JPH0439130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disc reproducing apparatus that reads information signals recorded on a disc using optical pickup means.

Micro pits are formed in response to FM modulated video signals and digitized audio signals, and these pits form a spiral signal track. Disc playback devices that play back signals and audio signals have already been proposed. In this disc reproducing apparatus, a laser beam, for example, from an optical pickup means is focused on the signal recording surface of the disc.
1A, B and C show the structure of the optical pickup means of this disc playback device. The laser light beam from the laser light source 1 passes through a diffraction grating 2, a spot lens 3, mirrors 4 and 5,
The disk 11 is transmitted through the Woollaston prism 6, the λ/4 plate 7, the tracking control mirror 8, the mirror 9, and the objective lens 10 (see FIG. 1C).
is irradiated. The reflected laser beam from the disk 11 passes through the objective lens 10, the mirror 9, and the tracking control mirror 8 and returns in the same manner as when it was incident. Then, by the λ/4 plate 7 and the Woollaston prism 6, the optical path of this reflected laser beam is changed from that at the time of incidence, and reaches the cylindrical lens 12 via the mirror 5 and the mirror 4. The reflected laser light beam is supplied to a light receiving section 13 consisting of a photodiode.

For example, as shown in FIG.
Photodiodes 14a, 14b, 14c, 14 each having a light receiving area that divides a square into four equal parts.
d, and photodiodes 14e and 14f which are offset in the opposite direction on the extension of the signal track with respect to the photodiodes 14a to 14d. Photodiodes 14a to 14d
The photodiode 14 is used for signal reproduction and detection of the focus state of the laser beam.
e and 14f are used to detect the tracking state of the laser beam. As shown in FIG. 3, the diffraction grating 2 generates a main beam spot 15a and auxiliary beam spots 15b and 15c for tracking control on the disk 11. These two auxiliary beam spots 15b and 15c are located one behind the other in the direction along the signal track 16 with the main beam spot 15a as the center, and are offset in opposite directions in the width direction of the signal track 16. Therefore, the positional relationship of the two auxiliary beam spots 15b and 15c with respect to the signal track 16 changes depending on the tracking state of the main laser beam forming the main beam spot 15a. Main beam spot 15a
is correctly connected to the signal track 16 as shown in FIG. 3A.
In the normal tracking state located above,
The two auxiliary beam spots 15b, 15c scan the signal track 16 by mutually equal widths. Furthermore, as shown in FIGS. 3B and 3C, if a deviation occurs in the positional relationship between the main beam spot 15a and the signal track 16, the auxiliary beam spot 15a
The positional relationship of signals b and 15c with respect to the signal track 16 is also different from the state shown in FIG. 3A. The reflected beams of the auxiliary beams forming the auxiliary beam spots 15b, 15c are guided to photodiodes 14e, 14f of the light receiving section 13. The output signals Se and Sf of the photodiodes 14e and 14f are supplied to an arithmetic circuit, and a tracking error signal S _T is generated by calculating Se-Sf=S _T . This tracking error signal S _T becomes 0 in a normal tracking state, and a tracking control circuit is provided to do so. and,
As shown in FIG. 1B, the tracking control is performed to control the arrival position of the signal reading laser beam Babim on the disk, in other words, the main beam spot 15a.
This is done by changing the angle of the tracking control mirror 8, which controls the position of the mirror 8, according to the output of the tracking control circuit, and a mirror drive device is provided for this purpose. In addition, the hold operation in which the laser beam from the pickup means is repeatedly made to follow one arbitrary revolution of the signal track can also be performed by changing the angle of the tracking control mirror 8 and applying the laser beam to the laser beam every time the disk 11 rotates once. This is done by making a one-track jump back by one signal track.

Furthermore, although not shown, a feed drive mechanism is provided for moving the entire pickup means having the optical configuration shown in FIG. 1 in the radial direction of the disk 11. This feed drive mechanism contributes to the movement of the pickup means in the tracking mode in the normal reproduction mode, the search mode for cueing, or the random access mode. In search mode or random access mode,
A large-scale track jump is performed in which the laser beam from the pickup means traverses a plurality of signal tracks on the disk 11 at high speed.

