JPH0661133B2 - Optical information recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information on / from a disc-shaped medium by using laser light, and particularly to an information recording area in a standby state. The present invention relates to an optical information recording / reproducing device suitable for preventing erroneous recording of data.

[Conventional technology]

In an optical disc device that records or reproduces information by irradiating a rotating disc-shaped medium with laser light, there are three states of recording, reproduction, and standby during operation. When information is recorded, the power of the irradiation light is increased, the temperature of the recording film of the medium is raised, and the physical shape or crystal structure is changed to perform recording.
On the other hand, during reproduction and standby, the irradiation power must be sufficiently small so that the irradiation light does not deteriorate or damage the medium. However, it is desirable that the irradiation power be as high as possible from the viewpoint of the signal detection level during reproduction.

Particularly, in a recordable optical disk device, a recording film having high sensitivity is used so that high-speed recording can be performed with low irradiation power. For this reason, when a laser spot is irradiated on the same track for a long time in the standby state, the temperature of the medium rises, and the recording film may be gradually deteriorated and deteriorated or damaged.

FIG. 6 is a diagram showing the relationship between the thermal energy density of the recording film and the reflectance of the recording film when a medium for recording information by changing the reflectance is used as the recording film of the optical disc. The heat energy density is plotted on the horizontal axis, and the reflectance of the recording film is plotted on the vertical axis. The thermal energy density is a thermal energy per unit area on the surface of the optical disc, and is proportional to the irradiation power of the laser beam and inversely proportional to the relative velocity between the optical disc and the laser spot.

As can be seen from this figure, when the irradiation power of the laser light is small, the thermal energy is small and the temperature rise is also small, so that the recording film does not change. When the irradiation power is increased, the thermal energy density rises, and when it exceeds a certain critical level W _th , the physical structure is changed to be crystallized and the reflectance increases,
Information can be recorded.

Therefore, at the time of recording, as shown by W _W in this figure, W
_The recording power is set so that the thermal energy density is higher than _th , and the reproducing power is set so that the thermal energy W _r is sufficiently lower than W _th in the data reproducing and standby states. However, in terms of data reproduction, the detection signal level can be increased as the reproduction power is increased. If you close the W _r to W _th by increasing the reproduction power,
Even if there is no change in the recording film during one-time reproduction, the temperature of the recording film gradually rises and the recording film may be deteriorated or damaged if the same track is continuously irradiated for a long time after the standby state continues. , Disk life and reliability will be affected.

FIG. 7 is a diagram showing the temperature change when the laser beam spot passes through a certain point on the optical disk, where the horizontal axis represents time and the vertical axis represents the temperature of the recording film. The point at time 0 is the time when the center of the spot has just passed. This figure was obtained by computer simulation.

From this figure, it can be seen that the temperature change of the recording film is slower than the temperature rise, and it takes a long time to return to room temperature. Therefore, when the same track is continuously irradiated, the light spot hits again before the temperature of the recording film reaches the room temperature, thermal energy is accumulated and the temperature gradually rises, and the recording film is damaged. I will let you.

In order to solve such a problem, the conventional apparatus forcibly focuses the light beam on the disk when the apparatus enters a standby state during operation, as disclosed in JP-A-59-186143. The recording film is protected by shifting from the top and making the energy density of the beam light on the optical disk sufficiently smaller than that at the time of recording or reproducing. Further, as another conventional example, a method of electrically controlling the reproduction irradiation power to reduce it can be considered.

[Problems to be solved by the invention]

In the above-mentioned related art, the response time of the focus control system is not taken into consideration, and an extra time is required for the response time. Also, because the irradiation power is low, the playback signal level is not sufficient, and the address of the track in standby cannot be read, or tracking is lost, which may result in extra recording when the recording / playback state is switched from the standby state. There was a problem that it took time.

Further, since the laser beam is basically applied during the standby state, there is a problem that the recording film may be deteriorated or damaged.

An object of the present invention is to eliminate these problems, to obtain a sufficient reproduction signal level without lowering the access speed, and to record and reproduce optical information in which the recording film is not deteriorated or damaged even during a long standby. To provide a device.

[Means for solving problems]

As an example of a method for performing focus and tracking in an optical disk recording / reproducing apparatus, a focus servo and tracking servo signal obtained from reflected light of an optical disk is sampled, its state is held for a certain period, and then repeated. There is a method.

