JP4766912B2 - Optical disc apparatus and optical disc identification method - Google Patents

Description

  The present invention provides a focusing means for displacing a focusing position of an optical pickup in a perspective direction with respect to an optical disc in accordance with a control signal to a focus coil, and a detection method from the optical disc detected when the focusing position is displaced by the focusing means. The present invention relates to an optical disc apparatus provided with an optical disc identification means for identifying the type of the optical disc based on surface reflection light and recording surface reflection light, and an optical disc identification method.

  In recent years, for example, types of optical discs having different recording formats such as CD (Compact disc) and DVD (Digital Versatile Disk) are identified, and recording on the optical disc or the optical disc can be performed regardless of which optical disc is inserted. An optical disc apparatus capable of reproducing data from has been proposed.

  Here, both CD and DVD have a diameter of 12 cm and a plate thickness of 1.2 mm. However, a CD has a recording layer formed on one surface of a 1.2 mm thick substrate, while a DVD has a 0.6 mm thick substrate and a 0.6 mm thick protective layer. A recording layer is formed. That is, as shown in FIG. 12, the optical pickup irradiates the recording layer with a laser beam through a substrate having a thickness of 1.2 mm in the case of a CD, and has a thickness of 0 in the case of a DVD. The recording layer is irradiated with laser light through a 6 mm substrate, and the laser light reflected by the recording layer is detected.

  Further, in order to detect information recorded on the recording layer of the optical disc with high sensitivity, the optical pickup needs to detect laser light reflected by the recording layer with high reflectance. It is effective to make the focused position of the laser beam coincide with the recording layer surface. For this reason, the optical pickup detects the reflection intensity of the laser beam, and moves the focusing position of the objective lens for condensing the laser beam in the vertical direction with respect to the optical disc, thereby reflecting the reflection intensity of the laser beam. Is adjusted to maximize.

  The identification of the type of the optical disk inserted in the optical disk apparatus applies the detection of the focus position of the laser beam as described above. Since the optical pickup irradiates the optical disk with laser light through a substrate, when the focus position of the objective lens is gradually brought closer to the optical disk, as shown in FIG. Apart from the large reflection intensity peak Pb obtained when the in-focus position coincides with the recording layer, a small reflection intensity peak Ps can also be obtained when the in-focus position of the laser light coincides with the substrate surface. . In other words, since the thickness between the substrate surface and the recording layer differs between CD and DVD, when the objective lens is brought close to the optical disk at a constant speed, a peak Ps of a small reflection intensity of the laser beam is obtained. The time until the peak Pb having a large reflection intensity of the laser beam is obtained is different, but in discriminating the type of the optical disc in the conventional optical disc apparatus, the optical disc is a CD by measuring this time. Or DVD.

The objective lens is fixed by a leaf spring or a suspension wire, and a focusing direction comprising the leaf spring or the suspension wire and a moving coil motor that generates an electromagnetic force for displacing the leaf spring or the suspension wire is used to move the objective lens in the perspective direction. The relative position at is displaced. Here, the moving coil type motor generates an electromagnetic force corresponding to the focus coil current as a control signal when a focus coil current is supplied to the focus coil in the moving coil type motor. That is, the focusing means displaces the relative position of the objective lens in the perspective direction with respect to the optical disc by adjusting the focus coil current.
JP 11-149640 A JP 2000-260109 A

  As shown in FIG. 14, the relationship between the focus coil current and the focus position by the objective lens is different from the linear region in which the focus coil current and the focus position by the objective lens are proportional to each other. There is a non-linear region that does not have a proportional relationship before and after that. In addition, the relationship between the focus coil current and the in-focus position by the objective lens changes depending on the ambient temperature. However, in the prior art, it corresponds to the target focus position of the objective lens on the assumption that the objective lens is displaced within a linear region where the relationship between the focus coil current and the focus position by the objective lens is always linear. Focus coil current was supplied. For this reason, when the optical disc is identified, the focusing means is operated in a region where the relationship between the focus coil current and the position of the objective lens is non-linear, and the objective lens is displaced. When discriminating the type of optical disk, which is performed by measuring the time from when the peak Ps of reflection intensity is obtained until the peak Pb of high reflection intensity of the laser beam is obtained, the peak of the low reflection intensity of the laser beam is identified. There is a possibility that the time from when Ps is obtained until the peak Pb having a large reflection intensity of the laser beam is obtained is unstablely measured, and the optical disc is erroneously detected.

