JPH0656666B2 - Tracking controller - Google Patents

Description

The present invention relates to reproducing a signal recorded on a record carrier by irradiating a recording medium with a light beam generated from a light source, and reproducing the signal recorded on the record carrier. The present invention relates to an optical recording / reproducing apparatus for recording data, and particularly to tracking control for controlling, in an optical recording / reproducing apparatus, a light beam converged and irradiated on a record carrier to track a track.

Structure of Conventional Example and Problems There are mainly two record carriers used in the optical recording / reproducing apparatus.
It can be roughly divided into two. One is a record carrier having a recording material layer and the other is a record carrier having no recording material layer. The former is one in which a recording material layer is formed on the surface of a base material having concave and convex groove tracks by means such as vapor deposition and a protective layer is provided on the recording material layer surface, and this type of record carrier newly records a signal. Although it is possible, it is very difficult to reproduce a large number of record carriers on which signals are recorded,
It has the disadvantage that the price of the record carrier is high when reproduced. The latter is one in which signals are recorded in the form of concavities and convexities, and although this type of record carrier cannot record new signals, it can be very easily duplicated by means of injection molding or the like. It has an advantage that the price of the carrier can be reduced.

There are various types of information, but for example, information used for personal computers and the like can be roughly classified into two. That is, one is information commonly used by the device, and the other one is information not commonly used by the device and recorded by a person who uses the device as needed. Since the former requires a large amount of the same material, a record carrier without a recording material layer that can be easily duplicated is suitable as the record carrier, and the latter needs to be capable of recording a signal. It must be a record carrier with a material layer.

However, the two types of record carriers described above are loaded in the same device to record or record a signal because the reflectivity of the record carrier surface is greatly different or the form of the track traced by the light beam is different. It was not possible to reproduce the existing signal.

OBJECT OF THE INVENTION The object of the invention is to eliminate the disadvantages of the above-mentioned conventional devices and to provide a device which can be loaded with the two types of record carriers mentioned above, ie a signal when loaded with a record carrier having a layer of recording material. It is an object of the present invention to provide a device capable of recording or reproducing a recorded signal and reproducing a signal even when a record carrier having no recording material layer is loaded.

The present invention is directed to a moving means for moving a light beam focused on a record carrier in a direction substantially perpendicular to the track direction, and a track deviation detection for detecting a positional deviation between the light beam and the track on the record carrier. Means, and a tracking control means for driving the moving means in response to the signal of the track deviation detecting means so that the light beam on the record carrier is always positioned on the track, and an information pit in which the track on the record carrier is uneven. Discriminating means for discriminating between the continuous guide groove and
And gain switching means for switching the circuit gain of the tracking control means in accordance with the signal of the determination means,
It is intended to reduce the loop gain variation that occurs due to the different track forms and to perform stable tracking control.

The present invention also provides a moving means for moving the light beam focused on the record carrier in a direction substantially perpendicular to the track direction,
A light amount detection means for detecting the light amount of the reflected beam reflected by the record carrier, and a positional deviation between the light beam on the record carrier and the track is detected from the reflected beam from the record carrier, and based on the detected track deviation signal. In order to control the light beam on the record carrier to always be positioned on the track by driving the moving means, it is constituted by tracking control means in which the circuit gain changes in inverse proportion to the magnitude of the signal of the light amount detection means, By switching the circuit gains of the light amount detection means and the tracking control means at almost the same ratio during recording and during reproduction, stable tracking control can be performed even when the amount of light irradiated onto the record carrier during recording and during reproduction differs greatly. It is something to do.

Further, the present invention is provided with a discriminating unit for discriminating the record carrier loaded in the apparatus, and is configured to switch the circuit gains of both the light amount detecting unit and the tracking control unit according to the signal of the discriminating unit. The tracking control can be stably performed on different record carriers.

Description of Embodiments The present invention will be described in detail below with reference to the drawings. The same numbers are used for the same numbers in the description of the drawings.

FIG. 1 shows an embodiment of the present invention.

A disk-shaped record carrier 1 having concentric tracks is attached to a rotation shaft of a disk motor 2 and is rotated at a predetermined rotation speed. The record carrier 1 is covered with a jacket 3 and is protected so as to prevent dust and dirt from adhering thereto.

