JP2929712B2 - Optical pickup device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called sliding type optical pickup device used for an optical disc reproducing device, for example.

SUMMARY OF THE INVENTION The present invention relates to a so-called shaft-sliding type optical pickup device, for example, and relates to a light generating means for generating laser light, a condensing lens for causing the laser light from the light generating means to enter an optical disc, and A bobbin that supports the condenser lens, is movable in the focusing direction by an axis parallel to the optical axis of the condenser lens, and is rotatably supported in the tracking direction, and receives reflected light from the optical disk. A signal generating means for generating a signal of a predetermined frequency, a first signal for driving the bobbin in the focusing direction based on a focus error detection output signal from the light receiving means and an output signal from the signal generating means. Driving means for driving the bobbin in the tracking direction based on a tracking error detection output signal from the light receiving means; And driving the bobbin in the tracking direction based on the tracking error detection output signal while the bobbin is vibrated in the focusing direction based on the output signal from the signal generating means. This is to stabilize the servo.

2. Description of the Related Art Conventionally, as an optical pickup device used for an optical disk reproducing device or the like, a so-called shaft sliding type optical pickup device as shown in FIG. 3 has been proposed.

That is, in FIG. 3, (1) is a rotating shaft rotated by a spindle motor (not shown), and the optical disk (2) is mounted on a turntable provided on the rotating shaft (1). (3) is a support shaft, and the lower part of the support shaft (3) is fixed to a base (10). (4) is a bobbin, and the above-mentioned support shaft (3) is inserted into a hole provided at the center of the bobbin (4). At this time, the gap between the support shaft (3) and the hole of the bobbin (4) is, for example, about 10 to 30 μm.
Further, the bobbin (4) has, for example, one end of a suspension (9) made of silicon rubber fixed to the pin (8) of the bobbin (4), and the other end of the suspension (9) connected to the base (10). It is supported as shown in the figure by being fixed to the projection. A hole having a predetermined diameter is provided on the left side of the bobbin (4) in the figure, and a condenser lens (11) is arranged in the hole as shown in the figure. And
A coil (5) for a focus servo described later is wound around the bobbin (4), and further, coils (6a), (6b), (7a), and (7b) for a tracking servo described later are arranged. .

The focus servo coil (5) and the tracking servo coils (6a), (6b), (7a)
The illustration and description of the yoke, magnet and the like in (7b) are omitted.

(14) is a laser diode, and a laser beam from the laser diode (14) is divided into, for example, three beams by a grating g. The three beams of laser light, that is, the main beam and the two sub-beams are respectively collimated by a beam splitter (13).
After being made into parallel rays by the collimator lens (12), it is incident on the condenser lens (11), and is condensed on the disk (2) by the condenser lens (11). The light beam reflected by the disk (2) is passed through a condenser lens (11), a collimator lens (12) and a beam splitter (13) to a photo detector (15).
Incident on.

This photodetector (15) is composed of a four-segment detector and two detectors, and the main beam of the three light beams described above is the main beam of the photodetector (15).
The two side beams are made to be incident on the split detector, and the remaining two side beams are made to be incident on the two detectors of the photodetector (15). Then, a plurality of detection signals are output from the photodetector (15), and the plurality of detection signals are supplied to the drive circuit (16). That is, a, -b,
Detection signals c and -d are output, and detection signals e and f are output from the two detectors. The drive circuit (16) is based on a plurality of detection signals from the photodetector (15) and is used for reproducing signals and focusing coils (5) and tracking coils (6a), (6b), (7a) and (7b). Are output. Therefore, when the drive signal from the drive circuit (16) is supplied to the coil (5), the bobbin (4) slides in the direction of the support shaft (3), and the coils (6a), (6b), (7a) And (7b) drive circuit (1
When the drive signal from (6) is supplied, the bobbin (4) slides in the horizontal direction about the support shaft (3), thereby performing focusing and tracking servos.

Now, this drive circuit (16) is configured as shown in FIG. Illustration and explanation of a circuit and the like for a reproduction signal are omitted.