  For example, when the discriminating target of the type of the optical disc is an optical disc with surface runout as shown in FIG. 15 (hereinafter referred to as “surface runout disc”), detection of reflection intensity from the optical disc is detected. When the position is a position with a large amount of surface shake, the relative positional relationship between the objective lens and the surface shake disc is greatly different from the initially assumed relative positional relationship. The objective lens position from when the peak Ps is obtained until the peak Pb having a high reflection intensity of the laser beam is obtained may be the non-linear region, and the optical disc is erroneously detected. The potential increases.

  Further, the difference in mounting position of the support portion of the optical disk attached to the rotating shaft of the spindle motor or the mounting position of the pickup, and adjustment of the moving shaft for moving the pickup in the radial direction of the optical disk (adjustment of mechanical skew) ) And the like, there is a possibility that the position of the objective lens is driven in the non-linear region, and there is a possibility that the optical disc may be erroneously detected.

  In view of the above-described conventional drawbacks, the present invention can be securely inserted even in an environment where the relationship between the control signal to the focus coil and the focus position is a non-linear region when the focus position is displaced. Another object of the present invention is to provide an optical disc apparatus and an optical disc identification method capable of identifying the type of the optical disc.

In order to achieve the above-mentioned object, a first characteristic configuration of the optical disc apparatus according to the present invention is a focusing means for displacing the focusing position of the optical pickup in the perspective direction with respect to the optical disc in accordance with a control signal to the focus coil, An optical disc apparatus comprising optical disc identification means for identifying the type of the optical disc based on surface reflected light and recording surface reflected light from the optical disc detected when the focusing position is displaced by the focusing means, wherein the focusing means , the focus coil and the relationship between focus position control signal value regardless of the region indicating the region and the non-linear characteristics shown a linear characteristic, the control so as to change at a constant change rate set in advance The in-focus position is displaced by controlling a signal value, and the optical disc identification means And the type of the optical disc is identified based on the magnitude relationship between the time difference when the recording surface reflected light is detected and a preset threshold value of the time difference, and the surface reflected light or the recording surface reflected When light is detected in the region showing the non-linear characteristic, the time difference is corrected by a preset correction coefficient so as to correspond to a threshold value set when the light is detected in the region showing the non-linear characteristic. It is in the point comprised as follows.

According to the above-described configuration, the focusing unit has a predetermined constant value regardless of whether the relationship between the control signal value of the focus coil and the in-focus position has a linear characteristic or a non-linear characteristic. The in-focus position is displaced by controlling the control signal value so as to change at a change rate of the optical disc, and the optical disc identification means is preset with a time difference when the surface reflected light and the recording surface reflected light are detected. The surface reflection light or the recording surface reflection light is detected in an area exhibiting the non-linear characteristic because the type of the optical disk is identified based on the magnitude relationship with the threshold value of the time difference. The time difference is corrected with a correction coefficient set in advance so as to correspond to a threshold value set in the case where detection is performed in a region showing the linear characteristic. In, without erroneously detecting the type of the inserted optical disc it is become possible to reliably identify.

  The second feature configuration is that, in addition to the first feature configuration described above, the correction coefficient is corrected based on the ambient temperature of the optical pickup.

  According to the above configuration, even if the relationship between the control signal value to the focus coil and the in-focus position changes due to a change in the ambient temperature of the optical pickup, the correction coefficient is set corresponding to such change. Since the correction can be made, the optical disc apparatus can be surely identified without erroneously detecting the type of the inserted optical disc.

The third feature structure, in addition to the first characteristic feature of the above is that a difference before Symbol time based on the ambient temperature of the optical pickup is corrected.

According to the above configuration, even if the relationship between the control signal value to the focus coil and the in-focus position changes due to a change in the ambient temperature of the optical pickup, the time difference is corrected in response to such a change. Therefore, it is possible to provide an optical disc apparatus that can be surely identified without erroneously detecting the type of the inserted optical disc.

In order to achieve the above-mentioned object, the first characteristic configuration of the optical disc identification method according to the present invention is that the in-focus position of the optical pickup is displaced in the perspective direction with respect to the optical disc in accordance with a control signal to the focus coil. An optical disc identification method for identifying the type of the optical disc on the basis of surface reflected light and recording surface reflected light from the optical disc detected when the focus position is displaced, the control signal value to the focus coil and the focus Regardless of whether the positional relationship is a linear characteristic region or a non-linear characteristic region , the focus position is displaced by controlling the control signal value so as to change at a predetermined constant change rate. a step of thereby Ru is, on the basis of the magnitude relationship between the threshold value of the time difference between preset the time difference when detecting the surface reflection light beam and the recording surface reflected light, When identifying the type of serial optical disk, the surface reflection light or the recording surface reflected light is detected by the region showing the non-linear characteristics, it is set if it is detected in the region showing the linear characteristic It lies in that; and a step of correcting the time difference at a preset correction coefficient so as to correspond to that threshold.