The discriminator 4 for discriminating the record carrier 1 is composed of a light emitting diode and a light receiving element. The jacket 3 has different shapes depending on the type of the record carrier 1. When the jacket 3 containing the record carrier 1 is loaded, the light beam generated by the light emitting diode of the discriminator 4 is shielded by the jacket 3 and received. The element may not be irradiated with the light beam, or the light beam generated by the light emitting diode may not be shielded and may be irradiated onto the light receiving element. The signal of the light receiving element of the discriminator 4 is input to the processing circuit 5, and the processing circuit 5 outputs a signal according to the type of the record carrier 1.

Explaining the optical system, a light beam 7 generated from a light source 6 such as a semiconductor laser is converted into substantially parallel light by a coupling lens 8, and a polarization beam splitter 9 and a λ / 4 plate 10 (λ is a wavelength of the light beam 7). And is reflected by the reflecting mirror 11 and converged and irradiated on the record carrier 1 by the converging lens 12. The reflected light 13 of the light beam 7 reflected by the record carrier 1 again passes through the converging lens 12, the reflecting mirror 11, the λ / 4 plate 10, the polarizing beam splitter 9, and the convex lens 14. Further, the light passes through the cylindrical lens 15 and is irradiated onto the photodetector 16 having a four-division structure, which will be described in detail later.

The converging lens 12 is supported by rubber or the like, and when an electric current is passed through the focus element 17, the converging lens 12 moves in a direction substantially perpendicular to the surface of the record carrier 1 by an electromagnetic force,
When a current is passed through the tracking element 18, the converging lens 12 is configured to move in a direction substantially perpendicular to the track direction on the record carrier 1, that is, in the radial direction of the record carrier 1 by an electromagnetic force.

Light source 6, coupling lens 8, polarization beam splitter 9, λ / 4 plate 10, reflecting mirror 11, focus element 1
7, the tracking element 18, the convex lens 14, the cylindrical lens 15, and the photodetector 16 are attached to the transfer table 19, and are configured to move integrally in the radial direction of the record carrier 1 when the linear motor 20 is driven. Has been done.

The detection of the control signal will be described. The respective signals of the photodetector 16 are output through the lines 21, 22, 23 and 24. The synthesizing circuits 25, 26, 27, 28 and 29 are circuits for adding the input signals. Lines 21 and 22 are provided at the input end of the synthesizing circuit 25, and lines 23 and 24 are provided at the input end of the synthesizing circuit 26. However, lines 21 and 23 are connected to the input end of the synthesizing circuit 27, lines 22 and 24 are connected to the input end of the synthesizing circuit 28, and lines 21, 22, 23, and 24 are connected to the input end of the synthesizing circuit 29, respectively. ing. The signals of the combining circuits 27 and 28 are input to the differential amplifier 30, and the differential amplifier 30 outputs a difference signal between the signal of the combining circuit 27 and the signal of the combining circuit 28. As will be described later in detail, the differential amplifier 30 outputs a signal indicating the converged state of the light beam 7 on the record carrier 1, that is, a focus control signal. The signals of the combining circuits 25 and 26 are input to the differential amplifier 31, and the differential amplifier 31 outputs a difference signal between the signal of the combining circuit 25 and the signal of the combining circuit 26. As will be described later in detail, the differential amplifier 31 outputs a signal indicating the positional deviation between the light beam 7 focused on the record carrier 1 and the track, that is, a tracking control signal.

Focus control will be described. The signal of the differential amplifier 30 is composed of a divider 32, a gain switching circuit 33, a phase compensation circuit 34 for compensating the phase of the focus control system, a switch 35 for disabling the focus control, It is added to the focus element 17 via a drive circuit 36 for power amplification, and the focus element 17 is a differential amplifier 30.
The converging lens 12 is moved in a direction substantially perpendicular to the surface of the record carrier 1 in accordance with the signal of 1, and the light beam 7 on the record carrier 1 is controlled so as to be always in a constant converged state.

The tracking control will be described. The differential amplifier 31
The signal of is passed through a divider 37, a gain switching circuit 38, a phase compensation circuit 9 for compensating the phase of the tracking control system, a switch 40 for disabling tracking control, and a drive circuit 41 for power amplification. The tracking element 18 moves the converging lens 12 in the radial direction of the record carrier 1 in accordance with the signal from the differential amplifier 31, so that the light beam 7 on the record carrier 1 is always on the track. Control it to be. The signal from the drive circuit 41 is the drive circuit 42 for driving the linear motor 20.
Is input to the linear motor 20 so that the output of the drive circuit 41 becomes zero on average, in other words, the converging lens 12 moved by the tracking element 18 moves around a natural state. Move 19

If focus control and tracking control do not operate stably, high-quality recording and reproduction cannot be performed. In order to stably operate the focus control and tracking control, it is extremely important that the loop gain of the control system does not change. The dividers 32 and 37 and the gain switching circuits 33 and 38 are provided for this purpose.
These operations will be described below.

