JPH04195827A - Light pickup device - Google Patents

Abstract

PURPOSE:To reduce weight of an optical head and deviation of optical axis by separating a movable optical system and a fixed optical system, and by detecting rotation angle of a galvano-mirror. CONSTITUTION:An optical disk 1 mounted on a spindle motor 2 is driven for revolving. Then, the movable optical system 3, constituting a part of the light pickup device, is arranged being capable to move along radial direction of the optical disk 1 at the position opposed to the bottom of the optical disk 1, while, the fixed optical system 4, constituting a part of the device, is arranged at outer side radial direction of optical disk 1. Furthermore rotation angle of the galvano-mirror 18 is detected by an LED (light emitting diode) 23 installed in the galvano-mirror 18 and PSD (position detector element) 24 fixed to a carriage base 17. Thus the weight of the optical head can be reduced and deviation of the optical axis that is generated in the state of the revolving mirror being inclined can be reduced, too.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an optical pickup device.

[Prior Art] Generally, in an optical disk device, when data is recorded/reproduced on an effective storage medium of an optical disk that is rotated at a constant angular velocity by a spindle motor, an optical device consisting of a laser light source, a condensing lens, a beam splitter, etc. An optical head consisting of a galvanomirror for focusing the laser beam irradiated from this optical device onto a predetermined track position of the optical disk and a focusing actuator for controlling the focus and focusing the laser beam on the surface of the optical disk. This was done by mounting it on a head carriage that was movable in the radial direction of the disk.

However, in such conventional devices, the optical head itself is large and heavy, and a smaller and lighter optical head is desired.

In order to solve such problems, for example,
-206934 (“Optical Held Actuator”)
), it has been proposed that a focus actuator and a galvanometer mirror are installed on the same plane on a head carriage that accommodates an optical head, and a deflection prism is installed on the carriage below the focus actuator. There is.

According to this, by deflecting the laser beam reflected by a galvanometer mirror by 90 degrees with a deflection prism and making it incident on the objective lens of the focus actuator, the thin structure allows only the size needle where the focus actuator is installed to be reduced compared to conventional devices. An optical head is obtained.

[Problems to be Solved by the Invention] However, in such a conventional device, since the entire optical pickup device moves in the radial direction of the optical disk,
There is a problem that the weight of the movable part becomes heavy.

Furthermore, tilting the angle of the galvano mirror causes a problem of optical axis misalignment.

SUMMARY OF THE INVENTION In order to solve the problems of conventional devices, it is an object of the present invention to provide an optical pickup that reduces the weight of an optical head, reduces optical axis deviation, and speeds up access time.

[Means for Solving the Problems] The present invention provides a detection means for detecting the position of the second movable part with respect to the first movable part, a detection means for detecting the rotation angle of the galvanometer mirror, and a first movable part. a control means for controlling the position of the second movable part to be constant with respect to the first movable part; and control means for controlling the position of the second movable part so that the amount of beam axis deviation is at the initial position.

Further, in the first movable part having an objective lens, a focus actuator, and a deflection member, the deflection member is fixedly disposed on the fixed part directly below the objective lens in a shape that spans the entire movable range of the first movable part. It is equipped with the following.

[Function] Therefore, by dividing the optical system into a moving optical system and a fixed optical system, the weight of the optical pickup device can be reduced, and by detecting the rotation angle of the galvanomirror, optical axis deviation can be prevented.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a configuration diagram of an optical pickup device according to an embodiment of the present invention.

This embodiment shows an optical pickup device that accesses an optical storage medium with a guide groove.

In the figure, an optical disk 1 is placed on a spindle motor 2 and driven to rotate. At a position facing the lower surface of the optical disc 1, a movable optical system 3 constituting a part of the optical pickup device is arranged so as to be movable in the radial direction of the optical disc 1. A fixed optical system 4 constituting a part of the optical disc 1 is disposed radially outward of the optical disc 1.

The light beam emitted from the semiconductor laser 5 in the fixed optical system 4 is converted into a parallel beam by the coupling lens 6, and is sent to the moving optical system 3 via the polarizing beam splitter 7 and 1/4 wavelength plate 8.
added to.