  As described above, according to the present invention, the objective lens is reliably inserted even in an environment where the relationship between the control signal to the focus coil and the in-focus position is a non-linear region during the displacement operation of the objective lens. An optical disc apparatus and an optical disc identification method capable of identifying the type of an optical disc can be provided.

  Hereinafter, a first embodiment of an optical disc apparatus and an optical disc identification method according to the present invention will be described. As shown in FIG. 1, the control block configuration involved in the identification of the optical disc in the optical disc apparatus is an optical pickup 03 that irradiates the optical disc 01 with the laser beam 02 and receives the reflected light of the laser beam 02 from the optical disc 01. And the reflected light intensity detecting means 04 for detecting the intensity of the reflected light received by the optical pickup 03, and the type of the optical disc 01 is identified based on the intensity of the reflected light detected by the reflected light intensity detecting means 04. Optical disc identifying means 05 and a focusing controller 08 for controlling a focusing means 07 to be described later.

  The optical pickup 03 includes an objective lens 06 for condensing the laser beam 02 on the optical disc 01 and an objective lens 06 formed integrally with the objective lens 06 in the perspective direction with respect to the optical disc 01. Focusing means 07 to be displaced is provided.

  The focusing means 07 includes a leaf spring (not shown) and a suspension wire (not shown) that fix the objective lens 06, and a moving coil motor (not shown) that generates an electromagnetic force that displaces the leaf spring and the suspension wire. Etc. The moving coil motor is configured to generate an electromagnetic force corresponding to the focus coil current when a focus coil current is supplied to a focus coil (not shown) in the moving coil motor.

  That is, the focusing means 07 displaces the in-focus position by the objective lens 06 by displacing the objective lens 06 in the optical axis direction via the leaf spring or the suspension wire to a position corresponding to the focus coil current. It is configured. That is, the objective lens 06 is installed to face the installation position of the optical disc 01, and when the position is displaced by the focusing means 07, the relative position with the optical disc 01 is displaced in the perspective direction. The focusing controller 08 is configured to adjust and control a focus coil current for driving the focusing means 07 as a control signal value.

  For example, a relationship table PA that prescribes the focus coil current If and the position Da of the objective lens 06, that is, the absolute position Da in the optical disc apparatus, as shown in FIG. The position Da of the objective lens 06 is stepped through the focusing means 07 between the predetermined focus coil currents If1 and If2, that is, between the first position Da1 and the second position Da2 of the objective lens 06. Or it is comprised so that it may be displaced substantially continuously. Here, the relationship table between the focus coil current and the position of the objective lens will be described. The relationship table is substantially the same as that defining the relationship between the control signal value to the focus coil and the focus position by the objective lens. Is. Therefore, as the relationship table, a table indicating the relationship between the control signal value to the focus coil and the focus position by the objective lens may be used directly. In the following embodiment, “position of objective lens” and “focus position” "Means a substantially equivalent value.

  When the objective lens 06 is displaced stepwise or substantially continuously between the first position Da1 and the second position Da2, the focus coil current If and the position Da of the objective lens 06 are The relationship is not only the linear region Ri where the relationship between the focus coil current If and the position Da of the objective lens 06 is linear, but also the relationship between the focus coil current If and the position Da of the objective lens 06 is non-linear. The non-linear area Nr is also included, and the relationship table PA shown in FIG. 2A is configured so as to obtain consistency with the linear area Ri and the non-linear area Nr.

  When the type of the optical disc 01 is identified by the optical disc identification means 05 described later, the position Da of the objective lens 06 is controlled so as to be displaced in the direction approaching the farthest portion with respect to the optical disc 01, and the objective lens 06 is controlled to be uniformly displaced at a preset displacement speed Va. That is, the displacement amount and the displacement time Tx of the displacement from the position Da (t−1) of the objective lens 06 before displacement to the new position Da (t) of the objective lens 06 after displacement for an arbitrary time t. The focus coil current If is controlled on the basis of the relation table PA so that is constant.

