JPH08287490A - Tracking controller - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a highly reliable tracking control device even when a disc for recording information by changing the groove depth of an information track by a light beam is used. A gain variable circuit 22 that amplifies an output of an AGC circuit 20 that amplifies a tracking error signal in accordance with a light intensity sum signal, and has its gain switched from the outside, and an information detection circuit that detects the presence or absence of information on an information track. 21 is provided and the gain of the variable gain circuit 22 is changed in accordance with the output from the information detection circuit 21, so that the gain of the entire tracking system is irrespective of the presence or absence of information recording even in an optical disc in which the groove depth is changed and recording is performed. It is always constant, and tracking control can be performed stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking controller for controlling a light beam to follow an information track provided on a record carrier for recording and reproducing information.

[0002]

2. Description of the Related Art Nowadays, write-once type and rewritable type optical disk devices are widely used. Minute tracks are provided spirally or concentrically on a record carrier used in these devices, and information is recorded on the tracks. In order to record information on this minute information track or read information from this minute information track, the recording or reproducing light beam must always be positioned on the information track. Therefore, tracking control is required in the optical disk device.

A simple block diagram of a conventional tracking control device is shown in FIG. A conventional tracking control device will be described below with reference to FIG.

The disk 1 is rotationally driven by a motor 2. The light beam 4 emitted from the light source 3 is converted into parallel light by the coupling lens 5 and is converted into a polarization beam splitter 6
And passes through the quarter-wave plate 7 and is incident on the total reflection mirror 8. The light beam 4 which is reflected by the total reflection mirror 8 and whose traveling direction is changed is converged by the converging lens 9 to the disc 1 which is a record carrier.
Is focused on. The reflected light 10 of the light beam 4 reflected by the disk 1 passes through the converging lens 9 again, is converted into parallel light, and the total reflection mirror 8 changes the optical path so that it is incident on the ¼ λ plate 7. The reflected light 10 whose polarization plane has been converted by 90 ° by passing through the 1/4 λ plate 7 is reflected by the polarization beam splitter 6 and the total reflection mirror 14 and enters the photodetector 15 which is a two-divided tracking detector. The output of the photodetector 15 is converted into a voltage signal by the current-voltage converters 16 and 17 and input to the differential amplifier 18. Differential amplifier 18
Then, a signal indicating the positional relationship between the information track and the light beam, that is, a tracking error signal is detected. Here, the principle of detecting the tracking error signal will be briefly described with reference to FIG. FIG. 6A shows the positional relationship between the information track on the disc and the light beam (beam spot). Figure 6 (b)
Is the reflected light from the disk incident on the photodetector (15 in FIG. 5) when the positional relationship between the information track and the light beam is in the states shown in (1) to (5) of FIG. 6A. The intensity distribution of 10) in FIG. 5 is shown. Further, FIG. 6C shows the difference signal between the outputs of one detector (a) and the other detector (b) of the above-described two-divided photodetector. From FIGS. 6A, 6B, and 6C, it can be seen that the positional relationship between the information track and the light beam corresponds to the difference signal (that is, tracking error signal) of the photodetector divided into two. As described above, the tracking error signal is output from the differential amplifier 18.

In FIG. 5, the output of the differential amplifier 18 is AG
It is input to the C circuit 20. The AGC circuit 20 is generally composed of a divider or the like. The gain of the AGC circuit 20 is controlled by the output of the light quantity sum detection circuit circuit 19 including an adder or the like. Assuming that the output of the AGC circuit 20 is V, the output of the light quantity sum detection circuit 19 is AS, the tracking error signal output from the differential amplifier 18 is Vo, and the basic gain of the AGC circuit 20 is K, the AGC circuit 20 has V = K * (Vo
/ AS). The light quantity sum detection circuit 19 adds the outputs of the current-voltage converters 16 and 17 and outputs the result. That is, the output signal AS of the light quantity sum detection circuit 19 is a signal proportional to the intensity of the reflected light 10 from the disk which is incident on the photodetector 15.

The tracking control device shown in FIG. 5 is used in a recording / reproducing device. When recording information on the disc 1 by the recording / reproducing apparatus, the intensity of the light beam 4 emitted from the light source 3 is increased. Then, the intensity of the reflected light 10 from the disk that is incident on the photodetector 15 is also increased, and the differential amplifier 1
8 changes the magnitude of the tracking error signal obtained. If the magnitude of the tracking error signal changes, the gain of the tracking control system changes, and the stability of the tracking control system is impaired. The AGC circuit 20 is provided in the tracking control device shown in FIG. 5 in order to deal with this instability. As described above, both the tracking error signal Vo and the light quantity sum signal AS are signals proportional to the intensity of the reflected light 10 from the disk 1 incident on the photodetector 15. That is, Vo / AS always has a substantially constant relationship on the same disk. Therefore, V = K * Vo /
By providing the AGC circuit 20 operating in the relationship of AS in the tracking control device, the gain of the tracking control system is kept constant even when the intensity of the light beam 4 is increased when the information is recorded on the disc 1 by the storage / reproduction device. The control system becomes stable.

