JPH0419871A - Optical disk reproducing device - Google Patents

Abstract

PURPOSE:To prevent malfunction of a defect processing means due to a low revolving speed operation at the time of starting up a starting means by inhibiting the operation of the defect processing means during the starting state of a driving means based on a signal for detecting the starting state of the driving means. CONSTITUTION:The starting state of the driving means 3 is detected by a start-up detecting means 8, and a start-up detecting signal is outputted. The operation of the defect processing means 6 is prohibited by a defect processing control means 9 for a prescribed period of time from the drive commencing time of the driving means 3 based on the start-up detecting signal 7. By this method, since the defect processing means 6 is never operated until the prescribed time is passed from the drive commencing time of the driving means 3, malfunction of the defect processing means 6 due to low revolving speed at the starting time of the driving means 3 can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a CD (Compact Disk) L
The present invention relates to an optical disc playback device that plays back optical discs such as VD (La+e+ Vision Disk), and particularly relates to a technique for preventing malfunctions caused by defects such as scratches and dirt on the optical disc (hereinafter referred to as defects).

[Conventional technology]

The recording surface of an optical disc such as a CD has defects such as scratches generated during mastering during optical disc production, scratches during use, and dirt.

If these defects exist, the RF signal level will drop when the data recorded at the defect position is reproduced as an RF multiplied signal.

Therefore, the tracking servo, which operates based on the RF multiplied signal, will be affected, resulting in malfunction of the servo.

Therefore, CD players and the like are provided with a defect processing circuit in order to avoid the influence of these defects.

A conventional CD player is shown in FIG.

The CD player includes a spindle motor 1 that rotates a CD. The pickup 12 reads data recorded on a CD which is rotationally driven by the spindle motor 1, and outputs an RF signal S1, a focusing error signal FE, and an RF signal S1.

Regenerate the tracking error signal TE. The audio reproduction section reproduces and outputs the reproduced RF multiplied signal R as an audio signal. The servo section servos the pickup 12 based on the focusing error signal FE and the tracking error signal TE. The control unit 14 controls the entire CD player.

The control section 14 includes a defect detection section 17 and a defect processing section 18 that function as the above-described defect processing circuit.

As shown in FIG.
The device includes a low-pass filter 19 for detecting the envelope of the double signal R, and a comparator 20 for outputting a defect detection signal 16 by comparing the output signal of the low-pass filter 19 and the reference signal. There is.

Next, the general operation of the defect processing circuit will be explained.

The defect detection section 17 detects defects such as scratches and dirt on the CD from the RF multiplied signal R, and outputs a defect detection signal 16. The defect processing section does not output the focusing error signal FE and the tracking error signal TE to the servo section 15 based on the defect detection signal 16.

Therefore, if a defect exists on the recording surface of the CD, the servo unit 15 outputs the focusing servo signal FS.
, tracking servo signal TS etc. is not output, so
The servo will not malfunction due to defects.

Next, the operation of the defect detection section 17 will be explained.

The low-pass filter 19 of the defect detection unit 17 extracts the envelope of the input RF double signal s (see FIG. 9(a)) (see FIG. 9(b)). Comparator 2
0 compares the extracted envelope and the reference signal ■. In addition, if the signal voltage corresponding to the envelope of the RF doubler S is lower than the voltage of the reference signal V, it is assumed that there is a defect in el CD, and the defect detection signal 16 is set to "H" level and output. (See time t1 to t2 in FIG. 9(C)). As a result, the defect processing section 1
8 does not output the focusing error signal FE and the tracking error signal TE to the servo section 15. Therefore, the servo unit 15 does not perform focusing servo or tracking servo, and malfunctions due to CD defects are prevented.

[Problem to be solved by the invention]

In the conventional CD player described above, when the spindle motor 11 is activated, the rotation speed of the spindle motor 11 is low, so the frequency of the RF signal Si is low. Therefore, in the defect detection section 17, the RF doubler SR itself passes through the low-pass filter 19. This means that the RF doubler SR itself is erroneously detected as the envelope of the RF doubler SR, and if the signal voltage level of the RF doubler S becomes el lower than the voltage level of the reference signal , which means that it will be detected as a defect.

