JPS6126942A - Information device - Google Patents

Abstract

PURPOSE:To improve the feedback control performance with high stability by outputting the mean value of the corrected error signals obtained based on the scan data on the preceding information signal in the form of an input variable for feedback control while a code signal area of a recording medium is detected. CONSTITUTION:Both an information signal area N and a code area M for discrimination of the information signal are recorded on a disk 5 which is scanned by a light source 1. A corrected error signal C supplied to a mean value sampling/holding circuit 23 contains a high frequency component. The control signal D is set at ''0'' in the area N. In this case, the mean value Ca of the signal C is sampled by a resistance R1 and a capacitor C1. Then the signal D is changed to ''1'' in the area M, and a switch SW1 is turned off with a switch SW2 switched toward the R1 and the C1. Therefore the value Ca is outputted while the signal D is kept at ''1''. As a result, the signal C of the area N is supplied to a drive circuit 19 even in the area M. Thus the action of an objective lens 4 can be controlled stably.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention focuses light on a recording medium on which an information signal and a code signal for identifying the information signal are recorded through an objective lens, and reflects the light. The present invention relates to an information device configured to control the positioning of an objective lens using a corrected error signal obtained by detecting light, and particularly relates to a feed bank control mechanism of the device.

[Prior Art] FIG. 1 is a simplified configuration diagram showing the main parts of an optical disk device as a conventional example of the above-mentioned information device. In the figure, 1 is a light source made of, for example, a semiconductor laser, 2 is a collimator lens that converts the light from light source 1 into a parallel beam, and 3 is a prism that corrects the spread angle of the light from light source 1, which differs depending on the direction. , 4 is an objective lens for condensing the parallel light flux,
Reference numeral 5 denotes a disk on which a circular guide track 6 is formed in advance and has a recording medium made of a reflective film or the like, and is rotated by a disk motor. 8 drives the objective lens 4 in the radial direction of the guide trunk 6 of the disk 5, and the condensed spot focused by the objective lens 4 is directed to the guide track 6.
This is an objective lens drive device, for example, made up of something like a speaker's voice coil, which maintains the lens at the center of the groove.

9 shifts the phase of the light from light source 1 by x wavelength, and the disc 5
A two-wavelength plate for shifting the reflected light by a total of two wavelengths in a round trip, 10 is a two-wavelength plate that shifts the optical path of the reflected light whose phase is shifted by two wavelengths.
6, a beam splitter 11 is a two-split photodetector consisting of light receiving elements 11a and 11b that receive the reflected light and convert it into an electrical signal. On the other hand, 12 is an arithmetic circuit that extracts the difference between the respective outputs of the light receiving elements 11a and llb of the two-split photodetector 11, 13 is an arithmetic circuit that also extracts the sum, and 14 and 15 are the outputs of the arithmetic circuits 12 and 13, respectively. an amplifier circuit for amplifying signals a and b; 16 is the amplifier circuit 14;
This is a division circuit that divides the output A of the amplifier circuit 15 by the output B of the amplifier circuit 15 and outputs a corrected error signal C (-A/B), and the above-mentioned 12
16 constitute a calculation means 17 for controlling the positioning of the objective lens 4 described above. Further, 18 is a compensation circuit for compensating for the phase delay of the corrected error signal C, 19 is a drive circuit for operating the objective lens drive device 8 based on the output from the compensation circuit 18, and 2o is a drive circuit for modulating the light source 1. It is a drive circuit.

Next, the operation of the conventional example configured as described above will be explained with reference to waveform diagrams for explaining the operation shown in FIGS. 2 and 3.

The light emitted from the light source 1 is turned into a parallel beam by the collimator lens 2, and after being shaped by the prism 3, it passes through the beam splitter 10, and the A wavelength phase is shifted by the A wavelength plate 9.
The light is focused by an objective lens 4 onto a guide track 6 of a disk 5.

At this time, when recording information on the disk 5, a drive circuit 20 directly modulates the light source 1 according to the information signal to be recorded.
As a result, the energy density of the focused spot repeatedly rises above a level that can change the reflectance of the recording medium in the groove of the guide track 6 and falls below it. For example, when recording an information signal as shown in Figure 2 (a), "0" and "1"
”, the emitted light power of the light source 1 is increased to evaporate the recording medium of the guide track 6, and the reflectance of that portion is significantly reduced. ” records the information signal.

