a conventional disc type optical information recording medium. In FIG. 9, lands 2a and 2b and grooves 3a and 3b are formed on the disc 1. Usually, the data to be recorded on the disc 1 is continuously formed in a predetermined amount, and this is generally called a track. Further, in the case of the disc type recording medium as shown in FIG. 9, the data tracks are formed in a concentric circle shape or a spiral shape, but from the viewpoint of continuity of data transfer, it is preferable to form the tracks in a spiral shape. This is advantageous when dealing with a large amount of data. That is, as shown in FIG. 9, a guide groove (groove 3) is spirally formed on the disk 1, and the space between lands (land 2) is used as a data track.
By scanning the data track with the recording / reproducing light beam, a large amount of data can be continuously recorded / reproduced. Further, recently, a technique called land / groove recording has been developed in order to increase the recording capacity. This is to record data on both the land and the groove in the disk having the shape shown in FIG. 9, thereby doubling the recording capacity.

[0004]

In the conventional land / groove recording method, when data having a large amount of information is recorded on the land / groove recording medium, for example, the polarity of tracking control is set to the land side. Then, after recording the data on the land 2a, the polarity of the tracking control is switched to the groove side and the data is recorded on the groove 3a. That is, land, groove, land, and groove are alternately recorded in this order from the inner circumference side or the outer circumference side of the disc 1. However, with this recording method, the polarity switching of the tracking control and the track jump operation of the light beam are performed each time data is recorded for one track or one round of the disk, so the continuity of the recording operation is significantly impaired. I will end up. This is the same in the case of reproduction.

In addition, the land 2a is followed by the land 2b, 2
It is also possible to record data in order on the land portion like c, and when the recording capacity of the land portion runs out, switch the polarity of tracking control to the groove side and record in order in the group like the grooves 3a and 3b. . However, with this recording method, when moving from land to groove, if the last recorded land and the first recorded groove differ greatly in radial position, the optical head must be greatly sought, and high speed operation is still required. Will be damaged. As described above, in the conventional land / groove recording, although the recording capacity is doubled, the amount of data that can be continuously processed at one time is the same as the conventional one, so that the speed of data recording and reproduction is impaired. was there.

In view of the above-mentioned conventional problems, the present invention has an object to provide an optical information recording / reproducing apparatus capable of continuously performing recording / reproducing switching of a land and a groove.

It is another object of the present invention to provide an optical information recording / reproducing apparatus capable of simply and accurately performing tracking control and focus control of two light beams of a land and a groove.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical information recording / reproducing apparatus for recording information on both lands and grooves of an information track of an optical information recording medium, or for reproducing both information. A means for irradiating the land and the groove of the information track with a light beam, a first error signal generating means for generating a tracking error signal of the light beam applied to the land, and a light beam applied to the groove Second error signal generating means for generating the tracking error signal of 1), and by generating the phase difference between the tracking error signals of the first and second tracking error signal generating means to substantially 0, the land and the groove The switching of the tracking servo of the light beam is performed without inverting the polarity of the tracking servo. It is achieved by an optical information recording and reproducing apparatus according to claim.

It is another object of the present invention to provide an optical information recording / reproducing apparatus which records information on both lands and grooves of an information track of an optical information recording medium, or reproduces both information. Means for irradiating the land and the groove with a light beam respectively, and generating a tracking error signal of the light beam with which the land is irradiated and the light beam with which the groove is irradiated, respectively.
And a tracking error signal generating means for generating a phase difference between the tracking error signals of the land and the groove to substantially 0, and an adding means for adding two tracking error signals of the light beams of the land and the groove. The optical information recording / reproducing apparatus is characterized in that the tracking control of the two light beams of the land and the groove is simultaneously performed by using the output signal of 1.

