JP3741475B2 - Discriminating device in disc player - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a disc player loaded with a disc whose signal recording surface is constituted by a reflecting surface, such as a CD (compact disc) or a DVD (digital video disc), and more particularly to the light from the signal recording surface. The present invention relates to a discriminating apparatus that discriminates whether or not a disc is loaded using reflection, and that can discriminate between different disc types such as CD and DVD.
[0002]
[Prior art]
Optical recording or magneto-optical recording discs are used for various purposes, but some of these discs have the same diameter and the like, and disc playback devices can play back different types of discs. May require a compatible configuration.
[0003]
For example, both a CD (compact disc) and a DVD (digital video disc) have a diameter of 120 mm, and an inner diameter of a central hole for clamping is 15 mm. The disk recording method is a light modulation method using pits, and the rotation control method is also CLV (constant linear velocity). Therefore, it is possible to develop an upward compatible playback device that can play back both discs.
[0004]
FIG. 7 is a plan view showing a general mechanism of a conventional compact disc player.
The rotary table 4 driven by the spindle motor is provided with a centering protrusion 4a, and the center hole of the disk is fitted and clamped on the centering protrusion 4a. The pickup 1 is guided by a pair of guide shafts 3 and 3 so as to be movable in the radial direction (X direction) of the disk, and is moved in the X direction by a pickup moving means (not shown) using a stepping motor or the like. . The pickup 1 is provided with an objective lens 2 facing the recording surface of the disk, and detection light (laser light) emitted from a light emitting means provided in the pickup 1 is irradiated from the objective lens 2 to the signal recording surface of the disk. Is done. The pickup 1 is provided with a light receiving means such as a photodiode for detecting the return light reflected from the signal recording surface. A signal recorded by the pits on the signal recording surface can be detected by the light receiving output of the light receiving means, and a focus error signal and a tracking error signal are also detected.
[0005]
Further, a contact type limit switch 5 for detecting that the pickup 1 has reached the innermost peripheral position of the disk is provided, and when the detector 6 of the limit switch 5 is pushed in the side surface 1a of the pickup 1, the pickup is picked up. The movement of 1 in the inner circumferential direction is stopped.
In the player shown in FIG. 7, the center holes of both the CD and the DVD can be fitted and clamped on the same centering protrusion 4a, and the movement area of the pickup in the X direction is almost the same in the CD and the DVD. is there. Therefore, a player having compatibility between a CD and a DVD can be configured using the same type of mechanism as shown in FIG.
[0006]
However, since the distance from the surface of the disc to the signal recording surface is different between the CD and the SD standard DVD, the numerical aperture and working distance of the objective lens used are different, and when the CD is loaded. It is necessary to change the objective lens when the DVD is loaded. Furthermore, since the track pitch is different between the CD and the DVD, the pickup feed speed must be switched between when the CD is loaded and when the DVD is loaded. Further, since the signal formats are different between the two disks, it is necessary to switch the signal processing circuit.
[0007]
[Problems to be solved by the invention]
However, if a player capable of loading different types of discs such as a CD and an SD standard DVD is configured, the following problems occur.
(1) Since the external dimensions of the disc are the same between the CD and the DVD, even if the shape of the loaded disc is detected by a photo reflector or a switch, the type of the disc cannot be determined from this detection output. .
[0008]
(2) The starting point on the inner peripheral side of the TOC recording area of the CD is a position with a diameter of 46 mmφ, and with a DVD at a position of 45.2 mmφ, which is almost the same for both discs. For this reason, it is almost impossible to determine whether the pickup is a CD or a DVD by determining the position at which the pickup starts detecting the track of the TOC signal. Further, in the conventional CD player, the limit switch 5 is provided. However, since the start point of the TOC is the same on both discs as described above, the limit switch 5 can detect the inner peripheral position of the pickup. , It cannot contribute to disc identification. Therefore, it is difficult to automatically discriminate the type of the disc and change the objective lens or the processing circuit when the disc is loaded. The user presses an identification button or the like to It is necessary to switch manually. However, such an operation is complicated.
[0009]
(3) Although it is also a problem of the entire disc player, when a CD or DVD is loaded on the rotary table, it is necessary to detect whether or not a disc is loaded using a detecting means such as a photo reflector or a switch. . However, providing the detection means only for determining the presence or absence of a disc only complicates the structure of the player.
