JPH10320900A - Automatic track pitch discriminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately discriminate a track pitch without having influence of a time measuring error by moving two tracking control light spots in the track traversing direction and detecting the track traversing of both light spots after traversing of the precedent spot across the track. SOLUTION: The light spots from an optical system 21 are projected to home positions of an optical card C, and are moved in the direction of traversing a track after performing an AF setting operation. Changes of reflected beams of light at the time of track traversing of the two spots arranged apart from each other in the track traversing direction are detected by photodetectors 34 and 36 respectively. When a track pitch is 12 μm, the 1st track is detected by the photodetector 36 before the 2nd track is detected by the photodetector 34. When the track pitch is 8 μm, the 1st track is detected by the photodetector 36 after detecting first two tracks successively by the photodetector 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic track pitch discriminating apparatus for automatically discriminating track pitches of recording media having different track pitches.

[0002]

2. Description of the Related Art Various types of information recording media for optically recording or reproducing information, such as a disk, a card, and a tape, are conventionally known. Of these, card-shaped optical information recording media (hereinafter referred to as optical cards) are convenient to carry and have a relatively large capacity.
In addition, since it is an information recording medium that cannot be erased and rewritten at present, it is expected to be applied to a field where this property is advantageous, such as a medical card.

FIG. 4 is a schematic plan view of an optical card. FIG.
In the optical recording area C1 of the optical card C, a large number of information tracks Ta and tracking tracks Tb for recording information are alternately arranged in parallel as shown in a partially enlarged manner. The tracking track Tb is used as a guide for auto-tracking (AT) for controlling a light spot so as not to deviate from a predetermined information track when recording and reproducing information. At a corner of the recording area C1, a home position HP is provided as a reference position for accessing the information track. There is no information track and no tracking track at the home position. The information track Ta is provided with a track number sequentially from a position closer to the home position.

Here, in order to access a target information track, a seek operation for moving a light spot in a direction perpendicular to a plurality of tracks arranged in parallel is performed. Recording and reproduction are performed by scanning. In addition, when actually recording or reproducing information, autofocus (AF) control for focusing a light spot on a recording medium surface and autotracking (AT) for scanning the light spot following an information track are performed. Perform control. These AT and AF controls are general techniques that are more often used in optical information recording / reproducing apparatuses than before.

FIG. 5 is a block diagram showing a conventional optical card information recording / reproducing apparatus. 5, reference numeral 1 denotes an information recording / reproducing apparatus (hereinafter, referred to as an information recording / reproducing apparatus) for recording and reproducing information on / from an optical card C.
2) C which is the above control device
PU. The drive 1 performs recording and reproduction on the optical card C based on a command issued from the CPU 2. The configuration of the drive 1 will be described.

Numeral 8 drives a transport mechanism (not shown) to introduce the optical card C into the drive 1 and to reciprocate the optical card C at a predetermined position in the track direction (X direction). This is a motor for ejecting the optical card C. A sensor 7 is provided near the card insertion slot 6, and when the sensor 7 detects that the optical card C is inserted, the optical card C is transported to a predetermined position. Reference numeral 21 denotes an irradiation optical system including a light source.
The light flux from the optical card C is radiated onto the optical card C by focusing on a minute light spot. The optical card C is reciprocally driven in the track direction by driving the card feed motor 8, whereby the light spot and the optical card C reciprocate relatively in the track direction to scan the light spot on the information track. 34-36
Is a photodetector for receiving the reflected light of the light spot applied to the optical card C, and the recorded information is reproduced based on this detection signal.

Reference numeral 13 denotes an AF actuator for driving a part of the irradiation optical system 21 to move the light spot in the Z direction, that is, in a direction perpendicular to the card surface, to perform AF control. Is driven to move the light spot in the X direction, that is, in the direction orthogonal to both the Y direction and the Z direction. The optical head 20 includes the irradiation optical system 21, the photodetectors 34 to 36, the AF actuator 13 and the AT actuator 14.

Reference numeral 3 denotes an MPU having a built-in ROM and RAM, which controls various parts such as a card feed motor 8 and a CPU.
The communication and control of data with the CPU 2 are performed by the control of (2).
Reference numeral 10 denotes an AT / AF control circuit for driving the AF actuator 13 and the AT actuator 14 based on the detection signal of the photodetector to perform AF control and AT control. Reference numeral 4 denotes a modulation / demodulation circuit for modulating the recording information and demodulating the reproduction signal based on the detection signal of the photodetector to reproduce the original recording information. Reference numeral 5 denotes a light source driving circuit for driving the intensity of a light source (not shown) in accordance with the modulation signal of the modulation / demodulation circuit 4, whereby information by light modulation is recorded on the information track.

