JP2695398B2 - Optical playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam generated from a light source.
The laser beam is focused on the record carrier and irradiated, and recorded on the record carrier.
Reproduce the recorded signal or the signal on the record carrier
The present invention relates to an optical recording / reproducing device for recording. [0002] 2. Description of the Related Art A recording medium used in an optical recording / reproducing apparatus.
The body can be roughly divided into two. One of them
A record carrier having a recording material layer, the other one being a recording material.
It is a record carrier having no material layer. The former is an uneven groove tiger.
Of the recording material layer on the surface of the base material having
The recording material layer surface is provided with a protective layer.
Yes, this kind of record carrier can record new signals,
It is very difficult to reproduce a large number of record carriers on which signals are recorded.
Difficult to make, and the price of the record carrier is high when duplicated
It has the drawback that In the latter, signals are recorded in the form of unevenness.
This type of record carrier newly records a signal.
It is not possible, but it can be duplicated by means such as injection molding.
It can be done very easily and the price of the record carrier can be reduced.
Have the advantage. There are various kinds of information.
Classifying the information used for personal computers, etc.
It can be divided into two. That is, one is a device
Information that is commonly used in the
Information that is not common and is recorded by the person who uses the device as needed.
It is news. The former requires a large amount of the same thing, so
Do not have a recording material layer that can be easily duplicated as a recording carrier.
Suitable record carrier, the latter needs to be able to record signals
Therefore, the record carrier has a recording material layer.
It must be a carrier. [0005] Two types of recording described above
The carrier differs greatly in the reflectivity of the record carrier surface, or
Is it because of the different track shapes that the light beam tracks?
From the same device and record or record the signal.
The signal being reproduced could not be reproduced. Also, note
In the case of a record carrier that can record, irradiation light is used during recording and during reproduction.
Due to the large difference in the amount,
Stable recording / playback cannot be performed due to large fluctuations in the IN
Was. The object of the present invention is to eliminate the drawbacks of the above-mentioned conventional devices.
It can be removed and loaded with the two types of record carriers described above.
Loading the incoming device, ie the record carrier with the recording material layer
Signal is recorded or recorded if
Recording that can reproduce signals and does not have a recording material layer
The signal can be reproduced even when the carrier is loaded
It is to provide equipment. [0007] Means for Solving the Problems The present invention provides:Emits a light beam
Recording the light source generated and the light beam generated from the light source
The focusing means for focusing and irradiating on the body and the focusing means are described.
Moving means for moving in a direction substantially perpendicular to the recording carrier surface,
On the record carrier from the reflected beam reflected by the record carrier
Detects the focus shift of the light beam and detects this focus
On the record carrier by driving the moving means based on the signal
Control so that the converged state of the light beam is always in a predetermined state
And an optical reproducing device having a focus control unit for
On the information pit formed in the uneven shape.
New recording carrier and signal with metal reflection film such as minium
Rewritable with a record carrier having a recordable recording material film
Discriminating between the above two record carriers as well as
Means for responding to the signal from the discriminating means.
Switch the circuit gain of the control meansAlso configured
It is. Further, the present invention providesDifferent types of records with different reflectance
The record carrier is loaded and the information recorded on the record carrier is reproduced.
This is an optical playback device that
Focusing means for irradiating the recording medium on the record carrier in a focused manner;
Move the focusing means in a direction substantially perpendicular to the surface of the record carrier.
First moving means and a reflective bee reflected by the record carrier
Defocus detection of light beam on record carrier
The first movement based on this focus shift signal
Drive means to ensure that the converged state of the light beam on the record carrier is always
Focus control means for controlling to a predetermined state
And switching the circuit gain of the focus control means
First gain switching means and converged on the record carrier
The moving light beam in a direction almost perpendicular to the track direction
Second moving means, light beam and track on the record carrier
Track deviation detecting means for detecting the position deviation of the
The second moving means according to a signal from the rack deviation detecting means.
Drive so that the light beam on the record carrier is always on the track.
Tracking control means for controlling the
A second game for switching the circuit gain of the racking control means.
IN switching means and type of record carrier loaded in the device
A discriminating means for discriminating the
The first gain switching means and the first gain switching means
If the switching gain of the gain switching means of 2 is different
The focus control means and the tracking control hand.
