JPH0821192B2 - Optical disc player - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention According to the present invention, a disc on which information is recorded is mounted on a disc mounting portion, and light is incident on the disc with an appropriate focus state. The present invention relates to an optical disc reproducing device that is used.

[0002]

2. Description of the Related Art A digital audio disk has been proposed in which an audio signal is pulse-coded and recorded with an array of pits, and the audio signals can be reproduced by optically reading the pits. There is. In such a digital audio disc, unlike a conventional record disc in which a sound groove is formed, only one surface of the digital audio disc is an information reading surface (hereinafter referred to as a surface) and the other surface is a non-information surface. The mainstream is a so-called single-sided reading type, which is a reading surface (hereinafter referred to as a back surface), and for example, a label on which recorded music titles and the like are attached is attached. Therefore, when a digital audio disc to be reproduced is mounted in the disc mounting portion of the optical disc reproducing device for reproducing the audio signal from the digital audio disc, the disc may be erroneous by the operator. It is expected that the front surface and the back surface of the will be confused and installed. In such a case, for example, unless the operator himself / herself notices a mistake in mounting the disc, the disc reproducing apparatus performs a normal operation at the start of reproduction, such as a laser beam on the disc as described later. Even if the focus pull-in operation is performed with the light incident, the playback start state, that is, the focus control operation state after the focus pull-in cannot be performed, so the focus pull-in operation is repeatedly performed in vain. Moreover, it is extremely inconvenient. Further, continuing useless repetitive operations may cause a failure of the disk reproducing device.

Therefore, in the optical disc reproducing apparatus, the focus pull-in operation is performed, and when the state in which the focus pull-in operation is repeated reaches a predetermined period, or the focus pull-in operation is repeated a predetermined number of times. When it reaches the number of times, it is judged that the disc is mounted in the disc mounting portion in an improper state, for example, the state where the disc is turned upside down, and therefore it is not possible to shift to the focus control operation state. It has been proposed to stop the execution of the focus pull-in operation.

Further, in the optical disc reproducing apparatus, even if the disc is not actually mounted in the disc mounting portion, it is erroneously recognized that the disc is mounted in the disc mounting portion, and the focus is focused. It is conceivable that an operation including a pull-in operation at the start of reproduction will be performed. In such a case, as a matter of course, the disc reproducing apparatus cannot shift to the focus control operation state even if the focus pull-in operation is performed. Therefore, for example, a state where the focus pull-in operation is repeatedly performed is a predetermined state. When the period is reached or the number of times the focus pull-in operation is repeated reaches a predetermined number, the focus pull-in operation is stopped.

The focus pull-in operation in the optical disc reproducing apparatus is performed for the following reasons. That is, when signal reproduction from a disc on which signal recording is performed by arraying pits like a digital audio disc is performed by reading the pits by an optical reading means, that is, an optical pickup, For example, laser light from the optical pickup is made incident on a pit on the disc, and reflected laser light modulated according to the pit from the disc is again received by the optical pickup and converted into an electric signal. In this case, a focus detection photodetector, which is a component of the optical pickup, is used so that the laser light from the optical pickup always takes an appropriate focus state on the recording surface on which the pits of the disc are formed. Focus control using the error voltage is performed. This focus control is performed by providing a focus control circuit system that gives a focus drive signal to the focus adjusting means based on the focus error voltage, and the focus adjusting means is, for example, the recording surface of the disc of the objective lens of the optical pickup. Adjust the distance to. However, in order to actually cause such a focus control circuit system to perform focus control, the objective lens of the optical pickup is positioned at a distance of a certain range with respect to the recording surface of the disc, and the laser which is incident on the disc. It is necessary to set the focus state of light to a range of a constant defocus state centered on the proper focus state. Therefore, the focus state of the laser light incident on the disk is set to a range of the constant defocus state. The focus pull-in operation is performed to pull the focus control circuit system into the focus control operation state. A focus pull-in circuit for performing such a focus pull-in operation is provided in the optical disc reproducing device.