This type of method is described, for example, in Congress of SPI Eye Vol 695 Optical Mass Data Storage II, (1986), pages 239 to 242 (Congress of SPIE Vol.695 Optical Mass).
Data Storage II (1986), pp239-242).

An example of the format of this system is shown in FIG. Similar to a magnetic disk, one track is divided into sectors, and one sector is further divided into blocks having a servo area and a data area (hereinafter referred to as a segment).

Therefore, the servo information for tracking and focus is taken out only from the servo area, and in the data area,
The state in the previous servo area is maintained and the reflected light in the data area is not used as servo information.

In this way, if the servo area and the data area are separated and the servo is discretely applied, it is not necessary to irradiate the disk with laser light in the data area in a standby state or the like.

Therefore, the present invention achieves the above object by providing means for irradiating the laser beam only in the servo area and in the ID area where track addresses and control data are recorded in the standby state. There are features.

[Action]

In the optical information recording / reproducing apparatus of the present invention, in the standby state during operation, the focused laser beam is irradiated only on the servo mark area and the ID area on the track designated for the standby state, Therefore, the additional recording area for recording and reproducing data is not irradiated with laser light.

As a result, the track address data can be reproduced,
Moreover, since the focus and tracking servo are still applied, the access is not delayed and the laser beam does not cause the alteration or damage of the recording film in the additional recording area.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a timing chart of signals of its main part.

In these figures, 100 is an optical disk. On the optical disc 100, signals for tracking, focus servo, and clock reproduction, and an ID signal including a track address and the like are preformatted in a concentric circle shape or a linear shape. An example of the one track is shown in FIG.

In this example, one track is divided into 32 sectors, and one of the sectors is composed of 43 segments, one segment including the servo area and the data area. In the data area of the first segment of the sector, a sync signal Sync. Indicating that it is the first sector and an ID signal such as a track address are preformatted. The number of sectors and the number of segments differ depending on the application of the optical disc.

Returning to FIG. 1 again, description will be made. The optical disc 100 is provided with a hole for coupling with a motor for rotating the optical disc 100, and the optical disc 100 is driven and rotated by a spindle motor 101 through the hole.

An optical head 122 includes a laser diode 110, a collimator lens 109, a deflecting beam splitter 107,
Objective lens 105, light receiving element 108 and λ / 4 plate 10
It is composed of 6. The laser light is the laser diode 11
The light is emitted from 0, is collimated by the collimator lens 109, and is incident on the deflection beam splitter 107. The irradiation light incident on the deflection beam splitter 107 passes through as it is, passes through the λ / 4 plate 106, becomes circularly polarized light, and is condensed by the objective lens 105 to form a minute spot on the recording film of the optical disc 100. .

The light reflected by the optical disc 100 is again reflected by the λ / 4 plate 10
It passes through 6 and is returned to the linear deflection. The plane of polarization of the reflected light is
Since the polarization plane of the irradiation light is deviated by 90 °, the irradiation light is reflected without passing through the polarization beam splitter 107. Then, the reflected light is applied to the light receiving element 108.

In general, when data is recorded / reproduced on / from an optical disk, the laser beam applied to the servo area enters the light receiving element 108 as described above, is amplified by the preamplifier 115, and then is demodulated by the demodulation circuit 117 and the servo mark detection protection circuit. 11
8 and the tracking / focus servo circuit 121.

The servo mark detection and protection circuit 118 detects and protects the servo mark and generates the servo area gate signal. On the other hand, the tracking / focus servo circuit 12
At 1, the servo signal is detected and generated. The detected and generated servo signal is sampled by the servo mark detection signal and held until the next servo mark is detected. Tracking held in this way
The focus servo signal is sent to the actuator drive circuit 116 according to the control signal from the controller 114, and the optical head 122 is controlled.

The tracking / focusing servo is performed as described above.

Next, the operation of data reproduction will be described. As a data reproduction path, the data is sent from the preamplifier 115 to the demodulation circuit 117 and demodulated, and then enters the Sync. Detection protection circuit 119 and is sent to another signal processing circuit (not shown). At this time, the demodulation circuit 117 and the Sync. Detection protection circuit 119 require the clock 303 synchronized with the data, but these circuits 117 and 119 include
A clock whose phase is discretely compared with the signal in the servo area is sent from the PLL circuit 120.