[0010]
The present invention makes it possible to perform various discrimination operations by reciprocating the focus of the detection light emitted from the objective lens separately from the focus servo operation. In addition, it is possible to discriminate between different types of discs, and further to discriminate whether or not the disc itself has been loaded using the same principle. Furthermore, instead of the limit switch shown in FIG. It is an object of the present invention to provide a disc player discriminating apparatus that can detect a movement limit position.
[0011]
[Means for Solving the Problems]
  The present invention provides an objective lens and,RecordTwo types of discs with different recording surface positions in the optical axis direction of the objective lens can be loaded.Rotating tableA light emitting means for providing detection light to the objective lens, and a light receiving means for detecting return light returning from the recording surface of the disc through the objective lens,
  The objective lensRashoThe first distance at which the focus of the detection light emitted can pass through all the recording surfaces of the two types of discs,andOne kindDeVibration means for reciprocating at a second distance that can pass only through the recording surface of the disk;
  Return light detection means for monitoring whether or not return light is detected by the light receiving means when the focal point is reciprocating.When,
  Pickup moving means for moving the pickup including the objective lens in the radial direction of the disk;Have
  In a state where the objective lens is located outside the edge of the rotary table,The focusTheThe first distanceOnlyReciprocal movementLet meDepending on whether or not the return light reflected from the recording surface of the disk is detected by the light receiving means,SaidOn rotating tableTo determine whether the disk exists,
  After confirming the presence of the disc, the pickup is moved to the inner circumferential direction of the disc by the pickup moving means while continuing the reciprocating movement of the focal point, and the detection light from the objective lens is irradiated to the rotary table, When the return light is not detected, reverse the direction of movement of the pickup, and if reflected light from the recording surface of the disc is detected,The focusTheReciprocating by the second distanceLetWhether the return light reflected from the recording surface of the disk is detected by the light receiving meansThan,What kindDeA discriminating unit for discriminating whether or not a disc exists is provided.
[0015]
  In the above, DeImmediately after the disc type is determined, the playback operation is started.
[0016]
In the present invention, the focal position is reciprocated by reciprocating the focal position by moving the objective lens in the direction of the optical axis, for example, or by reciprocating the light emitting means while the objective lens is stopped. Move. This reciprocation of the focus position is different from the focus servo operation, and the focus position is forcibly reciprocated with a constant amplitude at a low frequency of about 30 Hz, for example. When the signal recording surface of the disc is located within the range of the reciprocating distance of the focal point, the return light reflected from the signal recording surface is detected by the light receiving means. This light receiving means may be an element that detects a reproduction signal or a focus error signal, or may be a light reception output (E, F output) of a sub beam when performing a three-beam tracking servo.
[0017]
In the present invention,FirstYesEven if the recording surface of the disc is out of rangeSaidBy moving the focus back and forth, any type of discIt is possible to detect whether or not the disc exists in the loading area, and there is no need to provide a disc detecting means separately.
[0018]
Next, the aboveThe reciprocating range of the focal point is set to a range in which only the signal recording surface of one type of disk can pass and not the signal recording surface of the other disk.If you do this,The type of the disc can be discriminated based on whether or not the reflected light from the signal recording surface is detected by the light receiving means.
[0020]
Of the present inventionIf the discriminator or discriminating method detects the presence or absence of a disk and then moves the pickup directly to the inner circumference side so that the detection light strikes the rotary table, the inner circumference of the pickup moves due to a decrease in the detection output at the light receiving means. The limit position can be detected, and immediately after that, the pickup can be moved in the outer circumferential direction to shift to disc type determination. For example, if the lower surface of the rotary table is made a non-reflective surface, the detection output at the light receiving means will decrease, or even if the focal point reciprocates, the detection light will not be focused on the lower surface of the disk. Output decreases.
[0021]
As described above, according to the present invention, not only the type of the disc can be determined using the pickup, but also whether the disc is loaded using the pickup having the same structure, and further, the limit of movement of the pickup in the inner circumferential direction is determined. The position can also be detected.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
FIG. 1 shows the structural difference between a CD and an SD standard DVD (hereinafter referred to as “SD”), (a) is an enlarged partial sectional view of the CD, and (b) is an enlarged portion of the SD. It is sectional drawing.