[0006]

As described above, in the optical disc reproducing apparatus, the focus pull-in operation is performed while the disc is properly mounted in the disc mounting portion to shift to the focus pull-in state. Not only when the disc is not mounted in the disc mounting part, or when the disc is mounted in the disc mounting part but the mounting is improper, for example, when the disc is turned upside down. Under this condition, the focus pull-in operation may be repeatedly performed, and eventually, it may not be possible to shift to the focus control operation state. Then, normally, when the focus pull-in operation is performed in the optical disc reproducing apparatus, the disc mounting portion and its peripheral portion are
It is inside the disc reproducing apparatus and cannot be visually recognized from outside the disc reproducing apparatus.

Therefore, in the case where the optical disc reproducing apparatus does not shift to the focus control operation state despite the focus pull-in operation, the cause is from the outside of the apparatus to the disc mounting portion. There is an inconvenience that it cannot be discriminated whether the disc is not mounted or the disc is not properly mounted on the disc mounting portion. Also, if the focus pull-in operation is repeated without the disc being mounted in the disc mounting part, light such as laser light will be directly incident on the disc mounting part, thereby causing unnecessary power consumption. As a result, unexpected and undesired situations may occur in the disc mounting portion and the portion related thereto.

In view of the above point, the present invention provides a focus pull-in operation which is performed under normal conditions by causing light to be incident on a disc properly mounted in the disc mounting portion. Appropriate status detection processing and status determination processing shall be performed in both cases where the disk is not mounted in the disk mounting section or when the disk is not properly mounted in the disk mounting section. An object is to provide an optical disc reproducing device.

[0009]

In order to achieve the above object, an optical disc reproducing apparatus according to the present invention is a disc
The focus control system for the light incident on the
The focus pull-in operation can be repeated.
Set the focus retracting means and the number of focus retracting operations.
Counting means for counting, and the counting means
When the count value reaches the specified value, the disc is
To detect that it is incorrectly attached to the attachment part
None, moreover, mounting the disc at the disc mounting part
Equipped with a disc presence / absence determining means for detecting the presence or absence of
The disc is detected by the disc presence / absence determining means.
The focus pull-in operation is not performed by the focus pull-in means when the unmounted state is detected .

[0010]

In the optical disc reproducing apparatus according to the present invention, the focus pull-in operation by the focus pull-in means is performed.
Is performed, the count value by the counting means is predetermined.
Depending on the value, the disc may not be
That is mounted What is detected, in addition, the disc existence discrimination means, when the disc is not mounted is detected in the disk mounting portion, for example
If is supplied to a detection signal canvas <br/> Okasu retraction means sent from the disk presence judging means, the focus pull means is controlled by the detection signal from the disc presence determination means does not perform the full Okasu pull-in operation To be taken. As a result, it is possible to reliably avoid the situation where the focus pull-in operation causes the focus pull-in operation to be performed when the disc is not loaded in the disc loading portion. It will be done only under the circumstances. When the focus pull-in operation is performed by the focus pull-in means, the disc is mounted.
If the disc is mistakenly attached to the section and the disc is not properly attached , that state is the focus pull-in state.
The number of focus pull-in operations by
Detected and appropriate action is taken.

[0011]

1 shows an example of an optical disc reproducing apparatus according to the present invention. In the example of FIG. 1, a disc mounting portion 10 is arranged, and the disc mounting portion 10 is rotated by a disc rotating motor 11. Then, for example, a disc 12, which is a digital audio disc, is mounted on the disc mounting portion 10 as indicated by a chain line. Further, in the example of FIG. 1, in connection with the disc mounting portion 10, a voltage generating circuit 13, a focus driving circuit 20, a focus adjusting means 21, an optical pickup 22, a focus discriminating circuit 23, a switch 2 are provided.
4 and a switching control circuit 25, which constitute a focus pull-in circuit with a focus control circuit system as shown in FIG. In the following, the configuration and operation of the focus pull-in circuit shown in FIG. 2 will be described with reference to the time charts of FIGS. 3 and 4.