Characterized in that the control loop gain of each stage is made almost constant
To do. [0009] The present invention has the above-mentioned structure and is installed in the device.
The type of recording carrier depends on the shape of the covering that covers the recording carrier.
The focus control means is discriminated based on the discrimination result.
Since the circuit gain is switched, high-speed and reliable communication is possible with a simple configuration.
It is possible to reliably determine the type of record carrier, and
Since the gain of the focus control loop is almost constant,
Focus control becomes extremely stable. The present invention also responds to the signal from the discrimination means.
First gain switching means and second gain switching means
When switching the circuit gain with
Step switching gain and tracking control means switching
Since the gain is different, focus control loop and
Both gains of the racking control loop are almost constant.
Stable focus control and tracking control
can do. [0011] The present invention will be described in detail below with reference to the drawings.
You. Note that the same numbers are used in the numbers used in the description of the drawings.
The same number is used for this. FIG. 1 shows an embodiment of the present invention. Concentric
The disc-shaped record carrier 1 having the tracks of
Attached to the rotating shaft of
I have. The record carrier 1 is covered by a jacket 3,
Protected against dust and dirt. The discriminator 4 for discriminating the record carrier 1 is
It is composed of a photo diode and a light receiving element. Jacket
The grate 3 has a different shape depending on the type of the record carrier 1.
When the jacket 3 containing the record carrier 1 is loaded,
The light beam generated from the light emitting diode of the separate device 4 is
The light beam is emitted to the light receiving element while being shielded by the window 3.
Light lost or generated by light emitting diode
The beam is not shielded and is irradiated onto the light receiving element. processing
The signal of the light receiving element of the discriminator 4 is input to the circuit 5.
The processing circuit 5 outputs a signal according to the type of the record carrier 1.
I do. Explaining the optical system, a semiconductor laser
Beam 7 generated from the light source 6 such as a coupling lens
By 8 it becomes almost parallel light,Polarizing beam splitter
9, Λ / 4 plate 10 (λ is the wavelength of the light beam 7),
Reflected by the reflecting mirror 11 and recorded by the converging lens 12.
It is converged and irradiated on the carrier 1. By record carrier 1
The reflected light 13 of the reflected light beam 7 is again convergent
12 and is reflected by the reflecting mirror 11, and the λ / 4 plate 1
0 and is reflected by the polarization beam splitter 9.
And passes through the convex lens 14 and the cylindrical lens 15.
Then, as will be described in detail later, irradiation is performed on the photodetector 16 having a four-division structure.
Have been. The converging lens 12 is supported by rubber or the like.
Therefore, when a current is applied to the focus element 17, an electromagnetic force is generated.
Therefore, the converging lens 12 should be substantially perpendicular to the surface of the record carrier 1.
It moves in the opposite direction and converges when a current is applied to the tracking element 18.
The lens 12 is tracked on the record carrier 1 by electromagnetic force.
Direction substantially perpendicular to the direction, that is, in the radial direction of the record carrier 1.
Configured to move. Light source 6, coupling lens 8, polarization beer
Splitter 9, λ / 4 plate 10, reflecting mirror 11, four
The dust element 17, the tracking element 18, the convex lens 14,
The cylindrical lens 15 and the photodetector 16 are the transfer table 1
9 is attached to drive the linear motor 20
So that they move together in the radial direction of the record carrier 1.
It is configured. Control signal detection will be described. Photo detector
Each of the 16 signals is represented by lines 21, 22, 23 and
It is output through 24. Synthesis circuit 25, 26, 2
7, 28 and 29 are circuits for adding input signals
And the lines 21 and 22 are connected to the input end of the synthesis circuit 25.
However, the lines 23 and 24 are combined at the input end of the synthesis circuit 26.
Lines 21 and 23 are provided at the input end of the synthesis circuit 27 to form a synthesis circuit.
Lines 22 and 24 are connected to the input end of 28
Lines 21, 22, 23 and 24 are at the input end respectively
It is connected. The differential amplifier 30 includes a combining circuit 27 and
28 signals have been input, and the differential amplifier 30 is
It outputs the difference signal between the signal on the path 27 and the signal on the combining circuit 28.