By the way, the moving optical system 3 moves the disk 1 through the rail 9.
a first movable part 10 disposed so as to be movable in the radial direction;
A second movable part movable in parallel with the first movable part by the rail 11
It is composed of a movable part 12.

The first movable part includes a carriage base 13 and an objective lens 14.
, a deflection prism 15, and a focus actuator 16, and the second movable part includes a carriage base 17 and a galvanometer mirror 18 rotatably disposed on the carriage base 17 (in the n direction in the figure).

The parallel light added from the fixed optical system 3 is a galvanometer mirror.
18, is deflected again by the deflecting prism 15, and is focused by the objective lens 14 to form the optical disc 1.
A minute spot is formed on the optical disc, and data is recorded and reproduced on the effective storage medium of the optical disc.

On the other hand, the reflected light from the optical disc 1 is turned into parallel light by the objective lens 14, and is then passed through the deflection prism 15 and the galvano mirror.
18 and applied to the fixed optical system 4.

In the fixed optical system 4, the parallel light that has passed through the 1/4 wavelength plate 8 and the deflection beam splitter 7 is deflected by the deflection prism 19, and is focused on the light receiving element 22 via the condenser lens 20 and the cylindrical lens 21. be done.

Note that the galvano mirror 18 is provided with an angle detection mechanism, and the LED attached to the galvano mirror 18 (
The rotation angle of the galvanometer mirror 18 is detected by a light emitting diode (LED) 23 and a PSD (position detection element) 24 fixed to the carriage base 17. The movable portion 10 is controlled to be driven so that the angle detection signal KK of the galvanometer mirror 18 is at O (neutral position).

Further, an LED 25 is also attached to the end of the surface of the movable part 12 facing the movable part 10, and an LED 25 is attached to the end of the side face of the movable part 10.
PSD26 is attached to face D25,
The movable part 12 is controlled so that the position detection signal PK from the PSD 26 is constant, that is, the position of the movable part 12 with respect to the movable part 10 remains in the initial state.

FIG. 2 shows an example of a control system of an optical pickup device.

In the figure, a focus error signal, a tracking error signal, and an information signal are detected from the light receiving element 22.

Focus error processing uses the astigmatism method, etc.
The a, b, c, and d parts of the light receiving element 22, which is divided into four parts a, b, c, and d, are paired, respectively, and the output signals output therefrom are added by respective adders 30 and 31. Then, the output signals from the respective adders 30 and 31 are applied to the subtracter 32.

Based on the difference signal from the subtracter 32, the focusing servo controller 34 calculates the displacement of the focus actuator 16, applies this signal to the drive circuit 34, and applies the output current from the drive circuit 34 to the drive coil attached to the focus actuator 16. 35 to displace the objective lens 14 in the optical axis direction to perform focusing.

In addition, for tracking error signals, push-pull method etc. are used to detect 4
The a part and the C part, and the b part and the d part of the divided light receiving element 22 are each made into a pair, and the output signals outputted therefrom are added by the respective adders 36 and 37, and the respective adders 3
6. Add the output signal from 37 to a subtracter 38 and an adder 39.

From the subtracter 38, the tracking error signal ERt is applied to the mirror control unit 40, and the tracking error signal E
The rotation angle of the galvanometer mirror 18 is controlled by Rt,
The angle of the galvano mirror 18 is displaced by the drive coil 42 attached to the galvano mirror 18 by the output current from the drive circuit.

By the way, in the mirror control unit 40, the angle detection signal KK detected by the PSD 24 is applied to the arithmetic circuit 43,
The displacement signal H8I calculated by this arithmetic circuit is applied to the mirror control section 40, and the drive circuit 41 is controlled so that the galvanometer mirror 18 is placed in the neutral position.

Also, the tracking error signal ERt output from the subtracter 38 and the reproduction signal RF output from the adder 39
is added to the next stage circuit.

FIG. 3 shows an example of a data reproducing system of an optical disc device.

In the figure, a control section 50 controls the operation of each section of the magneto-optical disk device and exchanges predetermined data with a host device (shown in the figure) such as a personal computer that uses the optical disk 1.

