JPH10162491A - Optical information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure margins with respect to LD rated outputs even though a scanning speed is raised and moreover to perform a constant recording and reproducing without generating noise by respectively arrangingly provided a light source for recording and a light source for reproduction while respectively separating them to a fixed optical system and a movable optical system. SOLUTION: This device performs a recording and reproducing with respect to a card shaped recording medium by the relative motion between the movable optical system and the card shaped recording medium while separating optical systems to the fixed optical system and the movable optical system. A semicondductor laser 12 as a light source emiting a luminuous flux for recording as the fixed optical system and a semiconductor laser 22 as a light source emitting a luminous flux for reproduction as the movable optical system are provided by being respectively separated. Then, since the respective light sources are made to generate luminous fluxes with only needed powers, the speed of the recording and reproducing is raised by dispensing with control systems of powers of the semiconductor lasers. Moreover, since only the light source for reproduction is made to be mounted on the movable optical system, the movable optical system is made light in weight to promote the speeding up of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of separating an optical system into a fixed optical system and a movable optical system, and performing relative movement between the movable optical system and a card-shaped recording medium to be recorded and reproduced. The present invention relates to an optical information recording / reproducing device configured to perform recording / reproduction on a recording medium.

[0002]

2. Description of the Related Art Conventionally, discs, cards, and the like have been used as information recording media for recording and reproducing information using light.
Various types of recording media such as tapes are known. In particular, a card-shaped optical information recording medium (hereinafter, referred to as an optical card) is not only convenient to carry, but also has a relatively large capacity, and cannot be erased or rewritten at present. Therefore, applications in fields where this property is advantageous are expected.

FIG. 6 is a schematic plan view of the above-mentioned optical card. Here, information for recording information is shown in the optical recording area C1 of the optical card as partially enlarged and extracted. A number of tracks Ta and a plurality of tracking tracks Tb, which are guides for automatic tracking (AT) for controlling a light spot so as not to deviate from a predetermined information track during information recording / reproduction, are arranged in parallel.

Further, the optical recording area C1 of the optical card
Is provided with a home position HP serving as a reference position for access to the information track.
Are assigned track numbers in order from the one closer to the home position HP. The access to the target information track is performed by a seek operation for moving the light spot in a direction perpendicular to a large number of tracks arranged in parallel, and an operation when the light spot scans the information track.

When information is actually recorded / reproduced, a light spot is focused on a recording medium surface.
Automatic focusing (AF) control is performed. The control for the auto tracking (AT) and the auto focusing (AF) is a general technique often used in a conventional optical information recording / reproducing apparatus.

FIG. 7 is a block diagram showing a conventional optical card information recording / reproducing apparatus. Here, reference numeral 1 denotes an optical card information recording / reproducing apparatus (hereinafter referred to as a drive), and reference numeral 2 denotes a higher-level control apparatus. It is a certain CPU. Drive 1
Recording and reproduction are executed based on a command issued from the CPU 2. The configuration of the drive 1 is as follows. That is, reference numeral 8 denotes a motor for introducing and discharging the optical card C into and from the drive 1 via a transport mechanism (not shown), and a sensor 7 is provided near the card insertion slot 6. When the sensor 7 detects that the optical card C has been inserted, the motor 8 is driven to convey the optical card C to a predetermined position.

Reference numeral 21 denotes an irradiation optical system including a light source, and a light flux from the light source is transmitted to the optical card C during recording / reproduction.
Irradiate the spot on the top. Then, the light spot and the optical card C relatively reciprocate, so that the light spot scans an appropriate position on the optical card C. Reference numeral 34 denotes 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 the 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. Reference numeral 14 denotes an AT actuator that drives a part of the irradiation optical system 21 to move the light spot in the X direction, that is, a direction orthogonal to both the Y direction and the Z direction, to perform AT control. . In short, the optical head 20 is configured to include the above-described irradiation optical system 21, photodetector 34, AF actuator 13, and AT actuator 14.