You. As will be described later in detail, the differential amplifier 30 is provided on the record carrier 1.
A signal indicating the converged state of the light beam 7, that is, the focus
Output a control signal. The synthesis circuit 2 is provided in the differential amplifier 31.
The signals of 5 and 26 are input, and the differential amplifier 31
Outputs the difference signal between the signal from the synthesis circuit 25 and the signal from the synthesis circuit 26.
Power. The differential amplifier 31 will be described later in detail on the record carrier 1.
The positional deviation between the light beam 7 focused on the
It outputs a signal for skipping, that is, a tracking control signal. Focus control will be explained.
The signal of the amplifier 30 is divided by the divider 32, the gain switching circuit 33,
Phase compensation circuit for compensating phase of focus control system
34, switch 3 for disabling focus control
5. Focusing via drive circuit 36 for power amplification
The focusing element 17 is added to the focusing element 17
The converging lens 12 is used as a record carrier according to the signal from the dynamic amplifier 30.
The light on the record carrier 1 is moved in a direction substantially perpendicular to the surface of 1.
The beam 7 is controlled so as to always have a constant convergence state. The tracking control will be explained below.
The signal from the dynamic amplifier 31 is divided by the divider 37 and the gain switching circuit 3
8. Complementary for compensating the phase of tracking control system
Compensation circuit 39, a switch for disabling tracking control.
Via switch 40 and drive circuit 41 for power amplification
It is added to the tracking element 18 for tracking
The element 18 is the converging lens 1 according to the signal from the differential amplifier 31.
2 is moved in the radial direction of the record carrier 1,
The light beam 7 is controlled so that it is always on the track. Ma
The signal from the drive circuit 41 drives the linear motor 20.
Input to the drive circuit 42 for the linear motor 2
0 means that the output of the drive circuit 41 becomes zero on average.
In other words, the movement moved by the tracking element 18
Transfer so that the bundle lens 12 moves around the natural state
The table 19 is moved. Focus control and tracking control are cheap
If it does not operate properly, perform high-quality recording and playback.
Cannot be done. Focus control and tracking control
To ensure stable operation, the loop gain of the control system must be changed.
It is extremely important not to turn it on. Divider 3
2, 37 and the gain switching circuits 33, 38 are provided for this purpose.
Therefore, these operations will be described below. As described above, the combining circuit 29 is a photodetector.
The signal which added four outputs of 16 is output, and this signal is
Input to the dividers 32 and 37 via the gain switching circuit 43.
Have been. The divider 32 outputs the output of the differential amplifier 30 as X.
1. If the output of the gain switching circuit 43 is Y, X1 / Y
The signal corresponding to the value is output, and the divider 37 similarly increases the difference.
If the output of the width device 31 is X2, it corresponds to the value of X2 / Y.
Output a signal. The signal of the processing circuit 5 is the gain switching circuit 33,
38 and 43 respectively, and gain switching times
The paths 33, 38 and 43 are amplified in response to the signal of the processing circuit 5.
Switch the rate. For example, if the first record carrier is loaded
Gain of the gain switching circuits 33, 38 and 43 when
G1a, G2a, G3a, and the second record carrier is loaded
Of the gain switching circuits 33, 38 and 43 in
If the amplification factors are G1b, G2b, and G3b, G1b / G1a = G3b / G3a = K (K is a positive real number) Holds approximately, and as will be described later in detail, G2b / G2a <K
It is configured as follows. Prevents focus control loop gain changes
The operation to be performed will be further described. Anti-first record carrier
The emissivity is KR, the reflectivity of the second record carrier is KW, KR / K
If W = K, synthesis with loading first record carrier
The output of the circuit 29 is that of a second record carrier loaded.
Each gain is K times, but the gain of the gain switching circuit 43 is 1
/ K times, the output of the gain switching circuit 43 changes.
Absent. On the other hand, the unit fountain when the first record carrier is loaded
The output of the differential amplifier 30 with respect to the focus shift is
It is K times that of a recording carrier loaded. Further, the gain when the first record carrier is loaded
The output of the switching circuit 43 and the output when the second record carrier is loaded
This is the same. So when loading the first record carrier
The output of the divider 30 for the unit defocus of
It is K times that when loaded with two record carriers. Only
Of the gain switching circuit 33 when the first record carrier is loaded.
