JPH069085B2 - Optical information recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention records information on an optical information recording medium, reproduces the information recorded on the medium, and / or is recorded on the medium. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus capable of erasing information, and more particularly to an autofocus or autotracking pull-in circuit.

[Conventional technology]

2. Description of the Related Art Conventionally, various types of media such as disk-shaped, card-shaped, and tape-shaped are known as a form of a medium for recording information using light and for recording and reading the recorded information. Among these, a card-shaped optical information recording medium (hereinafter referred to as an "optical card") is expected to be in great demand as a medium having a large recording capacity that is small and lightweight and convenient to carry.

FIG. 5 is a schematic plan view of such an optical card 101.
02 is an information recording area, 103 is an information track, and 104, 104 '.
Is the track selection area, and 105 is the home position of the light beam spot.

The optical card 101, by scanning with a light beam that is modulated according to the recording information and is focused on a minute spot,
Information is recorded as a record bit string (information track) so as to be optically detectable. At this time, in order to record information accurately without causing trouble such as crossing of information tracks, the irradiation position of the light beam spot is controlled in the direction perpendicular to the scanning direction within the optical card surface (auto tracking Hereinafter referred to as "AT"). In addition, in order to irradiate the light beam as a minute spot of a fixed size despite the bending and mechanical error of the optical card, control is performed in the direction perpendicular to the optical card surface (auto focusing,
Hereinafter referred to as "AT"). Also, the above-mentioned AT and AF are required at the time of reproduction.

FIG. 6 shows a block diagram of an apparatus for recording and reproducing information on and from an optical card. 106 is a motor for driving the optical card 101 in the direction of the arrow in the figure, and 107 is a semiconductor laser or the like. A light source, 108 is a collimator lens for collimating the light from the light source 107, 109 is a beam splitter, 110 is an objective lens,
Reference numeral 111 is a tracking coil, 112 is a focusing coil, 113 and 114 are condenser lenses, 115 and 116 are photoelectric conversion elements, 117 is a tracking control circuit, and 118 is a focusing control circuit. The objective lens 110 is moved by applying currents to the tracking coil 111 and the focusing coil 112 in accordance with commands from the control circuits 117 and 118 based on the tracking signals and focusing signals detected by the photoelectric conversion elements 115 and 116, thereby moving the objective lens 110. , AF
Do. 119 is a system controller for controlling the recording / reproducing apparatus, and 120 is a group of various control signals output from the controller. Although signals other than 120 are output from the controller 119, they are not shown here. 121 denotes an optical head, and 122 denotes the optical head.
In the figure, it is a drive motor for moving in the u direction.

The light from the light source 107 is collimated by the collimator lens 108, passes through the beam splitter 109, and then is condensed by the objective lens 110 on the recording track of the optical card 101. The light reflected by the recording track is now reflected by the beam splitter 109.
Through the beam splitter 109, and they are condensed by the condenser lenses 113 and 114 on the tracking signal detecting photoelectric conversion element 115 and the focusing signal detecting photoelectric conversion element 116, respectively. The signals obtained by the photoelectric conversion elements 115 and 116 are respectively the tracking control circuit 11
7. The focusing control circuit 118 causes the tracking error signal and the focusing error signal to flow through the tracking coil 111 and the focusing coil 112 to move the objective lens 110 to perform AT and AF.

FIG. 7 is a detailed diagram of the focusing control circuit 118.

In the figure, 201 is an amplifier that amplifies the electrical focusing signal from the photoelectric conversion element 116 to an appropriate voltage.
Reference numeral 203 denotes an analog switch, the output of the amplifier 201 is input to one of its input terminals and the C input to the other input terminal.
The output of the adding circuit 208 is input via the point, and one of the input terminals is selected by the signal from the focusing roller 205. 206 is a triangular wave generating circuit and 207 is a rectangular wave generating circuit, and the two outputs are added by an adding circuit 208. 204
Is a driver for receiving a signal from the analog switch 203 and passing a drive signal current through the focusing coil 112. A focusing controller 205 receives the signal 120 from the system controller 119 and controls the entire focusing control circuit 118. The seventh
In the figure, it is shown that a signal is input from the focusing controller to only the analog switch 203. However, the focusing controller 205 also outputs other signals (not shown).

FIGS. 8 and 9 show changes with time of points A and C in the focusing control circuit shown in FIG.

