JPH0467321A - Servo circuit for optical information recording and/or reproducing device - Google Patents

Abstract

PURPOSE:To always appropriately and stably control an objective lens by selecting an error signal which is the output signal of an error signal detection means and which is not influenced by means of the defect of a servo line when the defect is detected. CONSTITUTION:The error signal detection means 83, a defect detection means 39, a judgement means 84, selection means 87a and 87b, position detection means 90a and 90b and holding means 86a and 86b are provided. When the defect detection means 39 detects the defect, relative dislocation is corrected based on the error signal which is not influenced by the defect and relative dislocation can be corrected by the output of the holding means 86a and 86b. Thus, the dislocation of servo as against internal disturbance owing to the defect and the scar of an optical information recording carrier and servo controlling can always appropriately be executed.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides an optical information recording and/or reproducing device that improves malfunctions caused by defects in an optical information recording carrier and vibrations to the optical recording carrier. Regarding servo circuits.

[Prior Art] Conventionally, as an optical information recording device, a card-shaped device called an optical card, for example, as shown by reference numeral 1 in FIG. 12, has been proposed. Information is recorded on the optical card 1 based on the presence or absence of light reflection, the density of the reflected light, the presence or absence of holes, and is optically reproduced. These pieces of information are, for example, code 2
As shown in , recording or reproduction is performed in units called tracks, and one optical card 1 is configured with a plurality of tracks 2 arranged parallel to each other. For example, in the optical card 1 shown in FIG. 12, ID sections 2a and 2b are arranged at both ends of the track 2, and an ID section 2c is arranged at the center.By recording each track number here, the target track can be searched. is facilitated. Furthermore, data sections 2d and 2e store prerecorded data and recorded data. The present applicant has proposed such an optical card 1 as shown in, for example, Japanese Utility Model Application Publication No. 145669/1983.

A device for recording or reproducing information on the optical card 1 includes:
For example, the configuration is as shown in FIG. 13(A) and FIG. 13(B). The optical card 1 is placed on a frame 5, and is reciprocated by a card motor 6 via rubber rollers 7a and 7b in correspondence with the data section 2d or 2e. Further, an optical pickup 8 for recording or reproducing information on the optical card 1 is arranged opposite to the optical card 1, and is driven by a rake motor 9 via a screw 10 in the theta direction, which is approximately perpendicular to the track. be done.

FIG. 14 shows an example of the configuration of an optical pickup in an optical information recording/reproducing apparatus. In this optical pickup 8,
For example, using LED 13 as a light source, this LED 1
3 is irradiated onto the recording surface of the optical card 1 through a sapphire spherical lens 14 having a refractive index of about 1.8 and spherical aberration, a collimator lens 15, a beam splitter 16, and an objective lens 17. The reflected light is passed through the objective lens 17, the beam splitter 16, and the imaging lens 1.
8 and then received by a photodetector 19.

As shown in FIG. 15, for example, the sapphire spherical lens 14 is brought into contact with the light emitting part 13a of the LED 13 so that the center of its optical axis coincides with the light emitting part 13a, and is fixed to the LED 13 by adhesive. For example, the diameter of the light emitting part 13a of the LED 13 is 35 μm, and the diameter of the sapphire ball lens 14 is 500 μm.
In this case, the radiation angle θ of the light irradiated from the sapphire spherical lens 14 is about 11 degrees, and for example, as shown in FIG. A ring-shaped bright portion 4a is formed.

FIG. 17 shows an example of the track format in the optical card 1 shown in FIG. 12. The track 2 has a guide pattern consisting of a black and white pattern extending in the track direction on the clock/servo line 22 at the center thereof. 2
On both sides of the clock servo line 22, data 24-1 to 24-16 of 8 bits each, 16 bits in total, are recorded in the track width direction.

An example of the photodetector 19 shown in FIG. 14 is shown in FIG. 18. The photodetector 19 receives images of 16 data reading light receiving areas 19-At-19-^16 arranged corresponding to 16-bit data recording positions in the track width direction and the guide pattern 23. Five pairs of clock generation light receiving areas 19 are spaced apart in the track direction so that
-B1-19-810, and four pairs of servo signal detection light-receiving areas 19-C1 to 19-C4, 19-01 arranged to be spaced apart and facing each other in the track width direction of the guide pattern 23.
~19-04. In addition, the code 26
1 shows an image of the light emitting portion 13a of the LED 13 reflected by the optical card 1 and formed on the photodetector 19. FIG.

Here, the optical card 1 and the optical pickup 8 shown in FIG. As shown by the solid line in FIG. 19, the illuminance distribution in the diametrical direction of the image of the light emitting part 13a formed on the inner servo signal detection light receiving areas 19-01, 19-02, 1
The arrangement position of the LED 13 to which the sapphire ball lens 14 is adhesively fixed and the magnification of the optical system are set so that a protruding portion is formed near the outside of 9-03 and 19-04.