FIG. 6 is a perspective view showing the internal structure of the optical head 20 in detail. In the figure, reference numeral 22 denotes a semiconductor laser as a light source. A light beam emitted from the light source is collimated by a collimator lens 23 and then shaped into a light beam having a circular cross section by a shaping prism 24. The light beam emitted from the shaping prism 24 enters the diffraction grating 25 and is split into three light beams. The light beam is further split by the polarization beam splitter 26 into transmitted light and reflected light.

On the other hand, the transmitted light of the polarizing beam splitter 26 is incident on an objective lens 29 through a bending mirror 27 and a 波長 wavelength plate 28, is narrowed by the objective lens 29, and is tracked on the optical card C by a tracking track T ₁ , Information Track T ₂
Light spots S ₁ , S ₂ , S on the tracking track T ₃
Imaged as ₃ . The reflected light from the light spots S ₁ , S ₂ , S ₃ is again guided to the detection optical system 30 via the objective lens 29, the １ ／ wavelength lens 28, and the beam splitter 26, and to the photodetectors 34, 35, 36 Each is projected.
The detection optical system 30 has a spherical lens 31 and 45
It is an astigmatism system composed of cylindrical lenses 32 arranged at an angle, and AF control by the astigmatism method is performed based on the outputs of the photodetectors 34 to 36. Also,
AT control by the three-beam method is performed.

FIG. 7 is a block diagram of an AT and AF control loop circuit. 7, light detectors 34 and 36 detect light spots S ′ ₁ and S ′ ₃ reflected from the tracking tracks T ₁ and T ₃ shown in FIG. Is sent to the AT control circuit 12 via the current-voltage converters 37 and 39. A
The T control circuit 12 generates a tracking error signal by taking the difference between the two outputs, drives the AT actuator 14 based on the obtained tracking error signal, and displaces the objective lens 29 in the tracking direction. AT control is performed so that the light spot does not deviate from the information track.

[0012] Similarly the photodetector 35 is for detecting the light spot S _'2 being reflected from the information track T ₂ shown in FIG. 6, the sum of A and D of the four-division photodetector 35 sensor The signal and the sum signal of B and C are sent to the AF control circuit 11 via the current-voltage converter 38. AF control circuit 11
Then, a focus error signal is generated by taking the difference between the two signals, the obtained focus error signal is applied to the AF actuator 13, and the objective lens 29 is changed in the focus direction, so that the light spot is focused on the card surface. AF control is performed.

FIG. 8A shows the output of the photodetector 34 (ie, the track crossing signal TA) obtained when the light spots S ₁ and S ₃ cross the information track and tracking track on the optical card, and the light detection. 3 shows the output of the detector 36 (ie, the track crossing signal TB). FIG. 8B shows a tracking error signal (ATS = TA-TB). Normally, the tracking error signal ATS is by AT controlled so that ATS = O (shown in figure A), the light spot S ₂ is controlled so as to just scan the center of the information track T _2.

Incidentally, in order to perform higher-density recording on an optical card, it is necessary to further reduce the track pitch. In addition, in order to perform recording and reproduction on an optical card having a different track pitch by one device, the track pitch of the optical card must be determined in advance. Therefore, an optical information recording / reproducing apparatus for recording / reproducing information on two types of recording media having different track pitches (track pitch P1 and track pitch P2, P1> P2) is disclosed in, for example, Japanese Patent Application Laid-Open No. 105549.

FIG. 9 shows the relationship between the two types of optical card recording surfaces and the three-beam spot disclosed in the publication. FIG. 9A shows an optical card A (track pitch P1 = 1).
FIG. 9B shows an optical card B (track pitch P).
2 = 8 μm). The discrimination of the track pitch of the optical card inserted into the device is made based on the track crossing signal interval when _one of the light spots S _{1 to} S ₃ crosses the track at a constant speed, that is, the difference in the time required for the track crossing. By performing a predetermined setting based on the determination result, recording and reproduction with respect to the type of optical card can be performed.

[0016]

In the conventional track pitch determination method, as described above, the track pitch is measured as time, and whether the track pitch is P1 or P2 is determined based on the measured value. However, when the track pitch is measured as time, a measurement error occurs if the moving speed of the light spot or the optical card is uneven. In addition, since the measurement itself includes an error corresponding to the sampling cycle, in order to reduce the measurement error, it is necessary to increase the accuracy of the mechanism for moving the light spot or the optical card or to increase the sampling frequency. Although it is conceivable, any of these may complicate the configuration of the apparatus and increase the cost. Current track pitch P1
= 12 μm and the track pitch P2 = 8 μm, the measurement error is at a level that does not cause any problem. However, if the track pitch is further reduced in order to perform high-density recording in the future, the ratio of the error to the measurement time increases, and there is a problem that the track pitch cannot be determined.