As shown in FIG. 1A, in the CD, a disk substrate 12 is formed of translucent polycarbonate, for example. A reflective film 15 such as Al (aluminum) is formed on the disk substrate 12, and the surface on the disk substrate 12 side is a signal recording surface 15a2, and a PCM signal is formed on the signal recording surface 15a2 by a pit 16. It is formed by. A protective film 17 made of an ultraviolet curable resin or the like is formed on the upper surface of the reflective film 15. In the CD, the thickness dimension dc from the surface of the disk substrate 12 to the signal recording surface 15a2 is standardized to 1.2 mm. The tolerance on the standard is -0.1 mm to +0.3 mm.
[0023]
As shown in FIG. 1B, in SD, the thickness ds of the transparent disk substrate 12 is 0.6 mm, which is half of the CD, and the two disk substrates 12 are laminated on both sides via the protective film 17. Yes. The signal recording surfaces 15a1 formed by the reflective film 15 are formed on both surfaces of the protective film 17, and pits 16 are formed on the respective signal recording surfaces 15a1.
In SD, the thickness ds from the surface of the disk substrate 12 to the signal recording surface 15a1 is standardized to 0.6 mm, and the tolerance is in the range of -0.1 mm to +0.2 mm.
[0024]
The signal recording surfaces 15a1 and 15a2 of the disc are about 10 μm for CD and about several tens of μm, which is about twice as large as that for SD.
The so-called TOC (Table of contents) area in which the contents of a CD or SD are written is standardized to 46 to 50 mmφ for CD and 45.2 to 48 mmφ for SD.
[0025]
FIG. 2 shows the structure of the optical pickup P and the rotary table 21 of the disc player of the present invention, and FIG. 3 is a block diagram showing the internal structure of the optical pickup P and the configuration of the electric circuit.
As shown in FIG. 2, a movable hub (centering protrusion) 21a for centering through which a center hole (center hole) having the same inner diameter dimension is inserted between the CD and SD is provided on the rotary table 21. A clamp area 21b is formed in the outer peripheral direction from the outer edge of the hub 21a. And the flange part 21c thinner (0.5 mm or less) than the clamp area 21b is integrally formed in the outer peripheral direction of the clamp area 21b. The diameter 2R of the edge portion of the flange portion 21c is 46 mmφ. Therefore, as shown in the figure, when the CD is installed on the clamp area 21b, the edge of the flange portion 21c faces directly inside the TOC area of the signal recording surface 15a2 of the disc. Yes. When the SD is installed on the clamp area 21b, the edge of the flange 21c and a part of the TOC area of the signal recording surface 15a1 of the disk overlap each other. However, this overlap dimension is very small, and the edge of the flange portion 21c substantially coincides with the starting point of the inner periphery of the TOC area.
[0026]
An optical pickup P on which the objective lens 23a is mounted is provided under the flange portion 21c, and the optical pickup P is driven in the X-axis direction by the pickup moving means. The moving range of the optical pickup P is from the position where the optical axis of the objective lens 23a faces the back surface of the flange portion 21c to the edge portion of the maximum outer diameter (120 mm) of CD or SD. The entire back surface of the flange portion 21c is a non-detection surface 21d. The non-detecting surface 21d may be a non-reflecting surface that does not reflect the light from the objective lens 23a, or, as will be described later, within a range in which the objective lens 23a reciprocates in the optical axis direction, If the detection light to be irradiated does not form an image on the non-detection surface 21d, no return light is given from the flange portion 21c to the light receiving means during the discrimination operation.
[0027]
Therefore, when the objective lens 23a is located directly below the non-detection surface 21d, the detection light (laser light) emitted from the objective lens 23a is not reflected or imaged, and the return light is reflected from the optical pickup P. Cannot be detected. As shown in FIG. 3, the optical pickup P is provided so that two objective lenses 23a and 23b can be switched, and the two lenses are different in numerical aperture, working distance, and the like. The objective lens 23a is for SD, and the objective lens 23b is for CD. In the present invention, when the disc discrimination operation is performed, only one objective lens 23a is used.