With the above-mentioned settings, when the optical card 1 approaches the objective lens 17 more than the focusing position of the objective lens 17, the illuminance distribution on the photodetector 19 is as shown by the broken line in FIG. As shown in FIG. 19-
The amount of incident light begins to decrease at C4. Furthermore, when the optical card 1 moves further away from the objective lens 17 than the in-focus position of the objective lens 17, the illuminance distribution on the photodetector 19 changes as shown by the dashed line in the 19th section. Light receiving areas 19-C1 and 19-C2 for signal detection.

As the amount of light incident on 19-C3 and 19-C4 decreases, the inner light receiving area for servo signal detection 19-01°19
-02, 19-03, and 19-04, the amount of incident light increases.

In the servo circuit of the optical information recording and reproducing device, for example, due to the characteristics of the illuminance distribution on one of the photodetectors described above, the outer servo signal detection light receiving areas 19-C1 and 19-C2 are
, 19-C3, and 19-C4, and the inner servo signal detection light receiving area 19-Dl.

19-02, 19-03, and 19-04, and a focus error signal (FES) is obtained based on the difference between the former and latter output sums, and the servo signal detection light receiving area 19-DI, The output sum of 19-03 and the output sum of servo signal detection light receiving areas 19-C2 and 19-C4 are determined, and a tracking error signal (TES) is obtained based on the difference between the former and latter output sums. There is. In addition, one light receiving area 19-81 forming a pair for clock generation
．． 19-83.19-85, 19-8719-89
and the other light receiving area 19-82°19-84
. -^1~19-16 bit data is read simultaneously from the output of Al6.

Generally, the recording surface of an optical card has abnormal parts due to dirt, defects, scratches, etc., and when recording or reproducing information using the above-mentioned optical information recording/reproducing device, track deviations due to the abnormal parts occur. There is.

The present applicant has proposed, for example, in Japanese Patent Application No. 1-343424, an objective lens servo device that compensates for the above-mentioned track deviation in order to record or reproduce information normally. This objective lens servo device includes a plurality of photodetectors that generate servo signals, and generates two focus error signals (FE1, FE2) and two tracking error signals (TEI, TE2) from the output signals of the photodetectors. and two focus error signals (FE1, FE2
) and two tracking error signals (TE1, TE2)
and a switching means for switching to select one of the
Normally, one focus error signal and tracking error signal are used, when the abnormal part is reached, the other focus error signal and tracking error signal are used, and when the abnormal part is passed, the first selected focus error signal and tracking error signal are used. This is used to perform servo control of the objective lens. For example, if servo control is performed using TEI FEl initially, TE2. Using FE2, after passing through this abnormal part, servo control is performed using TEL and FEl. Also, if servo control is performed using TE2FE2 at the beginning, TEl and FEl are used in the abnormal part.
After passing through this abnormal part, use TE2. FE2
Servo control is performed using

[Problems to be Solved by the Invention] However, in the objective lens servo device described above, even during normal operation when no defects, scratches, etc. are detected, only focus error signals and tracking error signals that are not affected by defects, scratches, etc. are detected. Since the objective lens is controlled by the optical sensor, the amount of light received by the photodetector that generates the error signal decreases, resulting in a decrease in focus and tracking detection sensitivity, and vibrations associated with recording or reproducing information may cause the object to go off track. The problem remained that it was easy to cause

Another problem is that if a defect, scratch, etc. is large, it will affect the amount of light received by all photodetectors, making it difficult to perform servo control by selecting an error signal that is not affected by defects, scratches, etc. There were also points left.

The present invention has been made in view of the above-mentioned points, and is not limited to disturbances such as vibrations, but also defects in optical information recording carriers.
It is an object of the present invention to provide a servo circuit for an objective lens that can always perform proper servo without causing servo failure even in the case of internal disturbances caused by scratches or the like.

[Means for Solving the Problem] A light beam emitted from a light source is irradiated onto the servo line of an optical record carrier having servo lines formed in the track direction, and the optical a servo of an optical information recording and/or reproducing device that detects an error signal for correcting a relative positional deviation between the optical information recording carrier and the optical beam, and corrects the relative positional deviation based on the error signal; The circuit includes error signal detection means for detecting a plurality of error signals based on reflected portions of the reflected light from the servo line at different positions; and the light beam emitted from the light source detects a defect in the servo line. a defect detection means for detecting the irradiation of the servo line; a determination means for determining an error signal which is an output signal of the error signal detection means and is not affected by a defect in the servo line; and when the defect detection means detects a defect. , selection means for selecting an error signal that is an output signal of the error signal detection means and is not affected by defects in the servo line in accordance with the output of the judgment means; and detecting the irradiation position of the light beam emitted from the light source. and a holding means for holding an output signal of the position detecting means when the relative positional deviation is corrected based on an error signal that is not affected by defects in the servo line.