An output signal of the AGC circuit 20 passes through a tracking control circuit 23 composed of a filter and an amplifier for phase compensation and is output to a drive circuit 24. Reference numeral 30 is a loop switch for turning on / off the tracking control. A current corresponding to the output of the tracking control circuit 23 flows through the tracking coil 13 by the drive circuit 24. The converging lens 9 is driven in the radial direction of the disk by the electromagnetic force generated by the current flowing through the tracking coil 13. That is, the converging lens 9 is the differential amplifier 18
Since the light beam is driven according to the output of, the tracking control can be performed so that the light beam is always on the desired information track.

[0008]

By irradiating the information track with a strong light beam in the disk, the crystal state of the part hit by the strong light beam on the information track is changed, and the light is reflected from other parts. Create different parts of the rate,
By changing the shape of the portion of the information track hit by the strong light beam by irradiating the information track with a strong light beam, the reflectivity differs from that of the phase change type that records information by the light and shade pattern. There is a modification type in which a portion is created and information is recorded according to the gradation pattern.

In the case of a deformable type disk for recording information by deforming such an information track shape (groove shape),
When the groove shape is deformed by recording information,
The depth of the groove changes at that portion. In this way, when the groove depth is different, the tracking error signal changes regardless of the amount of light reflected from the groove.

A specific example in which the relationship between the reflected light amount and the tracking error signal changes due to the change in groove depth will be briefly described with reference to FIG. FIG. 7 shows the relationship between the groove depth of the disc, the amount of reflected light, and the tracking error signal.
The tracking error signal Vo is Vo = a * SIN ² (2 * 2πn, where d is the groove depth, n is the refractive index of the disk film, and λ is the wavelength of light.
/ λ * d) (a is a constant). On the other hand, the reflected light quantity AS is A
It is represented by S = b * COS ² (2πn / λ * d) (b is a constant). Normally, the groove depth of the disk is made in the vicinity of λ / 8 so that the tracking error signal becomes maximum. In the disc of the type in which information is recorded by deforming the groove, the groove is deformed by recording as described above, so that the groove depth is reduced.
Now, assuming that the groove depth is reduced from λ / 8 to depth α in FIG. 7, the change amount of the tracking error signal is SIN ² (2 * 2π
The amount of change is small due to the change near the maximum of the function n / λ * d). The amount of reflected light AS changes at the point where the slope of the function of COS ² (2πn / λ * d) is the largest, so the amount of change increases. Therefore, when the same light amount of light beam is applied to the same track on the disc before and after recording, the reflected light amount after recording increases but the tracking error signal remains almost constant or the amplitude decreases. A state occurs in which the tracking signal amplitude is non-linear.

Therefore, the tracking error signal Vo before recording
When the relationship Vo / AS between the light quantity sum signal AS and the relationship V1 / AS1 between the tracking error signal V1 and the light quantity sum signal AS1 after recording are compared, Vo / AS ≠ V1 / AS1 and Vo≈V1.

Further, during recording, the light quantity of the light beam increases and the groove is also deformed, so the relationship Vo / AS between the tracking error signal Vo before recording and the light quantity sum signal AS, the tracking error signal V2 during recording and the light quantity sum signal AS2. Comparing the relationship V2 / AS2, Vo / AS ≠ V2 / AS2 and Vo <V2.

That is, the output V of the AGC circuit 20 operating in the relationship of V = K * Vo / AS changes before and after recording or during recording, and the gain of the tracking control system also changes. Therefore, there is a problem that the stability of the tracking control system is impaired.

In view of the above problems, the present invention uses a light beam as a groove (information track) in both cases of reproducing information and recording information using a disk of a type in which the groove is deformed for recording. It is an object of the present invention to provide a tracking control device that can stably follow the above.

