JPH1027357A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow an optical device to read out data in a short time by selecting an arbitrary reflection layer in a multi-layer optical disk and servo-controlling a focus. SOLUTION: A drive control means 5 moves an objective lens to one side along an optical axis. A focus detection means 1 detects the coincidence between a reflection layer of an optical disk and a focus of the objective lens. A reflection layer discriminating means 2 sequentially counts detection signals from the detection means 1, and discriminates each layer of the reflection films from the number of counts. A count setting means 4 presets the number of counts corresponding to a layer intended for recording or reproducing. A coincidence between a count of the discriminating means 2 and that of the setting means 4 is detected by a coincidence detection means 3, and being timed to this coincidence detection signal, the focus servo-control loop is shut off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device, and more particularly, to an optical disk device that improves focus servo control of an optical disk device for reproducing or recording an optical disk having a multilayer reflective film.

[0002]

2. Description of the Related Art In a conventional optical disk apparatus, a laser beam is focused on a mounted optical disk via a pick-up lens, and a converging optical system for detecting the reflected light with a photodetector, and a laser beam. A focus pull-in control system having an actuator for condensing light on an optical disk is provided to perform recording and reproduction. FIG. 13 shows a configuration block diagram of such a conventional optical disk device.

The device shown in FIG. 13 comprises a photodetector 31 composed of a total of four unit elements A, B, C and D, and an amplifier 32 for amplifying detection signals from each of the unit elements A, B, C and D. , 33, 34, and 35, an RF amplifier 36 that amplifies so as to add up all the amplified outputs, and a focus error that adds up the outputs of the amplifiers 33 and 35 and amplifies them so as to subtract them from the outputs of the amplifiers 32 and 34. (Hereinafter abbreviated as FE).

In addition, the present optical disk apparatus uses the sum signal (A + B + C + D) of the 4-split photodetector or the RF signal 38 obtained by band-limiting the sum signal to a positive phase input (+), and the divided voltage of the variable resistor 42 An RF comparator 40 that outputs a focus ok (FOK) signal 55 as the negative phase input (−);
7 as the positive-phase input (+) and the resistor 4
An FZ that outputs a focus zero cross (FZC) signal 56 using the divided voltage of 3 and 44 as the negative phase input (−)
A C comparator 41, an ON / OFF switch 46 of a servo system, a resistor 45 connected between the switch 46 and the output of the FE amplifier 37, one end of the switch 46, and a control signal from the controller 54 are input. A servo circuit 47, a driver 48 for power amplifying a signal from the servo circuit 47, an actuator 49 including a focus coil connected to an output of the driver 48, and a FOK signal 55 and an FZC signal 56 as inputs. A controller 54 including a microcomputer for controlling a servo system such as a switch 46 and a servo circuit 47 is provided. Here, the FOK signal 55 and the FZC signal 56 are defined as a focus error signal.

The above-described variable resistor 42 has a power supply voltage of + V
And a constant voltage VC, which is provided to detect the focal point of the reflective film of the optical disc without detecting the surface of the optical disc by appropriately adjusting the FOK level described later. The terminal 53 of the constant voltage VC is connected to the output of the buffer 50 which receives the connection point between the divided resistors 51 and 52 as an input. The resistors 43 and 44 are connected in series between the power supply voltage + V and the ground. In order to accurately detect the zero-cross point of the FE signal 39, the bias of the negative-phase input (-) is set to a predetermined voltage in advance. It is for setting. The block diagram of FIG. 13 described above is a block diagram mainly related to the focus pull-in control system.

FIG. 14 is a flowchart showing a control procedure of the optical disk apparatus shown in FIG. 13, and FIG.
Referring to the time chart, first, in step S31, the laser power is turned on, and the laser beam hits the mounted optical disc. Next, in step S32, the focus servo system starts moving the pickup lens from below to above at a constant speed so as to approach the optical disk. As a result, the focal point gradually moves from the outside to the inside of the optical disc.