[0028]
The optical pickup P includes a semiconductor laser 24 as a light emitting means for applying detection light (laser light) to the signal recording surface 15a1 or 15a2 of the disc from the objective lens 23a or 23b, and a beam splitter 25 for refracting the detection light from the semiconductor laser 24. A photodiode 26 as a light receiving means for receiving the return light reflected from the signal recording surface 15a1 or 15a2 of the disk and transmitted through the objective lens 23a or 23b and the beam splitter 25, and an objective lens driving means 27 are mounted. .
[0029]
The objective lens driving means 27 includes a focus servo mechanism (focus servo mechanism) and a tracking servo mechanism, and the movable member holding the objective lens can be moved in the optical axis direction and the direction crossing the track of the signal recording surface. A supporting spring member, a focus coil and a tracking coil mounted on the movable member, a magnet for applying an external magnetic field to the focus coil and the tracking coil, and the like.
[0030]
In the discriminating operation to be described later of the present invention, the focus servo mechanism is used, a drive current having a fixed period is applied to the focus coil, the objective lens is driven in the optical axis direction with a fixed amplitude, and the focus position of the detection light is detected. Reciprocates with a constant amplitude. As described above, the SD objective lens 23a is used when performing this discrimination operation. The reference position F (0) of the focus of the detection light focused by the objective lens 23a is loaded with SD. Sometimes this position is almost coincident with the SD signal recording surface 15a1. The maximum movable distance of the objective lens 23a in the optical axis direction is reciprocated in the range from F (-) to F (+) (amplitude W0 / 2) with the reference position F (0) as the amplitude center. The distance to move. The maximum amplitude W0 / 2 is set so that the focal point can pass through the signal recording surface 15a2 of the CD when the CD is loaded. For example, W0 / 2 is ± 1 mm, and the focal range W0 is 2 mm.
[0031]
As shown in FIG. 3, outside the system of the optical pickup P, a focus error detection means 31 for detecting a focus error from the amount of light received in the main detection area (usually a four-division diode) of the photodiode 26, and this focus error detection means Based on the focus error signal detected at 31, a phase compensation drive amplifier 32 that provides a drive current (or drive voltage) for focusing to the focus coil of the objective lens driving means 27 is provided, and the focus servo system is It is configured. AlsoTheExcitation means 33 is provided for applying a constant period of drive current to the focus coil. The drive current (drive power) given from the vibration means 33 to the focus coil is completely different from the focus drive current in the focus servo system, and is a low frequency signal of about 30 Hz, for example. The driving current is switched in two stages, and the objective lens 23a is driven within the first distance or the second distance.
[0032]
The first distance at which the objective lens 23a is driven is W0, and the focal point shown in FIG. 2 is reciprocated with a maximum amplitude of ± 1 mm around the reference position F (0) on the SD signal recording surface. When the drive current in the excitation means 33 is switched, the objective lens 23a is driven by the second distance. At this second distance, the focal point has an amplitude of ± 0.3 mm with F (0) as the center. Move back and forth. In FIG. 6, the reciprocating distance of the objective lens 23a and the reciprocating distance of the focal point at this time are indicated by W1. The tolerance of the thickness dimension ds of the SD substrate 12 is −0.1 to +0.2 mm, and the tolerance of the thickness dimension dc of the CD substrate 12 is −0.1 to +0.3 mm. When the signal recording surface 15a1 is loaded, the signal recording surface 15a1 varies within a range of -0.1 mm to +0.2 mm with respect to the reference position, and the position of the CD signal recording surface 15a2 is the reference position of the SD signal recording surface. It will vary in the range of 0.5 mm to 0.8 mm above the point. Therefore, when the objective lens 23a is reciprocated by a first distance (W0 = 2 mm, amplitude is ± 1 mm) from the reference position of the SD signal recording surface 15a1, the focal point is the SD signal recording surface 15a1 and the CD signal recording surface. You can always pass through both 15a2. When the objective lens 23a is reciprocated by a second distance (W1 = 0.6 mm, amplitude is ± 0.3 mm), the focal point passes only the SD signal recording surface 15a1, as shown in FIG. The signal recording surface 15a2 of the CD does not pass.
[0033]
The tracking error signal component in the light reception output of the photodiode 26 is detected by the tracking error detection means 35. When the tracking servo is a three-beam system, E and F outputs from the sub-detection area for sub-beam detection are given to the tracking detection means 35. This tracking error signal is given to the phase compensation drive amplifier 36, and the drive current (drive voltage) from the phase compensation drive amplifier 36 is given to the tracking coil in the objective lens drive means 27, so that the objective lens 23a is at the time of signal reproduction. Tracking correction drive. This operation system is a tracking servo system.