[0015]

DISCLOSURE OF THE INVENTION The present invention is directed to recording information, reproducing information from a disc having an information track on which information is recorded, or outputting light emitted from a light source for recording information. Condensing means for condensing on the disk, and track deviation detecting means for detecting positional deviation between the position of the light beam formed on the disk by the condensing means and the track from reflected light from the track. First reflected light amount detecting means for detecting the quantity of reflected light from the reflected light, and first gain varying means for amplifying the output signal of the track deviation detecting means and controlling its gain by the output of the reflected light quantity detecting means. When,
Second gain variable means for amplifying the output of the first gain variable means and having its gain switchable from the outside; moving means for moving the light collecting means in a direction substantially orthogonal to the track; The control means for driving the moving means in accordance with the output of the gain varying means to control the position of the light beam so that it is always on the track, and the information on the track from the output of the reflected light amount detecting means. Recording information detecting means for detecting whether or not information is recorded, and the recording information detecting means when the recording information detecting means detects that information is recorded on the track where the light beam is located. The output of the second gain changing means is switched by an external command signal when information is recorded on the track.

Alternatively, a condensing means for condensing the light output from the light source for recording information or reproducing information from a disc having an information track on which the information is recorded or for condensing the information on the disc. Track deviation detecting means for detecting a positional deviation between the position of the light beam formed on the disk by the condensing means and the track from the reflected light from the track, and a light quantity of the reflected light from the reflected light Reflected light amount detecting means, and recording information detecting means for detecting whether or not information is recorded on the track from the output of the reflected light amount detecting means,
A storage unit that is controlled by the output signal of the recording information detection unit or a command signal input from the outside, stores the output of the light amount detection unit for a predetermined time, and outputs a storage end signal at the end of storage, and output from the storage unit. The output signal of the light amount detection means and the output of the storage means and output to the first gain changing means and the output signal of the track deviation detection means by the storage end signal or the command signal input from the outside. First gain varying means for amplifying and controlling its gain by the output of the switching means, and second gain varying means for amplifying the output of the first gain varying means and having its gain switchable from the outside. A moving means for moving the light collecting means in a direction substantially orthogonal to the track, and an output of the second gain varying means. And a control means for driving the moving means to control the position of the light beam so that it is always on the track, and the position of the light beam is not recorded by the recording information detecting means. The output of the light amount detection means is stored in the storage means when it is detected that it is on a recording track, and the switch means is switched when a storage end signal is input from the storage means to the switch means after the storage is completed. The output of the storage means is connected to the first gain varying means, and the gain of the first gain varying means is controlled by the output of the storing means, or external when recording information on a track. In this configuration, the gain of the second gain varying means is switched by the command signal from.

[0017]

According to the present invention, with the above-mentioned structure, when the information is recorded / reproduced by using the disk of the type which records the information by deforming the information track as the groove, the recording signal is already recorded on the groove reproduced by the light beam. If the information is present, the information detecting means detects it and switches the gain of the second gain varying means to obtain the gain of the entire tracking loop when the information is recorded and when the recording signal does not exist. You can do the same with case. Alternatively, while the information is being recorded on the disc, the gain of the entire tracking loop is recorded by switching the gain of the second gain varying means in response to an external command, and an unrecorded state in which no recording signal exists. You can do the same with case. That is, the gain of the entire tracking control system can be kept constant. As a result, it is possible to configure a recording / reproducing apparatus capable of stable recording / reproducing even when a disc of a type in which the groove is deformed to record information is used.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment. In FIG. 1, 1 is a disc, 2 is a motor for rotating the disc 1, 3 is a light source, and 4 is light emitted from the light source. Beam 5 is a coupling lens that changes the divergent light of the light source into parallel light, 6 is a polarization beam splitter that changes the optical path by passing the light beam and reflecting the reflected light from the disc, and 7 rotates the polarization plane of the light by 90 degrees. 1 / 4λ
A plate, 8 is a total reflection mirror, 9 is a converging lens for converging the light beam 4 generated from the light source 3 on the disk, 12 is a mount on which the converging lens 9 and the like are mounted, 13 is a tracking coil,
Reference numeral 15 is a photodetector, 16 and 17 are current-voltage converters for converting currents of the photodetectors into voltages, 18 is a differential amplifier, 19 is a light quantity sum detection circuit for adding reflected light quantities converted into voltage signals, 21 Is an information detection circuit for detecting whether or not information is recorded on the track of the disc 1 according to the output of the sum of light amount detection circuit 19. 20 is an AGC circuit that changes the gain according to the output of the light quantity sum detection circuit 19, 25a is a microcomputer, 22 is a variable gain circuit whose gain is switched according to signals from the information detection circuit 21 and the microcomputer 25a, and 23 is phase compensation A tracking control circuit composed of a filter, an amplifier, etc. for performing the above, a driving circuit 24 for amplifying the power supplied to the tracking coil, 30
Is a loop switch that turns tracking control ON / OFF.