On the other hand, in the case of reproduction, if the information signal is maintained above the above level and is recorded in the guide trunk 6, for example as shown in FIG. After the wavelength A is further shifted in phase by the × wavelength plate 9, it is bent by about 90° by the beam splitter 10 and input to the two-split photodetector 11. [However, since the guide track 6 has a convex or concave structure by about 178 wavelengths from its surroundings, the reflected light is diffracted by the side walls of the guide trunk 6, so the positional deviation between the focused spot and the guide trunk 6 causes the reflected light to be anisotropic. evoke sexuality. Therefore, by taking the output difference between each light receiving element 11a and llb of the two-split photodetector 11, an error signal a for tracking control of the objective lens 4 can be obtained. If recording is performed in a direction that reduces the reflectance, then in the case of recording, the information signal b1 as shown in FIG. 2 (b) is (output of the arithmetic circuit 13 at the time of recording), in the case of reproduction, the information signal b2 (reproduction) as shown in FIG. (output of the arithmetic circuit 13) can be obtained respectively.

On the other hand, the output A amplified by the amplifier circuit 14 is divided by the output B, which is also amplified by the amplifier circuit 17, via the divider circuit 16. The output of this dividing circuit 16 becomes a corrected error signal C, which is compensated for its phase etc. by a compensation circuit 18, and inputted to a drive circuit 19 of an objective lens drive device 8, where the spot focused by the objective lens 4 is transferred to a guide track 6. The objective lens 4 is controlled by feed hack so that it is located at the center of the .

The reason why the output of the divider circuit 16 is used as the corrected error signal C as an input variable for feedback control of the objective lens 4 is that the amount of light changes by a factor of 5 to 10 between recording and playback, and the change in light intensity during playback. This is to make it possible to correct fluctuations in the tracking servo loop gain due to changes in the recording medium's transmissivity and changes in the transmittance of the optical system.

However, unlike information signals, code signals are generally recorded on recording media with unevenness, so even if the amount of incident light is the same in the coat signal area and the information signal area, the magnitude of the error signal and the amount of reflected light will be different. different. However, since the '7f4 region of the code signal is smaller than the information signal region, the servo gain is adjusted based on the information signal region, so the conventional feed hack control method described above If the focused spot is located in the area of the code signal, large fluctuations in human power will occur, which is a major cause of disturbances in the servo operation, such as an increase in the amount of overshoot.

An example of this will be described with reference to FIG. 3, in which a code signal is previously recorded on the disk 5 with unevenness having a depth equal to the depth of the groove of the guide track 6. In the figure, M indicates a code signal area, and N indicates an information signal area.

The front side of the disk and the cross section of the disk are shown in Figure 3 (E1), (
Assuming that the information recording state is as shown in E2), (the information signal is recorded by punching a hole in the recording medium of the guide trunk 6), the information signal as the output of the arithmetic circuit I3 The output B of the amplifier circuit 15 is as shown in FIG.
It will look like figure (c). On the other hand, the error signal a as the output of the arithmetic circuit 12 is based on the principle that the signal level Vo of the relatively convex portion of the code signal and the hole portion of the information signal does not cause anisotropy of reflected light due to diffraction. is zero, but in reality an offset occurs as shown in Figure 3 (d),
The output A of the amplifier circuit 14 has a waveform as shown in FIG. 3(E) for the same reason as the waveform in FIG. 3(B). Therefore, the corrected error signal C as the output of the division circuit 16 has a waveform as shown in FIG.
Servo operation is disrupted when moving to .

In order to solve these problems, Ganto Toyama developed a technique prior to the present invention in which, in the code signal region, the corrected error signal obtained in the immediately preceding information signal region is used as an input variable for foot hack control. I suggested that.

An embodiment of the above-mentioned prior art will be described below with reference to FIGS. 4 and 5. Incidentally, the same elements as those in the conventional example are given the same reference numerals and their explanations will be omitted.

2I is a coat signal area detection circuit as code signal area detection means for detecting the code signal area M upon receiving the output of the arithmetic circuit 13 which inputs the signal from the two-split photodetector 11; 22 is a code signal area detection circuit; When the circuit 21 is not detecting the code signal area M, the correction error signal C which is the output of the time division circuit 16 is - While the code signal area detection circuit 21 is detecting the code signal area M, the correction error signal C is the output of the time division circuit 16. The sample value of the corrected error signal C of the information signal area N immediately before is
This is a sample hold circuit that outputs to the compensation circuit 18.

