JPH0241823B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information reproducing apparatus having a high-speed reproduction function.

As a reproducing apparatus for reproducing recorded information, an apparatus having not only a normal reproducing function but also a high-speed reproducing function such as double speed or triple speed is already known from Japanese Utility Model Application Publication No. 164878/1983. In this conventional playback device, the information detection point of the pick-up assembly (hereinafter simply referred to as pick-up) jumps over two or more adjacent recording tracks at once while opening the racking servo loop in response to a skipping command signal. The tracking servo loop is closed and the generation of the drive signal is cut off when it is detected that the information detection point of the pick-up has skipped a predetermined number of recording tracks of two or more. , the jump command signal is periodically generated for a desired period desired by the user to achieve high-speed reproduction.

However, in conventional playback devices, when the distance the pickup jumps becomes long, the speed of movement of the information detection point relative to the recording track during the jump operation changes depending on the eccentricity of the recording disk, etc. As the time fluctuated, the lock-in operation of the tracking servo after the completion of the jumping operation was unstable. For this reason, the conventional reproducing apparatus has the disadvantage that the high-speed reproducing operation performed by performing the skipping operation within a limited time such as the vertical retrace period becomes unstable.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an information reproducing apparatus that can perform stable high-speed reproducing operation by keeping the moving speed of the information detection point relative to the recording track constant during the jumping operation.

The information reproducing device having a high-speed reproducing function according to the present invention opens a tracking servo loop in response to a jump command, generates a position signal according to the relative position of a state detection point to a target track, and To detect the relative movement speed of the detection point in the radial direction with respect to the recording track based on the track jumping frequency of the information detection point, and move the information detection point so that this movement speed corresponds to the position signal. The tracking servo loop is closed when the information detection point reaches the target track.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, three spot lights 2 to 4 obtained by converging a laser beam are irradiated onto a recording track 1 in the illustrated positional relationship. That is, when the information detection spot light 2 is on the recording track 1, the other two spot lights 3 and 4 are located on both side edges of the recording track 1. Therefore, when the detection spot light 2 shifts in the direction perpendicular to the track (the radial direction of the recording disk), the difference in the amount of light reflected by the two spot lights 3 and 4 corresponds to the direction and magnitude of the shift. The reflected lights of both spot lights 3 and 4 are converted into electrical signals by photoelectric conversion elements 5 and 6, respectively. Each output of these photoelectric conversion elements 5 and 6 is supplied to a differential amplifier 7. The differential amplifier 7 outputs a signal corresponding to the level difference between the outputs of the photoelectric conversion elements 5 and 6, that is, a signal corresponding to the difference in the amount of reflected light of the spot lights 3 and 4. The output of the differential amplifier 7 is supplied as a tracking error signal to an equalizer amplifier 9 via a loop switch 8 for phase compensation. The output of this equalizer amplifier 9 passes through an adder 10 and becomes an input to a drive amplifier 11. The output of this driving amplifier 11 causes the spot light 2 to
The driving coil 13 of the tracking mirror 12 is driven to shift the information detecting spot light 2 in a direction perpendicular to the recording track 1, and the information detection spot light 2 is controlled to accurately track the recording track. Note that the loop switch 8 is configured to be in an open state when a high level signal is supplied to the control input terminal.

A tracking servo loop is formed by the above portion. Further, the DC component of the output of the drive amplifier 11 is extracted by a low-pass filter (not shown), etc., and then the tracking mirror 12
is supplied to a drive circuit (not shown) for a slider motor for moving the slider in a direction perpendicular to the track. The control input terminal of loop switch 8 has an OR (logical sum)
R-S flip-flop 15 via gate 14
The Q output a of the track detection circuit 16 and the output b of the track detection circuit 16 are supplied. A jump command signal is supplied to the set input terminal of the R-S flip-flop 15 from a high-speed reproduction operation control circuit (not shown) or the like. This R
The Q output a of the -S flip-flop 15 is also supplied to the drive signal generation circuit 17. The track detection circuit 16 also generates a signal corresponding to the sum of a signal obtained by removing the RF component from the information detection output obtained by the information detection spot light 2 and each output of the photoelectric conversion elements 5 and 6. The information detection spot light 2 is compared in level and outputs an on-track signal consisting of a low level signal when the information detection spot light 2 is present on the recording track. The output b of this track detection circuit 16 indicates the point in time when the information detection point crosses the track, and the output b of the track detection circuit 16 indicates the time point when the information detection point crosses the track.
Down counter (hereinafter abbreviated as counter)
18 clock input terminals and drive signal generation circuit 1
7 is also supplied. It is well known that a signal waveform such as output b can be obtained by waveform shaping a tracking error signal. counter 18
Data N corresponding to the distance from the information detection spot light 2 to the target track is supplied to the load input terminal by the high speed reproduction operation control circuit etc. when the jump command signal is generated, and the data N is preset in the counter 18. Ru. Data indicating the count value of the counter 18 is supplied to a zero detection circuit 19 and a four-track detection circuit 20. Zero detection circuit 19
is configured to output a zero detection signal consisting of, for example, a high level signal when the supplied data becomes zero. The zero detection signal output from this zero detection circuit 19 is applied to the R-S flip-flop 1.
5 reset input terminal. Further, the 4-track detection circuit 20 is configured to output a 4-track detection signal c consisting of, for example, a high level signal when the supplied data becomes 4 or less.
The 4-track detection signal c outputted from this 4-track detection signal is supplied to the drive signal generation circuit 17.