  The focus coil current If is, for example, as shown in FIG. 2B, a new position Da (t) of the objective lens 06 after displacement from a position Da (t-1) of the objective lens 06 before displacement. Based on the relation table, the current addition value ΔIf of the focus coil current If for displacing the focus coil current If can be controlled. That is, an internal counter T that counts a time Tm from the start of displacement of the position Da of the objective lens 06 from the first position Da1 of the objective lens 06 as shown in FIG. The current addition value ΔIf corresponding to the count value Tm by the counter T can be controlled to be a new focus coil current If in addition to the focus coil current If.

  The operation of the focusing controller 08 will be described based on the flowchart of FIG. When the optical disc 01 is inserted into the optical disc apparatus (SA1), the focusing controller 08 controls the focus coil current If based on the relation table PA, that is, sets the focus coil current If to If1. As a result, the objective lens 06 is displaced from the optical disc 01 to the farthest position, that is, the first position Da1 via the focusing means 07 (SA2).

  When the objective lens 06 is displaced to the first position Da1, the focus coil current If is controlled based on the relation table PA so that the objective lens 06 has a constant displacement speed Va. An “objective lens constant velocity displacement operation” is started in which the objective lens 06 is displaced stepwise or substantially continuously to the position Da2.

  That is, when the objective lens 06 is displaced to the first position Da1, the count value Tm of the internal counter T is reset to 0 (SA3), and the current addition value ΔIf corresponding to the count value Tm of the internal counter T is reset. Is added to the focus coil current If to obtain a new focus coil current If (SA4), and the count value Tm of the internal counter T is incremented (SA5).

  The focusing controller 08 determines that the focus coil current If becomes the focus coil current If2 when the position Da of the objective lens 06 is the second position Da2, and the step SA4 and the step are performed at regular intervals. Repeat SA5 (SA6). Then, when the focus coil current If becomes the focus coil current If2, the “objective lens constant velocity displacement operation” is ended.

  The optical disc identification means 05 is the intensity of the reflected light detected by the reflection intensity detection means 04 while the objective lens 06 is performing the “objective lens constant velocity displacement operation” as described above by the focusing controller 08. For example, as shown in FIG. 4, the intensity of the reflected light detected by the reflected intensity detecting means 04 is stored in time series, and the number of the reflected light in the reflected light is determined. A time difference ΔT between the first time T1 when the first intensity peak P1 is detected and the second time T2 when the second intensity peak P2 in the reflected light is detected is calculated.

  Then, from the time difference ΔT and the displacement speed Va, the position of the objective lens 06 when the first intensity peak P1 is detected and the objective lens 06 when the second intensity peak P2 is detected. Relative position Lx is calculated, and for example, as shown in FIG. 5, the position of the objective lens 06 when the first intensity peak P1 that would be detected by various optical discs is detected. Compared with a relative distance table PB stored in advance, which is composed of a relative distance Lr with respect to the position of the objective lens 06 when the second intensity peak P2 is detected, the relative distance that is the closest to the relative distance Lx. The type of the optical disk of Lr is detected, and the type of the detected optical disk is identified as the type of the optical disk 01.

  When the focusing controller 08 displaces the objective lens 06 in a direction approaching from the farthest portion with respect to the optical disc 01 inserted in the optical disc apparatus, the first intensity peak P1 is , Detected when the focal point of the laser beam 02 coincides with the substrate surface of the optical disc 01, and the second intensity peak P2 is detected when the focal point of the laser beam 02 is the same as the recording surface of the optical disc 01. It is detected when they match. That is, the optical disc identification means 05 is configured to identify the type of the optical disc 01 based on the surface reflected light and the recording surface reflected light from the optical disc 01.

  Hereinafter, the operation of the optical disc identifying means 05 will be described with reference to the flowchart of FIG. When the “objective lens constant velocity displacement operation” is started by the focusing controller 08 (SB1), the reflected light intensity detection unit 04 detects the objective lens constant velocity displacement operation. The intensity of the reflected light received by the optical pickup 03 is stored in time series (SB2).

  The first time T1 when the first intensity peak P1 in the reflected light is detected and the second time when the second intensity peak P2 in the reflected light is detected from the time-series data on the intensity of the reflected light stored. A time difference ΔT with respect to the time T2 is calculated (SB3). Then, from the time difference ΔT and the displacement speed Va, the position of the objective lens 06 when the first intensity peak P1 is detected and the objective lens 06 when the second intensity peak P2 is detected. The relative distance Lx is calculated (SB4), the calculated relative distance Lx is compared with the relative distance table PB (SB5), and the relative distance Lr closest to the relative distance Lx is obtained. The type of optical disc is identified as the type of the optical disc 01 (SB6).