In the focus pull-in circuit shown in FIG. 2, the voltage generating circuit 13 forms a focus pull-in voltage, and the position of the objective lens in the optical pickup 22 is moved according to the change in the voltage, and the focus pull-in voltage is moved. By changing the distance between the objective lens and the recording surface of the disc 12, the focus state of the laser light that is incident on the recording surface of the disc 12 from the optical pickup 22 through the objective lens is changed. In that case, when the objective lens in the optical pickup 22 is within a certain range of distance in which the focus control circuit system can be in the focus control operation state, the focus state of the laser beam incident on the recording surface of the disk 12 is gentle. 3 changes smoothly from the focus pull-in operation state to the focus control operation state. Therefore, from the voltage generation circuit 13 to FIG.
At the time t ₀ of the pulling-in operation, as shown by the voltage e ₂ , the polarity suddenly changes to one having the one polarity from the ground potential, and then it gradually changes to the one having the opposite polarity via the ground potential. The focus pull-in voltage is obtained.

Therefore, the voltage generating circuit 13 is, for example,
It has two capacitors 14 and 15, and the capacitor 14
And 15 one end of each is grounded, and the resistor r ₁ and a switch 17 having a resistance value R ₁ between the terminal 16 the other end with a positive polarity voltage + E obtained capacitor 14 are connected in series, voltage -E other end and the negative polarity of the capacitor 14 is the resistance value resistor r ₂ having an R ₂ is connected between the terminal 18 obtained, between the other ends of the capacitor 15 of the capacitor 14 A resistor r ₃ having a resistance value R ₃ and a switch 19 are connected in series. And the resistance value R
₁ and R ₂ are selected so that R ₁ <R ₂ . In such a voltage generation circuit 13, the switches 17 and 1
When 9 is turned off, the voltage e ₁ obtained at the other end of the capacitor 14 is made equal to the negative voltage −E,
Further, the voltage e ₂ obtained at the other end of the capacitor 15 is set to the ground potential (zero).

Then, when the switches 17 and 19 are switched from the off state to the on state at the time t ₀ of starting the pull-in operation shown in FIG. 3, the electric charge of the capacitor 15 is charged through the resistor r ₃ and the voltage e ₂ becomes the ground potential. From voltage e
It sharply changes toward the negative voltage −E which is the value at time t ₀ at ₁ . However, on the other hand, since the switch 17 is turned on at the time t ₀ , the voltage e
_{Since 1} gradually changes from the negative voltage −E to the positive voltage (R ₂ −R ₁ ) · E / (R ₂ + R ₁ ) via the ground potential, the voltage e ₂ is the negative voltage. -E is reached, and the voltage of positive polarity (R
₂₋ R ₁ ) · E / (R ₂ + R ₁ ). The time from the start of the pull-in operation t ₀ to the time when the voltage e ₂ reaches the ground potential is 0.3 to 0.4.
It takes about a second.

The respective states of the switches 17 and 19 are switched by the output signal S ₁ of the switching control circuit 25,
When the pull-in operation start signal St is supplied to the switching control circuit 25 at the pull-in operation start time t ₀ , the output signal S ₁
Is changed from low level to high level,
As a result, each of the switches 17 and 19 is switched from the off state to the on state. As a result, as described above, the negative voltage −E from the ground potential after the pull-in operation start time t _0.
Changes sharply toward, then reverses, passes through the ground potential, and the positive voltage (R ₂ −R ₁ ) · E / (R ₂ + R ₁ )
A voltage e ₂ is formed as a focus pull-in voltage that gradually changes toward. Then, this voltage e ₂ is passed through the focus drive circuit 20 to the focus adjusting means 21.
The laser light is incident on the disk and the optical pickup 22 which receives the reflected laser light from the disk or the objective lens incorporated therein is displaced according to the voltage e ₂ and is incident on the disk 12. The focus state of the laser light is changed.
In this case, before and after the portion of the voltage e _{2 having} the ground potential, the focus state of the laser light incident on the disk 12 is changed, for example, from the overfocus state to the proper focus state and then to the underfocus state. As a result, as shown in FIG. 3, the focus error voltage ef obtained from the focus detecting photodetector of the optical pickup 22 is
For example, it changes from positive to negative.