[0034]
In the discrimination operation described later of the present invention, the focus servo system and the tracking servo system do not operate, and the objective lens 23a is forcibly driven by the excitation means 33. At this time, the light reception output of the photodiode 26 is It is detected by the return light detection means 37. The light receiving output at this time may be a light receiving output from a four-divided light receiving portion that is a light receiving region of the main beam of the photodiode 26, or light reception from a sub detection region that detects a sub beam for detecting a tracking error signal. An output may be used, or outputs from all light receiving regions may be used. An output signal is given from the return light detection means 37 to the disc discrimination section 34.
[0035]
The disc discriminating unit 34 is a CPU of a microcomputer or the like, and also serves as a control unit for the entire disc player. The vibration means 33 is controlled by the disk discriminating unit 34, and the switching state of the drive signal for exciting the objective lens 23a is fed back to the disc discriminating unit 34. A pickup moving means 38 for moving the optical pickup P in the X direction is also controlled by the disk discriminating section 34, and movement information of the optical pickup P is fed back from the pickup moving means 38 to the disc discriminating section 34.
[0036]
FIG. 4 is a flowchart showing the discriminating operation of the disc player configured as described above, and FIG. 5 shows the relationship between the received light output and the amount of movement of the optical pickup P (the amount of movement of the optical axis of the objective lens) during the discriminating operation. FIG. In the horizontal axis of FIG. 5, when the optical axis of the objective lens 23a is located at the boundary between the peripheral edge of the flange portion 21c of the rotary table 21 and the disk, the amount of movement is 0 mm, and the inside of the rotary table 21 is more than that. The distance moved in the direction is minus, and the distance moved in the outer circumferential direction of the disk is shown as plus. The light receiving output of the photodiode 26 in the light receiving area of the main beam is indicated by ◯, the E output in two sub light receiving areas for detecting the tracking error signal is indicated by □, and the F output is indicated by Δ.
Hereinafter, the processing steps shown in the flowchart of FIG. 4 will be described in the order of (1) to (14).
[0037]
Step (1); The disc D (CD or SD) is inserted from an insertion slot (not shown) of the disc player and loaded on the rotary table 21. The disk D loaded on the rotary table 21 is clamped and fixed to the clamp area 21b of the rotary table 21 by a clamper. At this time, the optical pickup P has been switched to the SD objective lens 23a, and the optical axis of the objective lens 23a has moved about 0.5 to 2 mm from the edge of the flange portion 21c to the outer periphery of the disk. Is in position. Further, the focus servo system and the tracking servo system are stopped, and the spindle motor M (see FIG. 2) for rotating the rotary table 21 is also stopped.
[0038]
Step (2): A low-frequency sine wave (or cosine wave) signal (driving current) of about 30 Hz, for example, is applied to the focus coil of the objective lens driving means 27 from the vibration means 33 shown in FIG. Is reciprocated in the optical axis direction. The reciprocating distance of the objective lens 23a at this time is the first distance W0, and the objective lens 23a is driven within a range of ± 1 mm with the position of the SD signal recording surface 15a1 as the reference position. In addition, detection light (laser light) is emitted from the semiconductor laser 24 which is a light emitting means, and this detection light is focused by the objective lens 23a, and its focusing point (focal point) is almost as the objective lens 23a moves. It is moved within a range of ± 1 mm.
[0039]
Step (3): When the disk D is accurately placed on the rotary table 21, the main beam and sub beam (tracking) emitted from the optical pickup PError signal) Is reflected by the signal recording surface (15a1 or 15a2) of the disk D. Since the amplitude of the objective lens 23a is ± 1 mm with respect to the position of the SD signal recording surface 15a1, the laser beam is reflected by the signal recording surface (15a1 or 15a2) regardless of whether the disk D is CD or SD. Is done. Therefore, when it is detected that the return light is received by the return light detection means 37 and the output from the return light detection means 37 becomes H (high level), the disc determination unit 34 performs the CD or SD. It is determined that any of the above has been securely loaded on the rotary table 21. In this step, when the output from the return light detection means 37 is L (low level), the disc discriminating unit 34 judges that the disc D is not securely loaded on the rotary table 21. For example, if a predetermined time after the detection means detects that the disk D has been inserted into the insertion slot is set, and the output from the return light detection means 37 does not reverse to H within this time, the disk D For example, it is determined that a loading error has occurred, and the disk loading device is shifted to a retry operation or a disk ejection operation, for example.