The operation of the tracking control device configured as described above will be described. Disk 1 is motor 2
It is attached to the rotating shaft of and rotates at a predetermined rotation speed. On the disc 1, a spiral track in which information is recorded or information is recorded is provided,
Address information for identifying the position of the track is recorded on this track. In addition, a sensor hole that indicates the type of the disk by the presence or absence of a hole is provided in the cartridge portion that is the protective cover of the disk 1.

A light beam 4 generated from a light source 3 such as a semiconductor laser is collimated by a coupling lens 5, passes through a polarization beam splitter 6 and a 1/4 λ plate 7, is reflected by a total reflection mirror 8 and is converged. Is radiated onto the disk 1.

Reflected light 1 of the light beam reflected by the disk 1
0 passes through the converging lens 9, is reflected by the total reflection mirror 8 and passes through the 1/4 λ plate 7, and then the polarization beam splitter 6,
The light is reflected by the total reflection mirror 14 and irradiated on the photodetector 15.

The converging lens 9 is attached to the pedestal 12 via a leaf spring 11 as an elastic supporting member, and when an electric current is applied to a focus coil (not shown in the figure), the focusing lens 9 is attached to the surface of the disk 1 by the electromagnetic force received by the coil. The focus is controlled so that the light beam moves in the vertical direction so as to always be in a predetermined convergent state, but the description thereof is omitted because it is not directly related to the present invention.

A total reflection mirror and a linear motor coil (not shown) are attached to the pedestal 12, and when a current is applied to the linear motor coil, the linear motor coil receives it from a magnet (not shown) provided on the fixed side. The gantry 12 is configured to be movable over the entire recordable area of the disk 1 in the radial direction by electromagnetic force. A tracking coil 13 is attached to the converging lens 9. When an electric current is passed through the tracking coil 13, the converging lens 9 is placed on the disk 1 by an electromagnetic force received from a magnet (not shown in the figure) attached to the tracking coil on the mount. It is configured to be movable in a direction orthogonal to the track. The photodetector 15 has a two-part structure,
This output is input to the current-voltage converters 16 and 17. The differential amplifier 18 outputs a signal according to the difference between the outputs of the current-voltage converters 16 and 17. The output of the differential amplifier 18 is a tracking error signal representing the positional deviation between the light beam focused on the disk 1 and the track.

The outputs of the current-voltage converters 16 and 17 are also input to and added to the light quantity sum detection circuit 19 which is an adder. The output of the light quantity sum detection circuit is a reflected light quantity sum signal proportional to the reflected light quantity of the disk, and this signal is input to the AGC circuit 20 which is a variable gain amplifier. The AGC circuit 20 changes the gain according to the magnitude of the reflected light amount sum signal output from the light amount sum detection circuit 19, and amplifies the tracking error signal output from the differential amplifier 18. The output of the light quantity sum detection circuit 19 is input to the information detection circuit 21. The information detection circuit 21 utilizes that the light amount sum signal output from the light amount sum detection circuit 19 becomes a predetermined level or more when information is already recorded on the track where the light beam on the track on the disk 1 converges. Then, the recording or non-recording of information is detected.

The output of the AGC circuit 20 is a variable gain circuit 22.
Is input to In the variable gain circuit 22, the information detection circuit 21
And the tracking error signal is amplified in accordance with the information recording command signal output from the microcomputer 25a during information recording. The output signal of the variable gain circuit 22 is applied to the tracking coil 13 via a tracking control circuit 23 and a drive circuit 24 which are composed of a filter and an amplifier for phase compensation. Therefore, the converging lens 9 is driven according to the signal of the differential amplifier 18, and the light beam 4 converged on the disk 1
Is controlled to be always located on the track. The loop switch 30 is for disabling the tracking control. Hereinafter, the operation of this embodiment will be described.

Although not shown in the recording / reproducing apparatus, the presence or absence of a sensor hole provided in the cartridge portion of the disk is detected at the time of startup, or the control information recorded in a specific information track is read to determine the type of disk. There is a function. In the case where the disc that is discriminated is a phase-change system in which crystalline or non-crystalline material is switched to record, or a magneto-optical system in which the polarization component of reflected light changes, the light intensity sum signal A
Since S and the tracking error signal Vo are always proportional to the intensity of reflected light, Vo / AS remains constant even if the amount of reflected light changes before and after recording. Therefore, when a disc of this type is used, the gain of the variable gain circuit 22 is fixed to a predetermined value and only the gain of the AGC circuit is made variable by the instruction of the microcomputer 25a so that the gain of the entire tracking control system is always constant. can do.