An object of the present invention is to provide an automatic track pitch discriminating apparatus capable of accurately discriminating the track pitch of a recording medium even when the track pitch is reduced in view of the above-mentioned conventional problems.

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic track pitch discriminating apparatus for discriminating the track pitches of a plurality of types of recording media having different track pitches. Means for moving a group of light spots including two light spots in the cross-track direction, and a first comparison for comparing the level of the tracking error signal when the light spot crosses the track with a predetermined first level lower than 0 level. Means, second comparing means for comparing the level of the tracking error signal with a predetermined second level higher than 0 level, and comparison between the first and second comparing means when the light spot group traverses a track. Means for determining the track pitch based on the result.

It is another object of the present invention to provide an automatic track pitch discriminating apparatus for discriminating the track pitches of a plurality of types of recording media having different track pitches, wherein a means for moving a light spot on the recording medium in a cross-track direction. When,
A track pitch automatic unit comprising: means for counting the number of track crossing signals when the light spot moves a predetermined distance; and means for determining a track pitch based on the counted number of track crossing signals. This is achieved by a discriminating device.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, the first of the present invention
An embodiment will be described. The configuration of the first embodiment is the same as that of FIG. 5, and the recording medium uses the optical card of FIG. However, as the optical cards, an optical card A having a track pitch of P1 (P1 = 12 μm) and an optical card B having a track pitch of P2 (P2 = 8 μm) are used. MPU in drive 1 in FIG.
Reference numeral 3 has a function of determining the track pitch of the inserted optical card, and performs a predetermined setting according to the determination result.

FIG. 1 shows an MPU when an optical card is inserted.
3 shows a track pitch determination process. FIG.
Shows various signal waveforms when the light spot crosses the information track and the tracking track on the optical card. FIG. 2A shows an optical card A (track pitch P1 = 1).
FIG. 2B shows an optical card B (track pitch P).
2 = 8 μm) for various signal waveforms.

The relationship between the recording surface of the optical card and the three-beam spot is the same as in FIG. 9, and FIG. This is the signal waveform obtained, that is, the signal waveform when the light spot moves from left to right in FIG. Further, in FIGS. 2A and 2B, T
Output waveform of the photodetector 34 A is that the light spot S ₁ as shown in FIG. 7 is irradiated, TB is the output waveform of the photodetector 36 to the light spot S ₃ is irradiated, ATS difference signals TA and TB It is a waveform (ATS = TA-TB). That is, ATS
Is a tracking error signal when crossing a track.

SL is a signal for detecting the ATS signal <0. The ATS signal is compared with threshold values V ₃ and V _4, and the ATS signal is generated as shown in FIGS. 2 (a) and 2 (b). It becomes below threshold V ₄ SL is high, inverted to a low level by the threshold V _3. SH is a signal for detecting an ATS signal> 0. The ATS signal is compared with thresholds V ₁ and V _2, and as shown in FIGS. 2A and 2B, the ATS signal is equal to or higher than the threshold V _1. to become the SH is inverted high level, the threshold value V ₂ at a low level. The MPU 3 has a comparator function and adjusts the level of the ATS signal to threshold values V ₁ , V ₂ ,
Alternatively, the levels of SL and SH are determined by comparing the thresholds V ₃ and V ₄ .

Next, a method of determining a track pitch according to the present embodiment will be described with reference to FIGS. 1, 2 and 5. First, when the optical card C is inserted into the insertion slot 6 of the drive 1, the MPU 3 controls each section to irradiate a light spot to the home position HP in FIG. 4, and performs an AF pull-in operation here. When the AF pull-in operation is completed normally, the three light spots from the irradiation optical system 21 are moved in a direction crossing the track on the recording surface of the optical card C. When the light spot starts moving, begin consuming light spot S ₁ on the first tracking tracks. As a result, the amount of light applied to the photodetector changes, and as shown in FIG.
The level of A decreases and, of course, the ATS also changes. When the level of the ATS signal is reduced to V _4, the level of SL becomes H, starts a track pitch discrimination flow of FIG. 1, MPU 3 (S1 in Fig. 1).