[0040]
Step (4): If it is determined that the disk D is installed on the rotary table 21, a control command is issued to the pickup moving means 38 while continuing the light emission from the semiconductor laser 24 and the vibration of the objective lens 23a. The optical pickup P is moved in the inner circumferential direction.
[0041]
Step (5): When the optical axis of the objective lens 23a reaches below the flange portion 21c of the turntable 21, the output of the return light detection means 37 becomes L as shown in FIG. Therefore, the disc discriminating unit 34 discriminates that the optical pickup P has reached the movement limit position toward the inner peripheral side of the disc D. Therefore, the conventional limit switch 5 as shown in FIG. 7 becomes unnecessary, and the number of parts and the cost can be reduced.
[0042]
Step (6): When the output of the return light detecting means 37 becomes L in the step (5), a control command is given to the pickup moving means 38, the moving direction of the optical pickup P is switched, and the optical pickup P is changed to the disk D. Move toward the outer circumference. At this time, the distance by which the objective lens 23a is reciprocally moved remains the first distance W0.
[0043]
Step (7): The detection light irradiation position (the optical axis position of the objective lens 23a) moves the flange portion 21c from the inner peripheral side to the outer peripheral side and passes the edge, and at the same time, the detection light is applied to the disk D (CD or SD). As shown in FIG. 5, the amount of light received by the photodiode 26 increases and the output from the return light detection means 37 becomes H.
[0044]
Step (8): When the output of the return light detection means 37 is inverted to H, the optical pickup P is immediately stopped. As a result, the edge of the flange portion 21c is detected. This edge is located at the start point of the TOC area of the signal recording surface regardless of whether the loaded disk D is an SD or a CD. The stop position of the optical pickup P is the TOC reading start position.
[0045]
Step (9): Immediately after the optical pickup P stops, the drive signal of the vibration means 33 is switched so that the reciprocating distance of the objective lens 23a is the second distance (W1 = 0.6 mm, amplitude is ± 0.3 mm). Switched. The driving frequency at this time is the same as that at the first distance W0, for example, about 30 Hz.
[0046]
Step (10): The focus of the detection light focused by the objective lens 23a is reciprocated with an amplitude of ± 0.3 mm around the reference position F (0) as shown in FIG. When the disc is SD, an image may be formed on the signal recording surface 15a1, the light receiving output of the photodiode 26 becomes high, and the output of the return light detecting means 37 becomes H. When the disc is a CD, the focal point does not pass through the signal recording surface 15a2, and no image is formed on the reflecting surface, and the output of the return light detecting means 37 is L.
[0047]
Step (11): When the output of the return light detection means 37 is H, the disc discriminating unit 34 discriminates that the loaded disc is SD, the vibration means 33 stops, and the objective lens 23a reciprocates. The movement stops.
[0048]
Step (12): The focus servo, tracking servo, and spindle servo functions are all set for SD and turned ON, and the processing circuit is also set for SD, and reading of the TOC area is started. Migrate to
[0049]
Step (13): When the output of the return light detecting means 37 in step (10) is L, the disc discriminating unit 34 discriminates that the loaded disc is a CD, and the vibration means 33 stops, The reciprocation of the objective lens 23a stops.
[0050]
Step (14): The objective lens 23b for CD is switched so as to move on the optical axis. In addition, the focus servo, tracking servo, and spindle servo functions are all switched to the CD and turned on, the reading of the TOC area is started, and the playback operation is immediately started.
[0051]
In the detection means described above, the type of the disk D can be determined in a state where the disk D is not rotated. Therefore, it is not affected by the runout of the disk D due to rotation. However, it can be determined even when the disk D is rotating.
Further, since the disc D can be discriminated while the focus servo, tracking servo, and spindle servo functions are stopped, the power consumption when disc type is discriminated can be reduced.