In the drive signal generation circuit, the output b of the track detection circuit 16 is supplied to the trigger input terminal of a monostable multivibrator (hereinafter abbreviated as monostable multi) 21 and one input terminal of a 3-input AND gate 22. has been done. The other two input terminals of the 3-input AND gate 22 are supplied with the Q output d of the monostable multi 21 and the Q output a of the R-S flip-flop 15, respectively. Resistor R ₁ and capacitor C ₁ for time setting of monostable multi 21
An analog switch 23 is connected between the two external terminals of
and capacitor C ₂ are connected in series. The analog switch 23 is configured to be turned on when a high level signal is supplied to the control input terminal. A control input terminal of this analog switch 23 is supplied with a 4-track detection signal c. 3
The output e of the input AND gate 22 is a monostable multi 2
4 trigger input terminal. The output f of the monostable multi 24 is supplied to a control input terminal of a changeover switch 25. One input terminal of the switching switch 25 is grounded. Further, the other input terminal of the changeover switch 25 is connected to R- through a resistor _R2 .
The Q output of the S flip-flop 15 is supplied. The output terminal of this changeover switch 25 is provided with a signal supplied to one input terminal when a low level signal is supplied to the control input terminal, and a signal supplied to the other input terminal when a high level signal is supplied to the control input terminal. The signal applied to the terminal is derived. The signal derived from the output terminal of the changeover switch 25 is supplied to the negative side input terminal of the operational amplifier 26. The positive input terminal of this operational amplifier 26 is connected to the Q
Output g is supplied. In addition, the operational amplifier 26
A feedback resistor R ₄ is connected between the negative input terminal and output terminal of. The output of the operational amplifier 26 is supplied to the adder 10 via a polarity inversion circuit 27 as a drive signal h. The polarity inversion circuit 27 is
It is configured to invert the polarity of the drive signal h in response to a FWD (forward direction)/REV (reverse direction) regeneration command.

In the above configuration, the jump command signal is output from the high-speed reproduction operation control circuit, etc., the R-S flip-flop 15 is set to the set state, and the Q output a of the R-S flip-flop 15 is set at time _t1 as shown in FIG. 2A. Loop switch 8 at high level
A high level signal is supplied to the control input terminal of. Then, the loop switch 8 is turned off,
The tracking servo loop becomes open. At the same time, the counter 18 receives, for example, "100" as data N output by the high-speed reproduction operation control circuit.
Preset to . At this time, monostable multi 24
is not inverted, and the output f is at a high level as shown in F of the figure. Therefore, the changeover switch 2
The output terminal of R-S flip-flop 15 is connected to one input terminal through a resistor _R2 .
The Q output a of is derived. Also, monostable multi 2
Since the Q output g of No. 4 is at a low level, the positive input terminal of the operational amplifier 26 is grounded, and the operational amplifier 26 and resistors R ₂ and R ₃ act as an inverting amplifier circuit that inputs the Q output a. I will do it. Therefore, the drive signal h output from the operational amplifier circuit 26 becomes lower than the ground level as shown in FIG. Start moving in the direction.

As the information detection spot light 2 moves, an on-track signal consisting of a low level signal is generated every time it skips a recording track, and the output b of the track detection circuit 16 becomes as shown in FIG. Then, when the on-track signal disappears, that is, when the output b of the track detection circuit 16 rises, the count value of the counter 18 becomes small. Furthermore, when the on-track signal is generated, that is, when the output b falls, the monostable multi 21 is triggered, and the Q output d remains at a high level for a time T ₁ corresponding to the time constant C ₁ R ₁ as shown in D of the same figure. Become.