Therefore, the defect processing unit 18 operates even though there are no defects on the CD.
This causes the focusing servo and tracking servo to stop working unnecessarily, causing malfunctions.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a CD player that can perform correct control and operation even when the spindle motor is started.

[Means to solve the problem]

FIG. 1 shows an explanatory diagram of the principle of the first invention according to claim 1.

The optical disc playback device IA includes a drive means 3 for rotationally driving the optical disc 2, a defect detection means 5 for detecting a defect in the optical disc 2 rotationally driven by the drive means 3 and outputting a defect detection signal 4, and a defect detection signal. 4, and a defect processing means 6 for performing defect processing based on the drive means 3.
a drive detection means 8 which detects the activation state of the drive means 3 and outputs a drive detection signal 7; and a defect processing control means which prohibits the operation of the defect processing means 6 while the drive means 3 is activated based on the activation detection signal 7. 9.

FIG. 2 shows an explanatory diagram of the principle of the second invention according to claim 5.

The optical disc playback device @lB includes a drive means 3 that rotationally drives the optical disc 2, and a pickup 5 that reads information on the recording surface of the optical disc 2 that is rotationally driven by the drive means 3.
0, a defect detection means 53 that detects a defect existing on the recording surface of the optical disc 2 based on the output signal 51 of the pickup 50 and outputs a defect detection signal 52;
a servo loop including a servo means 54 for correcting and controlling focusing errors or tracking errors of the pickup based on an output signal 51 of 0; and a defect detection signal 52;
a defect processing means 55 which opens and closes the servo loop based on the above, and further includes a drive detection means 8 which detects the activation state of the drive means 3 and outputs the activation detection signal 7.
and a defect processing control means 56 that prohibits the opening operation of the servo loop of the defect processing means 55 while the drive means 3 is in the activated state based on the activation detection signal 7.

[Effect]

According to the first aspect of the invention, the drive detection means 8 detects the drive state of the drive means and outputs the drive detection signal 7.

Based on the drive detection signal 7, the defect processing control means 9 prohibits the operation of the defect processing means 6 for a predetermined period of time from the start of driving of the drive means 3.

As a result, the defect processing means 6 does not operate until a predetermined period of time has elapsed from the start of driving of the driving means 3.

Therefore, it is possible to prevent the defect processing means 6 from malfunctioning due to the low rotational speed of the driving means 3 when it is started.

According to the second aspect of the invention, the activation detection means 8 detects the activation state of the drive means 3 and outputs an activation detection signal.

Based on the activation detection signal 7, the defect processing control means 56
While the driving means 3 is in the activated state, the opening operation of the servo loop is prohibited.

Therefore, when the driving means 3 is activated, the servo loop is always in a closed state, so it is possible to prevent malfunctions due to the servo loop not being formed due to the low rotational speed when the driving means 3 is activated. .

〔Example〕

The present invention will be described in detail with reference to FIGS. 3 to 6.

FIG. 3 shows a block diagram of a first embodiment of the present invention. Third
In the figure, the same parts as in the conventional example shown in FIG. 7 are given the same reference numerals and will be explained. In FIG. 3, the difference from the conventional example shown in FIG. The present invention is characterized in that it includes a defect processing control section 25 that outputs the defect detection signal 16 to the defect processing section 18 only after a predetermined period of time has elapsed from the start of the motor 1.

The pickup 12 includes two photodetectors NPD 5PDT, a that detect optical spots for tracking, a four-sided photodetector PDQ that detects optical spots for focusing and signal reproduction, and a photodetector PDQ on the diagonal of the photodetector PDQ. an adder 30 301ゝ-2 that adds the output signals of the two photodetector surfaces located at , and an adder 31 that adds the output signals of both photodetectors PD XPDT2 and outputs a tracking error signal TE;
Adder 30 30. An adder 32 outputs an RF double signal S by adding both image power signals, and a focusing error signal F is obtained by subtracting the output signal -1 of the two adders 3o, 2.
and a subtracter 33 that outputs E.