Further, an object of the present invention is to provide an optical information recording / reproducing apparatus for recording information on both lands and grooves of an information track of an optical information recording medium, or reproducing both information. Means for irradiating each of the land and groove with a light beam, and a focus error signal for the light beam for irradiating the land and the light beam for irradiating the groove, respectively, and a focus error signal for the land and groove. A focus error signal generating means for generating a phase difference of substantially 0, and an adding means for adding two focus error signals of the light beams of the land and the groove are provided, and the land and the groove are output by using an output signal of the adding means. An optical information recording / reproducing apparatus characterized in that focus control of two light beams of It is achieved me.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the optical information recording / reproducing apparatus of the present invention. FIG.
In the figure, reference numeral 1 denotes an optical disk which is an information recording medium, and is rotated at a predetermined speed by driving a spindle motor (not shown). A spiral track is formed on the disk 1 as shown in FIG. Further, in this embodiment, as the disc 1, a land / groove recording disc capable of recording data on both the land and the groove is used. The optical system 22 is provided with a light source for a land track and a light source for a groove track, and two light beams emitted from each light source are focused by an objective lens 21 to form a minute light spot on the information track of the disc 1. It is focused on the land and groove.

FIG. 2 is a diagram showing this state, in which the light beams of the two light sources are focused by the objective lens 21 and are centered on the lands 2a and the grooves 3b formed on the substrate 4 such as polycarbonate of the disk 1. 5 light spots each
It is collected as a and 5b. A part of the light spot thus condensed is reflected by each of the land and the groove, and the respective reflected lights pass through the objective lens 21 again and are respectively received by the optical sensors in the optical system 22. Optical system 2
2 corresponds to a known push control method such as a push-pull method, and AT error signal generation circuits 23 and 24
Generates a tracking error signal for each of the light spots of the land and groove based on the light reception signal of the optical sensor of the optical system 22. Optical system 22, AT error signal generation circuit 2
Details of 3, 24 will be described later. Although omitted in FIG. 1, a focus servo circuit and a focus actuator are provided, and the light beam emitted from the objective lens 21 in FIG. 2 by these control operations is on the information surface of the land and groove of the disc 1. It is controlled to always focus on.

The adder circuit 25 is an AT error signal generation circuit 2
A circuit for adding the tracking error signals S1 and S2 of 3 and 24, the switch 26 is a controller circuit 29.
It is a switch for selectively outputting one of the tracking error signals of the AT error signal generation circuits 23 and 24 and the addition circuit 25 based on the control of 1. The selection of the tracking error signal will be described later, but the switch 26
The tracking error signal selected in 1 is supplied to the actuator driver 31 through the phase compensator 27 for stabilizing the servo, the switch 28 for turning the tracking control on and off, and the adder 30. The actuator driver 31 converts the input signal into a current signal, drives the tracking actuator 32, and displaces the objective lens 21 in the tracking direction, thereby performing tracking control.

The controller circuit 29 is constituted by including a CPU, and controls the switch 28 in the apparatus to turn on / off the tracking servo, and by applying an acceleration pulse to the adder 30, an optical spot is formed on the target track. Control to move it. In addition, the control circuit 29 controls the switch 26 to perform control for selecting a tracking error signal according to the track position to be actually recorded and reproduced, and data is recorded on a desired track of the disc 1 by such control. Played or played.

FIG. 3 is a diagram showing a specific configuration of the optical system 22. In the figure, 41 is a light source such as a semiconductor laser,
A land light source 41a and a groove light source 41b are provided corresponding to the land and the groove. Land light source 4
1a, the light beam emitted from the groove light source 41b is collimated by the collimator lens 42, then passes through the beam splitter 43 and enters the objective lens 21. Then, the two light beams are focused by the objective lens 21 as described above, and are converged as a small light spot on the land and the groove as shown in FIG. On the other hand, the light reflected by the land and the groove again passes through the objective lens 21, enters the beam splitter 43, is reflected by the toric focusing lens 44, and is converged on the optical sensor 45. 46-49 have shown the current-voltage converter. Note that FIG. 3 shows an example of an optical system having the simplest configuration, and when a so-called magneto-optical disc that utilizes the magnetic Kerr effect is used as the type of the optical disc 1, a polarization beam splitter is used to obtain an information reproduction signal. Etc. are required. However, even when a new optical element is added to the optical path of the optical system in this way, it does not depart from the essence of the present invention.