[Operation] With the above-described configuration, when the defect detection means detects a defect, the relative positional deviation is corrected based on an error signal that is not affected by the defect, and then the relative positional deviation is corrected by the output of the holding means. That's what I do.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

Figures 1 to 11 relate to one embodiment of the present invention;
The figure is a schematic diagram of the servo circuit, Figures 2 and 3 are circuit diagrams of the servo circuit, Figure 4 is an explanatory diagram of the optical card, Figure 5 is an explanatory diagram of the optical pickup, and Figures 6 and 7. is an explanatory diagram of the sapphire ball lens, Fig. 8 is an explanatory diagram of the recording format of the optical card, Fig. 9 is an explanatory diagram of the photodetector, Fig. 10 is an explanatory diagram of the amount of incident light on the photodetector, and Fig. 11 is an explanatory diagram of the incident light amount of the photodetector. FIG. 3 is an explanatory diagram of the operation of the servo circuit.

First, an optical information recording carrier used in an optical information recording and/or reproducing device (hereinafter referred to as an optical information recording and reproducing device) will be explained.

As the optical information recording unit, for example, reference numeral 3 in FIG.
A card-shaped device called an optical card as shown in 1 has been proposed. Information is recorded on the optical card 31 based on the presence or absence of light reflection, the density of reflected light, the presence or absence of holes, and is optically reproduced. These pieces of information are, for example, code 3
As shown by 2, recording or reproduction is performed in units called tracks, and one optical card 31 has tracks 3 parallel to each other.
For example, in the optical card 31 shown in FIG.
a, 32b are arranged, and an ID part 32c is arranged in the center, and by recording each track number here, it is possible to easily search for a target track. In addition, the data section 32
Prerecorded data and recorded data are stored in d and 32e.

An example of the track format in the optical card 31 shown in FIG. 4 is shown in FIG. The track 32 has a guide pattern 4 formed of a black and white pattern extending in the track direction on the clock/servo line 42 at the center thereof.
On both sides of the clock servo line 42, data 44-1 to 44-16 of 8 bits each, 16 bits in total, are recorded in the track width direction.

The optical card 31 is operated by an optical information recording/reproducing device.
At least one of data recording and reproduction is performed.

FIG. 1 is a schematic diagram of a circuit related to a servo circuit of the optical information recording/reproducing apparatus.

The optical card 31 is placed on a frame (not shown) and is moved in the track direction by two card motors. Further, an optical pickup 28 is located on the recording surface of the optical card 31, and the optical pickup 28 is movable by a seek motor 30 in the theta direction substantially perpendicular to the track direction of the optical card 31.

An example of the configuration of the optical pickup 28 is shown in FIG.

This light pickup 28 uses, for example, an LED as a light source.
33, and a sapphire spherical lens 34 having a refractive index of about 1.8 and spherical aberration, for example,
Irradiates the recording surface of the optical card 31 through a collimator lens 35, a beam splitter 36 and an objective lens 37,
The reflected light of this irradiated light is received by a photodetector 39 through an objective lens 37, a beam splitter 36, and an imaging lens 38.

As shown in FIG. 6, for example, the sapphire spherical lens 34 is adhesively fixed to the LED 33, with the light emitting portion 33a of the LED 33 in contact with the center of the optical axis thereof. For example, the diameter of the light emitting part 33a of the LED 33 is 3
5 μm, and when the diameter of the sapphire ball lens 34 is 500 μm, the radiation angle θ of the light emitted from the sapphire ball lens 34 is about 11 degrees, and for example, as shown in FIG. 7, the spherical surface of the sapphire ball lens 34 A ring-shaped bright portion 4a with a diameter of 400 μm is formed above due to spherical aberration.

An example of the photodetector 39 shown in FIG. 5 is shown in FIG. The photodetector 39 receives images of the guide pattern 43 and 16 data reading light receiving areas 39-At-39-Ate arranged corresponding to 16-bit data recording positions in the track width direction. Five pairs of clock generation light receiving areas 39-8 are spaced apart from each other in the track direction.
1 to 39-810, and four pairs of servo signal detection light-receiving areas 39-C1 to 39-C4, 39-01 to 3, which are arranged facing each other in the track width direction of the guide pattern 43.
9-04. In addition, the code 46 is
An image of the light emitting portion 33a of the LED 33 reflected by the optical card 31 and formed on the photodetector 39 is shown.

Returning to FIG. 1, the data (including synchronization signals, etc.) recorded on the optical card 31 is input to the demodulation circuit 81 and reproduced, and is also input to the error signal detection circuit 83. There is.

The error signal detection circuit 83 is supplied with the logic signal OUT, which is a delay timer signal, and RESET, which is a reset signal, from the controller 82 that controls each part of the optical information recording and reproducing apparatus.
A focus error signal and a tracking error signal are generated from the data (synchronization signal) input from
It is designed to be outputted to an S/H signal generation circuit 84 that generates a ) signal.

The error signal detection circuit 83 outputs the deviation between the target position of the servo system and the current data reading position as the focus error signal and the tracking error signal. Analog switches 87a, 8 open and close the servo loop via a phase compensation circuit 17 that obtains the necessary characteristics of each system and stabilizes each system.
From the break end of 7b, the analog switch 87a,
a driver 88a connected to the transfer end of 87b;
88b.