The defect processing control unit 25 includes a differentiating circuit 34 that has resistors R1 and R2 and a capacitor C and that differentiates the activation detection signal 22 and outputs a differentiated signal 35, and a switching transistor 36 that operates based on the differentiated signal 35. It is composed of

The defect processing unit 18 receives the defect detection signal 16
There are switch circuits SW-1 and SW-2 that respectively output a focusing error signal FE and a tracking error signal TE to the servo section 15 based on the following.

Next, the general operation will be explained.

The defect detection unit 17 uses a low-pass filter to detect R.
Extract the envelope of F double SR and use it as a reference signal ■7. ]
When a CD defect is detected, the defect detection signal 16 is set to "H" level and output.

On the other hand, when the spindle motor 11 starts to start, the start-up detection section 23 notifies the defect processing control section 25 of the start of start-up using the start-up detection signal 22 . As a result, the defect processing control section 25 controls not to output the defect detection signal 16 to the defect processing section 18 until a predetermined period of time has elapsed from the time when the spindle motor 11 started to be started, that is, until the start-up state has ended.

As a result, the defect processing section 18 does not substantially operate for a predetermined period of time from the start of the spindle motor 11, so that the defect detection section 17 detects a CD defect error caused by the low rotational speed of the spindle motor 11. Malfunctions due to detection will no longer occur. Therefore, the CD player 10 can operate stably.

Next, more detailed operation will be explained.

When the activation detection signal 22 is as shown in FIG. 4(a), the differential signal 35 is as shown in FIG. 4(b). Therefore, when the voltage of the differential signal 35 is larger than the threshold voltage ■T of the switching transistor 37,
That is, the switching transistor 37 is turned on from time t1 to time t2 (see FIG. 4(C)), and the defect detection signal 16 is not output to the defect processing section 18.

As a result, each switch circuit S of the defect processing section 18
W SW, l; tOFF, force force = l Shing error signal FE and tracking error signal T
E is not output to the servo unit 15. Therefore, the focusing servo signal FS and the tracking servo signal TS are not output from the servo unit 15 to the actuator 37, and servo is not performed.

Therefore, it is possible to prevent malfunction of the servo unit 15 due to low rotational speed operation of the spindle motor 11 at the time of startup.

FIG. 5 shows the main parts of a second embodiment of the present invention.

The same parts as those in the embodiment shown in FIG. 3 will be described with the same reference numerals.

The defect processing control unit 40 includes a delay circuit 42 that delays the activation detection signal 22 for a predetermined time and outputs the delayed activation detection signal 41, and a delay circuit 42 that delays the activation detection signal 22 for a predetermined period of time and outputs the delayed activation detection signal 41 as a delayed activation detection signal 41. Switching transistor 43 outputting to the processing unit 18
It is configured with the following.

The delay circuit 42 includes a resistor R and a capacitor C, and its time constant τ is expressed as τ=R−C.

Next, the general operation will be explained with reference to FIG.

When the activation detection signal 22 becomes “H” level at time t1, the delayed activation detection signal 41 output from the delay circuit 42 becomes “H” level at time (1, +τ) based on the time constant τ. However, at time t2, the threshold voltage ■Tl of the switching transistor 43 is exceeded, and the switching transistor is turned on.As a result, the defect detection signal 16 is output to the defect processing section 18.

Therefore, by appropriately setting the time constant τ of the delay circuit 42, the defect detection signal 16 can be output to the defect processing section 18 until the spindle motor 11 finishes its starting state and the rotational speed increases sufficiently. There is no. Therefore, malfunction of the defect processing section 18 due to low rotation speed operation of the spindle motor 11 can be prevented.

In each of the above embodiments, the servo unit 15 receives the focusing error signal FE and the tracking error signal TE.
Although the configuration was configured so as not to output either of them, it is also possible to configure the configuration so that either one is not output.

In each of the embodiments described above, the defect detection signal is outputted from the defect detection processing control section to the defect processing section only after a predetermined period of time has elapsed from the start of starting the spindle motor 11, so that the defect detection signal is substantially output to the defect processing section. Although the configuration is such that it does not operate, it is also possible to always output the defect detection signal and output a control signal for prohibiting the operation of the defect processing section.