Reference numeral 3 denotes an MPU having a built-in ROM and RAM, which controls various parts such as a motor 8 for feeding a card, and controls and communicates data with the CPU 2 under the control of the CPU 2. Reference numeral 10 denotes an AF actuator 13 and an AT based on the detection signal of the photodetector.
An AT / AF control circuit for driving the actuator 14 to perform AF control and AT control. Also, reference numeral 4
Is a modulation / demodulation circuit for reproducing the detection signal of the photodetector and demodulating the reproduction signal to reproduce the original recording data. Reference numeral 5 denotes the intensity of the light source (not shown) and the output of the modulation / demodulation circuit 4. Is a light source drive circuit that modulates and controls the information, thereby recording information (pits) by light modulation on the information track.

FIG. 8 is a perspective view showing the internal structure of the optical head in detail. The optical head shown in the figure is
This is a separate type optical head including a fixed optical system 40 fixedly arranged on the apparatus side and a movable optical system 41 which can reciprocate in the Y direction in the figure. In the drawing, reference numeral 22 denotes a semiconductor laser (hereinafter, referred to as LD), and a light beam emitted from the semiconductor laser becomes a parallel light beam by a collimator lens 23.
The light enters the shaping prism 24. And shaping prism 2
The light reflected on the four surfaces is projected onto the photodetector 33, and LD power control is performed based on the output value of the photodetector 33.

The transmitted light exits from the fixed optical system 40, enters the diffraction grating 25 of the movable optical system 41, and is split into a zero-order light beam and a diffracted light beam. The zero-order light beam and the diffracted light beam generated by the diffraction grating 25 are further divided into a polarizing beam splitter 26, a bending prism 27, and a １ ／ wavelength plate 2.
8. The information track Ta and the tracking track Tb on the optical card C are irradiated and imaged as a light spot via the objective lens 29.

The light beam irradiated on the optical card C is reflected here, and is again reflected by the objective lens 29, the quarter-wave plate 28,
The light reaches the polarization beam splitter 26 via the folding prism 27, is reflected by the polarization beam splitter 26, is further reflected by a reflection surface formed integrally with the polarization beam splitter 26, and is emitted from the movable optical system 41. Then, the emitted light beam enters the fixed optical system 40 and is projected on the photodetector 34 via the detection optical system 30.

The detection optical system 30 is an astigmatism system in which a cylindrical lens 32 is arranged at an angle of 45 ° with respect to the spherical lens 31 and the track. Therefore, in this device, based on the output of the photodetector, AF control by the astigmatism method and AT control by the three-beam method
Control is performed. Then, the optical card C is moved in the direction of arrow X, which is a direction perpendicular to the information track and the tracking track, and the movable optical system 41 is moved in the direction Y, which is a direction parallel to the information track and the tracking track.
The information is recorded / reproduced by reciprocating.

FIG. 9 is a schematic diagram of a diffraction grating, where:
Reference numeral 25a denotes an AT diffraction grating forming unit for generating an AT control light beam, 25b denotes a DV diffraction grating forming unit for generating a direct verify (DV) light beam capable of reproducing information immediately after recording, and 25c denotes a recording light. An RF diffraction grating forming unit 45 for generating an information reproduction (RF) light beam for reproducing recorded information in an information track adjacent to the information track irradiated with the light beam is an incident light beam.

By the way, the diffraction angle θn of the diffracted light is determined by the equation θn = n · λ / d (where n is the order) from the grating pitch d and the wavelength λ of the incident light beam. The diffraction direction is determined by the inclination δ of the grating with respect to the incident light beam, and the direction is substantially perpendicular to the diffraction grating. Then, the diffracted light beam and the zero-order light beam are diffracted through the objective lens.
As shown in FIG. 10, light spots S0, ± SAT, ± SDV, ± SRF are applied to appropriate positions on the optical card, and reciprocal recording and simultaneous reproduction of 3Tr are performed.

FIG. 11 is a circuit diagram showing a conventional signal processing circuit. Here, reference numeral 34 denotes a photodetector, which includes light receiving elements 34a to 34c and light receiving elements 34e to 34e.
4g and a four-divided light receiving element 34d. The reflected light of each light spot shown in FIG. 8 is projected on each light receiving element surface, and the reflected light of the light spot ± SAT for AT control is reflected by the light receiving elements 34c and 34e and the AF
The reflected light of the control, recording, and reproduction light spot S0th order is received by the light receiving element 34d.