In the above-mentioned disc playback device, in the search mode or random access mode, the feed drive mechanism is operated to move the entire pickup means in the radial direction of the disc 11 at high speed, during which the laser beam passes through several hundred signal tracks. Since the operation of performing a large-scale track jump across the track and the operation of reading the address data are performed alternately, the time to read the address data is 20 minutes.
~100 msec, and the number of tracks in a large-scale track jump is about 100 to 200, resulting in considerable variation in both cases. By the way, when commanding and controlling access using a microcomputer or the like, the data is read from a large-scale track jump, for example, at the timing of transitioning to a hold operation state, or after a large-scale track jump by a pick-up means. The timing at which address data is decoded by a microcomputer and transferred to a small-scale track jump (for example, a track jump on one signal track) has a large effect on the required access time. Due to variations in the reading time and the number of tracks in the large-scale track jump, the address data read by the pick-up means is decoded by a microcomputer, and in order to transition from the large-scale track jump to the hold operation state or to the small-scale track jump. This method has the disadvantage that there is a delay in the time it takes to send the command signal to stop the large-scale truck jump to the sending drive mechanism, which increases the time required for access. Furthermore, even if a command signal is supplied to the feed drive mechanism to stop the large-scale truck jump, the pick-up means does not stop immediately due to mechanical errors in the feed drive mechanism, so the stop position may be far away from the desired position. It also has the disadvantage of being

This invention was made in view of the above-mentioned drawbacks, and its purpose is to significantly shorten the time required for access in search mode or random access mode, and to ensure that the stop position of the pick-up means is accurately determined during track jump operation. An object of the present invention is to provide an improved disc playback device.

Embodiments of the present invention will be described below with reference to FIG. 4 and subsequent figures.

FIG. 4 shows a main part of an example of a disc playback device according to the present invention, and an example of this disc playback device is also equipped with an optical pickup means as shown in FIG. In,
A control unit 17 that causes the disc playback device to perform various operation modes (modes such as normal playback, forward fast forwarding, backward fast forwarding, etc.) is provided with terminals 18 to 21, and a tracking error signal S _T is sent from the terminal 18. A large-scale truck jump command signal a is sent from terminal 19, a direction designation signal b for specifying the direction of the truck jump (forward or reverse) is sent from terminal 21, and a small-scale truck jump command signal a is sent from terminal 21. A jump command signal c is sent out. The terminal 18 provided in the control section 17 is connected to one input end of a switch circuit 22, and the output end of this switch circuit 22 is connected to the position where the laser beam reaches the disk via a tracking servo amplifier 23. For example, the tracking control coil 24 is connected to a tracking control coil 24 for driving the tracking control mirror 8. In addition, the control unit 17
Each of the terminals 19, 20, and 21 provided in the truck jump control signal is connected to a truck jump signal generating circuit 25 (details will be described later) that generates a truck jump control signal, and the output terminal of this truck jump signal generating circuit 25 is connected to a switch circuit 22. is connected to the other input end of the Furthermore, tracking servo amplifier 2
The output terminal of 3 is connected to a feed servo amplifier 27 via a low pass filter 26 consisting of a resistor and a capacitor.
is connected to the input end of the The output end of the feed servo amplifier 27 is connected to a feed drive mechanism 28 for moving the pickup means in the radial direction of the disk.