FIG. 4 shows an optical sensor 45 and A in the optical system 22.
It is a figure showing the example of T error signal generating circuits 23 and 24. As the optical sensor 45, a sensor divided into at least four is used. That is, in the present embodiment, the optical sensor 45 is divided into two in the track orthogonal direction corresponding to the land and groove light beams, and the divided sensor is further divided into two in the track direction. There is. Sensor 52
Reference numerals a and 52b are sensors for receiving the reflected light of the light spot 5a condensed on the land as shown in FIG. 2, and 5a 'shows the reflected light of the light spot 5a projected on the sensor.
Further, the sensors 51a and 51b are sensors for receiving the reflected light of the light spot 5b condensed in the groove, and 5b 'similarly shows the reflected light of the light spot 5b projected on the sensor. These sensors 52a and 52b, sensor 5
Positions of 1a and 51b are adjusted so that the centers of the light spots coincide with the dividing lines of the sensor in the track direction.

The output signals of the sensors 52a and 52b of the optical sensor 45 are output to the AT error signal generating circuit 23, and converted into voltage signals by the current-voltage converters 46 and 47 therein. The output signals of the current-voltage converters 46 and 47 are differentially detected by the differential amplifier 53, and the tracking error signal S1 is output. The tracking error signal S1 corresponds to the light spot 5a applied to the land as described above, and is a signal indicating the direction and amount of deviation of the light spot 5a. Further, the output signals of the sensors 51a and 51b are output to the AT error signal generation circuit 24 and converted into voltage signals by the current-voltage converters 48 and 49 inside thereof. The output signals of the current-voltage converters 48 and 49 are differentially detected by the differential amplifier 54, and the tracking error signal S2 is generated. The tracking error signal S2 is a signal representing the direction and amount of deviation of the light spot 5b irradiated on the groove as described above. The method of generating such a tracking error signal is similar to the push-pull method.

In this embodiment, when the AT error signal generating circuit 24 generates the tracking error signal S2 for the optical spot of the groove, the signal input to the differential amplifier 54 is input to the tracking error signal of the optical spot of the land. S
The case of 1 is reversed. That is, in the AT error signal generation circuit 23 for land, the output signal of the sensor 52a is input to the non-inverting input terminal of the differential amplifier 53, and the output signal of the sensor 52b is input to the inverting input terminal, whereas the A for groove is input.
In the T error signal generation circuit 24, the output signal of the sensor 51b on the side opposite to the sensor 52a is input to the non-inverting input terminal of the differential amplifier 54, and the output signal of the sensor 51a on the side opposite to the sensor 52b is input to the inverting input terminal. There is. This is to make the phase difference between the two tracking error signals S1 and S2 zero, which will be described later in detail.

FIG. 5 is a diagram showing signal waveforms of the tracking error signals S1, S2 and S3 when the light spot from the optical system 22 crosses the track in the radial direction of the disk 1. FIG. 5A shows the tracking error signal S1 obtained from the reflected light from the land, and the black circles indicate the points where the light spot coincides with the land center. FIG. 5B shows the tracking error signal S2 obtained from the reflected light from the groove, and the black circles similarly indicate the points where the light spot coincides with the groove center. In this way, the tracking error signal becomes a periodic sinusoidal signal every time the land and groove are crossed, so that a desired land or groove can be tracked by selecting an appropriate point.