This focus error voltage ef is
It is supplied to the dust discriminating circuit 23. And the focus format
Whether the focus error voltage ef is positive in the separate circuit 23
From zero to the negative crossing point,
The focus state of the laser light incident on the camera 12 is over.
Transition from focus state to under focus state
In the process, the point that is in the proper focus state is detected.
Then, at the detected point, the focus determination circuit 2
Output signal S of 3₂However, for example, from low level to high level
It changes to Le. In this way, the focus determination circuit
23 output signal S ₂Changes from low level to high level
Output signal S₂Switching control
Output signal S of circuit 25₁From high level to low level
Can be changed. As a result, the switching control circuit 25
Output signal S₁Generation circuit 1 switched and controlled by
Each of the switches 17 and 19 of 3 is turned off from the on state
The focus from the voltage generation circuit 13 is switched to the state.
Voltage e which is the pull-in voltage₂Is stopped.

At the same time, the output signal S ₂ of the focus determination circuit 23 changes from the low level to the high level, so that the switch 24 is switched from the off state to the on state, whereby the focus error voltage ef is increased. , Focus drive circuit 20 through switch 24
Is supplied to the focus adjustment circuit 21 as a focus drive signal from the focus drive circuit 20.
A state in which the focus control operation based on the focus error voltage ef is performed, that is, the focus control operation state is taken, and the formation of the output signal S ₁ having a high level by the switching control circuit 25 is stopped. In this way, the focus drive circuit 20, the focus adjustment means 21, the optical pickup 22, the focus determination circuit 23, and the switch 24.
Thus, the focus control circuit system is formed.

When the disk 12 is properly mounted on the disk mounting portion 10 as described above, normally, as shown in FIG.
In as shown in, after changes sharply toward voltage -E negative polarity from the ground potential, and inverted, positive voltage via a ground potential _{(R 2 -R 1) · E} / (R 2 + R _The voltage e ₂ that gradually changes toward ₁ ) is supplied from the voltage generating circuit 13 to the focus adjusting means 21 via the focus drive circuit 20 only once from the pull-in operation start time t ₀ , and the focus by the focus pull-in circuit is increased. When the pull-in operation is performed once, the focus pull-in state is established, and the focus determination circuit 23 detects the zero cross point in the portion of the focus error voltage ef that changes from positive to negative, and the focus error voltage ef is detected.
The focus control operation state is performed in which the focus control operation is performed.

On the other hand, the disk 12 is not properly mounted on the disk mounting portion 10.
Under the condition that the disk 12 is mounted on the disk mounting portion 10 with its front surface and back surface reversed, the laser light from the optical pickup 22 is transferred to the back surface of the disk 12 mounted on the disk mounting portion 10. In this case, since a label or the like is attached to the back surface of the disc 12, the optical pickup 22
The laser light from the disk is not reflected by the disk 12, and the optical pickup 22 cannot receive the reflected laser light from the disk 12. Therefore, even if the focus error voltage ef is not obtained from the focus detection photodetector of the optical pickup 22 and the scheduled time elapses from the pull-in operation start time t ₀ , the focus determination circuit 23 causes the focus error voltage ef to continue. The zero crossing point is not detected in the part where the value changes from positive to negative. In such a case, the focus pull-in operation is performed again by the focus pull-in circuit.