Next, a detailed configuration of an example of the truck jump signal generation circuit 25 will be explained with reference to FIG. In FIG. 5, terminals 19', 20', and 21' are terminals 1 provided in the control section 17 described above.
9, 20, and 21, respectively. The terminal 19' is connected to the input end of a monostable multivibrator 30 which generates a "1" level pulse when triggered by the rising edge of the input signal, and the output end of this monostable multivibrator 30 is normally It is connected to the input end of a monostable multivibrator 31 which generates a "1" level output when the input signal falls and generates a "0" level pulse when triggered at the falling edge of the input signal. Furthermore, the terminal 21' is connected to the input end of a monostable multivibrator 32 that is triggered by the rising edge of an input signal and generates a "1" level pulse.
The output end of the multivibrator 32 is a monostable multivibrator 33 that normally produces a "1" level output and generates a "0" level pulse when triggered at the falling edge of the input signal.
is connected to the input end of the The respective output ends of the monostable multivibrators 30 and 32 are
The two input terminals of the OR circuit 34 are connected to each other, and the output terminal of the OR circuit 34 is connected to one input terminal of an exclusive OR circuit 35. Further, the output terminals of the monostable multivibrators 31 and 33 are connected to the AND circuit 3.
The output terminal of this AND circuit 36 is connected to one input terminal of an exclusive OR circuit 37. The other input terminal of exclusive OR circuit 35 and the other input terminal of exclusive OR circuit 37 are commonly connected, and this common connection point is connected to terminal 20'. Furthermore, the respective output terminals of the exclusive OR circuits 35 and 37 are connected to the respective input terminals of a composite circuit 38 consisting of two resistors and a capacitor, and the output terminal of this composite circuit 38 is connected to the switch shown in FIG. It is designed to be connected to the input end of the circuit 22.

Next, the operation of an example of the disc playback device according to the present invention having the essential parts configured as described above will be explained with reference to the waveform diagram of FIG. 6.

When the tracking error signal _ST is sent from the terminal 18 provided in the control section 17, this tracking error signal _ST is supplied to the tracking servo amplifier 23 via the switch circuit 22, and this tracking servo amplifier The control signal obtained at the output end of the tracking control coil 23 is supplied to the tracking control coil 24, and, for example, the angle of the tracking control mirror 8 is controlled to perform predetermined tracking control. In this case, when the laser beam from the pickup means is in a tracking state as shown in FIG. 3B, for example, a positive voltage is applied to the tracking control coil 24, and the laser beam is in a tracking state as shown in FIG. 3C. When the tracking control mirror 8 is in the proper tracking state as shown in FIG. The tracking state is maintained. Furthermore, tracking servo amplifier 2
The signal based on the tracking error signal S _T obtained at the output terminal of 3 is passed through the low pass filter 26.
The low-frequency component signal is extracted by the servo amplifier 27, and the extracted low-frequency component signal is supplied via a feed servo amplifier 27 to a feed drive mechanism 28 that drives the pickup means in the radial direction of the disk. The radial movement of the disk of the pickup means by the feed drive mechanism 28 is controlled in accordance with this low frequency component signal.

Next, when a large-scale truck jump in the reverse direction (return direction) is performed, a signal is transmitted from each of the terminals 19 and 20 provided in the control section 17 as shown in each period P in FIGS. 6A and B. , a large-scale truck jump command signal a and a direction designation signal b are provided, respectively.
It is sent as “1”, “1”. Then, at the rise of the "1" level pulse of the large-scale truck jump command signal a, the monostable multivibrator 30 is triggered, and a "1" level pulse d with a width t ₁ shown in FIG. 6D is obtained. , the monostable multivibrator 31 is triggered at the falling edge of this pulse d, and a "0" level pulse e with a width t ₂ shown in FIG. 6E is obtained.
On the other hand, at this time, since the small-scale truck jump command signal c is not supplied to the input terminal of the monostable multivibrator 32, the output of the monostable multivibrator 32 is at the "0" level as shown in FIG. 6F. And along with this,
At the output end of the monostable multivibrator 33, a "1" level output is obtained as shown in FIG. 6G. Then, the OR circuit 34 calculates the logical sum of the pulse d and the "0" level output of the monostable multivibrator 32. The output signal is “1” as shown in Figure 6H.
The pulse level is h. Further, the AND circuit 36 calculates the logical product of the pulse e and the "1" level output of the monostable multivibrator 33, and the output signal is a "0" level pulse as shown in FIG. 6I. It becomes i. Furthermore, the pulse h
The exclusive OR circuit 35 calculates the exclusive OR of the direction designation signal b and the direction designation signal b, and its output signal becomes a "0" level pulse j as shown in FIG. 6J. Further, the exclusive OR circuit 3 of the pulse i and the direction designation signal b
7, and its output signal becomes a "1" level pulse k as shown in FIG. 6K. These pulses j and pulse k are combined by a combining circuit 38, and the output has a width t ₁ as shown in FIG. 6L.
A track jump control signal 1 is obtained having a drive pulse of negative polarity having a width t ₂ and a braking pulse of a positive polarity having a width t 2 .