When it is determined that the disk has a property that the groove depth of the track changes before and after recording and the tracking error signal Vo changes independently of the light quantity sum signal AS, the gain of the gain variable circuit 22 is instructed by the microcomputer 25a. Is variable. The amount of reflected light is large when information is recorded on the track where the light beam converges on the disk, and the amount of reflected light is small when information is not recorded, so the amount of light depends on whether or not information is recorded on the track. Since the output of the sum detection circuit 19 changes, the information detection circuit 21 detects the presence / absence of recorded information on the track by using the difference between the outputs.

In this type of disc, when the relationship Vo / AS between the tracking error signal Vo before recording and the light quantity sum signal AS and the relationship V1 / AS1 between the tracking error signal V1 after recording and the light quantity sum signal AS1 are compared, Vo / AS Since ≠ V1 / AS1, the output of the AGC circuit 20 before recording Va = K * (Vo / A
S) and the output Vb = K * (V1 / AS1) after recording have different values. Therefore, in the variable gain circuit 22, the information detection circuit 21
When there is no information, the gain is switched to Xa, and when there is information, the gain is switched to Xb in accordance with the output of the. The values of Xa and Xb are
Xa * Va≅Xb * Vb, which makes the gain of tracking control on the same disk almost constant.

Since the groove is deformed during recording, the tracking error signal Vo before recording and the light amount sum signal AS are recorded.
The relationship Vo / AS and the relationship V2 / AS2 between the tracking error signal V2 during recording and the light amount sum signal AS2 are compared to each other.
S ≠ V2 / AS2. Therefore, in the variable gain circuit 22, the gain of the variable gain circuit 22 is switched to Xc during recording of information. Xc is a value such that Xa * Vo / AS≈Xc * V2 / AS2.

Since the gain of the variable gain circuit 22 is switched in this way, the total gain of the tracking control is not present when the recording signal already exists or when information is being recorded (when the recording signal is not recorded). It can be equal to the gain.

A second embodiment of the present invention will be described below with reference to FIG. In the figure, reference numeral 26 is a gain variable circuit, which has a function of changing the gain of the output signal of the light quantity sum detection circuit. In FIG. 2, the same components as those shown in FIG. 1 are given the same numbers. Light intensity sum detection circuit 19
Is output to the variable gain circuit 26. As described above, when the microcomputer 25b determines that the type of the disc in which the groove depth of the track changes at the time of start-up,
The information detection circuit 21 determines whether or not information has been recorded on the track where the light beam is located, and the gain of the gain variable circuit 26 is switched according to the output signal of the information detection circuit 21. The output of the variable gain circuit 26 is input to the AGC circuit 20.
The AGC circuit 20 changes the gain according to the magnitude of the output of the variable gain circuit 26 and amplifies the tracking error signal which is the output of the differential amplifier 18. The output of the AGC circuit 20 is applied to the tracking coil 13 via a tracking control circuit 23 and a drive circuit 24 which are composed of a filter and an amplifier for phase compensation.

When recording information on the disc, the gain of the variable gain circuit 26 is switched by a command from the microcomputer 25b. As a result, the gain of the AGC circuit can be adjusted appropriately, and the gains of the entire tracking system can always be made equal.

Also, when it is determined that the disc is a type in which the track groove depth does not change before and after recording, the gain of the variable gain circuit 26 is set to a predetermined value by the output of the microcomputer 25b as in the first embodiment. By fixing and making only the gain of the AGC circuit variable, the output of the AGC circuit becomes constant before and after recording, and the gain of the entire tracking control system can be made constant.

The third embodiment of the present invention will be described below with reference to FIG. In the figure, reference numeral 28 denotes an external storage device, which has a function of storing the address of the recording position on the disc. The same numbers are attached to the same components as those in the first embodiment.

The present embodiment differs from the first embodiment in that whether or not information is already recorded on the track of the disk is detected and the recording position is changed each time information is recorded instead of switching the gain of the gain variable circuit. The address is stored in the external storage device 28 in accordance with a command from the microcomputer 25c, and the presence or absence of information on the track is determined by the microcomputer 25c based on the recorded address information in the external storage device,
The same effect as that of the first embodiment is realized by switching the gain of the variable gain circuit 22c according to the result.