[0025] In FIG. 1, SH continues to move the light spot even after the H level, the light spot S ₁ traverses a first tracking tracks, along with this level of ATS signal as in FIG. 2 When becomes V _3, SL becomes the L level again (S2). After SL goes low, the MPU 3 monitors whether the level of SL or SH goes high (S3, S4). Here, the card inserted into the drive 1 is an optical card A, that is, a track pitch P1 = 12 μm.
For m, before reaching the tracking tracks the light spot S ₁ is adjacent to the first tracking tracks, the light spot S ₃ begins consuming the first tracking tracks, the photodetectors as shown in FIG. 2 (a) 36 And the ATS changes. And
When the ATS reaches the level of V ₁ as shown in FIG.
Since the SH level becomes H, the drive 1
It is determined that the track pitch of the optical card inserted therein is P1 (S6).

On the other hand, the inserted card is an optical card B within the device, that is, when a track pitch P1 = 8 [mu] m, before the light spot S ₃ reaches the first tracking tracks, the light spot S ₁ is the first tracking tracks since begin consuming the tracking tracks adjacent to, similarly to the case where the light spot S ₁ is applied to the first tracking tracks, the ATS level as shown in FIG. 2 (b) reaches V _4, the level of SL and the H (S3). MPU3
Then, it is determined that the track pitch of the optical card inserted into the apparatus is P2 (S5). MPU
3. When the track pitch is automatically determined, a predetermined setting process is performed so that recording and reproduction can be performed according to the determined track pitch.

In this embodiment, as described above, the track pitch is determined based on the level of the ATS (tracking error signal) when the light spot crosses the track, so that the conventional determination failure due to the measurement error occurs. Without
The track pitch can be accurately determined. Also,
Since the track pitch is determined by moving the light spot from the home position of the optical card, after inserting the card,
The track pitch can be quickly determined without performing an extra operation.

In the present embodiment, the light spot is moved from the home position of the optical card. However, the present invention is not limited to this, and the light spot is moved from a position where no track exists on the recording surface to a direction where the track exists. You may move it. For example, the optical card may be moved from a position above the recording area C1 of the optical card in FIG. However, in this case, the moving direction changes, and A in FIG.
Since the polarity of the TS signal also changes, it is necessary to determine the track pitch accordingly.

Next, a second embodiment of the present invention will be described. The configuration of the present embodiment is the same as that of FIG. 5, and the optical card of FIG. 4 is used as a recording medium. As the optical card, an optical card A (track pitch P1 = 12 μm) and an optical card B (track pitch P2 = 8 μm) are used as in the first embodiment. The MPU 3 determines the track pitch when the optical card is inserted into the drive, and performs various settings according to the determination result. However, in the present embodiment, the track pitch is determined based on the number of track crossing signals, as described later in detail.

FIG. 3 shows how the light spot S ₂ emitted from the irradiation optical system 21 moves on the optical card surface in the cross-track direction, and the change of the cross-track signal TO. TO is an output signal of the photodetector 35 in FIG. 3A shows an optical card A, and FIG. 3B shows an optical card B.
An optical spot S ₂ and the track crossing signal TO of cases. The recording of the light spot S ₂ 3 two optical spots S ₁ as described above, S _2, S _3, reproduction, a light spot used for AF control. In the present embodiment, when an optical card is inserted, the MPU 3 controls each unit to move the light spot in the track cross direction as shown in FIG.

The moving distance L is predetermined and set to 24 μm, which is the least common multiple of the track pitches P1 and P2. When moving the light spot S _2, an encoder for detecting a relative position of the objective lens position detection signal and the optical head and the optical card of the position sensor for detecting the track direction position of the objective lens (not shown) (not shown) , The position of the light spot is detected. In the present embodiment, to detect the position of the light spot S ₂ by using an objective lens position detection signal, a light spot S ₂ with reference to the position of a predetermined distance before the tracking tracks as shown in FIG. 3 24
μm.

Here, when the inserted optical card is an optical card A having a track pitch of 12 μm, the number of track crossing signals TO when the light spot S ₂ is moved by 24 μm as shown in FIG. 2. On the other hand, in the case of the optical card B having the track pitch P2 = 8 μm, FIG.
The number of the track crossing signals TO when the light spot S ₂ is moved by 24 μm as shown in FIG. MPU3 counts the track crossing signal TO at which the light spot S ₂ by a predetermined distance moved, to determine the track pitch by the number. That is, if the number of track crossing signals is 2, the optical card A is determined to have a track pitch of 12 μm, and if the number of track crossing signals is 3, the optical card B is determined to have a track pitch of 8 μm.