The drivers 88a and 88b perform a predetermined power amplification on the focus error signal and the tracking error signal, and supply the amplified power to a focus actuator 90a and a racking actuator 90b.

Further, the outputs from the drivers 88a and 88b are supplied to low-pass filters 89a and 89b having approximately the same transfer function (characteristic) as the focus actuator 90a and the tracking actuator 90b.

The focus actuator 90a moves the objective lens 37 in a direction perpendicular to the optical card 1 by the output of the driver 89a, that is, varies the distance between the objective lens 37 and the optical card 1, and LED
The tracking actuator 90b drives the objective lens 37 so as to accurately focus the light beam from the driver 89 onto the recording surface of the optical card.
The output of b causes the objective lens 37 to be connected to the optical card 1.
16-bit data 44-1 to 44-1 in the track width direction of the optical card 1.
The objective lens 37 is driven so that the data reading light-receiving areas 39-At to 39-Al6 of the photodetector 39 substantially coincide with each other to compensate for track deviation.

Further, the low-pass filters 88a, 88b make the outputs of the drivers 88a, 88b substantially equal to those of the focus actuator 90a, racking actuator 90b, and sample and hold circuits 86a, 86b.
It is designed to output to . Therefore, the sample hold circuit 86a includes the focus actuator 9.
The position where 0a is driven is sampled, and the position where the tracking actuator 90b is driven is sampled into the sample hold circuit 86b. That is, the actual position of the objective lens 37 is sampled into the sample hold circuit 86a86b. It is now possible to do so.

The S/H signal generation circuit 84 detects the focus error signal and the tracking error signal from the error signal detection circuit 83 so that the photodetector 39 detects a signal on the recording surface of the optical card 1, for example, by the symbol shown in FIG. A defective portion indicated by 49 is detected and an S/H signal is output to the analog switches 87a, 87b and the sample and hold circuits 86a, 86b.

As a result, the sample hold circuit 86a.

86b stops sampling of the signals from the low-pass filters 89a and 89b and holds the signals.
and the analog switch 87a.

87b connects the transfer end to the make end. Therefore, the driver 88a.

The driving outputs of the focus actuator 90a and the racking actuator 90b immediately before the defective portion of the optical card 1 are applied to 88b, that is, the objective lens 37 is held at a position immediately before the defective portion of the optical card 1. It looks like this.

The error signal detection circuit 83 and the S/H signal generation circuit 84
For example, as shown in FIGS. 2 and 3, the light receiving area 39-C1 for servo signal detection outside the light receiving element 39,
IV conversion circuits 51-1 to 51-4 that convert the light detected by 39-C2, 39-C3, and 39-C4 into electrical signals, and a light-receiving area 3 for servo signal detection inside the light-receiving element 9.
9-DI, 39-02.