  The position of the objective lens 06 when the first intensity peak P1 is detected and the objective lens 06 when the second intensity peak P2 is detected from the time difference Tx and the displacement speed Va. In addition to calculating the relative distance Lx with respect to the position and detecting the type of the optical disc 01 based on the relative distance table, the displacement speed of the objective lens 06 is controlled at a constant displacement speed Va as described above. In this case, a time difference table between the first time T1 and the second time T2 that will be detected by various optical discs is stored in advance, and based on the detected time difference Tx and the time difference table. The type of the optical disc 01 may be identified.

  In addition to the one that the focusing controller 08 controls to displace the position Da of the objective lens 06 at a constant displacement speed Va between the first position Da1 and the second position Da2. The discriminating means 05 stores the intensity of the reflected light in time series while detecting the first intensity peak P1 from the intensity of the reflected light detected by the reflection intensity detecting means 04, and the focusing controller 08 stores the optical disc in the time series. The position Da of the objective lens 06 is displaced at a constant displacement speed Va only during the period from when the first intensity peak P1 is first detected by the identification means 05 until the second intensity peak P2 is detected. Also good.

  That is, the focusing controller 08 may be configured to adjust the displacement speed of the objective lens 06 based on the detection of the surface reflected light. For example, if the position Da of the objective lens 06 is displaced at high speed until the first intensity peak P1 is first detected by the optical disc identification means 05, it is necessary for identifying the type of the optical disc 01. It is possible to shorten the time required.

  In the above-described example, the case where the intensity of the reflected light detected by the reflection intensity detecting unit 04 is stored in time series has been described, but the first time T1 and the first time when the first intensity peak P1 is detected. If the second time T2 at which the second intensity peak P2 is detected is stored in an identifiable manner, it is not necessary to store all the reflected light intensities. In the above example, the case where the position Da of the objective lens 06 is controlled to be displaced in the direction approaching the farthest portion with respect to the optical disc 01 has been described. It may be controlled so as to be displaced. Furthermore, in the above-described example, although the position Da of the objective lens 06 is displaced from the farthest portion Da1 to the nearest portion Da2 with respect to the optical disc 01, at least the second intensity peak P2 is detected. What is necessary is just to be displaced to. The same applies to the embodiments described later.

  Furthermore, in the above-described example, when the position Da of the objective lens 06 (which may substantially define the in-focus position) defined by the relation table PA is the absolute position Da in the optical disc apparatus, that is, a frame or the like. Although the case where the position is relative to the reference position has been described, the position Da of the objective lens 06 (which may substantially define the in-focus position) defined by the relation table is such that the focus coil current is applied to the moving coil motor. It may be defined by a position in the separation direction or the proximity direction with respect to the optical disc from the reference position with reference to the neutral position when no voltage is applied.

  That is, the optical disc identification means detects a relation table that defines a preset applied current value to the focus coil and the position of the objective lens, and a relative physical quantity when the surface reflected light and the recording surface reflected light are detected. The type of the optical disc is configured to be identified based on the relative distance and the relative time, and the focusing means displaces the objective lens at a preset displacement speed based on the relation table, The optical disc identification means converts a detection time difference as the relative physical quantity into a relative distance based on the relation table.

  Furthermore, the optical disk device is provided with a temperature sensor such as a thermistor for detecting the ambient temperature of the optical pickup 03, and the focusing controller 08 stores the relation table PA corresponding to each temperature in advance, or based on the detected temperature. By correcting the relationship table PA, the focusing controller 08 is configured to perform the above-mentioned “objective lens constant velocity displacement operation” based on the relationship table PA corresponding to the temperature detected by the temperature sensor. The type of the optical disk can be identified with high accuracy by correcting the characteristics of the moving coil type motor that fluctuates due to the change.

  Another embodiment will be described below. As shown in FIG. 7A, the focusing controller 08 controls the focus coil current If from the position Da (t−1) of the objective lens 06 before displacement. A second embodiment in which the current addition value ΔIf for displacing to the correct position Da (t) is controlled to be always constant regardless of the position Da of the objective lens 06 will be described.

  That is, in the second embodiment, the focusing controller 08 moves the objective lens 06 according to the relationship between the focus coil current If and the position Da of the objective lens 06 as shown in FIG. The speed Va is configured to change. In other words, when the current addition value ΔIf is sequentially added to the focus coil current If at a constant time interval, as shown in FIG. 7C, the number Kt of times the current addition value ΔIf is added, A predetermined relation table PC based on the relation table PA is obtained between the objective lens 06 and the position Da.