Here, the signals 313 and 315 input to the PLL circuit 120 are input.
Is a signal for clock reproduction detected from the servo mark, the details of which will be described later.

The data demodulated in this manner is sent to the Sync. Detection protection circuit 119, and the Sync. Detection protection circuit 119 detects and protects the synchronization signal Sync. And generates an ID area gate signal.

Further, the servo mark detection protection circuit 118 counts the area of the next servo mark from the servo area detection signal 318 with a clock, and gates the area of the next servo mark. Servo area gate signal 310 (see FIG. 2)
Is generated and sent to the NOR gate 113. A concrete configuration example of the servo mark detection and protection circuit 118 will be described later with reference to FIG.

Further, the Sync. Detection protection circuit 119 similarly has the following ID.
Area signal, ie, ID area gate signal 320
(See FIG. 2) is generated from the previous Sync. Detection signal 319 and sent to the NOR gate 113. That is, in each period of the servo area gate signal period and the ID area gate signal period, the "H" signal is input to the NOR gate 113, and the output of the NOR gate 113 becomes "L". This “L” signal is applied to the NAND gate 11
2, input to the AND gate 123.

Here, the gate circuits 111, 112, 113, 12
3 and controller 114 are laser-dried circuit 1
A control means for generating a control signal 04 is configured.

The controller 114, according to the read mode, the write mode, and the standby state, shows the "H" and "L" mode signals a, the laser on / off signal b, and the read / write signal c shown in Table 1. Is output.

First, the operation of the control means in the read mode will be described with reference to FIG.

First, a “L” signal a indicating that the standby state is not entered from the controller 114 enters the NAND gate 112, and an “H” signal b indicating laser ON enters the AND gate 111,
An “L” signal representing a lead enters the AND gate 123.

Therefore, the output of the NAND gate 112 becomes "H", and the signal of "H" enters the AND gate 111. As described above, since the signal b of "H" indicating laser ON is input to the other input terminal of the AND gate 111, AND
An output “H” signal 321 of the gate 111 is input to the laser drive circuit 104 as a signal for irradiating a laser.

Further, since the "c" signal "L" indicating the read mode is input to one input terminal of the AND gate 123, its output is "L" regardless of the signal input to the other input terminal.
Signal. The "L" signal enters the laser drive circuit 104 as a read mode.

As a result, a signal for instructing the laser diode 110 to irradiate the laser with the light amount of the read mode level is input from the laser drive circuit 104. The irradiated laser light is reflected by the optical disk as described above, passes through the preamplifier 115, and then enters the demodulation circuit 117 and is output as data.

At this time, laser ON and read mode signals are continuously input to the laser drive circuit 104 from the AND gates 111 and 123, respectively.

Next, the operation of the control means in the write mode will be described.

In this case, the controller 114 outputs a signal “L” indicating that the standby state is not set, and “H” indicating that the laser is on.
Signal b, and an “H” signal c representing light are output.

Therefore, as in the case of the read mode, a continuous “H” laser-on signal 321 is output from the AND gate 111.
Is output and the signal is input to the laser drive circuit 104. Further, the signal “H” c is input from the controller 114 to one input terminal of the AND gate 123, while the output of the NOR gate 113 is input to the other input terminal. The input terminal of the NOR gate 113 is
The gate signals 310 and 320 are input from the Sync detection protection circuit 119 and the servo mark detection protection circuit 118, and the NOR gate 11 is provided at the gate signals.
The output of 3 becomes "L". Therefore, the servo mark,
The output of the AND gate 123 becomes "L" in the ID area and changes to the read mode, but becomes the write mode in the other data areas.

In the data area, data is input from the input terminal 103, is modulated by the modulation circuit 102 and then enters the laser drive circuit 104, and a control signal is transmitted so that the laser diode 110 emits a light amount of a level corresponding to the modulated data. Made

As described above, when the laser light emitted from the laser diode 110 is applied to the servo area and the ID area of the optical disc, the laser light is weakened. Therefore, the servo area and the ID area are not recorded. It is not destroyed by laser light.

Next, the operation of the control means in the standby state will be described.

The controller 114 outputs an "H" signal a indicating a standby state, an "H" signal b indicating laser-on, and an "L" signal c indicating read.

