JPS59171088A - Tracking servo device - Google Patents

Abstract

PURPOSE:To always compensate the variation of tracking error detecting sensitivity by controlling a tracking servo-loop by an average signal, etc. of a detecting signal by an information detecting point to a recording track. CONSTITUTION:Upper and lower envelopes of an average value of a detecting signal of an information detecting point to a recording track passing through an information detecting circuit 11 are detected by an upper and lower envelope detecting circuit. These average signals are synthesized by a synthesizing circuit 14, and the gain of a voltage control amplifier 4 for amplifying a tracking error signal is controlled through a controlling circuit 9. Also, even if the sensitivity is different in the inside and outside circumferential tracks, and depth of a track groove is uneven, etc., a variation of the tracking detecting sensitivity is always compensated, and the gain of a servo-loop is set to the optimum. In this regard, even in case when a level signal is used without using an average signal, the same result is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a racking servo device used in a recorded information reading device.

An example of the Tracking 1 Novo device is shown in block C43 in FIG. One error signal light device is installed to generate a corresponding tracking-11 signal. this"
- The error signal is manually inputted to the -(VCA (voltage controlled nononbu)) 4 via the L Fi)to (1" - bass filter) 2 and tEQ<Equal Reilly") 3. (The output of the second amplifier is for opening and closing the servo loop. The signal is supplied to the trunking actuator 6 via the input signal y5, and the recording information detection point (not shown) is biased in the IJ direction perpendicular to the recording track to perform racking servo.

-j), 1 he-shih\-ng-1-ra-jin-go 1.1, through switch 7 detects the level of 1-no (1-no2 has been
Error level (4i> U 1 This level is set to generate 8) This level (ie UVCA4 based on '5) (5 is generated by controller J'f- from controller 9) (The lower 1 gain of Revolube is 1 nt [
1-rule is possible. In addition, A of switches 5 and 7
'', /A) A small circuit 10 is installed for control of the IJ4 configuration (1'
2, when the revolve switch 5 is set to A) and the loop state C (not shown) is rotated 94 times, due to the eccentricity of the rack, the information detection point is ~Since it crosses the rack diagonally, the 1-racking]nilar signal changes iI sinusoidally (2).When the switch 7 is turned on at 5 o'clock, −The error signal level is detected by detector ε3−
(, this error signal is bell', ::-ii6 (ji'c
Set a gain of 4 to vc (Nolly-Poruso gain adjustment is done, so δ9).

It is scientifically important to do this (from J.
'1 quality (in the case of optical type) 'lV) Recording 1 level σ)
It is possible to obtain a constant apparent F loop gain by preventing the shape, etc. (tracking based on this) of error detection sensitivity.

In such a device, since it is necessary to set 1 for 1 at the same time as the setting of 1 for the rev gain, automatic adjustment of the volvo gain (so-called It is impossible to control A G C control) by 4rJ-C. However, since the same disk (acc4j) has a 5mm difference in C1~shigging L error detection on the inner and outer circumferences, the device C in Fig. - The object of the present invention is to improve the optical properties of the recording disk, for example, the recording l.
1~RatsuA-ng soil- due to changes in rack shape
By compensating for the change in detection sensitivity and performing the C-maximum distribution system m5j,', it is possible to improve the Toshi-A-ngurivo device (to premature death (゛A◇01-racking according to the present invention). The search device includes means for generating an average signal corresponding to the daytime average value detected by the information detection point, and a means for generating a high frequency signal corresponding to the daytime average value detected by the information detection point.
The means for generating the level signals is controlled by controlling the gain of the revolving loop by controlling one of the average signals Y and /\\ at least one of the signals. I am sorry that I did this in F1.

The present invention will be explained below with reference to the drawings.

FIG. 2 is a block diagram of an embodiment of the present invention, and parts equivalent to those in FIG. The upper envelope detection circuit 12 and the lower envelope detection circuit 13 are manually operated.

Both detection outputs are supplied to the synthesis circuit 14 and subjected to predetermined processing (C) and applied to the controller to become a gain control voltage of V'CΔ4. A/A is controlled by the switch control section.