When the tracking control device is activated, the type of disc is discriminated by the sensor hole provided in the cartridge of the disc 1. When the disc is of a type in which the groove depth of the track changes before and after recording, the address of the recording position where the information is recorded is stored in the external storage device 28 every time the information is recorded on the disc 1 by the instruction of the microcomputer 25c. The microcomputer 25c determines whether the current position of the light beam or the position to which the light beam will move is recorded based on the address information of the recording position stored in the external storage device. The output of the AGC circuit 20 is input to the variable gain circuit 22c, but in the variable gain circuit 22c, unrecorded data from the microcomputer 25c /
The gain is switched by the recorded discrimination signal. Further, also at the time of recording information, the gain of the gain variable circuit is switched by the information recording command signal from the microcomputer 25c. This makes it possible to keep the gain of the entire tracking control system constant.

When it is determined that the disc is a type in which the track groove depth does not change before and after recording, the gain of the variable gain circuit 22c is fixed to a predetermined value by the output of the microcomputer 25c, and only the gain of the AGC circuit is obtained. By making it variable, the output of the AGC circuit becomes constant before and after recording, and the gain of the entire tracking control system can be made constant.

A fourth embodiment of the present invention will be described below with reference to FIG. The components shown in FIG. 10 have a configuration in which the information detection circuit is deleted from the first embodiment and a memory function for recording the light intensity sum signal is added.

The groove depth of the disc 1 changes before and after recording, and when the same light amount of the light beam is applied to the same track of the disc 1 before and after recording, the reflected light amount after recording increases but after recording. In the case where the tracking error signal of 1 has a property that it is almost constant before recording, the convergent position of the light beam first moves to a predetermined unrecorded track of the disc 1, and the light amount sum detection circuit 19 detects it there. The light amount sum signal in the unrecorded portion is input to the AGC circuit 20 and is simultaneously stored in the external storage device 28d. After the storage is completed, the changeover switch 29 is switched by a command from the external storage device 28d, and then the light beam position on the disc is the unrecorded portion regardless of the unrecorded portion or the recorded portion. The sum signal is input to the AGC circuit 20. The output of the AGC circuit 20 is input to the variable gain circuit 22d. In the variable gain circuit 22d, the gain is switched according to the information recording command signal from the microcomputer 25d, and the tracking coil 13 is passed through the tracking control circuit 23 and the drive circuit 24 which are composed of a filter and an amplifier for phase compensation. Has been added to.

As described above, in this embodiment, the groove depth of the track changes before and after recording and the magnitude of the light quantity sum signal AS changes, but the tracking error signal Vo does not change so much.
Moreover, since the light intensity of the light beam becomes extremely large during the recording of information, when using a disc having a property that the ratio of AS and Vo is different from that before recording and the size thereof is also increased, the sum of the light intensity of the unrecorded part is previously calculated. The signal AS is detected and stored in the external storage device. After that, the stored light intensity sum signal AS of the unrecorded portion is A
Since it is input to the GC circuit 20, the calculation Vo / AS performed by the AGC circuit 20 becomes substantially the same value after recording as it does when it is not recorded. As a result, the gain of the AGC circuit 20 becomes substantially constant before and after recording. During recording, not only does Vo and AS increase, but also the value of Vo / AS before recording changes due to the change in groove depth. However, the gain of the gain variable circuit 22d is changed according to the information recording command signal from the microcomputer 25d. Since it is changed, the gain of the entire tracking control system can be made constant at all times.

Further, in the case of a disc of a phase change system, etc., in which the recording and the non-crystal of the substance are switched and recorded, the ratio between the light quantity sum signal AS and the tracking error signal Vo is always constant. When this type of disc is used, the changeover switch 29 is switched by the output from the microcomputer 25d so that the output of the light quantity sum detection circuit 19 is always input to the AGC circuit 20, and the information recording command signal from the microcomputer 25d is used. Gain variable circuit 22
By setting so that the gain of d does not change, AGC
The output of the circuit is always constant, and the gain of the entire tracking control system can be constant.

As described above, according to the present invention, the tracking control device is provided with an amplifier whose amplification factor can be switched independently of AGC proportional to the amount of reflected light from the disk, or by switching the operation of the ACG. It is difficult to achieve compatibility with the conventional system by providing an amplifier that performs non-linear operation, and detecting the type of the disk that the relationship between the reflectivity of the disk and the tracking signal amplitude is non-linear and operating the non-linear operation amplifier. Which is a phase change type or a magneto-optical type having a reflectance proportional tracking signal and a disc having a reflectance independent tracking signal like a modified type. The device enables stable recording and reproduction.