The synthesizing circuit 29 outputs a signal obtained by adding the four outputs of the photodetector 16 as described above, and this signal is input to the dividers 32 and 37 via the gain switching circuit 43. Divider 32, X ₁ the output of differential amplifier 30, the output of the gain switcher 43 and Y and outputs a signal corresponding to the value of X ₁ / Y, divider 37 equally difference amplifier 31 When the output of is X ₂ , the signal corresponding to the value of X ₂ / Y is output.

The signals of the processing circuit 5 are gain switching circuits 33, 38 and 43.
To the gain switching circuits 33 and 38, respectively.
And 43 switch the amplification factor according to the signal of the processing circuit 5. For example, the amplification factors of the gain switching circuits 33, 38 and 43 with the first record carrier loaded are G _1a , G _2a ,
G _3a, and the gains of the gain switching circuits 33, 38, and 43 loaded with the second record carrier are G _1b , G _2b , and G.
_{If 3b} , G _1b / G _1a = G _3b / G _3a = K (K is a positive real number) substantially holds, and as will be described later in detail, G _2b / G _2a <K.

The operation of preventing the focus control loop gain change will be further described.

Assuming that the reflectance of the first record carrier is K _R and the reflectance of the second record carrier is K _W and K _R / K _W = K, the output of the synthesizing circuit 29 when the first record carrier is loaded is It becomes K times that when the second record carrier is loaded, but since the amplification factor of the gain switching circuit 43 becomes 1 / K times, the output of the gain switching circuit 43 does not change. On the other hand, the output of the differential amplifier 30 with respect to the unit defocus when the first record carrier is loaded is
It becomes K times that of the case where the record carrier of the above is loaded. Further, the output of the gain switching circuit 43 when the first record carrier is loaded is the same as that when the second record carrier is loaded. Therefore, the output of the divider 30 with respect to the unit defocus when the first record carrier is loaded is K times that when the second record carrier is loaded. However, since the amplification factor of the gain switching circuit 33 when the first record carrier is loaded is 1 / K of that when the second record carrier is loaded, the output of the gain switching circuit 33 changes with respect to the unit focus deviation. do not do. Therefore, although the first record carrier and the second record carrier have different reflectances, the focus control loop gain does not change.

As described above, the loop gain of the focus control does not change regardless of whether the first record carrier is loaded or the second record carrier is loaded. This is because it can be switched between the case of loading and the case of loading the second record carrier.

The operations of the divider 32 and the gain switching circuit 43 will be described.

There are various factors that change the loop gain of the focus control. For example, variations in the reflectance of the same type of record carrier 1 and the light beam 7 generated from the light source 6 are used.
Change in light intensity, temperature characteristics of photodetector 16 or dust
For example, the transmission efficiency of the light beam 7 is reduced due to dust or the like.
All of these effects appear as changes in the output of the combining circuit 29. When the output of the combining circuit 29 becomes K _i times, the output of the differential amplifier 30 for the unit focus shift also becomes K _i times.
As a matter of course, since the output of the gain switching circuit 43 also becomes K _i times, the output of the divider 32 with respect to the unit focus deviation is always constant, and the loop gain of the focus control does not change due to the above-mentioned factors.

In order to keep the loop gain of the focus control constant, unlike the embodiment of the present invention, the gain is not switched between the first record carrier and the second record carrier. For example, the gain switching circuit 33 is omitted, and the combining circuit 29 is used. It may be configured such that the signal of the above is input to the divider 32, but when configured in this way, the divider 32
And the divider 32 becomes expensive.

Explaining this further, for example, variations in the reflectance of the same type of record carrier 1, changes in the light amount of the light beam 7 generated from the light source 6, changes in the temperature of the photodetector 16, light beams caused by dust, dust, etc. The rate at which the output of the synthesizing circuit 29 changes due to a decrease in the transmission efficiency of 7, that is, the value of V _max / V _min when the minimum value of the output of the synthesizing circuit 29 is V _min and the maximum value V _max is four times, If the value of K is set to 5 times, the division range is required to be 20 times, but according to the embodiment of the present invention, the division range is 4 times and can be configured by a simple divider. .