Next, the action will be explained.

The light from the light t1.1 is collected by the objective lens 4 as in the conventional example, while the reflected light from the disk 5 is also collected by the objective lens 4 and guided to the two-split photodetector 11. Light receiving elements 1'la, llb of this two-split photodetector 11
Since the respective outputs of are input to the arithmetic circuits 12 and 13, the same signals a and b as above are obtained (from the arithmetic circuit 13, as shown in FIG. 5(a), and from the arithmetic circuit 12, signals not shown) ) and are amplified by amplifier circuits 14 and 15 to become signals A and B. The signals A and B are processed by the divider circuit 16 to become a corrected error signal C (=A/B) having a waveform as shown in FIG. The sample hold circuit 22 also has a fifth
Since the output is input as a control signal as shown in FIG. When not detecting the information signal area N, outputs the corrected error signal C corresponding to the information signal area N; when detecting the code signal area M, outputs the sample value C1 of the corrected error signal C corresponding to the immediately preceding information signal area N. do. Therefore, the correction error signal C of the information signal area N is always input to the drive circuit 19 regardless of the code signal area M, and even in the code signal area M, the correction error signal C of the information signal area N immediately before is inputted. Sample value C of Nψ correction error signal C
-1 is input, it is possible to avoid sudden fluctuations in the control input for controlling the operation of the objective lens 4 and sudden changes in the loop gain, greatly improving the feedback control performance of the objective lens 4. can be done.

However, in general, the error signal and the corrected error signal are
It usually contains a considerable amount of high frequency components. In particular, in optical disk devices that use laser light as described above, the target to be tracked may change at high speed.
This high frequency component cannot be ignored. Therefore, simply sampling the immediately preceding correction error signal as described above will result in unnecessary amplification of high frequency components.
On the contrary, it has the problem of causing a loss in feedback control performance.

[Summary of the invention]

The present invention provides code signal area detection means for detecting a code signal area of a recording medium, averaging means for averaging a correction error signal, and said averaging means based on a signal from said code signal area detection means. By providing a holding means for supplying the output from the lens as a correction error signal to the objective lens driving device, the problems of the above-mentioned prior art and prior art are solved, and will be explained in detail below using examples.

[Embodiment of the Invention] FIGS. 6 to 8 are simplified configuration diagrams and operation explanatory waveform diagrams showing essential parts of an optical disk device as an embodiment of an information device according to the present invention, and FIGS. The same reference numerals are used for the same or corresponding parts as in the figures, and the explanation thereof will be omitted. In FIG. 6, 23 is an average value sample and hold circuit, and the average value sample and hold circuit 23 is the divider circuit 1.
The averaging circuit 23a serves as an averaging means for averaging the corrected error signal C from 6 and the code signal area detecting circuit 21 serves as a code signal area detecting means. The holding circuit 23b serves as a holding means for switching the output of the correction error signal as a correction error signal and supplying it to the objective lens driving device 8 via the compensation circuit 18 and the drive circuit 19. A circuit diagram of this embodiment of the average value sample and hold circuit 23 is shown in FIG.

The averaging circuit 23a includes a normally closed switch SWI provided at the input end of the corrected error signal C, a normally closed contact side of two contacts directly connected to the switch SWl, a switch SW2 provided at the output end, and the above switch SW2. The hold circuit 23b consists of a resistor R1 and a capacitor CI inserted between the normally open contact of the switch SWI and the switch SWI.
It is configured to be operated by.

Next, the operation of this embodiment will be explained with reference to FIG. It should be noted that the steps up to the stage before the average value sample and hold circuit 23 are the same as those of the prior art, so their explanation will be omitted.

The corrected error signal C input to the average value sample and hold circuit 23 actually has a waveform containing high frequency components as shown in FIG. 8(b). In the information signal region N, the control signal is in the "0" state as shown in FIG. 8 (a), and the switches SWI and SW2 shown in FIG. As shown in FIG. 8(d), the manually corrected error signal C is output as is.