Therefore, the AND gate 123 always outputs a signal of “L”, which is input to the laser drive circuit 104.

In addition, the gate signals 31 from the Sync. Detection protection circuit 119 and the servo mark detection protection circuit 118, respectively.
0 and 320 are output and input to the NOR gate 113. When either one of these gate signals becomes "H",
The output becomes "L" and is input to the NAND gate 112. Since the "H" signal indicating the standby state is input from the controller 114 to one input of the NAND gate 112, the output of the NAND gate 112 is "H" when at least one of the gate signals is "H". It becomes H ″ and is input to the AND gate 111. At this time, AND gate 11
Since the other input signal b of 1 is "H", the output 321 of the AND gate 111 also becomes "H", and the signal of "H" is input to the laser drive circuit 104.

Therefore, in the servo area or the ID area, the laser diode 110 emits light having the intensity at the time of reading.

However, when the gate signals from the Sync. Detection protection circuit 119 and the servo mark detection protection circuit 118 are both "L", that is, at the data area, the output of the NOR gate 113 becomes "H", which causes the NAND gate 112 to operate. Output becomes "L". Therefore, the output of the AND gate 111 also becomes "L" and the laser off signal 321 is output.
Is input to the laser drive circuit 104.

As a result, the laser diode 110 stops the irradiation, but the tracking focus servo circuit 121 holds the servo information in the servo area and supplies it to the actuator drive circuit 116. Absent.
Also, since the laser irradiation is stopped in the data area,
The recording film on the data area is not damaged by the laser light.

At this time, the waveform of the laser on / off signal 321 sent from the AND gate 111 to the laser drive circuit 104 is as shown by 321 in FIG.

Next, a case where the servo mark cannot be detected will be described.

FIG. 3 is a configuration diagram of the servo mark detection protection circuit 118, and FIG. 4 is an operation timing diagram of the circuit when it cannot be detected.

When the preamplifier output 300 having the waveform shown in FIG. 4 is input from the input terminal T1 of FIG. 3, the preamplifier output is converted by the digitizing circuit 301 into the shift register 30.
2 is converted into a digital signal that can be input to And
It is input to the shift register 302 by the clock 303 output from the PLL 120 of FIG. 1 synchronized with the data input from the input terminal T2. The shift register 3
The data converted from the serial signal to the parallel signal by 02 is input to the servo mark decoder 304.

Here, when a servo mark is input as data, the servo mark is detected by the decoder 304, and a signal 311 indicating the detection is sent to the counter 305, R-.
The signal is output to the reset terminal R and the output terminal T3 of the S latch 308. This is shown as a servo mark detection signal 311 in FIG. Therefore, the RS latch 308 and the counter 30
5 is reset.

After that, the counter 305 starts counting the clock 303 synchronized with the data, and is "H" in the next servo area.
The output of the counter 305 is decoded by the decoder 306 so that the signal is output. In this way, the signal that gates the next servo area is output from the decoder 306 and output to the output terminal T4 through the OR gate 309. This output terminal T4 is the NOR gate 1 of FIG.
13 is connected to one input terminal.

Further, in the servo mark decoder 304, the mark for reproducing the clock in the servo mark is decoded for gating, and an "H" level signal is output when the gate is applied. This signal is input to one of the AND gates 312, and the signal output from the digitizing circuit 301 is input to the other. As a result, only the clock reproduction signal (“H” level) 313 in the servo mark from the output terminal T5 is PLL.
It is output to the circuit 120.

The count output from the counter 305 is the decoder 3
The signal is input to 14, the signal cycle for clock reproduction is decoded, and is output to the PLL circuit 120 through the output terminal T6. As a result, the PLL circuit 120 outputs a clock synchronized with the data.

The above is the case where the servo mark can be detected. Next, the operation when the servo mark cannot be detected will be described.

If the servo mark cannot be detected, the counter 305 is not reset and continues counting. Then, when the timing at which the servo mark should be originally detected passes, the pulse decoded by the decoder 307 becomes RS.
Input to the set terminal S of the latch 308, RS latch 3
The signal of "H" is output from 08. This continues to output until a new servo mark is detected and the RS latch is reset. Output signal of RS latch is OR gate 3
It is output to the output terminal T4 through 09. The servo area gate signal 31 which is the output signal of the OR gate 309
The 0 pattern is shown in FIG. The laser on / off signal at this time is as shown by 321 in FIG.