At that time, first, at a position P1 at a time point t1 when the focal point reaches the surface of the optical disk, the RF signal 38
, A small peak waveform appears, and since this waveform is equal to or lower than the FOK level of the threshold value E set in the RF comparator 40, no change appears in the FOK signal 55. on the other hand,
An S-shaped curve or an inverted S-shaped curve appears in the FE signal 39, and a negative pulse having a falling edge at the focus zero cross point is output as the FZC signal 56. This position P1 is a focus position on the surface of the optical disc. At this point, it is meaningless to stop the servo system and fix the focus. Therefore, the switch 46 is in the ON state, that is, the servo system is still in the inoperative state. Therefore, without moving to step S35, the movement is further performed.

The position P2 at the time point t2 at which the FOK signal 55 is detected in step S33 is the focal point on the reflective layer inside the optical disk.
Since 8 exceeds the FOK level, a positive pulse FOK signal 55 having a pulse width in the period exceeding the FOK level is obtained. on the other hand,
The FE signal 39 becomes a large S-shaped impulse, and F
An FZC signal 56 which is shaped by the ZC comparator 41 and has a falling edge at the zero-cross point is obtained.

Here, the FZC signal 5 in step S34
6 is the L (low) level, and F in step S33.
Since the OK signal 55 is at H (high) level, step S
The flow shifts to 35, where the focus servo loop is closed, the movement of the pick-up lens is stopped, and the position P2 is set as the focus-on point, and the focal point on the reflective layer is established.

[0010] As the lens is moved at a constant speed, a point occurs where the focus is momentarily obtained. The detection of the in-focus point is performed when the RF signal 38 is larger than the FOK signal level and the amplitude of the FE signal is smaller than the threshold value E in a zero-zero period.
It is a cross point, and it is known that if the objective lens is located within a position corresponding to this period, stable focus pull-in can always be performed.

[0011]

In such a conventional optical disk apparatus, focus servo is applied to an optical disk having only one reflective layer, and an arbitrary reflective layer is selected for an optical disk having a multilayer film. And the focus servo could not be applied, and the focus jump could not be applied to a specific reflection layer.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disk apparatus which can select a target reflective layer and apply focus servo even in an optical disk having a multilayer reflective film.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an optical disk apparatus according to the present invention provides an optical disk apparatus for reproducing or recording an optical disk having a multilayered reflective film, for detecting a focus error signal. Focus coil drive control means for moving the objective lens of the optical pickup in one direction along the optical axis; focus detection means for detecting that the reflection film of the optical disc coincides with the focus of the objective lens; A reflection layer discrimination means for sequentially counting detection signals from the detection means and discriminating each layer of the reflection film based on the count value; and a count for presetting a count value corresponding to the reflection layer to be reproduced or recorded. Setting means for detecting that the count value of the reflective layer determining means matches the count value of the count setting means; Means out, configured with a focus servo loop is closed the control means at a timing of the output signal from the coincidence detection means.

Here, the objective lens for picking up the light is reciprocated along the optical axis, the total number of layers of the reflection film is detected by the forward movement, and the focus lens is moved to the target reflection layer by the backward movement. multiply

An optical disk apparatus according to another embodiment of the present invention is an optical disk apparatus for reproducing or recording an optical disk having a reflective film formed in multiple layers. When moving to the reflecting layer, a kick pulse is applied to the drive output of the focus coil to control the jumping amount of the reflecting layer, and count setting means for setting the number of jumping layers to the next reflecting film. The drive control unit controls the kick pulse length of the focus coil, and focuses on a target reflection layer.

[0016]

FIG. 1 is a block diagram showing a first embodiment of the present invention. The optical disk device shown in FIG. 1 differs from the conventional optical disk device in blocks of the microcomputer 6, and the other blocks are common to the conventional optical disk device in FIG. The common components are illustrated using common reference numerals, and the description is omitted.

The configuration of the first embodiment includes a drive control means 5 for a focus coil for moving an objective lens of an optical pickup in one direction along an optical axis for detecting a focus error signal, and a reflection film for an optical disk. Focus detecting means 1 for detecting that the focal point of the objective lens coincides with each other, and reflecting layer determining means 2 for sequentially counting detection signals from the focus detecting means 1 and determining each layer of the reflecting film based on the counted number.
A count setting means 4 for presetting the number of counts corresponding to a reflection layer to be reproduced or recorded; and a match detection for detecting that the count of the reflection layer determination means 2 and the count of the count setting means 4 match. Means 3 for closing the focus servo loop at the timing of the output signal from the coincidence detecting means 3.