In FIG. 4, (17), (18), (19) and (20) denote input terminals to which a detection signal is supplied from the four-divided detector constituting the photodetector (15). (17), (18), (19) and (20)
Are supplied with detection signals a, -b, c and -d, respectively.
These input terminals (17), (18), (19) and (20) are connected to the inverting input terminal of the operational amplifier (21) via resistors R1, R2, R3 and R4, respectively. The inverting input terminal of the operational amplifier (21) and the output terminal of the operational amplifier (21) are connected via a resistor R5, and the non-inverting input terminal of the operational amplifier (21) is grounded via a resistor R6. Is done. The output terminal of the operational amplifier (21) and the inverting input terminal of the operational amplifier (22) are connected via a resistor R7. Then, both ends of the resistor R7 are connected by a series circuit of the capacitor C1 and the resistor R8. An inverting input terminal of the operational amplifier circuit (22) and an output terminal of the operational amplifier circuit (22) are connected via a resistor R10, and a series circuit of a capacitor C2 and a resistor R11 is provided at both ends of the resistor R10. Are connected in parallel. The non-inverting input terminal of the operational amplifier (22) is grounded via a resistor R9. And this operational amplifier (2
The output terminal of 2) and the inverting input terminal of the operational amplifier (24) are connected via a resistor R12.
Are connected by a resistor R15. The non-inverting input terminal of the operational amplifier (24) is grounded via a resistor R14, and the operational amplifier (2)
The output terminal of 4) is grounded via the above-mentioned coil (focus actuator) (5). Now, the photodetector (15) sends the detection signals a,-to the operational amplifier (21) via the input terminals (17), (18), (19) and (20), respectively.
b, c and -d are supplied. The output signal from the operational amplifier (21) is boosted in high frequency by a series circuit of a capacitor C1 and a resistor R8 and a resistor R7, and supplied to an inverting input terminal of the operational amplifier (22).
The low range is boosted by the series circuit of C2 and resistor R11 and resistor R10. The signal is supplied to the inverting input terminal of the operational amplifier (24) via the resistor R12, and is supplied to the coil (5) as a focus error signal from the output terminal of the operational amplifier (24). Thus this coil (5)
Current flows through this, as described in FIG.
The bobbin (4) slides in the direction of the support shaft (3) to perform focusing.

(25) and (26) are input terminals to which detection signals from the two detectors constituting the photodetector (15) are respectively supplied. These input terminals (25) and (26) are connected to the two detectors. Detection signals e and -f are supplied. These input terminals (25) and (26) are each connected to a resistor R16
And R17 to the inverting input terminal of the operational amplifier (27). The inverting input terminal of the operational amplifier (27) and the output terminal of the operational amplifier (27) are connected by a resistor R18, and the non-inverting input terminal of the operational amplifier (27) is connected to a resistor R1.
Grounded via 9 A resistor is connected between the output terminal of the operational amplifier (27) and the inverting input terminal of the operational amplifier (28).
Connected with R20. Then, both ends of the resistor R20 are connected by a series circuit of the capacitor C3 and the resistor R21. The inverting input terminal of the operational amplifier (28) and the output terminal of the operational amplifier (28) are connected by a resistor R23, and a series circuit of a capacitor C4 and a resistor R24 is connected to both ends of the resistor R23. . In addition, this operational amplifier (2
The non-inverting input terminal of 8) is grounded via the resistor R22.
The output terminal of the operational amplifier (28) and the inverting input terminal of the operational amplifier (29) are connected via a resistor R25. The inverting input terminal and the output terminal of the operational amplifier (29) are connected by a resistor R27. Connected. The non-inverting input terminal of the operational amplifier (29) is grounded via a resistor R26, and the output terminal of the operational amplifier (29) is connected to the coils (tracking actuators) (6a), (6b), (7
Grounded via a) and (7b). When the detection signals e and -f are supplied from the photodetector (15) to the operational amplifier (27) via the input terminals (25) and (26), an output signal is output from the operational amplifier (27). The high frequency of this output signal is raised by the series circuit of the capacitor C3 and the resistor R21 and the resistor R20.
Then, it is supplied to the inverting input terminal of the operational amplifier (28),
Further, the low frequency range is raised by the series circuit of the capacitor C4 and the resistor R24 and the resistor R23. Then, the voltage is supplied to the inverting input terminal of the operational amplifier (29) via the resistor R25. The output terminal of the operational amplifier (29) supplies a tracking error signal to the coils (6a), (6b), (7a) and (7b). Supplied respectively. Thus these coils (6
Current flows through a), (6b), (7a) and (7b), which causes the bobbin (4) to slide horizontally about the support shaft (3) substantially as described with reference to FIG. Then, tracking is performed.

[Problems to be Solved by the Invention] By the way, in the so-called shaft sliding type pickup device as described above, when the optical disk (2) causes a so-called surface run-out, the focus follows the surface run-out of the disk. Become. That is, the focus error signal follows the disk runout and becomes a substantially rectangular wave as shown in the middle part of FIG. 5 due to the disk runout shown in the upper part of FIG. Here, the friction between the support shaft (3) and the bobbin (4) moves when the bobbin (4) of the optical pickup device shown in FIG. It changes with stillness and movement. Then, as shown in the lower part of FIG. 5, the tracking error signal has an oscillating waveform corresponding to the runout of the disk. Further, as shown in FIG. 6, when the tracking device characteristics of the above-described servo are represented in a graph, the gain for the actuator is significantly affected by the fluctuation of the phase, and the characteristics are deteriorated. Therefore, there is a disadvantage that the track jump cannot be normally performed even if the track jump is performed in such a case.

The present invention has been made in view of such a point, and an object of the present invention is to propose an optical pickup device capable of stabilizing a tracking servo.