The pulling of the focusing servo will be described below with reference to FIGS. 7, 8 and 9.

First, the signal D from the focusing controller 205 causes the analog switch 203 to be in a state where the point A side is open and the point C side is closed. This allows the adder circuit
The output C of 208 moves the objective lens 110.

Here, when the portion that drives the objective lens 110 is of a sliding type (the elastic coefficient is so small that it can be ignored), the objective against the force required to keep moving the objective lens (mostly the reaction force against dynamic friction). The force required to start moving the lens (the resistance to static friction) is large. In such a case, only the triangular wave generating circuit 206 is used
When I try to move 110, the movement becomes irregular. Therefore, usually, as shown in FIG. 8 (a), a method is used in which the output of the rectangular wave generation circuit 207 is superposed and the objective lens is always reciprocated by a minute amount to reduce the static friction force.

When the objective lens is moved by the above device, the voltage at the point A becomes S in the vicinity of the focus of the objective lens on the optical card.
It changes into a letter shape (so-called S-shaped curve) (see FIG. 8 (b)). Next, when pulling in the focus servo, see FIG.
At time t0 in (b), the focusing controller 205 detects that the point A reaches 0V, sends a signal D to the analog switch 203, closes the point A side, and opens the point C side. This makes it possible to pull in the focusing servo.

[Problems to be solved by the invention]

However, since the static friction cannot be completely reduced to 0 in the above-mentioned conventional example, in order to compensate for it, the objective lens is moved at a high speed, and the dynamic inertia of a movable object including the objective lens is also used for smoothing. Is getting a move. Since the objective lens is moved at high speed in this way, the frequency of the S-shaped curve that appears also becomes high, and it becomes necessary to detect 0V at point A at high speed, resulting in the disadvantage that the apparatus becomes expensive. .

Similarly, since the momentum of the objective lens when the focusing servo is pulled in is large, the overshoot voltage Vover after that also becomes large (see FIG. 9 (b)), and sometimes the servo pull-in fails. There is also a drawback that the device becomes unstable.

Further, there is a drawback that the objective lens is shaken when vibration is applied from the outside, and stable servo pull-in cannot be performed.

Further, the situation around here is not limited to the focus control, and the same problem occurs in the tracking control.

[Means for solving problems]

In view of the above-mentioned conventional problems, an object of the present invention is to provide an optical information recording / reproducing apparatus which can always stably pull in a tracking servo and a focusing servo.

The above-mentioned object is to perform spot irradiation of an optical information recording medium having a plurality of tracking tracks arranged in parallel at a predetermined track pitch through an objective lens movably supported on a base of the optical head, and In an optical information recording / reproducing apparatus for recording, reproducing and / or erasing information by relatively scanning a light beam spot along a tracking track, reflection that occurs when the optical bee spot is irradiated on the recording medium. A detector for detecting light, a means for generating a tracking error signal or a focusing error signal for the tracking track of the light beam spot based on the output of the detector, and the means based on the tracking error signal or the focusing error signal. Means for driving the objective lens A Ranaru first servo loop, and means for said detecting a displacement in a direction orthogonal to the direction or the surface of the medium perpendicular to the tracking tracks for the base of the objective lens, to generate a displacement signal,
A means for generating a predetermined drive signal for moving the objective lens in a direction traversing the tracking track or in a direction orthogonal to the surface of the medium; and a difference signal between the displacement signal and the predetermined drive signal for the drive means. And a second servo loop composed of the driving means, and whether or not the light beam spot is positioned on the tracking track based on the tracking error signal or the focusing error signal, or a focused state. And a means for detecting whether the light beam spot is on or not, and when the light beam spot is pulled into the tracking track or in a focused state, the first servo loop is made inoperative and the second servo loop is operated. Let
When the detection means detects that the light beam spot is located on the tracking track or is in focus, the second servo loop is made inoperative and the first servo loop is operated. It is achieved by a characteristic optical information recording / reproducing apparatus.

[Action]

The present invention as described above has the second servo loop that obtains a focusing or tracking signal of a different system from the signal of the focusing servo or tracking servo which is usually performed when the focusing servo or tracking servo is pulled in. Therefore, as compared with the conventional method shown in FIG. 7 in which the triangular wave generating circuit 206 and the rectangular wave generating circuit 2007 are simply used to drive the objective lens to perform focus or tracking servo retraction, the speed of the objective lens at the time of retraction can be increased. Can be lowered. Also,
As compared with the conventional method, the device can be made inexpensive, and the focusing servo or the tracking servo can be pulled in stably.