  The operation of the focusing controller 08 will be described with reference to the flowchart of FIG. 8. When the optical disc 01 is inserted into the optical disc apparatus (SC1), the focusing controller 08 will perform the focusing based on the relation table PA. By controlling the coil current If, that is, by setting the focus coil current If to If1, the objective lens 06 is moved to the farthest position from the optical disc 01 through the focusing means 07, that is, the first Is displaced to position Da1 (SC2).

  When the objective lens 06 is displaced to the first position Da1, the count value Kt of the internal counter K that counts the number Kt of times when the current addition value ΔIf is added to the focus coil current If is reset to 0 (SC3), An “equal current addition operation” is started in which a constant current addition value ΔIf is sequentially added to the focus coil current If.

  That is, by adding a constant current addition value ΔIf to the focus coil current If to obtain a new focus coil current If (SC4), the position Da of the objective lens 06 is displaced stepwise or substantially continuously. The count value Kt of the internal counter K is incremented (SC5), and the count value Kt is output to the optical disc identification means 05 described later (SC6).

  The focusing controller 08 performs the steps SC4 to SC6 at regular intervals until the focus coil current If becomes the focus coil current If2 when the position Da of the objective lens 06 becomes the second position Da2. Is repeated (SC7). Then, when the focus coil current If2 is reached, the “equal current addition operation” is terminated.

  The optical disc identification means 05 is based on the intensity of the reflected light detected by the reflection intensity detection means 04 while the objective lens 06 is performing the “equal current addition operation” as described above by the focusing controller 08. For example, as shown in FIG. 9, the intensity of the reflected light detected by the reflection intensity detecting unit 04 and the count value Kt output by the focusing controller 08 are identified. Are stored in time series, and the type of the optical disc 01 is identified based on the stored time series data and a predetermined relation table PD stored in advance.

  More specifically, the optical disc identification means 05 uses the first count value Kt1 of the internal counter K in the focusing controller 08 and the second intensity in the reflected light when the first intensity peak P1 in the reflected light is detected. A second count value Kt2 of the internal counter K in the focusing controller 08 when the peak P2 is detected is detected, and a difference ΔKt between the first count value Kt1 and the second count value Kt2 is calculated.

  Here, the predetermined relationship table PD includes the first case where the first intensity peak P1 is detected in the displacement speed region showing the non-linear characteristic shown in FIG. 7B and the first case in the displacement speed region showing the linear characteristic. Considering that the value of the difference ΔKtx calculated when the intensity peak P1 is detected varies, for example, as shown in FIG. 10, the first count value Kt1 that will be calculated for various optical discs and The difference ΔKtx from the second count value Kt2 is determined in accordance with the first count value Kt1 when the first intensity peak P1 is detected.

  That is, ΔKtx corresponding to various optical disks in the relation table PD corresponding to the first count value Kt1 detected by the optical disk identification unit 05 is compared with ΔKt calculated by the optical disk identification unit 05, and the optical disk is compared. The type of the optical disc having ΔKtx that is the closest approximation to ΔKt calculated by the identification unit 05 is identified as the type of the optical disc 01. In other words, based on the first count value Kt1 detected by the optical disc identification means 05, ΔKtx as a threshold value for discriminating the magnitude of the detection time difference, that is, the magnitude of ΔKt calculated by the optical disc identification means 05 is variable. Configured to set.

  Hereinafter, the operation of the optical disc identifying means 15 will be described with reference to the flowchart of FIG. When the “equal current addition operation” is started by the focusing controller 08 (SD1), the optical pickup 03 detected by the reflected light intensity detection unit 04 while the “equal current addition operation” is being performed. The intensity of the reflected light received by the above and the count value Kt output by the focusing controller 18 are correlated and stored in time series (SD2).

  A first count value Kt1 in which the first intensity peak P1 in the reflected light is detected and a second count value Kt2 in which the second intensity peak P2 in the reflected light is detected from the stored time-series data. The difference ΔKt is calculated (SD3). Then, ΔKtx in various optical discs in the relation table PD corresponding to the detected first count value Kt1 is compared with the calculated ΔKt (SD4), and ΔKtx which is closest to the calculated ΔKt Is identified as the type of the optical disc 01 (SD5).

