JPH0758549B2 - Optical information recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention records information on an optical information recording medium, reproduces information recorded on the medium, and / or information recorded on the medium. The present invention relates to an optical information recording / reproducing apparatus capable of erasing data, and more particularly to autofocus and autotracking during recording.

[Prior Art] Conventionally, various types of media such as a disc, a card, and a tape are known as forms of a medium for recording information using light 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 small recording capacity, a light weight, and a large recording capacity that is convenient to carry.

FIG. 3 is a schematic plan view of such an optical card 101.
02 is an information recording area, 103 is an information track, 104 and 104 'are track selection areas, and 105 is a home position of a 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"). Also, in order to irradiate the light beam as a minute spot of a stable size despite the bending and mechanical error of the optical card, control is performed in the direction perpendicular to the optical card surface (autofocusing, hereinafter referred to as "AF"). There is a need. Also, the above-mentioned AT and AF are required even during reproduction.

FIG. 4 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. Based on a tracking signal and a focusing signal detected by the photoelectric conversion elements 115 and 116, an electric current is applied to the tracking coil 111 and the focusing coil 112 in accordance with commands from the control circuits 117 and 118, respectively, to move the objective lens 110 to perform AT and AF. . Reference numeral 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 also output from the controller 119, they are shown here. Absent. 12
Reference numeral 1 denotes an optical head, and 122 is a drive motor for moving the optical head in the u direction in FIG.

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, 116 are tracking control circuits 117, respectively.
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, thereby performing AT and AF.

FIG. 5 is a detailed diagram of the tracking control circuit 117.

In the figure, 202 is an amplifier for increasing the tracking error signal A from the photoelectric conversion element 115, 203 is a phase compensation circuit for stabilizing the tracking servo, and 204 is a driver for supplying a current to the tracking coil 111. 205
Is a microprocessor and system controller 11
Upon receiving the signal group 120 from 9, the tracking control circuit 117
It controls the whole.

[Problems to be Solved by the Invention] In the information recording / reproducing apparatus as described above, the optical card 101
When the motor is reciprocated by the motor 106, vibration is generally generated in each of the AT direction and the AF direction. this is,
Regarding the AT direction, it causes the positional deviation of the light beam spot with respect to the information track based on the causes such as the parallel deviation (skew) of the information track with respect to the outer shape of the optical card and the rattling of the optical card feeding mechanism. Further, regarding the AF direction, it causes the out-of-focus of the light beam spot with respect to the recording surface of the optical card due to the warp of the optical card and the play of the optical card feeding mechanism.

Such vibration has a large value when the moving speed of the optical card 101 is high or when the moving direction of the optical card 101 is reversed. This is shown in FIG. 6 by taking the AT direction as an example.

In FIG. 6, the horizontal axis shows the frequency [Hz], and the vertical axis shows the vibration amplitude and open loop gain. In the figure a
Is the amplitude of vibration at low speed or non-inversion, and b is the amplitude of vibration at high speed or inversion. In order to keep the tracking deviation within 0.1 μm against such vibrations, the open loop gain of the tracking servo should be set.
Must be set as Gb (solid line). But,
Since the open loop gain in the high frequency band is unnecessarily high especially when the vibration amplitude is a, that is, at low speed or non-inversion, the AT is sensitive to minute defects and dust attached to the optical card surface. The servo system operates and stable tracking operation cannot be obtained, and as a result, accurate recording / reproduction becomes impossible.

[Means for Solving Problems] An object of the present invention is to provide an optical information recording / reproducing apparatus capable of realizing stable tracking and / or focusing servo operation in view of the problems of the above-mentioned conventional techniques. Especially.

An object of the present invention is to provide a tracking servo loop and a focusing servo loop for tracking control and focusing control of a light spot with respect to an information track of a card-shaped optical information recording medium, and the recording medium and the light spot relative to each other. An optical information recording / reproducing apparatus that includes a moving unit that reciprocates, and that records and / or reproduces information on the recording medium with the light spot while relatively moving the recording medium and the light spot with the moving unit. In the reversing of the reciprocating movement, gain adjusting means for increasing the gain of the tracking servo loop or the focusing servo loop as compared with other times.
This is achieved by an optical information recording / reproducing apparatus, characterized in that the optical information recording / reproducing apparatus is provided with an adjusting means for adjusting the frequency characteristic of the phase compensation of the tracking servo loop or the focusing servo loop and the offset voltage according to the change of the gain.

[Operation] In the optical information recording / reproducing apparatus of the present invention, the gain of the servo loop is increased only when reversing the relative reciprocal movement of the recording medium and the light spot compared to other times, and when the gain of the servo loop is varied, the servo Since the loop becomes unstable, the frequency characteristic of the servo loop phase compensation and the offset voltage are adjusted at the same time according to the change of the gain, thereby realizing stable tracking or focusing servo even at the time of inversion.

[Examples] Hereinafter, the optical information recording / reproducing apparatus of the present invention will be described in detail based on specific examples.

