JP2003099958A - Optical pickup position detecting method and optical disk apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the position of an optical pickup having a plurality of objective lenses without providing a new member and to provide an optical pickup position detecting method which eliminates an erroneous discrimination for the combination of an optical disk and the objective lenses. SOLUTION: In an optical disk apparatus 10 including an optical pickup 16 having a CD lens and a DVD lens as the objective lenses 12, in order to detect the position of the optical pickup 16, a step of switching to the DVD lens or the CD lens, a step of focusing, and a step of converting a reflective light amount into a voltage by a photodetector 15 at the time of focusing, binarizing the voltage with a prescribed threshold value at a comparison conversion part 17, discriminating the kind of the objective lens 12 in the optical path by a controller 18, and detecting the position of the optical pickup 16 by the discrimination result, are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup position detecting method and an optical disc device.

[0002]

2. Description of the Related Art Conventionally, there is an optical disk device capable of recording / reproducing an optical disk such as a CD (compact disk), a CD-R (compact disk recordable) and a DVD (digital versatile disk). In order to record / reproduce two or more kinds of optical disks having different layer configurations, a plurality of objective lenses are provided, and an objective lens suitable for the layer configuration is selected and used.

Permanent magnets and electromagnets are generally used as means for switching the objective lens. Then, a method is adopted in which a kick pulse is generated in the electromagnet so as to repel the permanent magnet and the objective lens is switched by the repulsive force.

Therefore, the optical pickup supporting the objective lens moves due to a large gravitational acceleration applied from the outside to some time, and the objective lens originally in the optical path should be present. It can change. Therefore, Japanese Patent Application Laid-Open No. 9-305980 discloses an optical pickup which can always keep track of which objective lens is located in the optical path. In the publication, there is provided a lens position detecting means, for example, means for providing a permanent magnet and a hall element so as to face each other and detecting a change in magnetic flux passing through the hall element depending on the position of the objective lens.

[0005]

However, since the switching of the objective lens is performed by the kick pulse as described above, the momentum at the time of switching may be too strong to cause the lens to bounce and switch. If the above publication is used as a means for detecting such a case, a new member called a lens position detecting means must be provided, which leads to cost increase, weight increase, volume increase, and the like.

In view of the above problems, the present invention detects the position of an optical pickup having a plurality of objective lenses without providing a new member and eliminates erroneous discrimination of a combination of an optical disc and an objective lens. An object is to provide a position detection method. Another object of the present invention is to provide an optical disc device using the detection method.

[0007]

In order to achieve the above object, the optical pickup position detecting method according to the present invention comprises C
An optical pickup position detecting method for detecting a position of the optical pickup in an optical disc device, which is compatible with D and DVD and has a lens for CD and a lens for DVD as an objective lens, the lens for DVD Alternatively, the step of switching to the CD lens, the step of applying focus, and the step of applying the focus, the amount of reflected light is converted into a voltage, and the voltage is binarized at a predetermined threshold to determine the type of the objective lens in the optical path. Discriminating, and detecting the position of the optical pickup from the discriminated result.

As described above, when the focus is applied, the amount of reflected light is converted into a voltage, and the CD is converted by using a predetermined threshold value.
Alternatively, by discriminating the objective lens suitable for the DVD, it is possible to eliminate the erroneous discrimination even when the focus is applied even though the combination of the optical disc and the objective lens is wrong.

The optical pickup position detecting method according to the present invention is an optical pickup position detecting method for detecting the position of an optical pickup having a plurality of objective lenses in an optical disc apparatus corresponding to a plurality of types of optical discs. The type of the objective lens in the optical path is discriminated from the difference in the amount of reflected light detected depending on the type of the objective lens, and the position of the optical pickup is detected from the discriminated result.

As described above, by discriminating the objective lens suitable for the set optical disc based on the change of the reflected light quantity, it is possible to eliminate the erroneous discrimination of the combination of the optical disc and the objective lens.

Further, the optical pickup position detecting method according to the present invention is an optical pickup position detecting method for detecting the position of an optical pickup having a plurality of objective lenses in an optical disc device corresponding to a plurality of types of optical discs. The step of switching the objective lens, the step of applying the focus, and the step of determining the type of the objective lens in the optical path from the difference in the amount of reflected light when the focus is applied, and detecting the position of the optical pickup from the result of the determination. And are provided.

In this way, when the focus is applied, the objective lens suitable for the set optical disk is discriminated based on the change in the reflected light amount, so that the combination of the optical disk and the objective lens is wrong. Even if the focus is applied, misjudgment can be eliminated.

In order to determine the type of the objective lens in the optical path from the difference in the reflected light amount, the reflected light amount may be converted into a voltage and the voltage may be binarized with a predetermined threshold value.

Further, the optical disk device according to the present invention is characterized in that it is provided with means for performing the detection by the above-mentioned optical pickup position detecting method.