39-D3, r-v conversion circuits 52-1 to 52-4 that convert the light detected by 39-DI into electrical signals, and the input terminal is the output terminal of the I-V conversion circuit 51-1, 51-2. an adder 53-1 connected to the I-V conversion circuit 51-1.512 and adding the output signals of the I-V conversion circuit 51-1.512; , an adder 53-2 that adds the output signals of the TV conversion circuit 51-3.
2-2, and the I-V conversion circuit 52-1
．． An adder 54-1 that adds the output signals of the I-V conversion circuit 52-2, and an adder 54-1 whose input end is connected to the output end of the I-V conversion circuit 52-1.52-3, an adder 54-2 for adding the output signals of the I-3, and an adder 54-2 whose input terminal is
An adder 54-3 connected to the output end of the V conversion circuit 52-3.52-4 and adding the output signals of the I-V conversion circuit 52-3.52-4; Conversion circuit 52
Adder 54- connected to the output terminal of -2.52-4 and adding the output signals of the I-V conversion circuit 52-2.52-4.
4, an adder 55 whose input end is connected to the output end of the adder 53-1.53-2 and which adds the output signal of the adder 53-1.53-2; 54-1゜54-3, and the adder 54-1.54
-3, an adder 56 whose non-inverting input terminal is connected to the output terminal of the adder 55 and whose inverting input terminal is connected to the output terminal of the adder 56;
A differential amplifier 57 differentially amplifies the output signal of the adder 53-1, a non-inverting input terminal is connected to the output terminal of the adder 53-1, an inverting input terminal is connected to the output terminal of the adder 54-1, and the differential amplifier 57 differentially amplifies the output signal of the adder 54-1. A differential amplifier 58 differentially amplifies the output signal of the adder 53-1. A differential amplifier 59 is connected to the output terminal of the adder 54-2 and differentially amplifies the output signal of the adder 53-2 and 54-3, and a non-inverting input terminal is connected to the output terminal of the adder 54-2, The inverting input terminal is connected to the output terminal of the adder 54-4, and the adder 54-2
．． A differential amplifier 60 differentially amplifies the output signal of 54-4, a non-inverting input terminal is connected to the output terminal of the IV conversion circuit 52-1, and an inverting input terminal is connected to the output terminal of the IV conversion circuit 52-1. 2
connected to the output terminal of the I-V conversion circuit 52-1.52
A differential amplifier 61 differentially amplifies the output signal of -2; a differential amplifier 62 which differentially amplifies the output signal of the r-v conversion circuit 52-3, 52-4; The differential amplifier 5
A switch 63-1 for switching whether or not to output the output signal of 7 as a focus error signal (FES) according to a selection signal to be described later, and a switch 63-1 whose input terminal is connected to the output terminal of the differential amplifier 58; A switch 63-2 for switching whether or not to output an output signal as a focus error signal (FES) according to a selection signal to be described later, and an input terminal connected to the output terminal of the differential amplifier 59, A switch 63 - 3 for switching whether or not to output an output signal as a focus error signal (FES) according to a selection signal to be described later, and an input terminal connected to the output terminal of the differential amplifier 60 , the output terminal of the differential amplifier 60 A switch 64-1 which switches whether or not to output a signal as a tracking error signal (TES) according to a selection signal described later, and an input terminal connected to the output terminal of the differential amplifier 61, output signal of the differential amplifier 61. a switch 64-2 for switching whether or not to output the tracking error signal (TES) as a tracking error signal (TES) according to a selection signal to be described later;
is connected to the output terminal of the differential amplifier 62, and the output signal of the differential amplifier 62 is converted into a tracking error signal (TES) by a selection signal to be described later.
A switch 64-3 which switches whether or not to output as
The output of the differential amplifier 57 is connected to a predetermined level V.
a comparator 65-1 for comparing with ul, and a comparator 65-2 having one input terminal connected to the output terminal (FE) of the differential amplifier 57 and comparing the output of the differential amplifier 57 with a predetermined level V11. , one input terminal is connected to the output terminal (■[) of the differential amplifier 60, and the differential amplifier 60
A comparator 6 that compares the output of Vu2 with a predetermined level Vu2.
6-1, a comparator 66-2 whose one input terminal is connected to the output terminal (TE) of the differential amplifier 60, and which compares the output of the differential amplifier 60 with a predetermined level VI2; is connected to the output terminal of the comparator 65-1, 65-2, and the other input terminal is connected to the comparator 66-
166-2, and the comparator 65-
1.65-2 output and the comparator 66-1.66
an OR gate 71 that takes the logical sum of the output signals of -2 and an AND gate 77 that takes the logical product of the logical signals of the TOUT and RESET signals from the controller, and a tarok terminal is connected to the output terminal of the OR gate 71, A reset terminal is connected to eight terminals of the AND gate 77, and the output signal of the OR gate 71 inverts the logic value of the output signal, and the output signal of the AND gate 77 inverts the logic value of the output signal to a predetermined value. A D flip-flop 73 whose starting end is connected to the output end of the OR gate 71, whose reset end is connected to the output end of the AND gate 77, and a predetermined time constant set by a capacitor 74a and a resistor 74b. A one-shot timer 74 inverts the logical value of the output signal for a period of The reset terminal is connected to the output terminal Q, and the reset terminal is connected to the output terminal of the AND gate 77, and the logic value of the output signal is inverted with the output signal of the one-shot timer 74, and the output signal is output with the output signal of the AND gate 77. A D flip-flop 75 that sets the logical value of the signal to a predetermined value, and one input terminal of which is connected to the one-shot timer 74.
An AND gate 79 is connected to the positive logic output terminal Q of , and performs the logical product of the DIR signal from the controller inputted to the other input terminal, and the logical value of the DIR signal inputted from the controller inputted to the input terminal. Inverter 7 to invert
6, one input terminal is connected to the positive logic output terminal Q of the one-shot timer 74, and the other input terminal is connected to the output terminal of the inverter 76, and the output signal of the one-shot timer 74 and the inverter 76 are connected to each other. and an AND gate 78 that performs logical product with the output signal.

The operation of the servo circuit configured in this way will be explained.

The optical card 31 and the optical pickup 28 shown in FIG. As shown by the solid line in FIG. 10, the illuminance distribution in the diametrical direction of the image of the light emitting section 33a formed is shown by the inner servo signal detection light receiving areas 39-01, 39-02, 39.
-03, L to which the sapphire ball lens 34 is adhesively fixed so that a protruding portion is formed near the outside of 39-04.
Set the placement position of the ED 33 and the magnification of the optical system.

With the above-mentioned settings, when the optical card 31 approaches the objective lens 37 more than the focal position of the objective lens 37, the illuminance distribution on the photodetector 39 becomes 10th.
As shown by the broken lines in the figure, the amount of light incident on the outer servo signal detection light receiving areas 39-C1, 39-C2, 39-C5, 39-C4 increases, and the inner servo signal detection light receiving areas 39-DI , 39-02 , 39-03
, 39-04, the amount of incident light begins to decrease. Furthermore, when the optical card 31 moves further away from the objective lens 37 than the focal position of the objective lens 37, the photodetector 3
The illuminance distribution on the outer servo signal detection light receiving areas 39-Cl, 39- as shown by the dashed line in FIG.
As the amount of light incident on C2, 39-C3, and 39-C4 decreases, the inner servo signal detection light receiving area 39-DI
, 39-02, 39-03, and 39-04, the amount of incident light increases.