Fig. 3 and Fig. 4 are the same as Fig. 2 (Noru 1 ~ Ratsuking King Ra 1) Specific examples of the signal light detector 1 and the information detection point 11 are shown in small 4 figures, and Fig. 3 is 2/1' An example of the so-called pushcobble method is shown in which 33 light beams 16.-'18 and 3 photoelectrons Conversion element 19-21
Here is an example of the so-called 33-Ji-Roku method of obtaining C soil and Shinyumi using .

The push-cobble method C' shown in FIG. J
'Cd5, where the direction of the track length j and the light-receiving surface dividing line of the light-receiving element 1 () satisfy 'lj<'i,
The 01 dividing line that is placed in the relationship
The respective outputs iJ△ of the cut light-receiving surfaces 15a and 15b are amplified by the amplifiers 24 and 25, and then
[Heto] J is done. The output (IJ) of this differential 7/mbu 2G
1-Knocking error No. 114. 3. Both light-receiving surfaces 15a.

Each output of 151) is amplified by C Kawaguchi and recorded information is detected (,'i (C) and 'cj:ru,').

In the 3-beam h type shown in FIG. The respective centers are located in a positional relationship such that they are on both sides of the square 22.The light-receiving elements f19 and 21 are installed to receive the reflected lights of the three beams 16'' and 18, respectively. (''
The output of each of these elements is head amplifier 28=
It is amplified by people's power to 30. Amplifier 2ε3,29
The amplified outputs (e) and (f) of are subjected to the differential processing 31 and subjected to the amplification processing to generate the tracking l-Shiha'r9 (j
l) There is C. The output of the head amplifier 30 is a gL recording information detection signal, which is the same as the output (C) of the j' rung 7 in FIG.

Fig. 5 shows the dynamic fl waveforms of the blocks in Figs. 2 to 4, and Figs.
~(g) shows the waveform of b. In the fifth figure, C is the waveform of each part when the servo loop switch 5 is between the ono C and C loops, and the -C and at axes are between 114 (
It is synonymous with a relative good device between the information detection point (18, 23) and 1 to rack, and each Ih point (t, , to, t)
, 1 The center of the spot light (18, 23>, which is the information detection point, is located on the center line of each track.) ) ,Mountain>
The phase difference δ between recording 1 and the pitch 1 forming the rack is
Based on the fact that the bit depth of the column is λ/'4, where λ is the information detection spot I ~ the wavelength of the light), based on the principle of diffraction 1,
At the phase difference, driri, pitch 1 close to λ/4 - δ is small and 4 at depth, pitch 1 close to /l/8 - depth 1
, 7, )-C1 diagram (A> is the case where the depth is close to λ (yes), and (B) is the case where the depth is J close to λ/4.

In accordance with Figure (C), the recorded information detection signal is the sum of trust in Figure (a) (Dokuwa) (corresponding to the number C), 11 is completely abolished in the mirror surface area between Record 1 and the rack. tjfi3 (Rinawara 1 < 1-Signal 8's upper ■below), and 12 accept the j-guto signal's 1st side soil belobe. Follow -(,
These 11 levels are the record ice cream's counter-eyes and mold mouths.
Lease is proportional to the light hanging. In addition, L12 changes with the phase difference δ, and in the range of ε30°, 0 < δ.
Therefore, I2 and δ have a substantially proportional relationship.

Figure 1 shows the output of 2 and the tracking signal (kl in Figure 2) in the push-pull system shown in (1).
J) is shown in <d), mountain), and the low frequency component C of i<- of ji4 wing is "Ru. That unity, Pushi 1
The sol method (, - the detection feeling is the distance from the recorded information detection point 11: I1: the -1 side of the moon, the human size of IJ-bu if (i! [: recording track It is proportional to the total amount of reflected light, and the small side envelop 1 of the detection
．． ]]' I-P I's size is proportional to the size of the person.

1~Ring-1-Ring Dou-i71 by 33-bi-18 method
(II in Figure 2) The output of F2) is the low-frequency component of the difference between (C and (f) i. As shown, there is a predetermined phase difference between the two signal waveforms. The IJ phase difference is 180
5. If this phase difference remains unchanged for a predetermined 1ift, the detection sensitivity of the 3-bi-18 method will be as high as 11 and as low as I2.