Reference is made to the timing chart of FIG. 2 showing the operation in such a configuration. FIG. 2 shows, by way of example, signal waveforms of various parts detected when an optical disk having a three-layered reflective film is used. First, a servo loop switch is turned on, a counter for detecting the number of reflection layers is initialized, and a count value corresponding to the reflection layer to be set as a date is set. Next, the laser is emitted, and the pickup lens is moved upward from below.

As shown in FIG. 2, the DC voltage of the RF signal 38 rises on the surface of the optical disk and on the reflection film. At this time, R
When the F signal 38 exceeds the FOK level, the FOK signal 55 becomes H. Then, the point in time when the focus error signal 39 crosses the center voltage VC is detected when the FZC signal 56 becomes L, and when the FOK signal 55 is H and FZ
At the moment when the C signal 56 becomes L, it is possible to detect the timing when the focus is adjusted to the reflection film. By sequentially counting the detection signals, it is possible to determine the number of layers of the reflection film from the surface of the optical disk.

In FIG. 2, the FOK level is level 1
There are two levels, Level 2 and Level 2. Level 1 is a level where only the reflective layer is detected. In the case of a multi-layer optical disc, there is a case where there is not much difference between the reflectivity of the disc surface and the reflectivity of the reflective film. At this time, level 2 is set as a detectable level, and counting is performed including the optical disc surface. In some cases, a malfunction can be prevented by converting the count value by one.

In the example of FIG. 2, when the FOK level is 1, the initial value of the counter is set to the counter value 1 (0 Oh),
At the time of K level 2, the initial value of the counter is set to the counter value 2
(FFh). In any case, when the reflection film is detected, the detection can be performed as 01h for the first layer, 02h for the second layer, and 03h for the third layer. Therefore, when the target reflection layer is the second layer, the count value is 02
When h is set and the counter for detecting the number of reflective layers reaches 02h, coincidence detection is established and the focus servo is closed. When the movement of the lens reaches the final end, the process ends as a disk-less state or an error.

Next, the flow of this embodiment will be described with reference to FIGS.
A description will be given along the flowchart of FIG. Steps S1 to S
4 is an initialization routine, and steps S5 to S13 are a focus routine 1. In FIG. 3, first, in step S1, the servo loop SW is turned on, that is, the input of the servo circuit is set to VC, and a switch operation for stopping the operation of the focus servo is performed. In the next step S2, the counter of the reflection layer discriminating means is initialized, that is, the counter for counting the number of times of detection of the reflection layer is initialized. In the case of the example of the counter value 1 in FIG.
h, the initial value is FFh in the example of the counter value 2.

In step S3, a counter corresponding to the target reflection layer is set, that is, 00h in the lower part of FIG.
From 0 to 03h means that the corresponding number of reflective layers can be selected. Step S4
Then, the laser diode inside the pickup is turned on to emit a laser.

Subsequently, in step S5, the pickup lens is started to move upward from the bottom, that is, while the pickup lens is slowly moved from the bottom to the top in order to focus on the reflective layer, the position where the focus is achieved is adjusted. Search. In step S6 of FIG. 4, it is determined whether the FOK signal is L or not, it is detected that the FOK signal is continuously L, and it is determined that the RF signal 38 has completely disappeared. In this method, the presence or absence of the next reflective layer is detected while reliably detecting the space between the layers of the multilayer film while preventing malfunction due to noise.

In step S7, it is determined whether the movement of the lens is completed or the lens is being moved. This is done by setting in advance a time during which the pickup lens can be sufficiently raised, measuring a certain time from the start of the movement of the pickup lens, and determining whether or not focusing is performed within that time. If not, it is determined that there is no disc or an error that the target reflection layer could not be detected in step S14.
Confirm with. Subsequently, in step S8, it is determined whether the FOK signal is H or not, and it is detected that the RF signal 38 has risen when the focus approaches the reflection film or the surface of the disk.

In step S9, it is determined whether the FZC signal is H or not. That is, after the FOK signal becomes H, when the point closer to the point where the focus is further matched is reached, FE
The signal 39 changes in an S shape. The time point when this change starts is detected by the change of the FZC signal 56 to H. Since chattering occurs in the FZC signal 56 at this time,
H is detected by continuous H.

In step S10, it is determined whether the FZC signal is L or not. That is, the timing at which the focus completely matches is detected. Here, the number of reflective layers is counted until the target reflective layer is obtained.