[0015]

1 is a block diagram showing the configuration of an optical disk device 10. As shown in FIG. 10 is a CD (or CD-
R) and a DVD capable of reproducing an optical disc, 11 is an optical disc set in the optical disc device 10, 12 is an objective lens for CD or DVD, 13
Is a laser light source, 14 is a beam splitter, and 15 is a photodetector that detects the reflected light from the optical disk 11 and converts the light quantity into a voltage and outputs the voltage. An optical pickup 16 is composed of the objective lens 12, the laser light source 13, the beam splitter 14, and the photodetector.

Further, 17 binarizes the voltage converted by the photodetector 16 with a predetermined threshold value, and the voltage exceeding the threshold value is "1".
Is a comparison and conversion unit that converts a voltage that does not exceed the threshold value into a signal of "0". The comparison / conversion unit 17 does not need to be provided as a new member, and a detection circuit (not shown) that detects a focusing error signal can be used. Reference numeral 18 denotes a controller that controls the optical disk device 10.

FIG. 2 is an enlarged plan view of the vicinity of the optical pickup 16 shown in FIG. Reference numeral 12a is a DVD lens, 12b is a CD lens, and 19 is an optical pickup 1.
A shaft for slidably fixing 6 to the main body of the optical disk device 10,
20 is an electromagnet coil, and 21a and 21b are permanent magnets.

In the state of FIG. 2, the lens 12b for CD is used.
Is in the optical path. When a kick pulse is applied to the electromagnet coil 20 from this state, the electromagnet coil 20 and the permanent magnet 21
a repels each other, the optical pickup 16 rotates about the shaft 19 in the direction of the arrow F, and stops at a position where the electromagnet coil 20 faces the permanent magnet 21b. This makes DV
The switching to the D lens 12a is completed.

The lens 12a for DVD and the lens 12b for CD have different numerical apertures (NA). Generally, the lens for DVD has NA = 0.6, and the lens for CD has NA = 0.45.
Is. Also, the reflectance of the optical disk 11 is DVD and CD.
Different. Therefore, the amount of light detected by the photodetector 15 differs depending on the combination of the two types of objective lenses 12 and the two types of optical disks 11. In the present invention, it is determined whether or not the objective lens 12 suitable for the set optical disk 11 is selected based on the difference in the detected light amount.

Next, the optical disk 1 is inserted into the optical disk device 10.
A method of detecting the position of the optical pickup 16 when switching to the objective lens suitable for the type of the optical disk when 1 is set will be described.

FIG. 3 is a flowchart showing the operation of the optical disk device 10. First, when the optical disk 11 is set, in step S30 the optical pickup 1
6 is moved to the read start position. The process proceeds from step S30 to step S31 to switch to the DVD lens 12a. Although the DVD lens 12a is used as the default here, the CD lens 12b may be used.

Next, steps S31 to S32
In step S33, 1 is added to the first counter (not shown), and in step S33, the count of the first counter is a predetermined value (=
N) is not exceeded. When the count of the first counter does not exceed N in step S33,
It proceeds to step S34. On the other hand, when the count of the first counter exceeds N in step S33, the D
As a result of performing the cycle of switching to the VD lens 12a N times, it is determined that the combination of the optical disk 11 and the objective lens does not match, the process proceeds to step S35, the process is terminated, and an error is output.

When the process proceeds from step S33 to step S34, the focus servo (not shown) is turned on, and the process proceeds to step S36 to determine whether or not the focus is applied.
When the focus is applied in step S36, the process proceeds to step S37 and it is determined whether or not the signal output from the comparison and conversion unit 17 is appropriate.

When the signal is appropriate in step S37, that is, when the photodetector 15 detects an appropriate amount of received light, the combination of the set optical disk 11 and the objective lens in the optical path is appropriate. Judge, step S
Proceeding to step 38, processing for reading the information from the optical disk 11 is performed.

On the other hand, when the signal is not appropriate in step S37, that is, when the photodetector does not detect an appropriate amount of received light, the combination of the set optical disk 11 and the objective lens in the optical path is suitable. Determined not to
It returns to step S31.

On the other hand, if the focus is not applied in step S36, the process proceeds to step S39 to switch to the CD lens 12b. After that, the process proceeds to step S40, the focus servo (not shown) is turned on, and the process proceeds to step S41 to determine whether or not the focus is applied.
When the focus is applied in step S41, the process proceeds to step S42, and it is determined whether or not the signal output from the comparison and conversion unit 17 is appropriate.

When the signal is appropriate in step S42, that is, when the photodetector 15 detects an appropriate amount of received light, the combination of the set optical disk 11 and the objective lens in the optical path is appropriate. Judge, step S
Proceeding to step 38, processing for reading the information from the optical disk 11 is performed.