Therefore, the switching control circuit 25 has the focus discriminating circuit 23 of the focus discriminating circuit 23 between the pull-in operation start time t ₀ at which the output signal S ₁ changes from the low level to the high level until the predetermined time T ₁ elapses. A detection circuit for detecting whether or not the output signal S ₂ has changed from the low level to the high level is provided, and as shown in FIG. 4, the output signal S 2 is output during a predetermined time T ₁ from the time t _{0. When 2} does not change from the low level to the high level and the transition to the focus control operation state is not made, a predetermined time T from the time t _0.
At the time t ₁ when ₁ has elapsed, the output signal S ₁ is changed from the high level to the low level, and the voltage generation circuit 1
Each of the switches 17 and 19 in 3 is switched from the on state to the off state. In the voltage generating circuit 13, when each of the switches 17 and 19 is turned off, as shown in FIG. 4, the voltage e ₁ obtained at the other end of the capacitor 14 of the voltage generating circuit 13 is at a predetermined time. The voltage is returned to the negative voltage −E with a constant, and the voltage e ₂ obtained at the other end of the capacitor 15 is also returned to the ground potential with a predetermined time constant.

Subsequently, a predetermined time T from the time t ₁
At the time t ₂ when ₂ has elapsed, the output signal S ₁ changes from the low level to the high level as in the time t ₀ , the switches 17 and 19 are switched from the off state to the on state again, and the voltages e ₁ and e ₂ changes again as in the case from the time point t ₀ , and the voltage e ₂ is supplied to the focus adjusting means 21 via the focus drive circuit 20 as the focus pull-in voltage. The retraction operation is performed again. Then, such a focus pull-in operation is repeated under the condition that the output signal S ₂ from the focus determination circuit 23 is maintained at the low level and the switch 24 is maintained in the OFF state, and the transition to the focus control operation state is not made. .

In the example shown in FIG. 1 in which the focus pull-in circuit as shown in FIG. 2 for performing the focus pull-in operation as described above is provided, when the disc 12 is properly mounted in the disc mounting portion 10. , The focus pull-in operation is performed by the focus pull-in circuit, the focus control operation state is set, and the signal reproduction from the disk 12 is performed under the state. Then, the read output obtained by reading the audio signal information recorded on the disc 12 by the optical pickup 22 is supplied to the signal processing circuit 29 to be subjected to necessary processing, and the reproduction signal is output to the output terminal 30. can get.

Further, the disk 12 is not properly mounted to the disk mounting portion 10, and, for example, the front surface and the back surface of the disk 12 are reversed so that the disk mounting portion 1
When mounted on 0, the laser beam from the optical pickup 22 is made incident on the back surface of the disk 12,
When the normal reflected laser light from the disk 12 is not obtained and the focus pull-in operation by the focus pull-in circuit is the sum of the predetermined time T ₁ and the predetermined time T ₂ (T
It is repeated at intervals corresponding to ( ₁ + T ₂ ). For this reason, the number of times the output signal S ₁ from the switching control circuit 25 rises from the low level to the high level matches the number of times the focus pull-in operation is started. Therefore, for example, in FIG. 4, by catching a change from the low level to the high level of the output signal S ₁ from the switching control circuit 25 as shown as N ₁ , N ₂ , N ₃ ... By counting the number of rises, it is possible to detect the number of start-ups of the focus pull-in operation. When the number of start-ups exceeds a predetermined number, the disk 12 is mounted with its front surface and back surface reversed. You will be able to judge that there is.