The amplification rate is 1 / K of that when the second record carrier is loaded.
Therefore, the gain switching circuit for unit focus deviation
The output of 33 does not change. Therefore, the first record carrier and the second
These record carriers have different reflectivities, but the focus control
The gain does not change. As explained above, the first record carrier is mounted.
Even if it is loaded or loaded with the second record carrier, the focus control
The loop gain does not change because the gain switching circuit 33
Amplification factor loaded with the first record carrier and the second record carrier
This is because it can be switched between when the body is loaded. Operation of divider 32 and gain switching circuit 43
Will be described. Change focus control loop gain
There are various factors that cause the same
Variation of the reflectance of the record carrier 1 of the same kind, which is generated from the light source 6.
Change in the light amount of the moving light beam 7, temperature characteristics of the photodetector 16
Alternatively, the transmission efficiency of the light beam 7 due to dust, dust, etc.
It is a decrease. All of these effects are output from the synthesis circuit 29.
Appear as change. The output of the synthesizing circuit 29 becomes Ki times
And the output of the differential amplifier 30 for unit defocus
Also Ki times. Naturally, the gain switching circuit 4
Since the output of 3 also becomes Ki times,
The output of the divider 32 is always constant.
Focus control loop gain changes depending on
There is no. Keep the focus control loop gain constant.
First, as in the embodiment of the present invention, the first record carrier and the second
For example, the gain is switched off without switching the gain with the second record carrier.
The conversion circuit 33 is omitted, and the signal of the synthesis circuit 29 is divided by the divider 32.
Can be configured to
Then, the division range of the divider 32 becomes wider and the divider 32 becomes higher.
It is worth it. To further explain this, for example,
For example, if the same type of record carrier 1 has a variation in reflectance and the light source 6
Change of the light beam 7 generated from the
Transmission of light beam 7 due to temperature change or dust / dust
The output of the synthesizing circuit 29 changes due to a reduction in reaching efficiency
The ratio, that is, the minimum value of the output of the combining circuit 29 is Vmi
Value of Vmax / Vmin, where n is the maximum value Vmax
Is 4 times and the value of K is 5 times, the division range is 2
It is necessary to multiply by 0, but according to the embodiment of the present invention, the division range is
It requires only 4 times and can be configured with a simple divider. Prevents tracking control loop gain changes
The operation to be performed will be described below. Mounting the first record carrier
Differential amplifier 31 for unit track deviation when filled
The output of K1T, when loaded with a second record carrier
Let K2T be the value of K1T / K2T
No. As will be described later in detail, the focus
The detection sensitivity of the control signal is independent of the type of record carrier.
It is proportional to the reflectivity of the record carrier, whereas the first
The reflectivity of the body is K times the reflectivity of the second record carrier
However, the detection sensitivity of the tracking control signal must be K times.
No. The value of K1T / K2T is Kc, and the first record carrier is loaded.
The gain of the gain switching circuit 38 in the activated state is set to G2.
a, G2 with the second record carrier loaded
If b, then G2b / G2a = Kc is almost established.
Is configured. The unit track when the first record carrier is loaded
The output of the differential amplifier 31 with respect to the deviation is
It is Kc times that when the body is loaded. As previously mentioned
The output of the gain switching circuit 43 is loaded with the first record carrier.
There is no change between when the second record carrier is loaded and when it is loaded
To the unit track deviation when loading the first record carrier
The output of the divider 37 for the second loaded record carrier
Kc times that of time. However, mounting the first record carrier
The gain of the gain switching circuit 38 when filled is the second recording value.
It becomes 1 / Kc of that when the body is loaded, so the unit tiger
The output of the gain switching circuit 38 does not change with respect to the clock deviation.
No. Therefore, the transfer between the first record carrier and the second record carrier is
Although the detection sensitivity of the locking control signal is different, tracking
The control loop gain does not change. The loop gain of tracking control is changed.
The factor that causes the loop control
The factors that change the in can be considered. Due to these factors
Therefore, if the output of the combining circuit 29 becomes Ki times,
The output of the differential amplifier 31 with respect to the deviation is also Ki times.