FIG. 1 is a schematic circuit diagram showing a tracking control circuit of an optical information recording / reproducing apparatus embodying the present invention.

In the figure, the same members as those in FIG. 5 are denoted by the same reference numerals, and 301 is an adder / subtractor circuit for giving the analog signal B output from the microprocessor 305 as an offset in the tracking servo loop, 302 Is an amplifier that changes the DC amplification degree by the digital signal C from the microprocessor 305, 306 is a phase compensation circuit that can change the frequency characteristic of phase compensation by the digital signal D from the microprocessor 305, and 319 is a tracking A system controller 320 for controlling the entire control circuit 117 is a group of signals sent from the controller to the microprocessor 305.

FIG. 2 is a diagram showing the open loop gain and vibration amplitude of the tracking servo shown in FIG. 1, and corresponds to FIG. 5 described above. In the present embodiment, the open loop gain is Gb when the optical card is moving at high speed during information reproduction or when the optical card is inverted. next,
When the optical card is moving slowly at the time of recording information or when the optical card is in the non-inversion state, the amplification degree of the variable gain amplifier 302 is lowered by the signal C to lower the DC gain of the servo loop. .

At the same time, the frequency characteristic of the phase compensation circuit 306 is changed by the signal D. Specifically, when the servo gain is Gb, the frequency that becomes OdB is f0 ′, so at this frequency, the phase advance angle becomes the largest, and fL ′ to f
Although the phase is advanced with respect to H ', when Ga, the frequency at which OdB becomes low becomes f0. Therefore, the phase advancing frequency is also set so that the phase advancing angle becomes the largest at this frequency.
The range is fL to fH. As a result, a sufficient phase margin can be obtained even at f0.

At the same time, the analog signal B is changed to change the offset given to the servo loop. The reason for this is that the tracking error signal A does not become 0 because the gain of the servo loop is finite. Therefore, the tracking error signal A is set to 0 by giving an offset to the servo loop. Therefore, when the gain of the servo loop is changed, the amount of offset to be given is also changed to set the tracking error signal A to zero.

The optimum value of the voltage of the analog signal B is, for example, when the optical card is stationary and the vibration is small, the gain of the servo loop is changed to Ga and Gb, and the tracking error signal A becomes 0 respectively. You just need to find a voltage that

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

For example, although the above embodiments have been described with respect to the tracking servo, the same applies to the focusing servo.

Further, due to the nature of the invention, the present invention can be applied not only to a device using a write-once recording medium but also to a rewritable device such as magneto-optical recording.

[Effects of the Invention] As described above, the present invention increases the gain of the tracking servo loop or the focusing servo loop at the time of reversing the reciprocating movement as compared with the other times, and according to the gain change, By adjusting the frequency characteristic of the phase compensation and the offset voltage, it is possible to realize stable tracking or focusing servo even when reversing the reciprocating movement.

[Brief description of drawings]

FIG. 1 is a block diagram of a tracking control circuit embodying the optical information recording / reproducing apparatus of the present invention. FIG. 2 is a diagram showing the relationship between the open loop gain and the vibration amplitude with respect to the frequency of the tracking servo of FIG. FIG. 3 is a schematic plan view of the optical card. FIG. 4 is a block diagram of an optical information recording / reproducing apparatus. FIG. 5 is a block diagram of a conventional tracking control circuit. FIG. 6 is a diagram showing the relationship between the open loop gain and the vibration amplitude with respect to the frequency of the tracking servo of FIG. 115: photoelectric conversion element, 301: addition / subtraction circuit, 302: variable gain amplifier, 306: phase compensation circuit, 204: driver, 305: microprocessor, 319: system controller, 320: signal group,
111: tracking coil, 117: tracking control circuit,
101: optical card, 102: information recording area, 103: information track, 104, 104 ′: track selection area, 105: home position of light beam spot, 106: motor, 107: light source such as semiconductor laser, 108: collimator lens, 109 : Beam splitter, 110: Objective lens, 112: Focusing coil, 113 and 114: Condensing lens, 116: Photoelectric conversion element, 118:
Focusing control circuit, 121: optical head, 122: drive motor for moving in u direction.

Claims (1)

[Claims] 1. A tracking servo loop and a focusing servo loop for tracking control and focusing control of a light spot with respect to an information track of a card-shaped optical information recording medium, and the recording medium and the light spot relatively reciprocate. An optical information recording / reproducing apparatus, comprising: a moving unit for moving the recording medium and the recording medium and the recording medium and reproducing the information on the recording medium by the optical spot while reciprocally moving the recording medium and the optical spot by the moving unit. Gain adjustment means for increasing the gain of the tracking servo loop or the focusing servo loop when the reciprocating movement is reversed, and the frequency of the phase compensation of the tracking servo loop or the focusing servo loop according to the change of the gain. Characteristics and offset voltage An optical information recording / reproducing apparatus comprising: an adjusting unit for adjusting the optical information recording / reproducing apparatus.