Therefore, the counter 31 is connected to the output terminal of the switching control circuit 25, and the counter 31 is connected to the output terminal.
Is supplied with the output signal S ₁ from the switching control circuit 25. The counter 31 outputs the output signal S ₁ of N in FIG.
_When the rising changes from the low level to the high level, which are shown as ₁ , N ₂ , N ₃ ..., are counted, and the count value obtained thereby reaches a preset predetermined value, that is,
When the number of times the focus pull-in circuit starts the focus pull-in operation reaches a predetermined number, for example, four times, the output signal S ₃ is generated. The output signal S ₃ obtained from the counter 31 is supplied to the disc loading mechanism 32 and the warning unit 33, and the disc loading mechanism 32
In response to the output signal S ₃ , the unloading operation for detaching the disc 12 from the disc mounting portion 10 is performed, and the warning unit 33 responds to the output signal S ₃ to the disc 12 for the disc mounting portion 10. A warning message is displayed to indicate that the
Alternatively, a warning operation state such as issuing a warning sound is set.

In this way, when the disk 12 is mounted on the disk mounting portion 10 with the front surface and the back surface reversed, the focus pull-in operation is repeatedly started, for example, four times, and the counter 31 is switched and controlled. When the rising change of the output signal S ₁ from the circuit 25 is counted four times, it is determined that the laser light from the optical pickup 22 is incident on the back surface of the disk 12, and the counter 31 outputs the output signal S _3. As a result, it is detected that the disk 12 is mounted on the disk mounting portion 10 with the front surface and the back surface thereof reversed. Although not shown, the output signal S ₃ from the counter 31 is also supplied to the voltage generation circuit 13 or the optical pickup 22,
Thereby, the operation of each part is stopped.

Further, in the example shown in FIG. 1, a disc presence / absence determining means 34 for detecting whether or not a disc is mounted in the disc mounting portion 10 is provided.
The disc presence / absence determining unit 34 is configured to include, for example, a light emitting diode and a phototransistor, and the light emitting diode and the phototransistor are, for example,
When the disc 12 is mounted on the disc mounting portion 10, the discs 12 are arranged so as to face each other with the disc 12 interposed therebetween.

Then, when the focus pull-in operation by the focus pull-in circuit is about to be started under the condition that the disc is not mounted in the disc mounting portion 10, the disc presence / absence discriminating means 34 outputs the light from the light emitting diode. Light is received by the phototransistor, the phototransistor performs an operation of generating a light reception output, and the disk presence / absence determining unit 34 confirms that the disk is not mounted in the disk mounting portion 10 based on the light reception output of the phototransistor. The detection signal S ₄ is transmitted. On the other hand, under the condition that the disk 12 is mounted in the disk mounting portion 10, the light from the light emitting diode in the disk presence / absence determining means 34 is the disk 12.
Since the phototransistor is not blocked by the phototransistor in the disc presence / absence discriminating means 34 and does not reach the phototransistor, the phototransistor does not generate a light reception output, and therefore the detection signal S ₄ is not transmitted from the disc presence / absence discriminating means 34. In this way, when the disc is not mounted in the disc mounting portion 10, the detection signal S ₄ obtained from the disc presence / absence determining means 34 is supplied to, for example, the voltage generating circuit 13, the disc loading mechanism 32, and the warning portion 33. To be done.

When the detection signal S ₄ from the disc presence / absence discriminating means 34 is supplied, the voltage generating circuit 13 causes the output signal S ₁ of the switching control circuit 25 to rise and change from low level to high level. However, in response to the detection signal S ₄ , the focus pull-in voltage e ₂ is not generated, so that the focus pull-in operation by the focus pull-in circuit is not started. That is, the focus pull-in circuit including the voltage generating circuit 13 detects the detection signal S ₄ from the disc presence / absence determining means 34.
Is not supplied to the voltage generation circuit 13, the disc mounting portion 1
Only under the condition that the disk 12 is attached to 0,
The focus pull-in operation is started in response to the rising change of the output signal S ₁ of the switching control circuit 25 supplied to the voltage generating circuit 13 from the low level to the high level.

Further, the disc loading mechanism 32
When the detection signal S ₄ from the disc presence / absence discriminating means 34 is supplied, the disc mounting portion 10 is returned to a state in which a disc can be mounted, and further,
When the detection signal S ₄ from the disk presence / absence determining means 34 is supplied, the warning section 33 accordingly displays a warning indicating that the disk is not mounted in the disk mounting section 10 or makes a warning sound. Takes a warning action state such as issuing.