Since the output of the gain switching circuit 43 also becomes Ki times,
The output of the divider 37 with respect to the rack deviation is not always constant.
Therefore, the loop gain of tracking control is kept constant.
You. In addition, it is used for tracking control in the embodiment of the present invention.
The divider 37 is used for the focus control described above.
It is possible to narrow the division range as with the divider 32.
Needless to say. The embodiment of the present invention is the first embodiment having a recording material layer.
When a signal is recorded by loading the second record carrier, the divider
It is configured so that the division range of 32 and 37 becomes narrow.
You. This will be described below. Focus control and tracking control are activated
The light source 6 emits light according to the signal to be recorded while
When the intensity of the light beam 7 is modulated strongly,
The part of the record carrier 1 irradiated with the light beam 7 is the light beam 7.
The heat causes the physical change to record the signal. When recording
The light amount of the light beam 7 depends on the location of the record carrier 1.
Is about 7 to 10 times the light amount of the light beam 7 during reproduction.
You. A recording period signal, that is, a recording period signal is input to the input terminal 44.
In order to record a signal on the recording carrier 1, the light amount of the light beam 7
A signal representing a period during which the intensity is modulated is input. Entering
The signal at the input terminal 44 is the gain switching circuits 33, 38 and 43.
And the recording period signal is transmitted to the input terminal 4 respectively.
4 is input, the gain switches 33, 38 and 43 are increased.
The width ratio is configured to be reduced to 1 / N. N is positive
Of the average light amount of the light beam 7 at the time of recording,
C, where PPB is the light amount of the light beam 7 at the time of reproduction, N =
It is set so that PREC / PPB is almost established.
You. Taking PREC = N × PPB as an example,
The output of the synthesizing circuit 29 at the time of recording is
It is N times that, but the gain switching circuit 43 is increased during recording.
Since the width ratio is 1 / N, the output of the gain switching circuit 43 is
It does not change during recording and playback. Unit focus during recording
The output of the differential amplifier 30 with respect to the shift is N of that at the time of reproduction.
Double. The output of the gain switching circuit 43 is during recording and reproduction.
Since it does not change with,
The output of the divider 32 is also N times, but the gain is cut off during recording.
Since the amplification factor of the conversion circuit 33 becomes 1 / N, the unit for recording
The output of the gain switching circuit 33 with respect to defocus is described.
Focus control loop gay that does not change between recording and playback
Is kept constant. The light amount of the light beam 7 at the time of recording is the same as that of the record carrier 1.
It depends on the location, and generally weak on the inner circumference of the record carrier 1.
It is strong on the periphery. Depending on the location of such record carrier 1
Loop gain of focus control system according to change of recording light intensity
The change is absorbed by the divider 32 and kept constant as described above.
Be drunk The operation of the focus control circuit during recording has been described above.
I explained about the operation of the tracking control circuit.
The description thereof is omitted because it can be easily understood from the above description. FIG. 2 shows a first recording medium having no recording material layer.
It is explanatory drawing of the body 1. In FIG. 2A, a shaded portion 51
Indicates the area where the signal is recorded in the form of unevenness.
You. 2B is indicated by a broken line 52 in FIG.
FIG. 53 is an enlarged view of the area, in which 53 is an uneven pit, 5
4 is a track in which pits 53 are lined up. Figure 2 (c)
FIG. 4 is a cut-off diagram taken along the alternate long and short dash line 55 shown in FIG.
56 is a base material, 57 is a metal layer such as aluminum, 58
Is a protective layer. 59 indicates the depth of the pit 53
If the depth of the pit 53 is d1, d1 = λ / (8 × n
It is 1). Here, λ is the wavelength of the light beam 7, n
1 is the refractive index of the base material 56. FIG. 3 shows a second record carrier having a recording material layer.
It is explanatory drawing of 1. In Fig. 3 (a), the shaded area is uneven
The area where the groove track is recorded in the form of
It is composed of a track portion 61 and an address portion 62.
FIG. 3B shows a region indicated by a broken line 63 in FIG.
FIG. 4 is an enlarged view of the track 64 with a groove-shaped tracking track.