The operation for preventing the loop gain change in tracking control will be described below.

_Letting K _{1T be} the output of the differential amplifier 31 with respect to a unit track deviation when the first record carrier is loaded and K _2T when the second record carrier is loaded, the value of K _1T / K _2T is K. Does not mean This will be described in detail later, but the detection sensitivity of the focus control signal is independent of the type of record carrier.
Although proportional to the reflectance of the record carrier, even if the reflectance of the first record carrier is K times the reflectance of the second record carrier, the detection sensitivity of the tracking control signal does not become K times. The value of K _1T / K _2T is K _c , the gain of the gain switching circuit 38 with the first record carrier loaded is G _2a , and the gain with the second record carrier loaded is G _2b. Then G _2b
It is configured such that / G _2a = K _c holds approximately.

The output of the differential amplifier 31 with respect to the unit track deviation when the first record carrier is loaded is K _c times that when it is loaded with the second record carrier. As described above, the output of the gain switching circuit 43 does not change when the first record carrier is loaded and when the second record carrier is loaded, so that the unit track deviation when the first record carrier is loaded Divider 32 for
Output is K _c times that when loaded with the second record carrier.

However, the amplification factor of the gain switching circuit 38 when the first record carrier is loaded is 1 of that when the second record carrier is loaded.
/ K _c , the output of the gain switching circuit 38 does not change with respect to the unit track deviation. Therefore, although the detection sensitivity of the tracking control signal is different between the first record carrier and the second record carrier, the loop gain of tracking control does not change.

As a factor that changes the loop gain of the tracking control, a factor that changes the loop gain of the focus control described above can be considered. When the output of the synthesizing circuit 29 becomes K _i times due to these factors, the output of the differential amplifier 31 for the unit track deviation also becomes K _i times. Gain switching circuit 4
Since the output of 3 also becomes K _i times, the output of the divider 37 with respect to the unit track deviation is always constant, and the loop gain of tracking control is kept constant. Needless to say, the divider 37 used in the tracking control in the embodiment of the present invention can have a narrower division range like the divider 32 used in the focus control described above.

Embodiments of the present invention include dividers 32 and 37 when loading a second record carrier having a recording material layer to record signals.
The division range of is narrowed. This will be described below. When the light amount of the light beam 7 generated from the light source 6 is strongly modulated according to the signal to be recorded while the focus control and the tracking control are operating, the portion of the record carrier 1 irradiated with the strong light beam 7 Is physically changed by the heat of the light beam 7 and a signal is recorded. The light amount of the light beam 7 at the time of recording varies depending on the location of the record carrier 1, but is 7 to 1 of the light amount of the light beam 7 at the time of reproducing.
It is about 0 times.

A recording period signal, that is, a signal representing a period during which the light amount of the light beam 7 is modulated in order to record the signal on the record carrier 1, is input to the input end 44. The signal at the input end 44 is transmitted to the gain switching circuits 33, 38 and 43, respectively. When the recording period signal is input to the input end 44, the gain switching circuits 33, 38 and 43 have an amplification factor of 1 / N.
Is configured to fall. N is a positive real number, where P _REC is the average light amount of the light beam 7 during recording and P _PB is the light amount of the light beam 7 during reproduction, and N = P _REC / P _pB is set to approximately hold. Has been done.

_{Taking the} case of P _REC = N × P _pB as an example, the output of the synthesizing circuit 29 at the time of recording is N times that at the time of reproducing, but the amplification factor of the gain switching circuit 43 becomes 1 / N at the time of recording. Therefore, the output of the gain switching circuit 43 does not change between recording and reproducing. The output of the differential amplifier 30 with respect to the unit focus deviation during recording is N times that during reproduction. Since the output of the gain switching circuit 43 does not change between recording and reproduction,
The output of the divider 32 for the unit focus shift at the time of recording is also N times, but since the amplification factor of the gain switching circuit 33 becomes 1 / N at the time of recording, the output of the gain switching circuit 33 for the unit focus shift at the time of recording. Does not change between recording and reproduction, and the loop gain of focus control is kept constant.

