JPH0734263B2 - Optical information recording / reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus, and more particularly to an optical information recording medium having an information track for tracking a light beam focused by an objective lens. The present invention relates to an optical information recording / reproducing apparatus that records / reproduces information by irradiating it while controlling focusing.

[Prior Art] Conventionally, in order to apply focus servo to an optical disc, focus pull-in is performed in advance.

Focus pull-in operation is tracking servo loop,
The focus servo loop is turned off, and signals such as triangular waves are forcibly added to move the objective lens up and down. In the astigmatic focus servo system, when passing through the focal point, the total light amount of the four-division photoelectric conversion element reaches a peak, and the difference signal of the diagonal comrades is a signal output proportional to the distance of the focusing deviation (so-called S curve). ) Is output, it is detected that it is near the in-focus point if the total light output is compared with a predetermined threshold value of zero, and the focus servo loop is turned on at the moment of the S-curve zero cross, and the forced vertical movement is performed. If you stop, the auto focus servo will be activated.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, since the tracking servo is simply opened at the time of pulling in the focus, the position of the objective lens in the tracking direction is set at the mechanical center (optical center adjustment point) that is supposed to be. ) To the mechanical spring balance position, and if there is an offset in the circuit, the lens is displaced by the offset. If this deviation occurs, for example, in a system where the optical output is guaranteed within a range of ± 250 μm from the optical center, and there is a center deviation of +100 μm, the optical output guarantee will be in the range of −350 μm to +100 μm. If you perform tracking pull-in immediately and perform 100 track jumps with a track width of 1.6 μm in the + direction, you will be out of the optical output guarantee.

[Means for Solving Problems] An optical information recording / reproducing apparatus of the present invention irradiates an optical information recording medium having an information track with a light beam focused by an objective lens while controlling tracking and focusing. In an optical information recording / reproducing apparatus for recording / reproducing information by moving the objective lens in the tracking direction and the focusing direction, the moving unit is controlled to move the objective lens in the focus direction. Focus pulling means for pulling the light beam into the medium, focus detecting means for detecting a shift position of the objective lens from the center position of the movable range in the tracking direction, and the objective lens shift position detecting means. Controlling the moving means according to the detection result of the means, Objective lens position control means for holding the objective lens at the center position of the movable range in the tracking direction, and when the focus pull-in of the light beam is performed by the focus pull-in means, the objective lens position control means moves the objective lens in the tracking direction. It is characterized in that it is held at the center position of the range.

[Operation] According to the present invention, in order to solve the above-mentioned problems that occur when the objective lens deviates from the center position within the originally movable range in the tracking direction at the time of pulling in the focus, the objective lens position control means at the time of pulling in the focus. Thus, the objective lens is held at the center position of the movable range of the objective lens in the tracking direction. According to the present invention, immediately after the pulling of the focus, the tracking is performed in either the + direction or the-direction in the tracking direction. Even when jumping is performed, since the objective lens moves from the center position of the movable range in the tracking direction, it is possible to perform many track jumps up to the maximum distance of the optical guarantee range.

EXAMPLES Examples of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an optical information recording / reproducing apparatus of the present invention.

As shown in the figure, the objective lens 1 is fixed to the lens barrel 2, and the LED 3 is attached to the lens barrel 2. A two-divided detector 4 is arranged in the irradiation direction of the light from the LED 3, and when the LED 3 moves due to tracking control or the like,
The light emitted from the LED 3 moves the same distance on the two-divided detector 4. Each output of the two-divided detector 4 is input to the differential amplifier 5.

The light emitted from the optical system (not shown) to the disc 20 through the objective lens 1 for recording and reproducing information is again emitted to the four-division detector 8 through the objective lens 1. The respective outputs of the 4-division detector 8 are input to the tracking error detection circuit 9 and the focus error detection circuit 11, and the outputs thereof are respectively the switch 17 and the switch 18.
It is input to the tracking equalizer 10 and the focus equalizer 12 via (hereinafter, the switch is referred to as SW).
The output of the tracking equalizer 10 and the output of the differential amplifier 5 applied through the SW 16 are applied to the subtractor 21, and this output is amplified by the tracking amplifier 6 and applied to the tracking actuator 15. On the other hand, the output of the focus equalizer 12 and the output of the triangular wave generator 13 applied through the SW 19 are added to the adder 22, and this output is amplified by the focus amplifier 14 and added to the focus actuator 7.

The focus actuator 7 and the tracking actuator 15 are moving means, a triangular wave generator 13, a SW 19, and an adder 2.
2, Focus amplifier 14 is the focus pull-in means, LED
The 3- and 2-divided detector 4 constitutes an objective lens position detecting means, and the differential amplifier 5, SW16, subtractor 21, and tracking amplifier 6 constitute an objective lens position controlling means.

Next, the operation of the optical information recording / reproducing apparatus will be described.

Now open SW17 and SW18 to turn off the focus servo and tracking servo. In this state, switch SW16 to O
When in the N state, the tracking amplifier 6, the tracking actuator 15, the LED 3, the two-divided detector 4, and the differential amplifier 5 constitute an optical system position control unit that forms a servo loop and is the mechanical center of the movable range in the tracking direction. The position of the objective lens 1 is controlled and held at the center (optical adjustment point). That is, the movement of the light beam in the tracking direction is restricted. When SW19 is turned on in this state, the output of the triangular wave generator 13 is applied to the focus actuator 7 through the focus amplifier 14, and the objective lens 1 is moved up and down to enter the focus search state. At the focus position, switch SW19 to OFF
When W18 is turned on, the focus is closed, but the objective lens 1 is held at the mechanical center in the focus closed state.

Furthermore, if SW16 is turned off and SW17 is turned on here, the tracking servo is turned on at the mechanical center.

[Effects of the Invention] As described in detail above, according to the optical information recording / reproducing apparatus of the present invention, focus pull-in is possible with the objective lens being held at the center position of the movable range of the objective lens in the tracking direction. Therefore, it is possible to jump a large number of tracks to the maximum distance within the optical guarantee range immediately after the focus is pulled in.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an optical information recording / reproducing apparatus of the present invention. 1: Objective lens, 2: Lens barrel, 3: LED, 4: 2 split detector, 5: Differential amplifier, 6: Tracking amplifier, 7: Focus actuator, 8: 4 split detector, 9: Tracking error detection circuit, 10 : Tracking equalizer, 11: Focus error detection circuit, 12: Focus equalizer, 13: Triangle wave generator, 14: Focus amplifier, 15: Tracking actuator, 16,17,18,19: Switch (SW), 20: Disk , 21: subtractor, 22: adder.

Claims (1)

[Claims] 1. An optical information recording / reproducing apparatus for recording / reproducing information by irradiating an optical information recording medium having an information track with a light beam condensed by an objective lens while controlling tracking and focusing. A moving means for moving the objective lens in the tracking direction and the focusing direction, and a focus pull-in means for controlling the moving means to move the objective lens in the focus direction to pull the focus of the light beam to the medium. An objective lens displacement position detecting means for detecting a displacement position of the objective lens from a center position of a tracking direction movable range, and the moving means according to the detection result of the objective lens displacement position detecting means to control the objective lens. Center position of the movable range in the tracking direction And an objective lens position control means for holding the objective lens at a center position of a movable range in the tracking direction by the objective lens position control means when the light beam is focused by the focus pulling means. Optical information recording / reproducing device.