The seek control unit 51 drives a seek motor 52 that drives the carriage base 13 to move the carriage base 13 to a recording track that includes a target sector of the optical disc 1, and the position sensor 53 drives a seek motor 52 that drives the carriage base 13. 1, and its detection signal PS is applied to the seek control section 51.

The sector address detection circuit 54 detects the sector address added to each sector of the effective recording area from the reproduction signal RF output from the optical pickup device, and the detection data DS is sent to the seek control unit 51. has been added.

The demodulation circuit 55 demodulates the reproduced signal RF and converts it into a reproduced signal R3 of NR2, and the reproduced signal R3 is
It is added to the data reproducing circuit 56.

The data reproducing circuit 56 refers to the error correction code added to the user data for one sector of 512 bytes of user data included in the reproduced signal R3, and detects a data error. The corrected data is output to the control section 10 as reproduced data RD.

The spindle motor control unit 57 controls the rotation of the spindle motor 2, and determines the rotation speed of the spindle motor 2 based on the detection signal SP of the speed sensor 58 that detects the rotation speed of the spindle motor 2. .

Therefore, the seek control unit 51 sends a detection signal P of the position sensor 53 so that the carriage base 13 moves to the position corresponding to the target sector specified by the control unit 50.
Referring to S, the carriage base 13 is roughly positioned by driving the seek motor 52, and the objective lens 14 reproduces the recording signal on the positioned recording track based on the reproduction signal RF obtained. When the sector address detected by the sector address detection circuit 16 matches the sector address of the target sector, the movement of the seek motor 52 is stopped.

Further, when the sector address detected by the sector address detection circuit 54 does not match the sector address of the target sector, the seek motor 52 is slightly moved according to the detected sector address and the sector address of the target sector, and the sector address of the target sector is changed. Objective lens 1 is ready for detection.
Move 4.

In this manner, the seek operation by the seek control section 51 is performed. Furthermore, when the seek operation is completed, the seek control unit 51 notifies the control unit 5° of this fact.

On the other hand, the spindle motor control section 57 controls the speed sensor 58
The rotational speed of the spindle motor 2 is controlled so that the detection signal SP becomes a value corresponding to the rotational speed designated by the control unit 5o.

Further, as shown in FIG. 4, a P
The position detection signal PK output from the SD26 is applied to the arithmetic circuit 59, and the galvanometer mirror 18 of the PSD24
Based on the angle detection signal KK and the displacement signal H9.2 calculated by the arithmetic circuit 59, the control unit 51 causes the movable unit 10 to bring the galvanomirror 18 to the neutral position and position the objective lens 14 at a predetermined target sector. The seek motor 52 is driven as follows.

With the above configuration, when the optical disk 1 is loaded into this optical disk device, the control section 50 controls the spindle motor control section 5.
7 controls the rotational speed of the spindle motor 2 to a predetermined rotational speed, and once the rotational speed of the spindle motor 2 is defined, the movable part 10 is moved to roughly position the target sector of the optical disc 1. At this time, the movable part 1
2 is also positioned at a predetermined position following the movable part 10 by the position detection signal of the PSD 26.

As described above, focusing is first performed using the focus error signal, and the distance between the objective lens 14 and the optical disc j is controlled so that the spot hits a predetermined position on the optical disc 1, and the angle of the galvano mirror 18 is adjusted. , so that the spot of the light beam emitted from the semiconductor laser 5 hits the target sector.

However, when the angle of the galvanometer mirror 18 is adjusted and the spot is applied to the optical disk, for example, as shown in FIG. 5(a), the light beam deflected at position B1 of the deflection prism 15 is reflected at position B2. come. Moreover, if it is deflected at the position of C1, it will be reflected to 02.

Therefore, when the tracking error signal ERt is detected, the tilt of the galvanometer mirror 18 is changed so that the spot hits a predetermined position on the optical disc 1. Then, based on the angle detection signal KK of the galvanic mirror 18, the normal position of the movable part 10 is calculated by the arithmetic circuit 59, and the galvanic mirror 18 is
18 to the neutral position, and controls the movable part 10 so that the optical axis is always at position A in Figure 5(a) and position A in Figure 5(b).
).The movable part 10 is moved so as to pass through the

In this way, by dividing the optical pickup device into a moving optical system and a fixed optical system, the weight of the movable part of the optical pickup device can be reduced, and the galvanometer mirror 18 can be separated from the fixed optical system and moved. Galvanometer mirror
It is possible to prevent optical axis deviation that occurs when the angle of 18 is tilted.