[0052]
In the above description, the amplitude W0 (2 mm) from -1 mm to +1 mm exemplified when the disk D is detected is not limited to this range, and can be detected as long as it is equal to or larger than the thickness dimension of the disk D. Further, the amplitude W0 (0.6 mm) from -0.3 mm to +0.3 mm exemplified when disc D is discriminated is not limited to this range, and the amplitude is less than the thickness dimension of the disc D. It can be determined.
[0053]
Further, the tracking error detection method is not limited to the three-beam method, and may be a push-pull method, a DPD method, or the like.
Further, the disc that can be discriminated in the present invention is not limited to the CD and the DVD of the SD standard, and any type can be used as long as the thickness dimension from the disc surface to the recording surface is different. Good.
[0054]
【The invention's effect】
According to the present invention described in detail above, it is possible to detect the presence or absence of a disc loaded in the disc player. Further, the detection accuracy of the TOC area of the disk can be improved, and the limit switch for detecting the inner peripheral position of the pickup, which has been conventionally required, can be eliminated, and the number of parts and the cost can be reduced. It is also possible to determine the type of disk.
[0055]
In addition, this determination operation may simply detect return light from the signal recording surface of the disk, and it is not necessary to perform focus, spindle, tracking servo, and signal reading operations. Therefore, the disc type can be determined in a short time regardless of the difference in the signal format of the disc.
[Brief description of the drawings]
FIG. 1 shows the structural difference between a CD and an SD standard DVD, (a) is an enlarged partial sectional view of a CD, (b) is an enlarged partial sectional view of an SD standard DVD,
FIG. 2 is a cross-sectional view showing a configuration example of a rotary table and a pickup provided in the disk device of the present invention;
FIG. 3 is a block diagram showing the structure of an optical pickup and the configuration of an electric circuit;
FIG. 4 is a flowchart showing a method for determining the presence / absence of a CD and an SD and a method for determining a type;
FIG. 5 is a diagram showing fluctuations in the amount of received light with respect to the amount of movement of the pickup;
FIG. 6 is an explanatory diagram showing the relationship between the focal position of the disc and the objective lens;
FIG. 7 is a plan view showing the structure of a conventional CD player;
[Explanation of symbols]
15a1 SD standard DVD signal recording surface
15a2 CD signal recording surface
16 pits
21 Rotating table
21c Flange
21d Non-detection surface
23a Objective lens for SD
23b Objective lens for CD
24 Semiconductor laser
26 Photodiode
27 Objective lens drive means
33 Exciting means
34 Disc discriminator
37 Return light detection means
D disc
CD compact disc
SD SD (Super Density Disk) standard digital video disc
dc CD disk substrate thickness dimension
ds SD disk substrate thickness dimension
F (0) Standard position of the focus of the objective lens for SD
P Optical pickup

Claims (2)

An objective lens, a light emitting unit position of record surfaces provide a rotary table which two kinds of disk that is different in the optical axis direction is possible loading of the objective lens, the detection light to the objective lens, the recording of the disc A light receiving means for detecting return light returning from the surface through the objective lens;
It said first distance the focal point of the objective lens or RaTeru Isa is detection light can pass through all of the recording surface of the two types of disks, and a second distance that can pass through only the recording surface of the one type of disk And vibration means for reciprocating,
Return light detection means for monitoring whether return light is detected by the light receiving means when the focal point is reciprocating ; and
Pickup moving means for moving the pickup including the objective lens in the radial direction of the disk ;
Wherein in a state where the objective lens is positioned outside the edge of the rotary table, either by the return light reflected the focal from the recording surface of the first distance by reciprocating the disc is detected by the light receiving means by whether, to determine whether the disk on the turntable are present,
After confirming the presence of the disc, the pickup is moved to the inner circumferential direction of the disc by the pickup moving means while continuing the reciprocating movement of the focal point, and the detection light from the objective lens is irradiated to the rotary table, When the return light is not detected, the pickup moving direction is reversed, and when the reflected light from the recording surface of the disk is detected, the focal point is reciprocated by the second distance to record the recording surface of the disk. the determination unit that determines whether the reflected return light from whether crab is detected by the light receiving unit, there is any type of disk is provided from the determination device in the disc player according to claim. 2. The disc player discriminating apparatus according to claim 1 , wherein the disc player immediately moves to the reproducing operation after disc discriminating.

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