Here, 11 and 12 are 1-1-p level to each of the + side and G side of the detection output of By detecting these two waves, the ΔGC of the servo loop can be determined as follows.

If we organize the facts mentioned in the story, it will look like the following table.

(Table) 4 However, in the push-pull method, the error detection sensitivity of
-Depending on the shape of the recipe 1~

Then, the C1 upper side energy level 11 is proportional to the anti-Q・J rate, and is (1+ + 2) / I + 1.
; is found to be approximately inversely proportional to the phase difference δ. ”, ta, second
The gain G of VCΔ4 shown in the figure needs to be set high when the detection sensitivity is low (IK < L, and conversely when the detection sensitivity is low ()), so the gain G of VCΔ4 is =K (1/I+) ((1+-12>/11)...
...(1) In the 3-beam h formula, G=K (1/It) (1+/(It-1,
? ) )−=に/ (II −12＞・・・・・・(
2) and 4, it is possible to always obtain constant detection sensitivity with rMO.
It becomes L.

Here, the first factor is the proportionality constant, which can be found analytically, but more practically, it is better to find it experimentally.

In order to reduce the gain G by 1q as shown in equation (1) or (2), the signal does not indicate 11 and I2 and is detected by the detection circuits 12 and 13.
, and Ryokawa's J3 is synthesized as desired in the synthesizing circuit 14, and the control signal 9 is input to the input signal 4f. Koushi-(
' The gain G of V CA 4 is given by the equation (1) or (2).

For example, the upper and lower Envelope [-1-1 detectors 12.13 are used to detect Since there is a value C which is proportional to the amount of total ablation light, the average level of this amount of foul light may be detected.

Maiko, IZ side "Ninbe I], 1-zo level 12 is [
Since it is proportional to the level of [1 IhaYshi's King L]-level, it is sufficient to use () to detect this RF level. For example, the average light amount is (Il+12)/
2, and the amplitude of the RF signal is (It-12>), and the gain G shown in equations (1) and (2) can be easily obtained by combining both methods.

In addition, although the embodiment described in -1- (-4) detects both envelopes and synthesizes them to obtain one gain G, it is not always necessary to use the rain detection output; Even if one is treated as a constant and the other is treated as a variable, better results can be obtained than in the past.

Furthermore, although the 3-beam system and the Push-1-sol h system are used as signal generating means, various other types of signal generation means are also used.

As described above, according to the present invention, J multiplied by 800 based on the detection signal from the information detection point, C゛, 1 of the sea urchin
~Racking'' No small loop remains closed. 1 - Racking operation is possible with the optimum loop gain for the user 4. 5.
This is especially effective when there is a change in the bit depth at the outer periphery of the recording disk.

[Brief explanation of drawings]

Figure 1 shows 1179 of a conventional 1-4-ring Gribo device.
2 is a block diagram of an embodiment of the present invention, and FIGS. 3 and 4 show specific examples of some of the blocks in FIG. 2, respectively.
FIG. 5 is an operational waveform diagram of each part of the engine shown in FIGS. 2 to 1. Explanation of main part numbers 4...V CΔ 12...-L side envelope []-B detector 13...
. . . lower envelope detector 18, . 23...
... Information detection point 22 ... Recording track applicant Patent attorney Motohiko Fujimura (9 tofu 3M (d) Act 4, X,) Fall: J (B.

Claims (1)

[Scope of Claims] (1) The information detection point is biased in accordance with the error signal to generate a tracking error signal corresponding to the deviation of the information detection heat in the direction perpendicular to the track for recording 1 to rack. 1-Racking Revo device, comprising:
comprising at least one of means for generating an average signal corresponding to the average value of the detection signal from the information detection point, and means for generating a level signal corresponding to the level of the high frequency signal from the information detection point; A tracking servo device, characterized in that the loop gain of the tracking 4-no-pole is controlled by at least -h of the level signal. 2) The racking servo device according to claim 1, wherein the average signal is a bellows signal or an average DC signal of the detection signal from the information detection point. (3) The level signal is a lower envelope signal of the detection signal from the information detection point or an envelope 1-1-1 signal of the high frequency signal, according to claim 1. No. 1 ~ Rucking servo device.