The truck jump control signal 1 produced in this manner is supplied to a switch circuit 22 shown in FIG. At this time, a signal obtained by passing a negative polarity driving pulse through an inverter and a positive polarity braking pulse are supplied to the OR circuit, and the switch circuit 22 is switched by the output signal of this OR circuit to switch the truck jump. A control signal 1 is supplied to a tracking control coil 24 via a tracking servo amplifier 23 . That is, the section including the switch circuit 22 and the tracking servo amplifier 23 supplies the tracking control coil 24 with a control signal based on the tracking error signal, and the section that supplies the tracking control coil 24 with a tracking jump control signal. This forms a selective signal supply control section. and,
The tracking control mirror 8 is driven during the negative drive pulse portion of the track jump control signal 1, and is braked during the positive brake pulse portion to perform a large-scale track jump in the opposite direction.

On the other hand, when a large-scale truck jump in the forward direction (advance direction) is performed, as shown in each period Q of FIGS. Since the large-scale truck jump command signal a and the direction designation signal b are sent as "1" and "0", respectively, the same pulses d, e, and
h, i, "0" level, and "1" level outputs are produced. Then, the exclusive OR circuit 35 calculates the exclusive OR of the pulse h and the direction designation signal b, and as its output signal, as shown in FIG. A pulse is obtained. In addition, the exclusive OR circuit 37 calculates the exclusive OR of the pulse i and the direction designation signal b, and as its output signal, as shown in FIG. A pulse is obtained. Such a pulse,
are combined by a combining circuit 38, and a track jump control signal having a polarity opposite to that described above as shown in FIG. 6L is obtained at its output.

The tracking jump control signal generated in this manner is supplied to the switch circuit 22 shown in FIG. 4, and then to the tracking control coil 24 via the tracking servo amplifier 23, as described above. Then, after the tracking control mirror 8 is driven in the opposite direction to that described above, braking is applied, so that a large-scale forward track jump is performed.

In addition, when a small-scale truck jump in the reverse direction is performed, the terminal 2 provided in the control section 17
0, 21 to each period R of FIG. 6 B, C.
As shown in , the direction designation signal b and the small-scale truck jump command signal c are sent out as "1" and "1", respectively. Then, at the rise of the "1" level pulse of the small-scale truck jump command signal c, the monostable multivibrator 3
2 is triggered and the width is small as shown in Figure 6F.
A “1” level pulse f at t ₃ is obtained, and at the falling edge of this pulse f, the monostable multivibrator 33 is triggered, and as shown in FIG. 6G, a small “1” level pulse at t ₄ is generated. g is obtained. On the other hand, at this time, since the large-scale truck jump command signal a is not supplied to the input terminal of the monostable multivibrator 30, the output of the monostable multivibrator 30 becomes "0" level as shown in FIG. 6D. Along with this,
At the output end of the monostable multivibrator 31, a "1" level output is obtained as shown in FIG. 6E. Then, the “0” level output of the monostable multivibrator 30 and the pulse f
The OR circuit 34 calculates the logical sum with the OR circuit 34, and its output signal becomes a "1" level pulse h' as shown in FIG. 6H. Further, the AND circuit 36 calculates the logical product of the "1" level output of the monostable multivibrator 31 and the pulse g, and the output signal is a "0" level pulse as shown in FIG. i′. Furthermore, the exclusive OR of the pulse h' and the direction designation signal b is
This is determined by the OR circuit 35, and its output signal becomes a "0" level pulse j' as shown in FIG. 6J. Further, the exclusive OR circuit 37 calculates the exclusive OR of the pulse i' and the direction designation signal b, and its output signal becomes a "1" level pulse k' as shown in FIG. 6K. . This kind of pulse
j' and pulse k' are combined by a combining circuit 38,
The output signal is a truck jump control signal l' having a negative polarity driving pulse having a width t ₃ and a positive polarity braking pulse having a width t ₄ as shown in FIG. 6L.