Next, FIG. 6 shows a configuration diagram of an optical pickup device according to another embodiment of the present invention.

This embodiment is an optical pickup device that accesses an optical storage medium in which a large number of plover marks are preformatted at regular intervals on a track, and in this case, optical axis deviation is detected by a light receiving element 22. In this figure, the same parts as in FIG. 1 are designated by the same reference numerals.

The device of this embodiment includes the LED 25 shown in FIG.
It has a configuration in which D26 is removed.

FIG. 7 shows an optical disc to which an embodiment of the present invention is applied.

This optical disk 60 has recording tracks TK formed concentrically at a predetermined pitch and is driven to rotate at a constant angular velocity, and as shown in FIG. Long servo areas SBA and 16 byte long data areas DTA are arranged alternately.

In this servo area SBA, as shown in FIG. 9(a), pits PA and PB are alternately arranged so as to be in contact with the center LC of the recording track TK and lined up on opposite sides.
, and a pip) PC arranged so that its center coincides with the center LC of the recording track TK are recorded.

Then, the tracking error of the laser beam (as shown in the diagram) of the optical pickup (as shown in the diagram) is detected based on the reproduction level at the timing of the pits PA and PB in the reproduction signal RF shown in (b) of the figure. Based on the tracking error, tracking servo control is performed to align the laser beam with the center LC of the recording track TK.

FIG. 1-0 shows an example of a control system of an optical pickup device according to another embodiment of the present invention. In addition, in the same figure, the second
The same parts as those in the figure are given the same reference numerals.

A focus error signal, a tracking error signal, and an information signal are detected from the light receiving element 22.

Focus error processing uses the astigmatism method, etc.
The a part and the b part, and the C part and the d part of the light receiving element 22 which are divided into four parts a, b, c, and d are paired, respectively.
The output signals outputted from the respective adders 30.
31 and the output signals from the respective adders 30, 31 are added to a subtracter 32.

Based on the difference signal from the subtracter 32, the focusing servo control unit 34 calculates the displacement of the focus actuator 16, applies this signal to the drive circuit 34, and outputs the current from the drive circuit 34 to the coil attached to the focus actuator 16. 35 to displace the objective lens 14 in the optical axis direction to perform focusing.

In addition, for the tracking error signal, using a sample servo method or the like, the a part and the C part, and the b part and the d part of the light receiving element 22, which is divided into four parts a, b, c, and d, are paired, respectively. The output signals output therefrom are added by each adder 70.71, and the output signal from each adder 70.71 is added to a subtracter 72 and an adder 73.

The output signal of the light receiving element applied to the subtracter 72 is applied to the optical axis deviation detection section 74 as the optical axis deviation amount KZ. At this time, according to the timing outputted from the timing extraction circuit 75, the playback level is detected from the output signal outputted from the a part and the C part, and the b part and the d part of the light receiving element 22, respectively, as a pair, and the difference is detected. The signal is output as the optical axis deviation amount KZ.

In addition, each light receiving element 22 added to the adder 73
The detection signal is added to the timing extraction circuit 75 and the tracking error determination section 76 as a reproduction signal RF, and the pits PA and P provided on the track of the optical disc are detected according to the timing output from the timing extraction circuit 75.
The playback level of B is determined and applied to the mirror control section 77 as a track error signal ERt.

The drive circuit 78 is controlled by the control signal from the mirror control section 77.
is controlled, and the output current is applied to the drive coil 42 of the galvanomirror 18 and the galvanomirror
Adjust the rotation angle of 18.

Further, in the mirror control unit 77, the PSD 24 sends a signal indicating the rotation angle of the galvano mirror 18 to an arithmetic circuit 7 based on a signal from the LED 23 attached to the galvano mirror 18.
In addition to 9, a displacement signal HS 3 is applied.

In the above configuration, the moving optical system 3 is attached to the target sector.
When the position is roughly determined, focusing is performed using a focus error signal, tracking error is detected using pits PA and PB provided on the optical disc 60, and the rotation angle of the galvano mirror 18 is adjusted.
Highlight traffic in the target sector.