As described above, according to the present embodiment, the laser beam is always emitted in the servo area, and the servo signal is held for a certain period. Therefore, the optical head 122 does not operate in an unstable state after the standby state or after the release thereof, and since the laser light is turned off in the data area during the standby state, the optical head 122 enters the standby state on the data area. However, there is an effect that the recording film in the data area is not damaged.

Further, the Sync. Detection circuit 119 can also be constituted by a circuit similar to the servo mark detection circuit shown in FIG. 3, and its timing is the ID area gate signal 32 having the waveform shown in FIG.
0 is output. The ID area gate signal 320 is the NOR gate 113, NAND gate 112 and A of FIG.
It is input to the laser drive circuit 104 through the ND gate 111. The signal after passing through the AND gate 111 is the laser on / off signal 321 in FIG.

As described above, according to the present embodiment, even if the sync signal Sync. Cannot be detected, the laser beam is turned on and waits so that the next Sync. May be performed at any timing.
It does not mean that Sync. Cannot be detected at all due to the lack of detection of Sync. For the second time, and normal operation can be continued.

The gate circuits 111, 112, 113, 1 shown in FIG.
The control signal generating means for the laser drive circuit 104 including the controller 23 and the controller 114 can easily have various circuit configurations by those skilled in the art. Therefore, the present invention is not limited to the circuit configuration shown in FIG. 1 and, needless to say, includes a circuit configuration within a range not departing from the spirit of the present invention.

〔The invention's effect〕

According to the present invention, in the standby state, when the optical head is irradiating the servo area or the ID area, the light having the same intensity as that in the read is emitted and the reproduction is continued. On the other hand, this irradiation is stopped for the data area, but at this time, the tracking focus servo circuit holds the servo information.

For this reason, when the standby state is released, the access speed does not decrease and a reproduction signal in a sufficient servo area can be obtained. Further, the recording film in the data area is not deteriorated or damaged even during a long standby.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical information recording / reproducing apparatus of the present invention, FIG. 2 is a timing diagram for explaining the operation of the circuit of FIG. 1, and FIG. 3 is a specific example of a servo mark detection protection circuit. FIG. 4 is a block diagram showing the operation of the circuit of FIG. 3, FIG. 5 is a timing diagram explaining the case where the Sync. Signal cannot be detected, and FIG. 6 is thermal energy density and recording on the optical disk. Diagram showing the relationship of the reflectance of the film, No. 7
The figure is a diagram showing a temperature change when a light spot passes on an optical disk. 100 ... Optical disc, 104 ... Laser drive circuit, 1
10 ... Laser diode, 111 ... AND gate, 11
2 ... NAND gate, 113 ... NOR gate, 114 ... Controller, 118 ... Servo mark detection protection circuit, 119 ...
Sync. Detection protection circuit, 120 ... PLL circuit, 121 ... Tracking / focus servo circuit, 122 ... Optical head, 123 ... AND gate.

Claims (3)

[Claims] 1. An optical information recording / reproducing apparatus for recording or reproducing data in the data area while sampling the servo information only from the servo area, holding the servo information in the data area and applying servo. Servo mark detecting means for detecting a servo area, sync signal detecting means for detecting an ID area in which information such as a track address is pre-formatted, and the next servo area based on the detected signals, and I
Timing of D area is counted, and servo area, I
A gate generation means for generating a gate signal having a width of the D area and a control signal for irradiating a laser beam in the area where the gate signal is generated and not irradiating the laser beam in other areas in the standby state are output. An optical information recording / reproducing apparatus comprising: 2. The optical information recording / reproducing apparatus according to claim 1, wherein when the gate generating means cannot detect a servo area in a predetermined area, the gate generating means will detect the servo area in the predetermined area. The optical information recording / reproducing apparatus is characterized in that the gate signal is continuously output until the servo area of the above can be detected. 3. The optical information recording / reproducing apparatus according to claim 1, wherein the gate generating means is an ID.
An optical information recording / reproducing apparatus characterized in that, when an area cannot be detected in a predetermined area, the gate signal is continuously output from the position where the area cannot be detected until the next ID area can be detected.