The light amount of the light beam 7 at the time of recording differs depending on the location of the record carrier 1, and is generally weak on the inner circumference of the record carrier 1 and strong on the outer circumference thereof. The change in the loop gain of the focus control system due to the change in the recording light amount depending on the position of the record carrier 1 is absorbed by the divider 32 and kept constant as described above.

The operation of the focus control circuit at the time of recording has been described above, but the operation of the tracking control circuit will be omitted because it can be easily understood from the above description.

FIG. 2 is an explanatory view of the first record carrier 1 having no recording material layer.

In FIG. 2A, a shaded area 51 indicates an area where a signal is recorded in the form of unevenness. FIG. 2B is an enlarged view of the area shown by a broken line 52 in FIG. 2A, 53 is a pit having an uneven shape, and 54 is a track in which the pits 53 are arranged. FIG. 2C is a cross-sectional view taken along the alternate long and short dash line 55 shown in FIG. 2B, wherein 56 is a base material, 57 is a metal layer such as aluminum, and 58 is a protective layer. Reference numeral 59 denotes the depth of the pit 53, where d ₁ = λ / (8 × n ₁ ) where d ₁ is the depth of the pit 53. Here, λ is the wavelength of the light beam 7, and n ₁ is the refractive index of the base material 56.

FIG. 3 is an explanatory diagram of the second record carrier 1 having a recording material layer.

In FIG. 3D, the shaded area is an area where groove tracks are recorded in the form of depressions and projections, and is composed of a tracking track portion 61 and an address portion 62.

FIG. 3E is an enlarged view of the area shown by the broken line 63 in FIG. 3D, and the track 64 is a groove-shaped tracking track 65.
And a pit 66 having an uneven shape. The tracks 64 are concentrically formed, and the pits 66 include address information for identifying the tracking tracks 65.
As a matter of course, the portion of the address information is the track 64.
It's only a minute. 3F is a cross-sectional view taken along the alternate long and short dash line 67 shown in FIG. 3E, in which 68 is a base material, 69 is a recording material layer, and 70 is a protective layer. Reference numeral 71 indicates the depth of the pit 66 and the tracking track 65, where d ₂ = λ / (8 · n ₂ ) where d ₂ is the depth. However, n ₂ is the refractive index of the base material 68. Needless to say, the signal is recorded on the tracking track 65.

The detection of the focus control signal and the tracking control signal will be described with reference to FIG. FIG. 4 shows the photodetector 16
It is the figure which showed the beam spot shape of the upper reflected light 13. The photodetector 16 includes 16a, 16b, 16c and 16
d has four light receiving regions, and the light receiving regions 16a, 16b,
The signals of 16c and 16d are the lines 21 and 2 of FIG.
2, 23 and 24. 13a, 13b
And 13c show the beam spot shape of the reflected light 13, the beam spot 13a has a regular distance between the record carrier 1 and the convergent lens 12, and the convergent point of the light beam 7 is on the record carrier 1. It shows the state. The beam spot 13b shows the reflected light 13 when the distance between the record carrier 1 and the converging lens 12 is too large, and the beam spot 13c shows the reflected light 13 when the distance between the record carrier 1 and the convergent lens 12 is too close. Shows. Differential amplifier 3
0 is a signal corresponding to the shape change of the reflected light 13, that is, the output of the light receiving regions 16a, 16b, 16c, 16d.
If S ₁ , S ₂ , S ₃ , and S ₄ are set, {(S ₁ + S ₃ ) − (S ₂ + S ₄ )}
The signal corresponding to is output. As a matter of course, when the focus control is operating, the reflected light 13
Is like a beam spot 13a.

The direction 81 indicates the track direction, that is, the longitudinal direction of the track. The differential amplifier 31 outputs a signal corresponding to {(S ₁ + S ₂ ) − (S ₃ + S ₄ )}. It is known that the differential amplifier 31 outputs a signal representative of the misalignment of the light beam 7 and the track being focused on the record carrier 1 and will not be described in detail.

The reflectance of the first record carrier is K of the reflectance of the second record carrier.
It will be described with reference to FIG. 5 that the detection sensitivity of the tracking control signal does not become K times, even if it is twice.