  Here, instead of the relation table PD that defines ΔKtx as a threshold value corresponding to various optical disks, a single threshold value for identifying a preset optical disk type is set to the first count value Kt1 or the second count value. You may comprise so that it may correct | amend based on Kt2. That is, the first count value Kt1 or the second count so as to absorb the fluctuation of the difference ΔKt between the first count value Kt1 and the second count value Kt2 when any one is detected in a non-linear displacement speed region. Threshold correction means for correcting the threshold value with a preset correction coefficient based on the value Kt2 is provided, and the type of the optical disc is identified based on the corrected threshold value. As a correction coefficient, based on a threshold when both the first count value Kt1 and the second count value Kt2 are in the linear characteristic region, a correction coefficient is tabled for each count value when any of the values indicates a non-linear region value. It can be set as data, and further, a non-linear region can be divided into regions and a correction coefficient can be set in advance for each region.

  That is, the focusing means displaces the objective lens at a preset displacement speed based on the relation table, and the optical disc identification means identifies the magnitude of the detection time difference as the relative physical quantity based on the relation table. The threshold value is variably set.

  In the above-described embodiment, the difference in detection time between the surface reflected light and the recording surface reflected light is detected by the difference between the first count value Kt1 or the second count value Kt2, and this value is used as the characteristic of the linear characteristic region of the relation table. It is also possible to provide distance detection means for detecting a distance value related to the distance between the surface of the optical disk and the recording surface based on the above. Then, when providing a discriminating means for discriminating the disc type by comparing the distance value detected by the distance detecting means with a threshold, depending on the detection status of the surface reflected light, that is, the first count value Kt1 or the second count. If any of the values Kt2 indicates a value in the non-linear region, the type of the optical disc can be accurately identified by correcting the threshold value by the threshold value correcting means as described above. The correction coefficient in this case is also a correction coefficient for each count value when any of the first count value Kt1 and the second count value Kt2 indicates a value in the non-linear region based on a threshold value when both are in the linear characteristic region. Can be set as table data, and a non-linear region can be divided into regions and a correction coefficient can be set in advance for each region.

  Similarly, in order to absorb the fluctuation of the difference ΔKt between the first count value Kt1 and the second count value Kt2, the difference is set with a correction coefficient set in advance based on the first count value Kt1 or the second count value Kt2. A time difference correction unit that corrects ΔKt may be provided, and the type of the optical disk may be identified based on a fixed threshold value set in advance after the correction.

  That is, the focusing means displaces the objective lens at a preset displacement speed based on the relation table, and the optical disc identification means converts the detection time difference as the relative physical quantity into a relative distance based on the relation table. To do.

  Further, the detection time difference between the surface reflected light and the recording surface reflected light detected by the difference between the first count value Kt1 or the second count value Kt2 is calculated based on the characteristics of the linear characteristic area of the relation table and the surface of the optical disc. When providing a distance detecting means for detecting a distance value related to the distance of the recording surface, and providing an identifying means for comparing the distance value detected by the distance detecting means with a threshold value to identify the disc type, the detection of the surface reflected light Depending on the situation, that is, if either the first count value Kt1 or the second count value Kt2 indicates a value in a non-linear region, by providing distance value correction means for correcting the distance value, The type can be accurately identified. Similarly to the above, the correction coefficient in this case is also counted when either of the first count value Kt1 and the second count value Kt2 is a linear characteristic region as a base and one of them indicates a value in the non-linear region. A correction coefficient can be set as table data for each value, and further, a non-linear area can be divided into areas and a correction coefficient can be set in advance for each area.

  When the optical disk device includes a temperature sensor for detecting the ambient temperature of the optical pickup 03, the optical disk identification means 05 stores the relationship table PD corresponding to each temperature in advance, and the optical disk identification means 05 The type of the optical disc 01 may be identified based on the relation table PD corresponding to the temperature detected by the temperature sensor, and the correction coefficient by the threshold correction unit or the time difference correction unit may be corrected based on the detected temperature. The optical disc identification means 15 can reliably identify the type of the optical disc 01 regardless of the ambient temperature of the optical pickup 03.

  When the detection position of the first intensity peak P1 or the second intensity peak P2 is detected in the non-linear displacement speed region by the reflection intensity detection unit 04, the displacement operation of the position of the objective lens 06 is stopped. Then, the spindle motor is driven to rotate the optical disc 01 by a predetermined angle, and after the detection position in the circumferential direction of the optical disc 01 is changed, the displacement operation of the position of the objective lens 06 is started again. Thus, when the optical disc 01 is a surface runout disc, both the intensity peaks P1 and P2 can be accurately detected in the displacement velocity region showing the linear characteristics.