The present invention is not limited to the above-mentioned embodiment. For example, in the first, third and fourth embodiments, AG
Although the gain for the output of the C circuit 20 is switched by the variable gain circuit 27, the positions of the AGC circuit 20 and the variable gain circuit 27 are exchanged, and the gain of the output of the differential amplifier 18 is switched by the variable gain circuit to the AGC circuit. It may be configured to output. Further, in the third embodiment, the address of the recording position is stored in the external storage device. However, the configuration is such that the recording address of the disc itself is written not only on the external storage device but also on the disc. It is within the scope of the present invention that the storage / playback device can be replaced by copying the data to the storage device. Further, in the fourth embodiment, the switch 29 is switched by the signal from the external storage device 28d in which the light intensity sum signal is stored, but an information detection circuit may be installed and the switch may be switched by the unrecorded track detection signal. . Further, although the light quantity sum signal is stored only once at the time of starting the recording / reproducing apparatus, it may be configured to move to the unrecorded portion and update the memory of the light quantity sum signal at a constant interval by a command from the microcomputer 25d. good. Alternatively, the stored light intensity sum signal may be updated when information recording and reading are not performed for a certain period of time.
Further, for example, in the pickup of the embodiment, the light source 3, the photodetector 15 and the like are fixed, and the converging lens 9 and the like are movable.
Although the description has been made by using the separate type pickup mounted on the substrate and having a reduced movable mass, it is obvious that the present invention can be applied to an integral type pickup in which an optical system and an actuator move integrally. Further, the differential amplifier 18, the light quantity sum detection circuit 19, the information detection circuit 21, the AGC circuit 20, the gain variable circuit 22, the tracking control circuit 23 and the like are configured by one dedicated microcomputer, and the configuration of the present invention is digital. It can also be applied to control.

Further, although the optical disk device has been described in the present embodiment, the present invention is applied to a device having a large number of tracks for recording / reproducing information on / from an optical card and recording / reproducing the information by using light. It is also obvious that it is possible.

[0046]

EFFECTS OF THE INVENTION Information detecting means for determining whether or not information is recorded on an information track of a disc on which a light beam converges, an AGC circuit for changing the gain of a tracking error signal according to a light quantity sum signal, and the information detection. By providing a variable gain means for switching the gain according to the output of the means and a control means for controlling the reproduction position of the optical head means so that it is always on the information track, the groove depth of the track changes before and after the recording, and the tracking error Even when a disc in which the proportional relationship between the signal and the amount of reflected light changes is used, the gain of the gain varying means is switched depending on the presence or absence of information on the information track, so that the gain of the entire tracking loop can be made equal before and after recording. That is, the gain of the entire tracking control system can be kept constant. As a result, it is possible to realize an excellent tracking control device capable of suppressing the fluctuation of the loop gain and performing stable tracking control even in the type of disk in which information is recorded by deforming the groove.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

FIG. 4 is a block diagram showing a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a conventional tracking control device.

FIG. 6 is a schematic diagram showing a detection principle of a tracking error signal.

FIG. 7 is a characteristic diagram showing the relationship between the track groove depth and the reflected light amount signal / tracking error signal.

[Explanation of symbols] 1 disk 2 motor 3 light source 4 light beam 5 coupling lens 6 polarization beam splitter 7 1 / 4λ plate 8 total reflection mirror 9 converging lens 10 reflected light 11 leaf spring 12 mount 13 tracking coil 14 total reflection mirror 15 Photodetector 16 Current-voltage converter 17 Current-voltage converter 18 Differential amplifier 19 Light intensity sum detection circuit 20 AGC circuit 21 Information detection circuit 22 Gain variable circuit 23 Tracking control circuit 24 Drive circuit 25 Microcomputer 26 Gain variable circuit 27 Gain variable Circuit 28 External storage device 29 Changeover switch 30 Loop switch

Claims (12)