At this time, since the galvano mirror 18 is tilted, the light receiving element 2
2, the optical axis misalignment occurs, and in order to control this, PSD24
The galvano mirror 18 is returned to the neutral position by the output signal from the movable mirror 18, and the movable part 10 and the movable part 112 are simultaneously sought to control the optical axis deviation and position the two carriage bases 13 and 17 in the target sector. .

By controlling the rotation angle of the galvano mirror 18 in this manner, optical axis deviation can be suppressed and high-speed access can be realized.

FIG. 11 shows an optical pickup device according to still another embodiment of the present invention.

In the same figure, 1. The movable part 1o is a carriage base 13
, an objective lens 14, and a focus actuator 16.The deflection prism 80 has a shape that covers the entire movable range of the movable part 10, and as shown in FIG. It is directly fixed to a fixing part 81 provided in the.

In such a configuration, the movable part 10 and the movable part 12 perform the operations of the two embodiments described above, and in the movable part 10, only the carriage base 13, objective lens 14, and focus actuator 16 move in the radial direction of the optical disc 1. It becomes possible.

In this way, the weight of the movable part 10 can be further reduced and high-speed access is possible.

[Effects of the Invention] As explained above, according to the present invention, since the optical pickup device is divided into a moving optical system and a fixed optical system,
By reducing the weight of the movable parts and making the rotating mirror movable, it is possible to reduce the optical axis shift that occurs when the rotating mirror is tilted, and it is also possible to separate the deflection prism from the moving optical system. As a result, the weight of the optical head can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical pickup device according to an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a control system of the optical pickup device, and FIG. 3 is a block diagram of an example of a control system of the optical pickup device. A block diagram showing an example; FIG. 4 is a block diagram showing a part of the data reproduction system in FIG. 3; FIG. 5(a) is an explanatory diagram showing the relationship between incident light and reflected light hitting the deflection prism;
Figure 5(b) is an explanatory diagram of Figure 5(a) seen from the side;
7 is a schematic diagram showing an example of the track structure of an optical disc. FIG. 8 is a schematic diagram illustrating the relationship between the servo area and the data area. 9 is a schematic diagram showing an example of a servo pattern, and FIG. 10 is a block diagram showing an example of a control system of an optical pickup device according to another embodiment of the present invention.
FIG. 1 is a configuration diagram of an optical pickup device according to still another embodiment of the present invention, and FIG. 12 is a side view of the optical pickup device according to still another embodiment of the present invention. 1... Optical disk, 2... Spindle motor, 3.
... Moving optical system, 4... Fixed optical system, 10... Movable part, 12... Movable part, 18... Galvano mirror 12
3...LED124...PSD, 25...LED
, 26... PSD33... Focusing servo control section, 40... Mirror control section, 51... Seek control section, 80... Deflection prism.

Claims (3)

[Claims] (1) A fixed optical system having a light beam output system including a semiconductor laser and a signal detection system for detecting a tracking error signal, a focus error signal, an information signal, etc., and a first lens having an objective lens, a focus actuator, and a deflection member.
a movable part, and a second movable part including a galvano mirror, and a detection means for detecting the position of the second movable part with respect to the first movable part, and a detection means for detecting the rotation angle of the rotating mirror. An optical pickup device comprising a detection means and a control means for controlling the position of the second movable part to be constant with respect to the first movable part. (2) a fixed optical system having a light flux emitting system including a semiconductor laser and a signal detection system for detecting a tracking error signal, a focus error signal, an information signal, etc.; and a first lens having an objective lens, a focus actuator, and a deflection member.
and a second movable part including a rotating mirror, and a detection means for detecting the amount of deviation of the axis of the light flux incident on the signal detection system from the initial position, and the first movable part. an optical pickup device comprising: control means for controlling the position of the second movable part with respect to the second movable part so that the amount of light flux axis deviation is at an initial position. (3) A deflection member according to claim 1 or 2, further comprising a deflection member fixedly disposed on a fixed portion directly below the objective lens in a shape that covers the entire movable range of the first movable portion. Optical pickup device.