The reflected light of the verifying light spot ± SDV is reflected by the light receiving elements 34b and 34f, and the reflected light of the information track reproducing light spot ± SRF adjacent to the information track irradiated with the recording light is reflected by the light receiving element 34a. And 3
At 4 g, each is received. Light receiving elements 34a to 34
The output signal of g is output to the recording / reproduction gain switching circuit 50. The recording / reproducing gain switching circuit 50 corrects a difference in signal amplitude level caused by a difference in LD power between a case where information is recorded on the optical card C and a case where information is reproduced, and a substantially constant level. This is a circuit for holding the signal amplitude level. That is, by switching the gain for amplifying the signal at the time of recording / reproduction, the signal amplitude level is maintained.

Light receiving elements 34a to 34c and light receiving element 3
The output signals 4e to 34g are output to gain switching circuits 50a to 50c and gain switching circuits 50e to 50g of the recording / reproduction gain switching circuit 50.
The output signal of d is output to gain switching circuits 50d1 to 50d4.

The output signals of gain switching circuits 50c and 50e become AT control signals via subtraction circuit 51. The output signals of the gain switching circuits 50d1 and 50d3 are summed by the adding circuit 52.
The output signals of 0d2 and 50d4 are summed by the addition circuit 53. The two sum signals become an AF control signal via the subtraction circuit 54. The output signals of the adder circuits 52 and 53 become the sum signal added by the adder circuit 55, and the gain switch circuits 50a and 50g
Is an information reproduction signal. That is, 3Tr simultaneous reproduction can be performed.

The output signals of the gain switching circuits 52b and 52f are output to a selection switch 57,
7 outputs one of the signals according to the scanning direction of the light spot. The output signal of the selection switch 57 is D
V signal. More specifically, if the scanning direction of the light spot is the F direction shown in FIG. 8, the selection switch 57 is connected to the F side, and the output signal of the light receiving element 34b becomes the DV signal. . On the other hand, if the scanning direction of the light spot is the R direction shown in FIG. 8, the selection switch 57 is connected to the R side, and the output signal of the light receiving element 34f becomes D.
V signal. In other words, at the time of recording, since the reproduction signal of the verifying light spot that scans the same track after the recording light spot is always a DV signal, reciprocal recording and simultaneous verify can be performed.

As described above, in the conventional optical card information recording / reproducing apparatus, the optical system is separated into the fixed optical system and the movable optical system, and the movable optical system is operated by operating the optical head equipped with the movable optical system. By reducing the weight of the unit, the access performance to information is improved and the scanning speed is increased. In addition to increasing the scanning speed, simultaneous verification of reciprocating recording and 3T
r simultaneous reproduction is performed.

[0022]

However, when the scanning speed is increased, it becomes difficult to control the LD power and the gain, and it becomes impossible to perform stable simultaneous recording verification. This will be described below.

FIG. 12A shows a change in LD power at the time of recording, where Pw is the LD power at the time of recording, Pr
Is the LD power at the time of verification and reproduction. Generally, in order to form a desired pit on an optical card, it is necessary to determine the LD power and the irradiation time to appropriate values. For example, as shown in FIG. 13, it is assumed that a desired pit can be formed with LD power: P1 and irradiation time: T1. Here, the scanning speed is doubled, that is, the irradiation time is T2 (= 1).
/ 2 · T1), the LD power becomes P2 (= 2 · P
Otherwise, desired pits cannot be formed. That is, as the scanning speed increases, the LD power during recording: Pw must be increased.

On the other hand, the LD power at the time of verification: Pr
Cannot be increased because of problems such as reproduction light degradation. Therefore, when the scanning speed is increased, the LD power during recording: Pw and the LD power during verification: Pw
The difference from r increases. Further, since the power switching frequency (recording modulation frequency) is also increased, noise during gain switching as shown in FIG. 12B is generated. As a result, this noise is superimposed on various output signals, which adversely affects the reproduction of information.