[Claims] 1. A light emitted from a light source for recording information, reproducing information from a record carrier having a track on which the information is recorded, or collecting information on the record carrier is collected on the record carrier. Light-collecting means, track-deviation detecting means for detecting positional deviation between the position of the light beam formed on the record carrier by the light-collecting means and the track based on reflected light from the track, and the reflected light. A reflected light amount detecting means for detecting the amount of reflected light more,
A first gain varying means for amplifying an output signal of the track deviation detecting means and a gain of which is controlled by an output of the reflected light amount detecting means, and an output of the first gain varying means, and a gain thereof. A second gain changing means that can be switched from the outside, a moving means that moves the light collecting means in a direction substantially orthogonal to the track, and the second gain changing means.
Information is recorded on the track by the control means for driving the moving means in accordance with the output of the gain varying means so as to control the position of the light beam so that the light beam is always on the track. Recorded information detecting means for detecting whether or not the information is recorded on the track on which the light beam is located, or the information on the record carrier. The tracking control device is characterized in that the gain of the second gain varying means is switched when recording is recorded. 2. When the external command device detects that the address of the recorded track on the record carrier stored in the external storage device and the address of the track where the light beam is located match, the command device causes 2. The tracking control device according to claim 1, wherein the gain of the second gain varying means is switched. 3. A medium detecting means for detecting the type of the information recording carrier, wherein the command device determines the operation or non-operation of the second gain varying means according to the output of the medium detecting means. The tracking control device according to claim 1 or 2. 4. Light emitted from a light source for recording information, reproducing information from a record carrier having a track on which the information is recorded or recording information on the record carrier is collected on the record carrier. Light-collecting means, track-deviation detecting means for detecting positional deviation between the position of the light beam formed on the record carrier by the light-collecting means and the track based on reflected light from the track, and the reflected light. A reflected light amount detecting means for detecting the amount of reflected light more,
Third gain varying means for amplifying the output of the reflected light amount detecting means and having its gain switchable from the outside, and third gain varying means for amplifying the output signal of the track shift detecting means and having the gain of the third gain varying means. First gain varying means controlled by output, moving means for moving the light collecting means in a direction substantially orthogonal to the track, and driving the moving means according to the output of the first gain varying means. A control means for controlling the position of the light beam so that it is always on the track, and a recording information detecting means for detecting whether or not information is recorded on the track from the output of the reflected light amount detecting means. The recording information detecting means detects that the information is recorded on the track where the light beam is located, or records the information on the record carrier. Tracking control unit and switches the gain of the variable gain means. 5. When the external command device detects that the address of the recorded track on the record carrier stored in the external storage device and the address of the track on which the light beam is located match, the command device 4. The tracking control device according to claim 3, wherein the gain of the fourth gain varying means is switched. 6. A medium detecting means for detecting the type of the information recording carrier, wherein the command device determines the operation or non-operation of the third gain varying means according to the output of the medium detecting means. The tracking control device according to claim 4 or 5. 7. A light beam emitted from a light source for recording information, reproducing information from a record carrier having a track on which the information is recorded, or recording information on the record carrier, onto the record carrier. Condensing means for condensing, track deviation detecting means for detecting a positional deviation between the position of the light beam formed on the record carrier by the condensing means and the track from reflected light from the track, and the reflection Reflected light amount detecting means for detecting the amount of reflected light from the light; first gain varying means for amplifying the output signal of the track deviation detecting means and controlling its gain by the output of the reflected light amount detecting means; The second gain variable means which amplifies the output of the first gain variable means and whose gain can be switched by an external command, and the condensing means A moving means that moves in a direction substantially orthogonal to the above, and a control means that drives the moving means according to the output of the second gain varying means and controls so that the position of the light beam is always on the track. Recording information detecting means for detecting whether or not information is recorded on the track based on the output of the reflected light amount detecting means, and the reflected light amount detecting means for detecting the light amount of the reflected light from the reflected light. Means and storage means that is controlled by an output signal of the recording information detection means or a command signal input from the outside and that stores the output of the light amount detection means for a predetermined time and outputs a storage end signal when the storage ends. The output of the light amount detection means and the output of the storage means are switched by a storage end signal output from the storage means or a command signal input from the outside. Switch means for outputting to the first gain varying means, and when the recording information detecting means detects that the position of the light beam is on an unrecorded track on which information is not recorded, The output of the light amount detection means is stored in the storage means,
When a storage end signal is input from the storage means to the switch means after the storage is completed, the switch means is switched and the output of the storage means is connected to the first gain varying means, so that the gain of the first gain varying means is increased. Is controlled by the output of the storage means. 8. The tracking control apparatus according to claim 7, wherein the output of the light amount detection means is stored in the storage means only once when the recording / reproducing apparatus is started. 9. The tracking control device according to claim 7, wherein the storage means stores the output of the light amount detection means only when a command signal is input from the outside. 10. The tracking control device according to claim 7, wherein the switch means is switched by a command signal from the outside regardless of the state of the storage means. 11. The second method for recording information on a record carrier
8. The tracking control device according to claim 7, wherein the gain of the gain varying means is switched. 12. A medium detecting means for detecting the type of the information recording carrier, wherein the state of the switch means is determined by the command device according to the output of the medium detecting means. , 9, 10, or 11 tracking control device.