In this way, in the example shown in FIG. 1, the focus pull-in circuit performs the focus pull-in operation only under the condition that the disc 12 is mounted in the disc mounting portion 10, and the focus pull-in operation is performed. With the retracting operation, it is determined whether or not the mounting state of the disc 12 with respect to the disc mounting portion 10 is proper, and the focus retracting operation is not performed when the disc 12 is not mounted in the disc mounting portion 10. . Therefore, useless focus pull-in operation is effectively avoided.

[0031]

As is clear from the above description, in the optical disc reproducing apparatus according to the present invention, when the disc presence / absence discriminating means detects that the disc is not mounted in the disc mounting portion, for example, is supplied to the detection signal canvas Okasu retraction means sent from the disk presence judging means, the focus pull means, in response to the detection signal from the disc presence judging means, since it is and does not conduct focus pull-in operation The situation that the focus pulling-in operation by the focus pulling-in means is performed without the disc being loaded in the disc loading portion is surely avoided, and the focus pulling-in operation by the focus pulling-in means is performed when the disc is loaded in the disc loading portion. It will be done only at the source. When the focus pull-in operation is performed by the focus pull-in means, the focus pull-in means performs the focus pull-in.
Counting by counting means for counting the number of operations
When the value reaches the specified value, it will be
If the disc is not properly attached to the disc mounting part , that state will be detected by the focus pull-in means.
Accurately detected based on the number of times the focus retracts,
Appropriate action will be taken.

Therefore, according to the optical disc reproducing apparatus of the present invention, under normal conditions, the focus pull-in is performed by making the light incident on the disc properly mounted in the disc mounting portion. In executing the operation, appropriate condition detection processing and status determination processing should be performed in both the situation where the disc is not loaded in the disc loading section and the situation where the disc is not properly loaded in the disk loading section. You will be able to do it.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an optical disc reproducing apparatus according to the present invention.

FIG. 2 is a block diagram showing a focus pull-in circuit configured in the example shown in FIG.

FIG. 3 is a time chart used for explaining the operation of the focus pull-in circuit shown in FIG.

FIG. 4 is a time chart provided for explaining the operation of the focus pull-in circuit shown in FIG.

[Explanation of symbols]

 10 Disc Mounting Section 12 Disc 13 Voltage Generation Circuit 20 Focus Drive Circuit 21 Focus Adjusting Means 22 Optical Pickup 23 Focus Discrimination Circuit 24 Switch 25 Switching Control Circuit 31 Counter 32 Disc Loading Mechanism 33 Warning Section 34 Disc Presence / Absence Discriminating Means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 56-130861 (JP, A) JP 55-38663 (JP, A) JP 55-4736 (JP, A) JP 56- 54667 (JP, A) JP 58-102340 (JP, A) JP 58-155524 (JP, A) Actual development Sho 52-79906 (JP, U)

Claims (2)

[Claims] And 1. A focus pull means capable of performing repeatedly the focus pull-in operation to draw the focus <br/> scan control system for the light incident on the disk controls the operation state, the follower
And a counting means for counting the number of times the retraction operation is performed
And the count value by the above counting means is set to a predetermined value.
When the disc becomes full, the above disc will be
It is not detected whether the disc is loaded or not, and whether or not a disc is loaded in the disc loading part is detected.
It is equipped with a disc presence / absence discriminating means to know
Than Moto of the disc in the disc mounting portion is not mounted is detected by another means, an optical disc reproducing apparatus where the focus pull-in operation by the upper notated Okasu retraction means has Do so not performed. 2. A detection signal obtained from the disc presence / absence determining means.
The optical disc reproducing apparatus according to claim 1, wherein the signal is supplied to the focus pull-in means .