FIG. 5 shows that when the first record carrier 1 is folded and the light beam 7 on the record carrier 1 crosses one track, S _T = {(S ₁ +
S ₂ ) − (S ₃ + S ₄ )}. Incidentally, it represents and track deviation amount in the x-axis, a y axis S _T. A signal (waveform 91) corresponding to the positional deviation between the light beam 7 on the record carrier 1 and the track 54 is output only when the light beam 7 scans the pit 53 shown in FIG. It is not output when the light beam 7 is scanning between the two. However, since the length of the pit 53 and the length between the pits are very short, the light beam 7 on the record carrier 1 can scan the track 54 when the tracking control is operated. For example, tracking control response is 10 KHz
The signal recorded on the record carrier 1 to a degree is several MHz. Therefore, the tracking control signal actually has a waveform 92 as if the waveform 91 was passed through a low pass filter, and the detection sensitivity of the tracking control signal is lowered.

Since the record carrier of FIG. 3 is a continuous track except the address part, the detection sensitivity does not decrease.

Therefore outputs K _1T of the differential amplifier 31 to a unit track shift when loaded with a first recording carrier, the value of it K _2T to the K _1T / K _2T when loaded with the second record carrier K However, K _1T <K × K _2T .

The present invention has been described in detail above, but the present invention is not limited to the above-described embodiments.

For example, the discrimination of the record carrier may be performed by detecting the difference in reflectance of the record carrier. More specifically, the size of the output of the combining circuit 29 can be used for the determination.

Also, various optical systems for detecting the focus control signal and the tracking control signal have been announced,
There is no problem with the present invention in any optical system.

EFFECTS OF THE INVENTION By applying the present invention, the track shape is discriminated and the gain of the tracking control is switched so that the loop gain becomes substantially constant, so that stable tracking control is performed even if the track shape is different. be able to. Also, since the circuit gains of both the circuit that detects the amount of reflected light and the tracking control circuit are switched at almost the same ratio during recording and playback, tracking is performed to change the circuit gain in inverse proportion to the amount of reflected light. The division range of the divider provided in the control circuit can be narrowed,
The circuit can be simplified and the cost can be reduced, and the effect is extremely large.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an illustration of a first record carrier having no recording material layer, and FIG. 3 is an illustration of a second record carrier having a recording material layer. FIG. 4 shows the beam spot shape of the reflected light on the photodetector, and FIG. 5 shows the tracking control signal when the first record carrier is loaded. 1 ... record carrier, 3 ... jacket, 4 ... discriminator, 5
...... Processing circuit, 16 ...... Photodetector, 18 ...... Tracking element, 25,26,29 ...... Combining circuit, 31 ...... Differential amplifier, 37 ...... Divisor, 38 ...... Gain switching circuit, 3
9 ... Phase compensation circuit, 40 ... Switch, 41 ... Drive circuit.

Claims (3)

[Claims] 1. A moving means for moving a light beam focused on a record carrier in a direction substantially perpendicular to the track direction, and a track deviation detecting means for detecting a positional deviation between the light beam on the record carrier and the track. Tracking control means for driving the moving means in response to a signal from the track deviation detecting means to control the light beam on the record carrier to always be positioned on the track, and an information pit having an uneven track on the record carrier. A tracking control device, comprising: a determination means for determining whether the tracking control means comprises a continuous guide groove or a continuous guide groove, and a gain switching means for switching the gain of the tracking control means according to a signal from the determination means. 2. A moving means for moving a light beam focused on a record carrier in a direction substantially perpendicular to the track direction, a light amount detecting means for detecting a light amount of a reflected beam reflected by the record carrier, and a record carrier. The positional deviation between the light beam on the record carrier and the track is detected from the reflected beam from, and the drive means is driven based on the detected track deviation signal so that the light beam on the record carrier is always located on the track. For controlling so that the gain is changed in inverse proportion to the magnitude of the signal of the light quantity detecting means, and the circuit gain of the light quantity detecting means and the tracking control means during recording and reproduction. The tracking control device is characterized in that the switches are switched at substantially the same ratio. 3. A moving means for moving a light beam focused on a record carrier in a direction substantially perpendicular to the track direction, a light quantity detecting means for detecting a light quantity of a reflected beam reflected by the record carrier, and a record carrier. The positional deviation between the light beam on the record carrier and the track is detected from the reflected beam from the optical disk, and the moving means is driven based on the detected track deviation signal so that the light beam on the record carrier is always located on the track. In order to control so that the gain is changed in inverse proportion to the magnitude of the signal of the light amount detection means, tracking determination means,
A tracking control device, comprising: a discriminating unit for discriminating a record carrier loaded in the device, and switching circuit gains of both the light amount detecting unit and the tracking control unit according to a signal from the discriminating unit.