〔Effect of the invention〕

According to the first invention, the defect processing control means prohibits the operation of the defect processing means while the starting means is in the activated state, and prevents the defect processing from being performed. Malfunctions of the defect processing means due to multiple operations can be prevented.

According to the second invention, the defect processing control means prohibits the opening operation of the servo loop of the defect processing means while the activation means is in the activated state, and always keeps the servo loop in the closed state. Therefore, by operating the drive means at a low rotational speed when starting up, it is possible to prevent malfunctions due to no servo loop being formed.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of the first invention, Fig. 2 is an explanatory diagram of the principle of the second invention, Fig. 3 is a block diagram of the first embodiment, and Fig. 4 is an explanatory diagram of the operation of the defect processing control section. , FIG. 5 is a block diagram of the main part of the second embodiment, FIG. 6 is an explanatory diagram of the operation of the second embodiment, FIG. 7 is a block diagram of a conventional CD player, and FIG. 8 is an explanatory diagram of the defect detection section. , FIG. 9 is an explanatory diagram of the operation of the defect detection section. 1... Optical disc playback device 2... Optical disc 3... Starting means 4... Defect detection signal 5... Defect detection means 6... Defect processing means 7... Starting detection signal 8... Activation detection means 9...Defect processing control means 10...CD player 11...Spindle motor 12...Pickup 13...Audio playback section 14...Control section 5...Servo section 6... - Defect detection signal 7... Defect detection section 8... Defect processing section 9... Low pass filter 0... Comparator 2... Start detection signal 3... Start detection section 4... Control section 5 ... Defect processing control section 0 ... Defect processing control section 1 ... Delayed activation detection signal 2 ... Delay circuit 3 ... Switch transistor

Claims (1)

[Scope of Claims] 1. A driving means for rotationally driving an optical disk; a defect detecting means for detecting a defect existing on a recording surface of the optical disk rotationally driven by the driving means and outputting a defect detection signal; An optical disk playback device comprising: defect processing means for performing defect processing based on a defect detection signal; startup detection means for detecting a startup state of the drive means and outputting a startup detection signal; An optical disc reproducing apparatus comprising: defect processing control means for inhibiting operation of the defect processing means while the driving means is in an activated state. 2. The optical disc playback device according to claim 1, wherein the defect processing control means prohibits output of the defect detection signal to the defect processing means while the driving means is in the activated state, based on the activation detection signal. An optical disc playback device characterized by: 3. The optical disc playback device according to claim 2, wherein the defect processing control means includes a differentiation circuit that outputs a differential signal of the activation detection signal, and a comparison circuit that compares the differential signal with a reference signal. An optical disc reproducing apparatus, wherein the defect detection signal is output when the differential signal is smaller than the reference signal. 4. The optical disc reproducing apparatus according to claim 2, wherein the defect processing control means includes a delay means for delaying the activation detection signal by a predetermined time and outputting the delayed activation detection signal as a delayed activation detection signal; An optical disc reproducing apparatus comprising a switch circuit for outputting a defect detection signal after the driving means is activated. 5. A driving means for rotationally driving an optical disk, a pickup for reading information on a recording surface of the optical disk rotationally driven by the driving means, and detecting defects existing on the recording surface of the optical disk based on an output signal of the pickup. a servo loop including a defect detection means for outputting a defect detection signal, a servo means for correcting and controlling a focusing error or a tracking error of the pickup based on the output signal of the pickup; An optical disc playback device comprising: a defect processing means configured to open and close a loop; a drive detection means for detecting a starting state of the driving means and outputting a starting detection signal; An optical disc reproducing apparatus characterized by comprising defect processing control means for prohibiting an opening operation of the servo loop of the defect processing means while the driving means is in an activated state. 6. The optical disc reproducing apparatus according to claim 5, wherein the defect processing control means prohibits an opening operation of a focusing servo loop or a tracking servo loop based on the activation detection signal.