In this state, the manually corrected error signal C
An average value Ca as shown in FIG. 8(C) is sampled by the resistor R1 and the capacitor C1. On the other hand, when moving from the information signal area N to the code signal area M, the control signal becomes "1", so the switch SWI
is turned off, and the switch SW2 is switched to the resistor R1 and capacitor C1 side. Therefore, the corrected error signal C from the divider circuit 16 is cut off, and instead, the average value Cal of the corrected error signal C sampled by the resistor R1 and the capacitor C1 immediately before switching becomes as shown in FIG. 8(d). It is output while the control signal is in the "1" state. Therefore, the drive circuit 19 includes:

- Even in the code signal area M, the corrected error signal C of the information signal area N is always input regardless of the code signal area M, and in the code signal area M, the corrected error signal C of the immediately preceding information signal area N Since the average value Cal will be calculated manually,
Rapid fluctuations in the control input for controlling the operation of the objective lens 4 and rapid changes in the loop gain can be avoided, and the influence of high frequency components included in the correction error signal C can be removed. It is possible to significantly improve and stabilize the feedbank control performance of the system. - Since the high frequency components included in the corrected error signal C are higher than the band including the vicinity of the upper limit of the servo band, it is better to set the cant-off frequency of the averaging circuit 23a narrower than the servo band. .

Furthermore, in the above embodiments, the case where the present invention is applied to trunking servo of an optical disk device has been described, but it goes without saying that it can also be applied to focus servo. Furthermore, any of a light beam, a scanning needle, a magnetic head, etc. may be used for signal modification for recording and reproduction, and the information signal may be anything that can be converted into a binary signal such as a video signal, audio signal, facsimile signal, etc. You can use all of them.

Further, the recording medium is not limited to a disc-shaped one, and may be any recording medium such as a tape-shaped or a drum-shaped one.

〔Effect of the invention〕

As explained above, according to the information device according to the present invention, the code signal area detection means detects the code signal area of the recording medium, the averaging means averages the correction error signal,
and a holding means for supplying the output from the averaging means as a correction error signal to the objective lens driving device based on the signal from the code signal area detecting means.
Since the high frequency components included in the corrected error signal can be removed in the code signal domain, there is an effect that the feed hack control performance can be greatly improved and stabilized.

[Brief explanation of the drawing]

1 to 5 are simplified configuration diagrams and operation explanation waveform diagrams of a conventional example of an optical disk device as an example of an information device, and FIGS. 6 to 8 similarly show an embodiment according to the present invention. They are a simplified configuration diagram and an operation explanatory waveform diagram. 4... Objective lens, 5... Disc, 8... Objective lens drive device, 11... 2-split photodetector, lla,
llb... Light receiving element, 17... Arithmetic means, 21...
- Code signal area detection means, 23... Average value sample hold circuit, 23a... Average value conversion circuit, 23b...
・Hold circuit. Note that the same reference numerals are used for the same or equivalent parts of the circuit. Acting author Masuo Oiwa (and 2 others) Figure 2 C
b) Tenichiichiichiichilight・□−μ −−１（I＼） B 0−−−−−−−−−−−−−−1−
−−=−,,,=−−to C) C0−−−−−−−−
−−−−11−=−====,,−Figure 5 Procedural amendment (voluntary) 2. Title of the invention ゛Information device 3. Person making the amendment Relationship with the case Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Co., Ltd. Representative Hitoshi Katayama 4, Agent address 2-2-3 Nr-5, Marunouchi 2-chome, Chiyoda-ku, Tokyo, amended. Scope of claims and detailed description of the invention. 6. Contents of amendment (1) The scope of claims will be amended as shown in the attached sheet. (2) The phrase ``1 circular center'' on page 2, line 14 and 15 of the specification is corrected to ``concentric''. Above 1, the movable part of the signal exchange device for exchanging signals with the recording medium on which the coat signal for identifying the information signal is recorded,
An information device configured to perform feedback control using a correction error signal based on scan data of a signal recorded on the recording medium, further comprising a coat signal area detection means for detecting a code signal area based on a signal from the signal exchange device. In addition, a holding means is provided for outputting the average value of the correction error signal based on the scan data of the information signal while the code signal region is detected by the detection means as an input variable for feed hack control. Characteristic information device.

Claims (1)

[Claims] an objective lens that focuses and irradiates light onto a recording medium on which a code signal and an information signal are recorded; a photodetector that detects reflected light from the recording medium with a plurality of light receiving elements; A code signal for detecting a code signal area of the recording medium in an information device comprising a calculation means for calculating a signal obtained from a light receiving element and outputting a corrected error signal to an objective lens driving device to control positioning of the objective lens. area detecting means, averaging means for averaging the corrected error signal, and supplying the output from the averaging means as a corrected error signal to the objective lens driving device based on the signal from the code signal area detecting means. An information device comprising: a holding means for holding the information;