The following is an example. FIG. 12C shows a normal DV signal recorded in FIG. 12A. D
The V signal (c) has a waveform that has a phase difference from the recording signal (a) by the spot interval. This DV signal is
When binarization is performed at the level indicated by the dotted line in FIG.
(D), which is a normal DV binarized signal. On the other hand, when the noise shown in FIG. 12B is superimposed on the normal DV signal, a signal as shown in FIG.
The quantified signal is as shown in FIG. As is apparent from the figure, a false signal is generated in the binarized signal due to noise, and normal reproduction cannot be performed. Further, it is also superimposed on a control signal used for controlling AT / AF, LD power, and the like, and adversely affects the control system.

In general, an optical information recording / reproducing apparatus has a single light source for recording / reproducing. Even when recording requires the most LD power, the light from the light source is used not only for recording but also for recording. , Other functions (light spot for AT, DV
Light spot, RF light spot). For this reason, there is a small margin for the LD rated output, and if the scanning speed is increased and the LD power is further increased, the LD may be destroyed. On the other hand, if an LD having a large rating is used, the above-described problem of destruction can be solved, but a high-output LD is expensive and expensive.

Furthermore, in the case of such a single light source, a gain switching circuit must be provided for each light receiving element in the signal processing circuit, and the electric circuit becomes complicated and the cost increases.

The present invention has been made based on the above circumstances. It is an object of the present invention to separate an optical system into a fixed optical system and a movable optical system so that a movable optical system and an object to be recorded and reproduced can be used. In an optical information recording / reproducing apparatus configured to perform recording / reproduction on the card-shaped recording medium by relative movement with respect to the card-shaped recording medium, a margin for the LD rated output is secured even when the scanning speed is increased. It is another object of the present invention to provide a configuration capable of performing stable recording / reproduction without noise that adversely affects an information reproduction signal and various control signals.

[0029]

Therefore, according to the present invention, as a means for solving the above-mentioned problems, a recording light source and a reproduction light source are separated from a fixed optical system and a movable optical system, respectively. It is characterized by having been arranged.

Thus, for recording and reproduction,
Since different light sources are used and light is emitted with only the required power in each specification, the speed of recording / reproducing is increased, except for the barrier of speeding up due to the intervening LD power control system. As a structural feature, since only the reproduction light source or the recording light source is mounted on the movable optical system, an increase in the weight of the movable part can be suppressed as much as possible, and high-speed operation can be promoted.

In this case, in the movable optical system of the optical information recording / reproducing apparatus, the recording / reproducing light beam is propagated as a parallel light beam, so that the movable optical system can change the spot diameter regardless of the moving position. Avoid such effects and do not adversely affect recording and playback. In addition, by mounting the detection optical system together with the reproduction light source on the movable optical system, the reproduction light can be emitted in a divergent state, so that the expensive collimator lens and the convex lens of the detection optical system can be used. It can be omitted and cost can be reduced.

In the embodiment of the present invention, a dichroic prism, a polarizing beam splitter (hereinafter, referred to as a polarizing beam splitter) will be described.
For example, the return light of the recording light beam (W light) can be prevented from entering the detection optical system and noise can be prevented.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a schematic configuration diagram showing a first embodiment of an optical head (optical system) in an information recording / reproducing apparatus according to the present invention. In FIG. 1, the same components as those of the above-described conventional device are denoted by the same reference numerals. Further, in FIG. 1, reference numeral 22 denotes a semiconductor laser as a light source for emitting a light beam for reproduction, and reference numeral 12 denotes a semiconductor laser as a light source for emitting a light beam for recording. The semiconductor laser 22 emits light having a wavelength of 780 nm as reproduction light, and the semiconductor laser 12 emits light having a wavelength of 830 nm as recording light.

Reference numerals 13 and 23 denote collimator lenses, reference numeral 25 denotes a diffraction grating, and reference numeral 51 denotes a dichroic prism, which has spectral characteristics shown in FIG. 2 for P-polarized light. Reference numeral 52 denotes a half-wave plate, which rotates the plane of polarization of transmitted light by an angle of 90 °.