The tracking jump control signal l' created in this way is supplied to the switch circuit ₂₂ shown in FIG. A reverse drive of 8 is made and braking is applied in the part of the braking pulse of width t ₄ . In this case, the widths t ₃ and t ₄ are small and a small backward track jump is performed.

When a small-scale truck jump in the forward direction is performed, the terminals 20 and 21 provided in the control section 17
As shown in each period S of FIGS. 6B and 6C, the direction designation signal b and the small-scale truck jump command signal c are sent out as "0" and "1", respectively, and as described above, the “0” level, “1” level output and pulse f as shown in Figure 6 D to G,
g is obtained, and based on this, pulses '-' are obtained as shown in FIG.
As shown in FIG. 2, a truck jump control signal 'is obtained which consists of a positive driving pulse having a small width t ₃ and a negative polarity braking pulse having a small width t ₄ .

Using the tracking jump control signal 'obtained in this manner, the tracking control mirror 8 is
is driven in the forward direction by a positive drive pulse with a small width t ₃ and braked by a negative polarity braking pulse with a small width t ₄ to generate a small-scale truck in the forward direction. A jump will take place.

As is clear from the above description, according to the present invention, the search mode of the disc playback device or
Large-scale and small-scale tracking jumps in random access mode, etc. are performed not by moving the entire pickup means, but by controlling the tracking control means, which is a means for controlling the arrival position of the laser beam on the disk. Therefore, there is an advantage that the scale of a large-scale truck jump can be accurately defined, and that a small-scale truck jump can be reliably performed.

Incidentally, the scale of each truck jump can be easily set by changing the widths of the driving pulse and the braking pulse of the truck jump control signal.

Note that in the above embodiment, the types of track jumps are large (for example, several hundred tracks).
There are two types of truck jumps: truck jumps and small-scale (for example, one truck) truck jumps.
The number of track jumps can be arbitrarily selected.

[Brief explanation of drawings]

Fig. 1 is a block diagram used to explain an example of an optical pickup device of a disc playback device to which the present invention can be applied, Fig. 2 is a plan view showing the arrangement of photodiodes in the light receiving section, and Fig. 3 is a tracking error diagram. 4 is a block diagram showing essential parts of an example of a disc playback device according to the present invention, and FIG. 5 is a track jump signal generation circuit in the block diagram shown in FIG. 4. FIG. 6 is a waveform diagram used to explain the operation of an example of the disc playback device according to the present invention having the essential parts shown in FIGS. 4 and 5. In the figure, 1 is a laser light source, 8 is a tracking control mirror, 10 is an objective lens, 11 is a disk, 13 is a light receiving section, 14a to 14f are photodiodes, 16 is a signal track, 17 is a control section, 1
8, 19, 19', 20, 20', 21, 21' are terminals, 22 is a switch circuit, 23 is a tracking servo amplifier, 24 is a tracking control coil,
25 is a track jump signal generation circuit, 26 is a low pass filter, 27 is a feed servo amplifier, 2
8 is a feed drive mechanism.

Claims (1)

[Claims] 1. Tracking that reads signals recorded by forming signal tracks on a disk using a light beam, and controls the arrival position of the light beam on the disk according to a supplied control signal. an optical pick-up means having control means; and a tracking error signal associated with the light beam caused to reach the disk from the optical pick-up means, and at least a track jump control signal for large-scale track jumps and a track jump control signal for small-scale tracks. a signal sending section for selectively sending out a tracking jump control signal for jump; and a signal sending section for selectively sending out a tracking jump control signal for a jump; A state in which tracking control is performed on the light beam that is caused to reach the disk from the pickup means, and a track jump control signal for a large-scale track jump from the signal sending section is supplied to the tracking control means to control the tracking. means for causing a light beam made to reach the disk from the optical pickup means to perform a track jump of jumping a predetermined number of the signal tracks; Supplying a track jump control signal for track jump, the tracking control means performs a track jump of jumping a number of the signal tracks less than the predetermined number in the light beam that is caused to reach the disk from the optical pickup means. A disc playback device comprising: a signal supply control section that selectively takes a state where it is enabled and a state where it is enabled;