Thereafter, the relative moving speed of the spot light 2 with respect to the recording track in the radial direction is accelerated, and the time during which the output b is at a low level becomes shorter, that is, the frequency of occurrence of the on-track signal increases, T ₁
As shown in E in the same figure, the three inputs are
The output e of the AND gate 22 becomes high level. When this output e becomes high level, monostable multi 2
4 is triggered, and the output f remains at a low level for a predetermined time _T2 from the time when the output e becomes a high level, as shown in FIG. Then, the operational amplifier 26
The negative side input terminal of is grounded, and the operational amplifier 26 and resistor R ₃ act as a non-inverting amplifier circuit which receives the Q output g of the monostable multi 24 as an input. The Q output g of the monostable multi 24 remains at a high level for a predetermined time _T2 from the time when the output e becomes a high level, as shown in FIG. Therefore, the drive signal h remains at a level higher than the ground level for a predetermined time _T2 from the time when the output e becomes high level, and the relative moving speed of the spot light 2 is decelerated to a predetermined speed.
V is controlled to be approximately constant at ₁ .

After that, spot light 2 covers the recording track by 4 more times.
When the vehicle moves to a position where it reaches the target track by jumping over the track, the count value of the counter 18 becomes 4. Then, as shown in Figure B, a 4-track detection signal c consisting of a high level signal is generated and the analog switch 23 is turned on (time _t2 ). As a result, the inversion time of the monostable multi 21 becomes a time _T3 corresponding to the time constant ( _C1 + _C2 ) _R1 , which is longer than _T1 . Therefore, _the relative moving speed of the spot light 2 is controlled to be substantially constant at the speed V2, which is lower than the speed _V1 , after time _t2 .

Then, when the spot light 2 skips the last recording track to be skipped, the count value of the counter 18 becomes zero and the four-track detection signal c disappears (time t ₃ ). At the same time, a zero detection signal is output from the zero detection circuit 19, and the R-S flip-flop 1
5 is reset and the Q output a becomes low level.
Then, the drive signal h becomes zero level, the tracking servo loop is closed, and the information detection spotlight 2 is positioned on the target track.

FIG. 3 is a circuit block diagram showing another embodiment of the present invention, in which only the drive signal generation circuit 17 is shown. Other blocks 1 to 16, 18 to 2
0 and 27 are omitted because they have the same connection configuration as the device shown in FIG. In the drive signal generation circuit 17 in this example, the monostable multi 21, 2
The 4,3-input AND gate 22, analog switch 23, resistor R ₁ , and capacitors C ₁ and C ₂ are connected in the same way as in the device shown in FIG. However, R-
Q output a of S flip-flop 15 is 3 inputs
The signal is supplied to one input terminal of the AND gate 22, and is also supplied via a capacitor _C3 and a resistor _R5 to one input terminal of an adder circuit 29 consisting of an operational amplifier 28 and resistors _R6 to _R8 . Capacitor C ₃
The cathode of the diode D ₁ is connected to the connection point J between the resistor R 5 and the resistor R ₅ . The anode of diode D ₁ is grounded. Further, the anode of the diode D ₂ is connected to the connection point between the resistors R ₅ and R ₆ which is one input end of the adder circuit 29 . The cathode of diode D ₂ is connected to the output terminal of monostable multi 24 . Further, the output f of this monostable multi 24 is supplied to a level shift circuit 30. The level shift circuit 30 is configured to shift the level of the output f so that when the output f becomes a high level, the output becomes a ground level, and when the output f becomes a low level, the output becomes a level below the ground level. has been done. The output of this level shift circuit 30 is supplied to the other input terminal of the adder circuit 29. The output of this adder circuit 29, that is, the output of the operational amplifier 28, is the drive signal h.
is output as

In the above configuration, the Q output a of the R-S flip-flop 15, the 4-track detection signal c, the output b of the track detection circuit 16, the Q output of the monostable multi 21
The output d, the output e of the three-input AND gate 22, and the output f of the monostable multi-channel 24 are as shown in FIGS. 4A to 4F, respectively, similar to the device shown in FIG.
Then, when the output f is at a high level during the period from time t ₁ to t ₃ , the capacitor C ₃
The signal i derived from the connection point J between the resistor _R5 and the resistor R5 is kept at a substantially constant level higher than the ground level, as shown in FIG. At this time, the signal i is supplied to one input terminal of the adder circuit 29, and the adder circuit 29
level shift circuit 3 supplied to the other input terminal of
Since the output of 0 is at the ground level, the drive signal h is at a level lower than the ground level, and the moving speed of the spot light 2 relative to the recording track in the radial direction is accelerated. Furthermore, when the output f becomes a low level, one input terminal of the adder circuit 29 becomes the ground level and the output of the level shift circuit 30 becomes lower than the ground level, so the drive signal h becomes a level higher than the ground level, and the spot The relative moving speed of the light 2 is slowed down and controlled to be approximately constant at a predetermined speed, similar to the device shown in FIG. In addition, in this example, when the output f becomes a low level, a negative charge is supplied to the capacitor _C3 via the resistor ₅ , and the capacitor _C3 is charged, so the level of the signal i derived to the connection point J is decreases with a time constant determined by capacitor _C3 and resistor _R5 . Therefore, as the relative moving speed of the spot light 2 accelerates, the level of the drive signal h gradually approaches the ground level as shown in H in the figure, and as the spot light 2 approaches the target track, the acceleration force decreases. is gradually weakened, and the lock-in operation becomes easier. Therefore, this embodiment is particularly preferred when the number of tracks to jump is known and relatively small.