The outer light receiving areas 39-C1 to 39 for detecting servo signals
-The amount of light detected by C4 is the 1-V conversion circuit 51-
1 to 51-4 and output as voltages VC1 to VC4.
-4, and is photoelectrically converted and output as voltages VD1 to VD4.

The voltages VC1 to VC4 are applied to the adder 53-1.53-
255 and outputted from the adder 55 to the differential amplifier 57 as a voltage VC1+C2÷C3+C4, and the voltages VDI to VD4 are added to the adder 54-1.54.
−3.56, and output from the adder 56 to the differential amplifier 57 as a voltage V D1+02+03+04, and the differential amplifier 57 differentially amplifies the voltage from the adder 55 and the voltage from the adder 56. , that is, adder 55
The voltage (
VC1+C2+C3+C4) -(VD1+02÷03
÷04) and outputs it to a subsequent stage as a signal FE which is a focus error signal using light receiving areas in both longitudinal directions of the optical card 1, and also outputs it to an analog switch 63-1.

Further, the voltages VC1 and VC2 are added by the adder 53-1, and from the adder 53-1 to the differential amplifier 5.
8 as a voltage VCl4C2, and the voltage VD1
．． VO2 is added by the adders 54-1, and the voltage VD1+0 is sent from the adder 54-1 to the differential amplifier 58.
2, and the differential amplifier 58 is outputted as an adder 53-1.
The voltage from the adder 53-1 and the voltage from the adder 54-1 are differentially amplified, that is, the voltage (VCI+C2) - (VD
1+02) and outputs it to the analog switch 63-2 as a signal FE1 which is a focus error signal using one light receiving area in the longitudinal direction of the optical card 1.

Further, the voltages VC3 and VC4 are added by the adder 53-2, and from the adder 53-2 to the differential amplifier 5.
9 as a voltage V C3 + C4, and the voltage VD
3. VO2 is added by the adder 54-3, and the voltage VD3+ is sent from the adder 54-3 to the five differential amplifiers.
04, and the differential amplifier 59 is outputted as an adder 53-
2 and the voltage from the adder 54-3, that is, the voltage from the adder 53-2 and the voltage from the adder 54-3.
The voltage that is the difference between the voltage from (VC30C4) − (V
D31D4) is obtained, and a signal "[2
The signal is output to the analog switch 63-3 as a signal.

The voltage VD1. VO2 is added by the adder 54-2, and outputted from the adder 54-2 to the differential amplifier 60 as a voltage VD1+03, and the voltage VD2°VO2 is added by the adder 54-4, and the adder 54-2 outputs the voltage VD1+03 to the differential amplifier 60. voltage V D2+04 from the amplifier 54-4 to the differential amplifier 60.
The differential amplifier 60 differentially amplifies the voltage from the adder 54-2 and the voltage from the adder 54-4.
That is, the voltage (VD1+D3) (VD2+
D4) and outputs it to the subsequent stage as a signal TE which is the amount of 1 to racking error using the light receiving areas in both longitudinal directions of the optical card 1, and also outputs it to the analog switch 64-1.

Further, the differential amplifier 61 operates to control the voltages MDI, VO2
A differentially amplified voltage V Dl-02 is obtained and the optical card 1 is
The analog switch 64-
Output to 2.

Further, the differential amplifier 62 is connected to the voltage VD3. A voltage VD3-04 is obtained by differentially amplifying VD4, and the analog switch 64-3 is used as a signal TE2 which is a tracking error signal using the other light receiving area in the longitudinal direction of the optical card 1.
Output to.

The analog switches 63-1 to 63-3, 64-1 to
64-3 are selection signals 5ELL and 5EL2.5, which will be described later.
The focus error signal FES is selectively selected by EL3, and the analog switches 63-1 to 63-3 output the focus error signal FES to the subsequent stage, and the analog switches 64-1 to 64-3 output the tracking error signal TES to the latter stage. Ru.

Next, analog switches 63-1 to 6B-3, 64 = 1
~64-3 selection signals 5EL1 to 5EL3 are generated by the third
This will be explained using figures.

The signal FE is input to the window comparator composed of the comparators 65-1 and 65-2, and the absolute value of the signal FE is compared, and when this absolute value exceeds a predetermined level Vul, Vll, or , the signal TE is input to a window comparator composed of the comparators 66-1, 66-2, the absolute value of the signal "F" is compared, and this absolute value is set to a predetermined level Vu2.VI.
2 is detected by the OR gate 71, and a logic signal "H" is input to the clock terminal (CK) of the D flip-flop 73 as a defect signal. This results in
The logic signal at the negative logic output terminal Q of the D flip-flop 73 changes from "H" to "L", that is, the selection signal 5E
The logic value of L1 changes from "H" to "L" to turn the analog switch 63-1.64-1 from the ON state to the OFF state.