Reference numerals 14 and 24 denote beam shaping prisms, 26 denotes PBS, 28 denotes a quarter-wave plate, 29 denotes an objective lens, 31 denotes a convex lens, 32 denotes a cylindrical lens,
34 is a photodetector, C is an optical card, which is the same as the conventional one.

As described above, in the configuration of the present invention, light sources having different rated powers are used for the light sources 22 and 12 for reproduction and recording, and the movable optical system includes only the light source 22 for reproduction. And stable high-speed recording and reproduction can be performed. In addition, in this embodiment, the recording light beam and the reproduction light beam are parallel light beams.
The change in the optical path length due to the change in the moving position of the movable optical system does not change the spot diameter and does not adversely affect recording / reproduction such as occurrence of vignetting. Note that the objective lens 29 is provided on the optical card C with two different wavelengths.
Chromatic aberration at two wavelengths is corrected to bring two lights into a focused state.

In this embodiment, the reproduction light source 2
By arranging 2 and the diffraction grating 25 in the movable optical system,
Since the light beam passes through the movable optical system while the distance between the diffracted lights is extremely small, parts having a small effective diameter can be used in the movable optical system, which reduces the weight, speed, and size. Will contribute.

Further, in this embodiment, since the half-wave plate 52 is disposed in the fixed optical system, the polarization plane of the light beam is rotated by an angle of 90 °, and the fixed optical system and the movable optical system are rotated. Can be configured on the same plane, which contributes to downsizing of the entire apparatus. Further, by combining the PBS 26, the dichroic mirror 51, and the quarter-wave plate 28, the recording light reflected from the optical card can be easily discarded outside the optical system, and the recording light enters the photodetector 34. Can be prevented.

(Embodiment 2) FIG. 3 is a schematic diagram showing a second embodiment of the optical head (optical system) of the optical information recording / reproducing apparatus of the present invention. In addition,
Here, the same components as those in the first embodiment are denoted by the same reference numerals. In the optical system of this embodiment, P
It has the spectral characteristics shown in FIG. 4 for polarized light.

Next, the features of this embodiment will be described. First, the first feature is that the movable optical system has a reproducing light source 2.
2 and the photodetector 34, thereby, from the light source to the photodetector can be integrally configured,
A divergent light beam can be used as a light beam propagating in the optical path. For this reason, a collimator lens and a convex lens become unnecessary, which contributes to cost reduction, downsizing, and high speed.

The second characteristic point is that the light source 22 for reproduction and the diffraction grating 25 are arranged in the movable optical system, so that the distance between the diffracted light beams is extremely small, and the light beam is transmitted to the movable optical system. Since it can pass through, a part having a small effective diameter can be used for the movable optical system, which contributes to a reduction in weight, speed, and size.

The third characteristic point is that the recording light beam is a parallel light beam, so that the spot diameter does not change due to the change of the optical path length due to the change of the moving position of the movable optical system. (Regeneration accompanying this) will not be adversely affected. Also, as a fourth feature point, PBS
26, a combination of the dichroic mirror 51 and the quarter-wave plate 28. Here, the recording light reflected from the optical card can be discarded out of the optical system, and the intrusion of the recording light into the photodetector 34 can be prevented.

(Embodiment 3) FIG. 5 is a schematic diagram showing an optical head (optical system) in an information recording / reproducing apparatus according to a third embodiment of the present invention. Here, the same components as those in the first embodiment are denoted by the same reference numerals. Further, the optical system according to this embodiment has the same spectral characteristics as that of the first embodiment (shown in FIG. 2) for P-polarized light.

Next, the features of the present invention will be described. The first feature is that the reproduction light beam is a parallel light beam, so that there is no change in the spot diameter due to the change in the optical path length due to the change in the moving position of the movable optical system, and the recording / reproduction such as vignetting occurs. Does not adversely affect

The second characteristic point is that the detection optical system having a relatively long optical path length is arranged in the fixed optical system by disposing the reproducing light source 22 and the photodetector 34 in the fixed optical system. Accordingly, the weight of the movable optical system can be reduced, and the space of the entire optical system unit can be reduced, which contributes to weight reduction, high speed, and compactness as a whole.