Here, since the land and the groove have a spatial relationship of 180 degrees in phase originally, the diffraction pattern reflected on the sensor also has a phase difference of 180 degrees. In this regard, in this embodiment, when the tracking error signals S1 and S2 are generated as described with reference to FIG. 4, the output signals of the sensor are input to the differential amplifier with opposite polarities, so the tracking error signals S1 and S2 are input. It is possible to ideally make the phase difference of 0. Therefore, when the tracking servo is switched from the land light spot to the groove light spot and the phase difference is 180 degrees, the polarity of the tracking servo is reversed, that is, the phase of the tracking error signal is set to 180 in the tracking servo loop. I have to flip it once. In contrast, in the present embodiment,
Since the phase difference between the tracking error signals of the land and the groove is set to 0, it is not necessary to invert the polarity of the tracking servo, and the tracking servo can be switched from the land to the optical spot of the groove simply by switching the switch 26. Therefore, when the tracking servo is switched from the land to the groove, it is not necessary to switch the polarity of the tracking servo or perform the track jump operation, so that recording and reproduction of the groove can be continuously performed from the land.

By the way, in the above description, the phase difference between the tracking error signals S1 and S2 is set to 0. However, the phase difference between the tracking error signals S1 and S2 is caused by the initial adjustment error of the optical system 22 and the optical axis shift due to aging. May not be completely zero. This state will be described with reference to FIGS. For example, now the AT error signal generation circuit 2
It is assumed that the tracking error signal S1 of 3 is selected and the tracking servo is applied to the light spot on the land.
At this time, if there is an optical axis shift as described above, FIG.
In contrast to the tracking error signal S1 of the light spot on the land, the tracking error signal S2 of the light spot on the cleave has a phase difference Δn as shown in FIG. 5B. Also,
In this state, the land light spot 5a is located at the center of the land 2a as shown in FIG. 6A, but the groove light spot 5b is displaced from the center of the groove 3b by Δμm.

On the other hand, if the tracking error signal S2 of the AT error signal generating circuit 24 is selected by the switch 26 and tracking servo is applied to the groove light spot, as shown in FIG. 6B, the groove light spot is obtained. 5b is located at the center of the groove 3b, but the light spot 5a on the land has a track shift of Δμm from the center of the land 2a. In such a case, when the tracking servo is applied to the two light spots by either of the tracking error signals S1 and S2, one of the light spots causes a track shift, and therefore, during normal information recording and reproduction,
When recording or reproducing only one of the land and the groove, it is desirable that the switch 26 selects the tracking error signal obtained from the optical spot of the recording / reproducing actually.

Further, in this embodiment, as shown in FIG.
The adder 25 for adding the tracking error signals of the T error signal generation circuits 23 and 24 is provided, and tracking servo is performed using the output signal of the adder 25 to remove the influence of the optical axis deviation as described above. are doing. This will be specifically described. FIG. 5C is a diagram showing the output signal S3 of the adder 25. The adder 25 outputs the signal S3 obtained by adding the tracking signals S1 and S2 as described above.
When 1 and S2 are added, the phase of the signal S3 has an intermediate value between the tracking error signals S1 and S2 as shown in FIG. 5C.

Therefore, when the tracking servo is applied by using the signal S3, the tracking offset caused by the optical axis shift is distributed to the land and the groove in half, so that as shown in FIG. Both the optical spots 5b of the groove have a track shift amount of Δμm / 2 with respect to the center of the land and the center of the groove.
Therefore, the influence of the optical axis shift can be substantially eliminated as compared with the case where the tracking servo is performed with either one of the light spots. Therefore, even if the optical axis shift occurs by selecting the output signal S3 of the adder 25 with the switch 26 and applying the tracking servo using this signal S3, although there is one tracking servo loop,
Both the light spot 5a on the land and the light spot 5b on the groove can be scanned substantially at the center of the land and at the center of the groove. Therefore, in this embodiment, since the light spots are emitted from both the light sources to both the land and the groove, the output signal S3 of the adder 25 is used to generate the two light spots in order to further demonstrate this advantage. By applying the tracking servo, the land and the groove can be simultaneously recorded and reproduced, and the information recording and reproducing speed can be significantly increased.