The output of the OR gate 7 is input to the starting terminal of the one-shot timer 74, and the one-shot timer 74 changes the logic signal at the positive logic output terminal Q from "L" to "H".
, and the logic signal at the negative logic output terminal Q changes from "'H" to L.
The logic signal at the positive logic output terminal Q of the one-shot timer 74 is input to one input terminal of the AND gate 78 and one input terminal of the seven AND gates.

A DIR signal indicating the drive direction of the optical card 1 is input to the controller 82 to the other input terminal of the AND gate 79, and a logic signal is input by the inverter 76 to the other input terminal of the AND gate 78. The inverted DIR signal is input. The DIR signal has a logic signal of "H" when the optical card 1 is driven in the forward direction, and a logic signal of "L" when the drive direction of the optical card 1 is in the reverse direction.

Therefore, when the driving direction of the optical card 1 is the forward direction, the logic signal of the selection signal 5EL3, which is the output signal of the seven AND gates, becomes "H", and the analog switch 63-3, 64-3 is activated. Change from OFF state to ON state. Further, when the optical card 1 is driven in the opposite direction, the logic signal of the AND gate 78 becomes 'H', and the analog switch 63-3, 64-3 is turned off.
From the state to the ON state.

Furthermore, the negative logic output terminal Q of the one-shot timer 74
The output signal is input to the clock terminal of the D flip-flop 75, and the D flip-flop 75 changes the logic signal at the positive logic output terminal Q from "L" to "H". Said D
The logic signal at the positive logic output terminal Q of the flip-flop 75 is S
/H signal as the sample and hold circuit 86 shown in FIG.
a, 86b and analog switches 87a, 87b, and when the S/H signal is H'', the sample and hold circuits 86a, 86b hold (retain), and the analog switches 87a, 87b output to the driver 88a,
88b and the sample and hold circuits 86a and 86b are connected.

After that, the defect is detected in the servo signal detection light receiving area 39-C1~
39-C4, 39-01 to 39-04, the controller 82 outputs a TOIIT signal indicating the completion of passage, and the TOU
The T signal is passed through the AND gate 77 to the D flip-flop 73, 75 and the one-shot timer 74.
Reset. This causes the selection signals 5EL1 to
In 5EL3, only 5EL1 becomes the logic signal "H", the analog switch 63-1.64-1 changes from the OFF state to the ON state, and the analog switch 63-2.6
3-3°64-2.64-3 is in the OFF state.

The timing of the operation when the optical card 1 is driven in the forward direction and there is a defect indicated by reference numeral 49 in FIG. 8 on the guide pattern 42 will be described with reference to FIG. 11. It is assumed that the optical card 1 is being driven in the forward direction.

In normal operation before the defect 49 is detected, the output of the D flip-flop 73.75 is not set, the selection signal 5ELL is at a logical value "H", and the analog switch 63-1.64- 1 is turned on, and the objective lens 37 is controlled by the tracking error signal TE and the focus error signal F[.

The defect 49 is the light receiving area 39-Cl for servo signal detection.
, 39-C2, the tracking error signal TE or the focus error signal TE is swayed by the change in the amount of received light (only FE is shown), and when it exceeds a predetermined level, for example Vul, the signal is output from the OR gate 71. A defect detection signal is output. The output of the D flip-flop 73 is set by the rising edge of this defect detection signal, and the selection signal 5EL1 changes from the logic value "H" to the logic value "L". At the same time, at the rising edge of the defect detection signal, the logic signal at the positive logic output terminal Q of the one-shot timer 74 becomes a logic value "H" for a predetermined period set by the capacitor 74a and the resistor 47b, and the objective lens 37 detects the defect. Unaffected tracking error signal T
E2 and focus error signal FE2. Therefore, the focus actuator 90a and the tracking actuator 9 are driven by noise caused by defects.
0b is settled during a predetermined period, and positioning to the target position is possible.

The D flip-flop 75 is set after a predetermined period of time, which is the rising edge of the logic signal at the negative logic output terminal Q of the one-shot timer 74, is set, and the S/H signal, which is the output signal of the D flip-flop 75, is Sample and hold circuit 86a.

86b is held (retained), and the analog switches 87a and 87b are controlled to connect the drivers 88a and 88b and the sample and hold circuits 86a and 86b.

That is, the servo system in which the defect has been detected is servo-controlled for a predetermined period using a tracking error signal and a focus error signal that are not affected by the defect, and then the error signal detection circuit 83
The output of the low-pass filters 89a and 89b during the servo control for the predetermined period described above is applied to the focus actuator 90a and racking actuator 90b, so that the objective lens 37 is held.