Further, when vibration is applied from the outside, the second servo loop itself detects the state thereof, so that the shake of the objective lens can be reduced, so that stable servo pull-in can always be performed.

〔Example〕

The optical information recording / reproducing apparatus of the present invention will be described below in detail with reference to the drawings.

The idea of the present invention can be applied not only to AF but also to AT, but in the following embodiments, a focusing control circuit will be described as an example.

FIG. 1 is a diagram showing an example of the configuration of a focusing control circuit according to the optical information recording / reproducing apparatus of the present invention.

In the figure, members having the same functions as those in FIG. 7 are designated by the same reference numerals, and the description thereof will be omitted. In the figure, 301 is a position detector of the objective lens, and 304 is an LED.
Light source such as 306, a mirror 306 that reflects light from the light source 304, 30
Reference numeral 5 is a sensor such as a photodiode that receives the light reflected by the mirror 306 and converts it into a voltage. Mirror 306
Is fixed to the objective lens 110 side which is a movable part, and the light source 304 and the sensor 305 are tracking coils 1 which are a non-movable part.
It is fixed on the 11 side. As a result, when the objective lens 110 moves, the distance between them changes,
The incident light on the sensor 305 changes, and the output voltage F of the sensor 305 changes. Further, 303 is an arbitrary voltage generation circuit, and 302 is an addition / subtraction circuit for the differential between the output E of the arbitrary voltage generation circuit 303 and the output voltage F of the sensor 305.

2 (a), (b) and (c) are respectively E of the embodiment shown in FIG.
It is a graph which shows the voltage change of a point, an F point, and an A point.

When pulling in the focus servo, first, the signal D from the focusing controller 205 causes the analog switch 203 to be in a state where the point A side is open and the point C side is closed. As a result, the position of the objective lens 110 is
Servo control can be performed by the position detection unit 301. The position of the objective lens 110 can be controlled by injecting the signal E of the arbitrary voltage generation circuit 303 into the servo control loop by the addition / subtraction circuit 302. Therefore, if the frequency of the triangular wave E, which is the output signal of the arbitrary voltage generation circuit 303, is lowered, the objective lens 11
The moving speed of 0 can also be reduced. The signals E, F, and A at this time are as shown in FIGS. 2 (a), (b), and (c), respectively, and the frequency of the S-shaped curve can be lowered. Further, as shown in FIGS. 3 (a), (b), and (c), since the momentum of the objective lens when the focusing servo is retracted is small, the overshoot voltage Vover after that can be also reduced, and the focusing can be reduced. The servo can be pulled in stably.

As described above, by providing the position detection unit which is inexpensive and has a small number of parts, the 0V detection circuit at the point A can operate at low speed.
It can be cheap.

In addition, when vibration is applied from the outside, the position detection unit 30
Since the second servo loop including 1 can reduce the shake of the objective lens, stable servo pull-in can be performed.

Next, another embodiment of the present invention will be described.

Although the above-mentioned embodiment describes the sliding type actuator, the present invention can be similarly applied to a spring supporting type actuator.

FIG. 4 is a detailed diagram of a tracking control circuit of a second example in which the present invention is applied to a spring-supported type actuator.

In the figure, 501 is a position detection unit, 504 is a light source such as an LED, 506 is a mirror that reflects the light from the light source 504, and 505.
Is a sensor such as a photodiode that receives the light reflected by the mirror 506 and converts it into a voltage. The mirror 506 is fixed to the side of the tracking coil 111 which is a movable part, and the light source 504 and the sensor 505 are fixed to an object (not shown) which is a non-movable part. As a result, when the objective lens 110 moves in the u direction, the distance 'changes,
The incident light on the sensor 505 changes, and the output voltage f of the sensor 505 changes. Note that 503 is an arbitrary voltage generation circuit, 502 is an addition / subtraction circuit, 401 is an amplifier that amplifies the electrical tracking signal from the photoelectric conversion element 115 to an appropriate voltage, and 403
Is an analog switch, 404 is a driver, and 405 is a tracking controller.