FIG. 7 is a diagram showing a second embodiment of the present invention. This embodiment is an example in which an optical axis shift detection circuit is further provided in the apparatus of FIG. 1 and the optical axis shift of the light beam is detected especially when simultaneous recording and reproducing by two beams. In FIG.
The AT window comparator 33 is an off-track detection circuit for detecting an off-track of the light spot 5a on the land from the tracking error signal S1 of the AT error signal generation circuit 23. AT window comparator 33
Then, the tracking error signal S1 is fetched and the track deviation amount (deviation amount with respect to the land center) of the light spot 5a is compared with a predetermined track deviation allowable value. When it exceeds, it outputs an AT deviation detection signal (AT optical axis deviation detection signal) to the control circuit 29. Further, the AT error signal generation circuit 2 is also used in the AT window comparator 34.
The tracking error signal S2 of No. 4 is taken in and the track deviation amount (deviation amount with respect to the groove center) of the light spot 5b of the groove is compared with the allowable value.
When the amount of track deviation exceeds the allowable value, the AT deviation detection signal (AT optical axis deviation detection signal) is similarly output to the control circuit 29. Other configurations are the same as those in FIG.

Here, the AT window comparator 33
The permissible values of the track deviations of Nos. 34 and 34 are set as follows. First, when the tracking error signal S1 is selected by the switch 26 and the tracking servo is applied to the light spot 5a on the land, the AT window comparator 34 is set to the allowable value of the AT window comparator 33.
The allowable value of is looser than that and is set to about twice. That is, in consideration of the case where there is an optical axis deviation as described above, the allowable value of the track deviation amount for which the tracking servo is not applied is set loosely. When the track deviation is detected as described above, if the track deviation amount due to the tracking error signal S2 exceeds the allowable value, it may be determined that the two light sources are no longer used to simultaneously record and reproduce the land and the groove. Therefore, in this case, when the AT detachment detection signal is output, the control circuit 29 performs control such as prohibiting recording / reproduction by two beams or generating a warning for urging optical adjustment. It is possible to prevent occurrence of double recording or the like due to track deviation of the light spot.

When the tracking error signal S2 is selected and the tracking servo is applied to the light spot of the groove, conversely, the allowable value of the AT window comparator 33 is set looser than that of the AT window comparator 34. Also in this case, the tracking error signal S
When the amount of track deviation due to 1 exceeds an allowable value, erroneous recording and reproduction can be prevented in advance by performing control such as prohibiting simultaneous recording and reproduction by two beams as in the above description. it can. Finally, when tracking servo is performed using the output signal S3 of the adder 25,
Since the land and groove light spots have the same track deviation amount, the allowable values of the track deviation amounts of the AT window comparators 33 and 34 are set to the same value. At this time, the track deviation may be detected by only one of the AT window comparators 33 and 34. Also in this case, when the track deviation is detected, the simultaneous recording / reproduction by the two beams is similarly prohibited, or the warning for urging the optical adjustment is generated to prevent erroneous recording / reproduction in advance. be able to.

FIG. 8 is a diagram showing a third embodiment of the present invention. This embodiment is an example in which the configuration of FIGS. 1 and 7 is applied to a focus servo. In FIG. 8, an AF error signal generation circuit 63 generates a focus error signal S4 of the light spot 5a irradiated on the land, and an AF error signal generation circuit 64 indicates the light spot 5b irradiated on the groove.
It is a circuit for generating the focus error signal S5. Further, in the present embodiment, for example, the knife edge method is adopted as the focus control method, and the AF error signal generation circuits 63 and 64 generate the focus error signal accordingly.