  That is, the optical disc identification means detects the surface reflected light or the recording surface reflected light based on a detection position of either the surface reflected light or the recording surface reflected light detected by the relation table. The detection position in the circumferential direction is changed.

  Although a plurality of embodiments have been described above, it is possible to configure the embodiments by appropriately combining them within the scope of the effects of the present invention, and the specific configuration of each control block can be appropriately changed and designed. Not too long.

Explanatory diagram of functional block configuration for optical disc identification (A) is an explanatory diagram of a relationship table between the focus coil current and the position of the objective lens, (b) is an explanatory diagram of a relationship table between the position of the objective lens and the current addition value, and (c) is a count value T and the current addition. Explanatory diagram of relationship table with values The flowchart for demonstrating operation | movement of the focusing controller in 1st embodiment. Explanatory drawing of the time-series data of the reflected light intensity from the optical disk stored by the optical disk identification means in the first embodiment Illustration of relative distance table Flow chart for explaining the operation of the optical disc identification means in the first embodiment. (A) is explanatory drawing of the relationship table of the position of an objective lens, and an electric current addition value, (b) is explanatory drawing of the relationship table of the position of an objective lens, and the displacement speed of an objective lens, (c) is an electric current addition value. Explanatory diagram of the relationship table between the number of additions and the position of the objective lens The flowchart for demonstrating operation | movement of the focusing controller in 2nd embodiment. Explanatory drawing of the time-series data of the reflected light intensity from the optical disk memorize | stored by the optical disk identification means in 2nd embodiment Explanatory drawing of the relationship table of count value Kt1 and the difference in various optical discs Flowchart for explaining the operation of the optical disc identification means in the second embodiment Explanatory diagram of the state of laser light irradiation on various optical disks Explanatory drawing of the difference in the relationship between the detection time of the reflection intensity peak at the substrate surface and the detection time of the reflection intensity peak at the recording layer in various optical disks when the position of the objective lens is gradually brought closer to the optical disk Explanatory diagram of relationship between focus coil current and objective lens position Illustration of runout disc

01: Optical disc 02: Laser beam 03: Optical pickup 04: Reflected light intensity detection means 05, 15: Optical disc identification means 06: Objective lens 07: Focusing means 08, 18: Focusing controller

Claims (4)

Focusing means for displacing the focusing position of the optical pickup in the perspective direction with respect to the optical disk in response to a control signal to the focus coil; and surface reflected light from the optical disk detected when the focusing position is displaced by the focusing means; An optical disc apparatus comprising optical disc identification means for identifying the type of the optical disc based on reflected light from the recording surface,
The focusing means, so that the relationship between the focus position and the control signal value of the focus coils regardless of the region indicating the region and the non-linear characteristics shown a linear characteristic changes at a constant change rate set in advance The focus position is displaced by controlling the control signal value to
The optical disc identifying means is configured to identify the type of the optical disc based on a magnitude relationship between a time difference when the surface reflected light and the recording surface reflected light are detected and a preset threshold value of the time difference. When the surface reflected light or the recording surface reflected light is detected in the region showing the non-linear characteristic, the threshold value is set in advance so as to correspond to a threshold set when the surface reflected light or the recording surface reflected light is detected in the region showing the linear characteristic. An optical disc apparatus configured to correct the time difference with the corrected correction coefficient.   The optical disk apparatus according to claim 1, wherein the correction coefficient is corrected based on an ambient temperature of the optical pickup. The optical disk apparatus according to claim 1, wherein the pre-Symbol time difference is corrected based on the ambient temperature of the optical pickup. In response to a control signal to the focus coil, the focusing position of the optical pickup is displaced in the perspective direction with respect to the optical disk, and the reflected light from the optical disk and the reflected light from the recording surface are detected when the focusing position is displaced. An optical disc identification method for identifying the type of optical disc based on:
Regardless of whether the relationship between the control signal value to the focus coil and the in-focus position is a linear characteristic area or a non-linear characteristic area , the control signal is changed so as to change at a predetermined constant change rate. a step of Ru by displacing the focus position by controlling the value,
Identifying the type of the optical disc based on the magnitude relationship between the time difference when the surface reflected light and the recording surface reflected light are detected and a preset threshold value of the time difference ;
When the surface reflected light or the recording surface reflected light is detected in the region showing the non-linear characteristic, the threshold value is set in advance so as to correspond to a threshold set when the surface reflected light or the recording surface reflected light is detected in the region showing the linear characteristic. disc discrimination method characterized by a step of correcting the time difference correction coefficient.