Also in this embodiment, since the track pitch is determined based on the number of track crossing signals when the light spot has moved a predetermined distance, it is necessary to determine the track pitch exactly as in the first embodiment. Can be.
In the second embodiment, by using the optical spot S ₂ are determined track pitch, the present invention is not limited thereto, is irradiated to the optical card in addition to the light spot S _1, S ₃ or it A light spot may be used. Also, the same track pitch can be determined by counting the ATS (tracking error signal) during track traversal.

Further, the moving distance L is set to the track pitch P1,
Although the minimum common multiple of P2 is set to 24 μm, the moving distance may be further increased. For example, if it is 120 μm, which is five times the least common multiple, the track pitch P1 = 12 μm
, The number of track crossing signals is 10, the track pitch P
In the case of 2 = 8 μm, the number is 15 and the difference in the number of crossing signals is also five times. Therefore, it is possible to provide a margin for the reference for determining the track pitch. For example,
The criterion for determining the track pitch P1 is (number of track crossing signals <13), and the criterion for determining the track pitch P2 is (number of track crossing signals ≧ 13). By doing so, even if the number of track crossings increases or decreases due to an error in the moving distance or dust / scratch on the card surface, it is possible to avoid a situation in which a discrimination error or a discrimination cannot be made.

[0035]

As described above, according to the present invention, the track pitch of the recording medium is determined by using the tracking error signal at the time of track traversal. It is possible to accurately determine the track pitch without causing a failure in determining the track pitch due to an error. Also, by determining the track pitch based on the number of track traversing signals when the light spot moves a predetermined distance, the track pitch can be accurately determined in the same manner. Even if the number of track crossing signals changes due to dust, scratches, etc.
It is possible to reliably determine the track pitch.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a track pitch determination operation according to a first embodiment of the present invention.

FIG. 2 is a diagram showing signals of respective parts when a light spot crosses a track according to the first embodiment of the present invention in the case of an optical card having track pitches of 8 μm and 12 μm.

FIG. 3 is a diagram for explaining a track pitch determination method according to a second embodiment of the present invention.

FIG. 4 is a plan view showing an example of an optical card.

FIG. 5 is a configuration diagram illustrating an example of an optical card information recording / reproducing device.

FIG. 6 is a diagram showing an optical head of the apparatus of FIG. 5 in detail.

FIG. 7 is a circuit diagram showing an AT and AF control loop of the device of FIG.

8 is a diagram showing a signal of a photodetector and a tracking error signal when a light spot of the apparatus of FIG. 5 crosses a track.

FIG. 9 is a diagram showing a positional relationship between recording surfaces of two types of optical cards having different track pitches and three beam spots.

[Explanation of symbols]

 Reference Signs List 1 drive 2 CPU 3 MPU 4 modulation / demodulation circuit 10 AT / AF control circuit 13 AF actuator 14 AT actuator 21 irradiation optical system 22 semiconductor laser 29 objective lens 34-36 photodetector

Claims (6)

[Claims] 1. An automatic track pitch discriminating apparatus for discriminating track pitches of a plurality of types of recording media having different track pitches, comprising: a light spot group including two light spots for tracking control on the recording medium; Means for moving in the transverse direction; first comparing means for comparing the level of the tracking error signal when the light spot traverses the track with a predetermined first level lower than 0 level; Second comparing means for comparing the light spot group with a predetermined second level higher than the zero level;
Means for determining the track pitch based on the comparison result of the comparing means. 2. The recording device according to claim 1, wherein the discriminating means records the first light spot among the two light spots for tracking control according to a comparison result of the first and second comparing means after crossing a predetermined tracking track. 2. The track pitch automatic determination device according to claim 1, wherein the track pitch of the medium is determined. 3. The automatic track pitch discriminating apparatus according to claim 1, wherein the moving means moves the light spot from a home position of the recording medium in a direction in which a track exists. 4. An automatic track pitch discriminating apparatus for discriminating track pitches of a plurality of types of recording media having different track pitches, wherein said means for moving a light spot on said recording medium in a cross-track direction; An automatic track pitch discriminating apparatus comprising: means for counting the number of track crossing signals when the vehicle has moved a predetermined distance; and means for discriminating the track pitch based on the counted number of track crossing signals. 5. When the predetermined distance is L and the least common multiple of a plurality of track pitches is M, the predetermined distance is L ≧
5. The track pitch automatic discrimination device according to claim 4, wherein M is set to M. 6. The track traversing signal is an output signal of a sensor that detects reflected light of any of the light spots on the recording medium, or a tracking error signal for tracking control. Automatic track pitch discriminating apparatus according to 1.