In the knife edge method, as shown in FIG. 4, two-divided photosensors are used corresponding to the lands and grooves, and the light-receiving signals of the sensor elements of the two-divided photosensors are differentially detected. , Land and groove focus error signals are obtained. In the focus servo, the phase of the focus error signal is not inverted between the land and the groove unlike the above-mentioned tracking error signal, so that it is not necessary to make the phase difference of the focus error signal zero. Therefore, for example, when the focus error signal is generated with the configuration as shown in FIG. 4, the polarities of the input signals are reversed when the signals of the respective sensor elements of the two split photosensors are input to the two differential amplifiers. No need. That is, in FIG. 4, the sensors 51a, 5a
1b and 52a, 52b received light signal to the differential amplifier 53,
When inputting to 54, the same polarity may be used.

The focus error signals S4 and S5 of the AF error signal generating circuits 63 and 64 are selected by the switch 66 according to the land and the groove under the control of the control circuit 29. The selected focus error signal is supplied to the actuator driver 71 through the phase compensation circuit 67, the switch 68, and the adder 70. Then, the focus driver 72 is driven by the actuator driver 71 to displace the objective lens 21 in the focus direction, thereby performing focus control so that the light spot or the information surface of the land or groove is focused. In this way, by selecting the focus error signal S4 corresponding to the recording / reproducing on the land by the switch 66 and selecting the focus error signal S5 corresponding to the recording / reproducing on the groove, the land and the groove are selected. Focus control can be performed accurately regardless of the situation.

Further, in the present embodiment, the focus error signals S4 and S5 of the AF error signal generation circuits 63 and 64 are added by the adder 65 and output as a signal S6. With respect to the output signal S6 of the adder 65, the value of the focus deviation due to the initial optical adjustment error or the change with time has an intermediate value between the focus error signals S4 and S5, based on the same principle as the tracking error signal S3. . Therefore,
By selecting the signal S6 with the switch 66 and applying focus servo using the signal S6, the focus offset can be divided into lands and grooves in half, so that the two light spots can be divided into lands and grooves without defocusing. It can be scanned, and in particular, it can be suitably used for simultaneous recording and reproducing of land and groove by two beams.

Finally, also in the present embodiment, the AF error signal generating circuit 6 is controlled by the AF window comparator 73.
The focus error signal S4 of No. 3 is taken in to detect the out-of-focus of the light spot 5a on the land, and the AF window comparator 74 causes the AF error signal generation circuit 64.
The focus error signal S5 of 1 is taken in to detect the defocus of the light spot 5b of the groove. In any of these cases, an allowable value for focus deviation is set in advance, and if it exceeds that value, an AF out-of-focus detection signal (AF optical axis deviation signal) is output.

When the focus servo is applied by the focus error signal S4, the AF window comparator 74
When the permissible value of the focus deviation is set to be loose and the focus servo is performed by the focus error signal S5, on the contrary, the permissible value of the focus deviation of the AF window comparator 73 is set to be gentle. Therefore, if out-of-focus is detected on either side, erroneous recording and reproduction can be prevented in advance by prohibiting recording and reproduction by two beams or issuing a warning prompting optical adjustment. it can. Further, when the focus servo is performed using the output signal S6 of the adder 65, the tolerance values of the focus deviations of the AF window comparators 73 and 74 may be set to the same value, or only one of them may be focused. The disconnection may be detected. Also in this case, when out-of-focus is detected, erroneous recording and reproduction can be prevented by performing control such as prohibiting recording and reproduction with two beams.

[0034]

As described above, according to the present invention, the phase difference between the tracking error signals of the two light beams irradiated on the land and the groove is generated to be substantially zero,
When the tracking servo is switched from the land light beam to the groove light beam, it is not necessary to reverse the polarity of the servo, and there is an effect that recording and reproducing of the land and the groove can be continuously performed.

Further, two tracking error signals of the light beams of the land and the groove whose phase difference is generated to be substantially 0,
By adding the two focus error signals and performing tracking control and focus control of the two light beams of the land and the groove by using the added signal, the tracking offset and the focus offset due to the optical axis misalignment can be applied to the land and the groove. Since it is divided into two light beams of, the effect of optical axis deviation can be substantially halved,
There is an effect that tracking and focusing of two light beams can be accurately and stably controlled by one servo loop.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an optical information recording / reproducing apparatus of the present invention.