When the time sufficient for the photodetector 39 to pass through the defect 49 has elapsed, the controller 82 outputs a TOOT signal indicating the end of the defect, and this 011T signal causes the output of the D flip-flop 73.75 to become It is reset, and the selection signal 5ELI changes from the logical value “L” to “H” again.
, only the analog switches 63-1 and 64-1 are turned on, and the objective lens 37 is controlled by the tracking error signal TE and the focus error signal FE.

Even when the optical card 1 is driven in the opposite direction, the effect is similar to that described above, but since the position at which the defect 49 is detected in the light receiving area for servo signal detection of the photodetector 39 is different, the selection signal 5EL2SEL3 is The output signal to is switched by the DIR signal indicating the driving direction.

Note that the broken lines and symbols in brackets in FIG. 11 indicate the case where the optical card 1 is driven in the opposite direction.

That is, during normal operation when no defects are detected, all the servo signal detection light receiving areas 39-C1 to 39-C4 and 39
The focus error signal "E" and the tracking error signal "T" are detected based on the amount of light incident on -D1 to 39-C4, and the objective lens 37 is controlled based on the focus error signal FE and the tracking error signal "T", and the focus error signal "E" is detected. When a defect is detected due to a change in the level of the signal "E" or the tracking error signal "T", the servo signal detection light receiving area 39-CI, 39 is not affected by the defect.
-C2,39-[)139-02 or 39-C3,3
9-C4, 39-C3 The focus error signal F[1 and the tracking error signal TE1 are determined by the amount of light incident on 39-C4.
, or, after controlling the objective lens 37 based on the focus error signal FE2 and the tracking error signal TE2, the focus error signal FE1 and the tracking error signal TE1+ or the focus error signal FE2 and the tracking are controlled for a predetermined period during which the objective lens 37 passes through the defect. Since the objective lens 37 is controlled based on the signal that holds the error signal TE2, there is no possibility that the servo will come off due to defects.
This has the advantage that the objective lens can always be controlled appropriately.

Note that the drive signals for the focus actuator and the 1-racking actuator may be held and controlled using independent S/H signals.

Further, the present invention can be applied even when sample-holding either one of the drive signals of the focus actuator and the tracking actuator.

[Effects of the Invention] As explained above, according to the present invention, during normal operation when defects, scratches, etc. are not detected, the signal S/ If a defect, scratch, etc. is detected, the servo signal can be secured after securing the servo signal using a servo signal receiving area that is not affected by the defect, scratch, etc. By using the servo signal until the defect, scratch, etc. passes, the servo will not come off even if there is a large defect, scratch, etc. on the servo line, and it is possible to always perform proper and stable objective lens control. There is an effect.

[Brief explanation of the drawing]

Figures 1 to 11 relate to one embodiment of the present invention;
2 and 3 are circuit diagrams of the servo circuit, 4 is an explanatory diagram of the optical card, 5 is an explanatory diagram of the optical pickup, and 6 and 7 are schematic diagrams of the servo circuit. is an explanatory diagram of the sapphire ball lens, Fig. 8 is an explanatory diagram of the recording format of the optical card, Fig. 9 is an explanatory diagram of the photodetector, Fig. 10 is an explanatory diagram of the amount of incident light on the photodetector, and Fig. 11 is an explanatory diagram of the incident light amount of the photodetector. The operation explanatory diagrams of the servo circuit, FIGS. 12 to 19, relate to the conventional technology.
FIG. 2 is an explanatory diagram of an optical card, FIGS. 13 (A) and (B) are explanatory diagrams of an optical information recording and/or reproducing device, and FIG.
The figure is an explanatory diagram of the optical pickup, FIGS. 15 and 16 are explanatory diagrams of the sapphire ball lens, FIG. 17 is an explanatory diagram of the recording format of the optical card, and 82nd... Controller 83.
...Error detection circuit 86 a. 86b...Sample hold circuit Figure 4 Figure 10 Cry! Figure 6 Figure 5 Figure 7 Figure 8 Figure 11 (5) Figure 13 (5) Figure 12 Figure 19 Figure 14 Figure 15 Figure 16

Claims (1)

[Scope of Claims] A light beam emitted from a light source is irradiated onto the servo line of an optical record carrier having servo lines formed in the track direction, and the optical information is recorded based on the reflected light from the servo line. A servo circuit of an optical information recording and/or reproducing device that detects an error signal for correcting a relative positional deviation between a carrier and the light beam, and corrects the relative positional deviation based on this error signal, error signal detection means for detecting a plurality of error signals based on portions of the reflected light from different positions of the reflected light from the servo line; and the light beam emitted from the light source illuminates defects in the servo line. a determination means for determining an error signal which is an output signal of the error signal detection means and is not affected by a defect in the servo line; and when the defect detection means detects a defect, the determination means selection means for selecting an error signal which is an output signal of the error signal detection means and is not affected by defects in the servo line according to the output of the means; and a position detection means for detecting the irradiation position of the light beam emitted from the light source. and holding means for holding an output signal of the position detection means when the relative positional deviation is corrected based on an error signal that is not affected by defects in the servo line, A servo circuit for an optical information recording and/or reproducing device, wherein the relative positional deviation is corrected.