It is composed of a groove 65 and a pit 66 having an uneven shape. G
The rack 64 is formed concentrically, and the pit 66 is
Including address information for identifying the tracking track 65
I have. As a matter of course, the address information part
It is only a small part of the Ku 64. 3 (c) is shown in FIG. 3 (b).
FIG. 68 is a cross-sectional view taken along the alternate long and short dash line 67 shown in FIG.
A base material, 69 is a recording material layer, and 70 is a protective layer. 71 is
Shows the depth of the pit 66 and the tracking track 65,
If the depth is d2, then d2 = λ / (8 · n2)
I have. However, n2 is the refractive index of the base material 68. Until I say
However, the signal is recorded on the tracking track 65. Focus control signal and tracking control
The signal detection will be described with reference to FIG. Figure 4 is optical inspection
The beam spot shape of the reflected light 13 on the emitter 16 is shown.
FIG. The photodetector 16 includes 16a, 16b, 16c and
And four light receiving areas 16a and 16d, and light receiving areas 16a, 1
The signals on 6b, 16c, and 16d are on line 21, FIG.
It is output through 22, 23, and 24. 13a, 1
3b and 13c show the beam spot shape of the reflected light 13.
The beam spot 13a and the record carrier 1 are
The distance of the converging lens 12 is normal, and the light beam 7
Shows the state where the convergence point of is on the record carrier 1. Bee
The spot 13b is the distance between the record carrier 1 and the converging lens 12.
Shows the reflected light 13 when the
The record carrier 1 and the converging lens 12 are close to each other.
The reflected light 13 in the state of being too much is shown. Differential amplification
The container 30 outputs a signal corresponding to the change in shape of the reflected light 13,
That is, the output of the light receiving areas 16a, 16b, 16c, 16d
If the force is S1, S2, S3, S4, {(S1 + S
3)-(S2 + S4)} is output. This
As it should be, the focus control is operating
, The reflected light 13 looks like a beam spot 13a.
It has become. The arrow 81 indicates the track direction, that is, the track.
Shows the longitudinal direction of. The differential amplifier 31 has {(S1
Output the signal corresponding to + S2)-(S3 + S4)}
You. Light focused by the differential amplifier 31 on the record carrier 1.
A signal indicating the positional deviation between the beam 7 and the track can be output.
Is immediately known and should not be detailed. The reflectivity of the first record carrier is the second record carrier.
Even if it is K times the reflectance of the
The fact that the output sensitivity does not become K times will be described with reference to FIG. Figure
5 is a light beam on the record carrier 1 loaded with the first record carrier
When 7 crosses one track, St = {(S1 + S
2)-(S3 + S4)}. The x-axis
Is represented by the amount of track deviation and the y-axis is represented by St. FIG.
When the light beam 7 is scanning over the pit 53 shown in
However, the position of the light beam 7 on the record carrier 1 and the position of the track 54 do not change.
A signal (waveform 91) corresponding to this is output and the pit and
Output when the light beam 7 is scanning between
No. However, the length of the pit 53 and the pit and pitch
The tracking distance is very short.
When operated, the light beam 7 on the record carrier 1 is
4 can be scanned. For example, the response of tracking control is
The signal recorded on the record carrier 1 at about 10 KHz is
It is several MHz. Therefore, in reality, the tracking control signal
Is a waveform 9 which is obtained by passing the waveform 91 through a low pass filter.
2, the detection sensitivity of the tracking control signal decreases.
You. On the other hand, the record carrier of FIG. 3 is continuous except for the address part.
Since it is a separate track, the detection sensitivity does not decrease.
Therefore, the unit track when the first record carrier is loaded
The output of the differential amplifier 31 with respect to the shift is K1T,
If K2T is used when the recording carrier is added, K1T /
The value of K2T does not become K, but K1T <K × K2T. [0045]In the above-described embodiment, the record carrier is identified by
Depending on the shape of the ket,For example, record carrier format
Alternatively, the difference in reflectance of the record carrier may be detected. Yo
More specifically, the size of the output of the combining circuit 29 is also used for the determination.
You can Focus control signal and tracking
Various optical systems for detecting control signals have been announced.
However, what kind of optical system is the present invention?