Further, the third feature is that the recording light source 12 is disposed in the movable optical system and used as a divergent light beam, thereby eliminating the need for a collimator lens and contributing to cost reduction, compactness, and high speed. can do. The fourth feature is that the recording optical system is divided into a movable optical system and the reproducing optical system is divided into a fixed optical system. Since each unit can be used alone, workability is improved and assembly time is shortened, that is, cost is reduced.
In addition, the fifth characteristic point is that the PBS 26, the dichroic mirror 51, and the quarter-wave plate 28 are combined. Here, the recording light reflected from the optical card can be discarded to the outside of the optical system, and the intrusion of the recording light into the photodetector can be prevented.

[0047]

As described above, according to the present invention,
Independent light sources are used for recording and playback, respectively.
Since each unit can be assembled and adjusted, workability can be improved, cost can be reduced, LD power control is not required, and reciprocal recording and simultaneous reproduction of multiple Trs can be performed in a separate optical system. Optical system for
Stable recording / reproduction can be performed, the configuration of the electric circuit can be simplified, and advantages such as cost and space can be obtained. can get.

[Brief description of the drawings]

FIG. 1 shows a separation method 2 according to a first embodiment of the present invention.
It is a schematic diagram of a light source type optical system.

FIG. 2 is also a spectral characteristic diagram of a dichroic prism here.

FIG. 3 is a schematic diagram of a two-light source type optical system showing a second embodiment of the present invention.

FIG. 4 is also a spectral characteristic diagram of the dichroic prism here.

FIG. 5 is a schematic view of a two-light-source optical system according to a third embodiment of the present invention.

FIG. 6 is a schematic plan view of the optical card.

FIG. 7 is a block diagram showing a conventional optical card recording / reproducing apparatus.

FIG. 8 is a perspective view of a conventional optical head.

FIG. 9 is a schematic view of a conventional diffraction grating.

FIG. 10 is an arrangement diagram of light spots on an optical card in a conventional example.

FIG. 11 is a circuit diagram showing a signal processing circuit in a conventional example.

FIG. 12 is a diagram showing various signal waveforms.

FIG. 13 is a characteristic diagram showing a relationship between LD power required for pit formation and irradiation time.

[Explanation of symbols]

 C Optical card 12,22 Semiconductor laser 13,23 Collimator lens 14,24 Beam shaping prism 25 Diffraction grating 26 Polarization beam splitter 28 1/4 wavelength plate 29 Objective lens 31 Spherical lens 32 Cylindrical lens 34 Photodetector 51 Dichroic prism 52 1 / 2 wavelength plate

Claims (9)

[Claims] An optical system is separated into a fixed optical system and a movable optical system, and recording / reproducing with respect to the card-shaped recording medium is performed by relative movement between the movable optical system and a card-shaped recording medium to be recorded and reproduced. In the optical information recording / reproducing apparatus configured to perform the above, the recording light source and the reproduction light source are separately disposed with respect to the fixed optical system and the movable optical system, respectively. Information recording and playback device. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the light source provided in the movable optical system is a reproducing light source and is arranged in a pair with a collimator lens. apparatus. 3. The optical information recording / reproducing apparatus according to claim 1, wherein the recording light beam and the reproducing light beam propagating between the movable optical system and the fixed optical system are parallel light beams. 4. The optical information recording / reproducing apparatus according to claim 1, wherein the recording light beam and the reproducing light beam propagating between the movable optical system and the fixed optical system are non-parallel light beams. 5. The optical information recording / reproducing apparatus according to claim 1, wherein a detection optical system is provided in the movable optical system. 6. The optical information recording / reproducing apparatus according to claim 1, wherein the light source provided in the movable optical system is a recording light source. 7. The optical information recording / reproducing apparatus according to claim 6, wherein the recording light beam propagating through the movable optical system is a divergent light beam. 8. The optical information recording / reproducing apparatus according to claim 6, wherein the reproduction light beam propagating between the movable optical system and the fixed optical system is a parallel light beam. 9. A light source for reproduction and a detection optical system are arranged in the fixed optical system.
The optical information recording / reproducing device according to any one of the above.