On the other hand, if the focus is not applied in step S41, or if the signal is not appropriate in step S42, it is judged that the combination of the set optical disk 11 and the objective lens in the optical path does not match, and step S43. Go to. In step S43, 1 is added to the second counter (not shown), and the process proceeds to step S44 to determine whether or not the count of the second counter exceeds a predetermined value (= N). When the count of the second counter does not exceed N in step S44, step S3
Return to 9.

On the other hand, when the count of the second counter exceeds N in step S44, the combination of the optical disk 11 and the objective lens is matched as a result of performing the switching cycle to the CD lens 12b N times. If not, the process returns to step S31.

Incidentally, step S37 or step S42
The reason why the signal may not be appropriate in the case is that the objective lens is not switched to the target objective lens even though the objective lens is switched in step S31 or step S39. For example, the kick pulse is too weak. It is possible that the optical pickup 16 did not rotate, or the kick pulse was too strong and the optical pickup 16 rotated vigorously and bounced off.

For example, a case where a CD is set as the optical disk 11 will be described. First, the optical disk device 10 moves the optical pickup 16 to the read start position and switches to the DVD lens 12a based on the default.

Next, the first counter is set to "1" and the first counter
It is determined whether or not the count of the counter of N exceeds N (for example, 3). Since the count of the first counter has not exceeded N at this time, the focus servo is turned on and it is determined whether or not focus is applied. Now the CD is set, DV
Since the D lens 12a is selected, focus is not normally applied.

Therefore, a kick pulse is applied so as to switch to the CD lens 12b. At this time, assuming that the kick pulse is too strong and the optical pickup 16 bounces and the lens is not switched, the focus is not normally applied even if the focus servo (not shown) is turned on.
Even if focus is applied, the signal output from the comparison and conversion unit 17 is not appropriate for the combination of the CD and DVD lens 12a.

Therefore, the second counter is set to "1",
It is determined whether or not the count of the second counter exceeds N. Since the count of the second counter has not exceeded N, the kick pulse is again applied to switch to the CD lens 12b. If the lens is switched to the CD lens 12b without any problem, the focus servo is turned on to focus the image, and the signal output from the comparison and conversion unit 17 is appropriate. Therefore, the information on the set CD can be read.

In this way, even if the optical disc 11 and the objective lens 16 are not properly combined and are in focus, the objective suitable for the optical disc 11 is obtained based on the change in the light amount detected by the photodetector 15. By discriminating the lens 16, erroneous discrimination can be eliminated.

[0036]

According to the present invention, it is possible to eliminate erroneous discrimination of the combination of the optical disc and the objective lens by discriminating the objective lens suitable for the set optical disc based on the change of the reflected light amount.

Further, according to the present invention, when the focus is applied, the objective lens suitable for the set optical disk is discriminated based on the change of the reflected light quantity.
Even if the optical disc and the objective lens are wrongly combined and the focus is applied, the misjudgment can be eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical disk device of the present invention.

2 is an enlarged plan view of the vicinity of the optical pickup of FIG. 1. FIG.

FIG. 3 is a flowchart showing an operation of the optical disc device of the present invention.

[Explanation of symbols] 10 Optical disk device 11 optical disc 12 Objective lens 12a DVD lens 12b CD lens 16 Optical pickup

Claims (5)

[Claims] 1. An optical pickup position detection method for detecting the position of an optical pickup in an optical disc device, which is compatible with CDs and DVDs and has an optical pickup having a lens for CD and a lens for DVD as an objective lens. , Switching to the DVD lens or the CD lens, applying a focus, and converting the reflected light amount into a voltage when the focus is applied, and binarizing the voltage with a predetermined threshold value in the optical path A method of determining the type of the objective lens, and detecting the position of the optical pickup from the result of the determination. 2. An optical pickup position detecting method for detecting the position of an optical pickup having a plurality of objective lenses in an optical disc device corresponding to a plurality of types of optical discs, wherein the amount of reflected light detected by the types of the objective lenses. The optical pickup position detecting method is characterized in that the type of the objective lens in the optical path is discriminated from the difference between the two, and the position of the optical pickup is detected from the discrimination result. 3. An optical pickup position detecting method for detecting the position of an optical pickup having a plurality of objective lenses in an optical disc device compatible with a plurality of types of optical discs, wherein the step of switching the objective lenses and applying focus An optical pickup comprising: a step, when the focus is applied, a type of an objective lens in an optical path is discriminated from a difference in reflected light amount, and a position of the optical pickup is detected from the discriminated result. Position detection method. 4. In order to determine the type of the objective lens in the optical path from the difference in the reflected light amount, the reflected light amount is converted into a voltage, and the voltage is binarized with a predetermined threshold value. 2. The optical pickup position detecting method according to 2 or 3. 5. An optical disk device comprising means for performing detection by the optical pickup position detecting method according to any one of claims 1 to 4.