In step S11, the count is incremented by one. In the process for determining whether or not the count values match in step S12, it is determined that the number of target reflective layers matches the counted number of reflective layers. The servo loop is closed by the operation of “turn off the servo loop SW” in step S13. In this way, servo is applied to the target reflection layer.

Next, a second embodiment of the present invention will be described with reference to the block diagram of FIG. 1, the time chart of FIG. 5, and the flowcharts of FIGS. The block diagram of the second embodiment is common to that of FIG. 1 and will not be described in detail. According to the second embodiment, the objective lens of the optical pickup is reciprocated along the optical axis, the total number of reflective films is detected in the forward operation, and the focus is focused on the target reflective layer in the next return operation. This is an optical disk device that is designed to be pressed.

The operation for detecting the total number of layers of the reflection film in FIG. 6 is substantially the same as that in the flow charts shown in FIGS. Is detected as the total number of reflective films on the optical disk. This operation is the same as the case where the FOK level is level 2 and the initial value of the counter is FFh in FIG. Then, the objective lens of the optical pickup is moved from top to bottom, which is the final end of the movement of the objective lens. FIG. 5 shows time charts of the signals of the respective parts at this time.

FIG. 5 is different from FIG. 2 in that the FE signal 39 is output in a form in which the polarity of the FE signal 39 is inverted because the movement of the pickup lens is reversed. Therefore, the zero crossing of the FZC signal 56 is detected by detecting the timing when the signal becomes H. The focus is detected when the FOK signal 55 is H
, And when the FZC signal 56 becomes H. The servo loop is closed when the value obtained by counting the detection signal and the count value corresponding to the reflective layer to be made coincide with each other.
In this manner, the reciprocating operation of the pick-up lens completes the detection of the total number of layers of the reflective film and the focus control on the target reflective layer.

The operation flow of the second embodiment is shown in FIG.
As shown in FIG. 7, an initialization routine, a detection routine for the total number of layers, and a focus routine 2 are provided. In the initialization routine, the FOK level is selected as level 2 and the surface of the optical disk is not detected.

The routine for detecting the total number of layers does not include steps S12, S13, and S14 in FIG. 4. If the lens movement is completed in step S7, the count value is equal to or greater than 01h in step S15. Moving to FIG. 7, it is determined that there is no disk. The other steps are common to FIG. 4 and are therefore only illustrated in FIG.
Not detailed.

In the focus routine 2 of FIG. 7, the pickup lens is started to move from top to bottom in step S18. Steps S19 and S20 are used to check whether the FZC signal 56 continuously becomes L. This point is different from steps S9 and S10 in FIG. 4, but the other points are common to FIG.

Next, a third embodiment of the present invention will be described with reference to FIG.
This will be described with reference to the time charts of FIGS. 9 and 10 and the flowcharts of FIGS. 11 and 12. Since the block diagram of the third embodiment is the same as that of FIG. 1, the description is omitted. In this embodiment, the reflection layer of the optical disc being reproduced is focused and moved to another reflection layer, and the next reflection is performed. This is an optical disk device that can focus on the film. In the case of a focus jump, the number of layers to be jumped from the currently reproduced reflection film to the target reflection film is calculated and set in the count setting means 4. Then, a focus jump pulse is output from the servo circuit. The jump pulse is a combination of a kick pulse for accelerating the objective lens and a brake pulse for decelerating the objective lens. The waveforms at this time are shown in FIGS.
This is shown in FIG.

The kick pulse is output for the time set by the timer 1 at the time of the one-layer jump shown in FIG. 8, and then switched to the brake pulse. In the case of the two-layer jump shown in FIG. 9, since the number of layers to be jumped is two, the half pulse 1 is counted, and the brake pulse is switched. At this time, the timer 2 need not be operated. In the case of the three-layer jump shown in FIG. 10, although the number of layers to be jumped is three, the count of substantially half thereof is counted as 1, and then the timer 2 is operated to switch to the brake pulse at the position shown in the figure. By doing so, the time of the acceleration pulse and the time of the deceleration pulse become substantially equal, and positioning can be performed near the target reflection layer.
Then, when the target reflection layer is detected by the coincidence detecting means 3,
Focus servo is applied to the target reflection layer by turning off the brake pulse. It is to be noted that the focus servo is performed in an all-on state during this operation.