There is no problem. [0047] 【The invention's effect】According to the present invention, the device loaded
Result of discriminating the type of record carrier by the discriminating meansBased on
Switch the circuit gain of the focus control means,
Easy and fast determination of record carrier type with simple structure
And the gain of the focus control loop is
Since it is almost constant, focus control is extremely stable.
You. Also, depending on the record carrier loaded in the device
The circuit gains of the light amount detection circuit and focus control circuit are almost
Since it switches at the same ratio, it is inversely proportional to the amount of reflected light
Focus control circuit to change the circuit gain
It is possible to narrow the division range of the divider provided inside
Therefore, the circuit can be made simple and inexpensive. [0049]Also,Focus control means switching gay
If the switching gain of the tracking control means is different from the
Focus control loop and tracking control rule.
Focus gain control
And tracking control can both be stable
You.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 2 is an explanatory view of a first record carrier having no recording material layer. FIG. 4 is an explanatory view of a second record carrier included therein. FIG. 4 is a diagram showing a beam spot shape of reflected light on a photodetector. FIG. 5 is a waveform diagram of a tracking control signal when the first record carrier is loaded. Explanation of 1 record carrier 3 jacket 4 discriminator 5 processing circuit 16 photodetector 17 focus element 27 combining circuit 28 combining circuit 29 combining circuit 30 differential amplifier 32 divider 33 gain switching circuit 34 phase compensation circuit 35 switch 36 drive circuit

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hiroyuki Yamaguchi               Matsushita, 1006 Kadoma, Kazuma, Osaka               Kiki Sangyo Co., Ltd.                (56) References JP-A-59-98324 (JP, A)

Claims (1)

(57) [Claims] A light source for generating a light beam, and a converging means for converging and irradiating the light beam generated from the light source onto a record carrier,
Moving means for moving the converging means in a direction substantially perpendicular to the surface of the record carrier, and detecting the focus shift of the light beam on the record carrier from the reflected beam reflected by the record carrier,
An optical reproducing apparatus having: a focus control unit that drives the moving unit based on the focus shift signal to control so that the converged state of the light beam on the record carrier is always in a predetermined state. The record carrier in which a metal reflection film such as aluminum is formed on the information pit formed in the shape and the record carrier having the recording material film capable of newly recording a signal are reproducible, and the two record carriers are An optical reproducing apparatus comprising a discriminating means for discriminating and switching a circuit gain of the focus control means according to a signal of the discriminating means. 2. The light source is the same at the time of reproduction regardless of whether the loaded record carrier is a record carrier having a reflective film of metal such as aluminum formed on the information pit formed in the form of concavo-convex or a record carrier having a recording material film. The optical reproducing apparatus according to claim 1, wherein an optical beam having a high intensity is generated. 3. The light amount detection means for detecting the light amount of the reflected beam reflected by the record carrier is provided, and the focus control means is configured so that the circuit gain changes in inverse proportion to the magnitude of the signal of the light amount detection means. 3. The optical reproducing apparatus according to claim 1, wherein the circuit gains of the light amount detecting means and the focus control means are switched at substantially the same ratio according to a signal. 4. An optical reproducing device for reproducing information recorded on a record carrier by loading different kinds of record carriers having different reflectances, and converging means for converging a light beam generated from a light source onto the record carrier. A first moving means for moving the converging means in a direction substantially perpendicular to the surface of the record carrier, and a focus shift of the light beam on the record carrier detected from the reflected beam reflected by the record carrier, A focus control means for driving the first moving means on the basis of the shift signal so as to control the converged state of the light beam on the record carrier to be always in a predetermined state; and a circuit gain for switching the focus control means. 1 gain switching means,
Second moving means for moving the light beam focused on the record carrier in a direction substantially perpendicular to the track direction; track deviation detecting means for detecting a position deviation between the light beam on the record carrier and the track; The circuit gain of the tracking control means and the tracking control means for driving the second moving means according to the signal from the track deviation detection means to control so that the light beam on the record carrier is always positioned on the track are switched. A second gain switching means, and a determination means for determining the type of the record carrier loaded in the apparatus,
The switching gains of the first gain switching means and the second gain switching means, which are switched according to the signal of the discrimination means, are made different, and the control loop gains of the focus control means and the tracking control means are made substantially constant. An optical reproducing device characterized in that