When the tracking is pulled in, the signal d first causes the analog switch 403 to be in a state in which the point a side is opened and the point C side is closed. Accordingly, the position of the objective lens 110 in the u direction can be servo-controlled by the position detection unit 501. In the servo control loop, the signal e of the arbitrary voltage generation circuit 503 is added / subtracted by the addition / subtraction circuit 5
By injecting with 02, the position of the objective lens 110 can be controlled. As a result, similarly to the focusing servo, it is possible to detect that the light spot is located on the track of the recording medium when the point a becomes 0V, and the tracking servo can be pulled in.

As a result, the objective at the low resonance frequency of the actuator that was generated when external vibration was applied (acceleration / deceleration at the seek time or when vibration occurred in the surroundings) before the tracking servo was pulled in Since the vibration of the lens 110 in the u direction can be made so small that it can be ignored, it is possible to perform stable tracking pull-in that is strong against vibration.

The present invention is not limited to the above embodiment, and various modifications and applications are possible.

For example, in the above-described embodiment, the objective lens position detection unit 301
The optical sensor is used as the position detecting unit of the position detecting unit 501 of the tracking coil 112, but a method using a Hall element, a method using a change in capacitance, or the like,
It is possible to use a known method or the like in position detection.

〔The invention's effect〕

As described above, according to the present invention, when the focusing servo or the tracking servo is pulled, when the focusing servo or the tracking servo is pulled by pulling the focusing servo or the tracking servo by operating the second servo loop different from these servos. Since the speed of the light beam spot can be reduced, the momentum of the objective lens can be reduced, and the overshoot voltage can be reduced, the focusing servo and the tracking servo can be always pulled in stably.

Further, when vibration is applied from the outside, the vibration of the light spot can be reduced, so that focusing and / or tracking servo pull-in can be stably performed.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of the configuration of a focusing control circuit according to the optical information recording / reproducing apparatus of the present invention. FIG. 2 shows (a), (b) and (c) and FIGS. 3 (a), (b) and (c) show voltage changes at points E, F and A of the embodiment of FIG. 1, respectively. Is a graph showing. FIG. 4 is a detailed diagram of a tracking control circuit of a second example in which the present invention is applied to a spring-supported type actuator. FIG. 5 is a schematic plan view of an optical card. FIG. 6 is a block diagram of a conventional optical information recording / reproducing apparatus. FIG. 7 is a detailed diagram of a conventional focusing control circuit. 8 and 9 are timing charts of signals in the focusing control circuit shown in FIG. 110: objective lens, 111: tracking coil, 112: focusing coil, 115, 116: photoelectric conversion element, 117:
Tracking control circuit, 118: Focusing control circuit, 119: System controller, 201, 401: Amplifier, 2
03,403: Analog switch, 204,404: Driver, 20
5: Focusing controller, 405: Tracking controller, 301, 501: Position detector, 304, 504: Light source,
Reference numerals 305 and 505 are sensors, 306 and 506 are mirrors, 303 and 503 are arbitrary voltage generation circuits, and 302 and 502 are addition and subtraction circuits.

Claims (1)

[Claims] 1. An optical information recording medium having a plurality of tracking tracks arranged in parallel at a predetermined track pitch through an objective lens movably supported on a base of an optical head, and the tracking track. In an optical information recording / reproducing apparatus for recording, reproducing and / or erasing information by relatively scanning a light beam spot along a line, reflected light generated when the recording medium is irradiated with the light beam spot. A detector for detecting, a means for generating a tracking error signal or a focusing error signal for the tracking track of the light beam spot based on the output of the detector, and the objective lens based on the tracking error signal or the focusing error signal. And the means to drive A first servo loop, a means for detecting a displacement in a direction orthogonal to the tracking track with respect to the base of the objective lens or a direction orthogonal to the surface of the medium, and generating a displacement signal; and the objective lens. Means for generating a predetermined drive signal for moving in a direction traversing the tracking track or in a direction orthogonal to the surface of the medium, and means for supplying a difference signal between the displacement signal and the predetermined drive signal to the drive means. And a second driving means including the driving means.
A servo loop, and means for detecting whether or not the light beam spot is located on the tracking track based on the tracking error signal or the focusing error signal, or whether the light beam spot is in focus, When the light beam spot is pulled into the tracking track or in the focused state, the first servo loop is made inoperative and the second servo loop is operated, and the detection means causes the light beam spot to move to the tracking track. An optical information recording / reproducing apparatus, wherein the second servo loop is made inoperative and the first servo loop is operated when it is detected that it is positioned above or in focus.