In FIG. 11, first, the number of layers to be jumped is set in a counter of the setting means 4 in step S21.
Next, a kick pulse is output (step S22). In step S23, if the predetermined time has elapsed by the timer 1, the process proceeds to step S27. If not, the process proceeds to step S24.
It is determined whether or not the reflection layer has been detected, and if detected, the process returns to step S25, and if not detected, the process returns to step S23. In step S25, when the counter value has become approximately half, it is determined in step S26 whether a predetermined time has elapsed,
If it has elapsed, the process proceeds to step S27, and a brake pulse is output.

Next, in FIG. 12, it is determined whether or not the target reflection layer has been detected in step S28, and if the reflection layer has been detected, it is determined in step 29 whether or not the target bit value has been reached. If it is not the counter value, the process returns to S28, and if so, the counter brake pulse is turned off.

[0039]

As described above, according to the optical disc apparatus of the present invention, it is possible to select an arbitrary reflection layer in a multilayer optical disc and to apply focus servo.
Focus jump can also be performed to any reflective layer from the reflective layer during playback or recording, or the objective lens of the optical pickup is reciprocated along the optical axis, and the number of reflective layers is detected by going forward and backward Then, focus servo can be applied to the target reflective layer in the next return operation,
Data can be read in a short time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of an optical disk device according to the present invention.

FIG. 2 is a time chart showing the first embodiment.

FIG. 3 is a flowchart illustrating a part of the first embodiment;

FIG. 4 is a flowchart illustrating another part of the first embodiment.

FIG. 5 is a time chart showing a second embodiment of the optical disc device according to the present invention.

FIG. 6 is a flowchart showing a part of the second embodiment.

FIG. 7 is a flowchart illustrating another part of the second embodiment.

FIG. 8 is a time chart showing detection of a first layer in the optical disc device according to the third embodiment of the present invention.

FIG. 9 is a time chart showing detection of a second layer in the third embodiment.

FIG. 10 is a time chart showing detection of a third layer in the third embodiment.

FIG. 11 is a flowchart showing a part of a flow in the third embodiment.

FIG. 12 is a flowchart illustrating a flow of another unit in the third embodiment.

FIG. 13 is a block diagram showing a conventional optical disk device.

And FIG. 14 is a flowchart showing a flow of an operation of the conventional optical disk device.

FIG. 15 is a time chart showing the operation of the conventional optical disc device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Focus detection means 2 Reflection layer discrimination means 3 Match detection means 4 Count setting means 5 Drive control means 6 Microcomputer 31 Photodetector 32-35 Amplifier 36 RF amplifier 37 FE amplifier 40 RF comparator 41 FZC comparator 46 Servo system ON / OFF Switch 47 Servo circuit 48 Driver 49 Actuator 50 Buffer

Claims (3)

[Claims] 1. An optical disc apparatus for reproducing or recording an optical disc having a multilayer reflective film, comprising: a focus coil for moving an objective lens of an optical pickup in one direction along an optical axis for detecting a focus error signal. Drive control means; focus detection means for detecting that the reflection film of the optical disk coincides with the focus of the objective lens; sequentially counting detection signals from the focus detection means; Reflective layer determining means for determining each layer of the film; count setting means for presetting a count value corresponding to the target reflective layer to be reproduced or recorded; count value of the reflective layer determining means and count of the count setting means A coincidence detecting means for detecting that the values coincide with each other, and a focus sensor at a timing of an output signal from the coincidence detecting means. Optical disk apparatus characterized in that it comprises a control means for closing the Borupu, the. 2. The objective lens of the optical pickup is reciprocally moved along the optical axis, the total number of layers of the reflection film is detected by a forward movement, and a focus servo is moved to the target reflection layer by a backward movement. The optical disk device according to claim 1, wherein 3. An optical disk apparatus for reproducing or recording an optical disk having a multilayer reflective film formed thereon, wherein a focus coil drive output is obtained when the optical disk being reproduced is moved from the reflective layer to another reflective layer. Drive control means for applying a kick pulse to the reflective layer to control the amount of jump of the reflective layer; and count setting means for setting the number of jump layers to the next reflective film. An optical disc device, wherein a target reflection layer is focused while being controlled by a control means.