[Means for Solving the Problems] The optical pickup device of the present invention is, for example, shown in FIGS.
Light generating means (14) for generating laser light as shown in the figure
And a condensing lens (11) for allowing the laser light from the light generating means (14) to enter the optical disc (2); and supporting the condensing lens (11), the optical axis of the condensing lens (11) A bobbin (4) rotatably supported in a focusing direction and rotatable in a tracking direction by an axis (3) parallel thereto, and a light receiving means (15) for receiving light reflected from the optical disk (2). The bobbin (4) based on a signal generating means (23) for generating a signal of a predetermined frequency, a focus error detection output signal from the light receiving means (15) and an output signal from the signal generating means (23). First driving means (5) for driving the bobbin (4) in the tracking direction based on the tracking error detection output signal from the light receiving means (15), and (6b). ), (7a) and (7 b), the bobbin (4) is driven in the tracking direction based on the tracking error detection output signal while the bobbin (4) is vibrated in the focusing direction based on the output signal from the signal generating means (15). It was made.

[Operation] According to the present invention described above, even if the focus follows the surface deviation of the optical disk (2), the bobbin (4) always moves the focusing direction based on the signal of the predetermined frequency from the signal generating means (15). Is driven in the tracking direction based on the tracking error detection output signal.
Thereby, the friction between the shaft (3) and the bobbin (4) moves when the bobbin (4) moves up and down the shaft (3),
There is almost no change between static and dynamic, and this friction substantially changes the dynamic, so that the tracking servo can be stabilized. The tracking servo can be stabilized.

Example An example of the optical pickup device of the present invention will be described below in detail with reference to FIG. The entire optical pickup device is the same as that shown in FIG. 3, and a description thereof will be omitted. In FIG. 1, parts corresponding to those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. The description of the reproducing system is also omitted.

In FIG. 1, an oscillator (23) is further connected to the drive circuit (16) described in FIG. 4 via a resistor R13 as shown in FIG. Then, a signal having a frequency of, for example, about 1 KHz is supplied to the inverting input terminal of the operational amplifier (24). Thus, the coil component (5) as a focus actuator is always supplied with the signal component having a frequency of about 1 KHz, and the bobbin (4) (see FIG. 3) is supported by the support shaft (3).
Will be constantly finely moved (vibrated) up and down. This vibration is a vibration that does not affect the reproduction system. By doing so, the bobbin (4) is always vibrating even if the focus follows the surface deviation of the disk (2), so that the bobbin (4) moves up and down the support shaft (3). Thus, the friction between the support shaft (3) and the bobbin (4) hardly changes between dynamic, static, and dynamic, and this friction substantially changes the dynamic. Therefore, as shown in FIG.
When the tracking device characteristic of the servo is represented on a graph, the gain for the actuator becomes stable because there is almost no phase fluctuation. Therefore,
Track jump can always be performed stably.

The above-mentioned transmitter (23) may be connected to connection points a and b in FIG.

In addition, the present invention is not limited to the above-described embodiments, and may take various other configurations without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention described above, tracking is performed in a state where the bobbin constantly vibrates in the focusing direction based on a signal of a predetermined frequency from the signal generating means even when the focus follows the surface shake of the optical disk. Driven in the tracking direction based on the error detection output signal. As a result, the friction between the shaft and the bobbin hardly changes between dynamic, static, and dynamic when the bobbin moves up and down the shaft, and this friction substantially changes in motion, thus stabilizing the tracking servo. There are benefits that can be planned.

[Brief description of the drawings]

1 is a circuit diagram showing a main part of an example of the optical pickup device of the present invention, FIG. 2 is a graph showing tracking device characteristics, FIG. 3 is a configuration diagram showing an example of the optical pickup device, and FIG. FIG. 5 is a circuit diagram showing a main part of an example of the optical pickup device, FIG. 5 is a graph showing each error signal corresponding to a disk runout, and FIG. 6 is a graph showing a tracking device characteristic. (1) is a rotating shaft, (2) is a disk, (3) is a supporting shaft,
(4) is a bobbin, (5), (6a), (6b), (7a) and (7b) are coils, (11) is a condenser lens, (12) is a collimator lens, (13) is a beam splitter, (14) is a racer diode, (15) is a photodetector, (16) is a drive circuit, and (23) is an oscillator.

Claims (1)

(57) [Claims] 1. A light generating means for generating a laser light, a condenser lens for causing the laser light from the light generation means to enter an optical disk, and a support for the condenser lens; A bobbin supported so as to be movable in the focusing direction by a parallel axis and rotatable in the tracking direction, light receiving means for receiving light reflected from the optical disc, and signal generating means for generating a signal of a predetermined frequency. First driving means for driving the bobbin in the focusing direction based on a focus error detection output signal from the light receiving means and an output signal from the signal generating means; and a tracking error detection output signal from the light receiving means. And second driving means for driving the bobbin in the tracking direction, and outputting the bobbin with an output signal from the signal generating means. In the focusing direction based on
An optical pickup device driven in a tracking direction based on the tracking error detection output signal.