FIG. 2 is a diagram showing a state in which a land and a groove of the disc of the embodiment of FIG. 1 are irradiated with a light beam.

FIG. 3 is a diagram showing a specific example of an optical system 22 of the embodiment of FIG.

4 is a diagram showing a specific example of an optical sensor of the optical system 22 and AT error signal generation circuits 23 and 24 in the embodiment of FIG.

5 is an AT error signal generation circuit 23 of the embodiment of FIG.
6 is a diagram showing tracking error signals of 24 and an adder 25. FIG.

FIG. 6 is a tracking error signal S1 of the embodiment of FIG.
It is the figure which compared and showed the track shift of the light spot of a land and a groove when tracking servo is each applied by S2 and S3.

FIG. 7 is a diagram showing a second embodiment of the present invention.

FIG. 8 is a diagram showing a third embodiment of the present invention.

FIG. 9 is a diagram for explaining tracks on a disc recording medium.

[Explanation of symbols]

 1 Optical Disc 2a, 2b Land 3a, 3b Groove 21 Objective Lens 22, 62 Optical System 23, 24 AT Error Signal Generation Circuit 25, 65 Adder 26, 66 Switch 29 Control Circuit 32 Tracking Actuator 33, 34 AT Window Comparator 63, 64 AF error signal generation circuit 72 Focus actuator 73, 74 AF window comparator

Claims (6)

[Claims] 1. An optical information recording / reproducing apparatus which records information on both lands and grooves of an information track of an optical information recording medium or reproduces both information.
Means for irradiating the land and groove of the information track with a light beam respectively, first error signal generating means for generating a tracking error signal of the light beam for irradiating the land, and light beam for irradiating the groove Second error signal generating means for generating a tracking error signal, and by generating a phase difference between the tracking error signals of the first and second error signal generating means to substantially 0, the light of the land and the groove is generated. An optical information recording / reproducing device, characterized in that the tracking servo of a beam is switched without inverting the polarity of the tracking servo. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the light beams of the land and the groove are detracked based on the tracking error signals of the first and second tracking error signal generating means. An optical information recording / reproducing apparatus characterized by detecting. 3. An optical information recording / reproducing apparatus which records information on both lands and grooves of an information track of an optical information recording medium, or reproduces both information.
Means for irradiating the land and groove of the information track with a light beam, respectively, and tracking error signals for the light beam irradiated on the land and the light beam irradiated on the groove, respectively, and for tracking the land and the groove. A tracking error signal generating means for generating a phase difference of the error signal to approximately 0 and an adding means for adding two tracking error signals of the light beams of the land and the groove are provided, and the output signal of the adding means is used to An optical information recording / reproducing apparatus characterized by simultaneously performing tracking control of two light beams of a land and a groove. 4. The optical information recording / reproducing apparatus according to claim 3, wherein the land and groove are generated based on the tracking error signal of at least one of the land and groove light beams generated by the tracking error signal generating means. An optical information recording / reproducing apparatus characterized by detecting a track deviation of a light beam. 5. An optical information recording / reproducing apparatus for recording information on both lands and grooves of an information track of an optical information recording medium, or reproducing both information,
Means for irradiating the land and the groove of the information track with a light beam, respectively, and a focus error signal generating means for generating a focus error signal of the light beam for irradiating the land and the light beam for irradiating the groove, respectively. And an adder for adding two focus error signals of the light beams of the land and the groove, and using the output signal of the adder, the two of the land and the groove.
An optical information recording / reproducing apparatus characterized in that focus control of two light beams is simultaneously performed. 6. The optical information recording / reproducing apparatus according to claim 5, wherein the land and groove are generated based on at least one focus error signal of the land and groove light beams generated by the focus error signal generating means. An optical information recording / reproducing apparatus characterized by detecting defocus of a light beam.