FIG. 5 is a circuit block diagram showing still another embodiment of the present invention, in which only the drive signal generating circuit 17 is shown as in FIG. 3. In FIG. Also in this example, the other blocks 1 to 16, 18 to 20 and 27 are omitted because they are connected in the same manner as in the apparatus shown in FIG. Drive signal generation circuit 17 in this example
Also monostable multi 21, 24, 3 inputs
AND gate 22, analog switch 23, resistor
R ₁ and capacitors C ₁ and C ₂ are connected in the same way as in the device of FIG. However, the Q output a of the R-S flip-flop 15 is
2, and is also supplied to the subtraction input terminal of an addition/subtraction circuit 32 consisting of an operational amplifier 31 and resistors R ₉ , R ₁₀ , and R ₁₁ . The addition input terminal of the addition/subtraction circuit 32 has a monostable multi-24 Q
Output g is supplied. Then, the output of the adder/subtracter circuit 32, that is, the output of the operational amplifier 32, is output as the drive signal h.

In the above configuration, the gain A ₁ of the addition/subtraction circuit 32 with respect to the Q output a is −R ₁₁ /R ₉ . Also, Q
The gain A ₂ of the addition/subtraction circuit 32 with respect to the output g is 1+
It becomes R ₁₁ /R ₁₀ . Therefore, if R ₉ = R ₁₀ = R ₁₁ , the gains A ₁ and A ₂ will be -1 and 2, respectively, and a drive signal h similar to that of the device shown in Fig. 1 will be obtained. This results in the following behavior. In this example, the circuit configuration is simplified, the number of parts can be reduced, and it is possible to reduce costs and improve reliability.

In the above embodiment, the counter 18 was used as the position detecting means, but a timer may also be used as the position detecting means. In addition, in the above embodiment, the inversion time of the monostable multi 24 is constant, but by changing the inversion time of the monostable multi 24 according to the output of the counter 18, the relative of the information detection point to the target track can be changed. It is conceivable to further stabilize the lock-in operation of the tracking servo by changing the braking force that reduces the relative moving speed of the information detection point depending on the position of the information detection point. Furthermore, if the 4-track detection circuit in the above embodiment is an M-track detection circuit that detects a relatively small number of tracks with value M, the value M can be set to any design value.

Although the optical information reproducing device has been described above, it is clear that the present invention can also be applied to a capacitive information reproducing device.

As described in detail above, according to the present invention, the relative moving speed of the information detection point in the radial direction with respect to the recording track during a jumping operation is detected based on the frequency with which the information detection point crosses the recording track, and the relative movement speed with respect to the target track is detected. The speed is maintained at a speed corresponding to the desired position, making it possible to keep the time required for the jumping operation constant and to stabilize the lock-in operation of the tracking servo after the jumping operation is completed, making stable high-speed regeneration operations easy and inexpensive. This can be obtained by having a suitable configuration.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing one embodiment of the present invention, FIG. 2 is a waveform diagram showing the operation of each part of the device in FIG. 1, and FIG. 3 is a diagram showing another embodiment of the present invention. FIG. 4 is a waveform diagram showing the operation of each part of the device shown in FIG. 3, and FIG. 5 is a circuit block diagram showing still another embodiment of the present invention. Explanation of symbols of main parts, 15...R-S flip-flop, 16...Track detection circuit, 17...
...Drive signal generation circuit, 18...Counter, 19...
...Zero detection circuit, 20...4 track detection circuit.

Claims (1)

[Claims] 1 a tracking servo loop that drives the tracking means of the pick-up to reduce the amount of deviation in response to a tracking error signal indicating the amount of deviation of the information detection point of the pick-up from the recording track; An information reproducing device comprising a jump drive means for opening a servo loop and supplying a drive signal to the tracking means to cause the information detection point to jump to a target track, and then closing the servo loop, position detection means for generating a relative position signal corresponding to the relative position of the information detection point with respect to the target track in response to the jump command; a track detection means for generating pulses; and a jump movement of the information detection point by monitoring the frequency of occurrence of the track detection pulse and switching the polarity of the drive signal so that the frequency falls within a range determined according to the relative position signal. An information reproducing apparatus comprising: a control means for controlling the speed; and a means for closing a tracking servo loop when it is determined by the position signal that the information detection point has reached the target track.