JP3828415B2 - Optical disc device and optical head device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in an optical disk apparatus and an optical head apparatus for recording / reproducing data on / from an optical disk.
[0002]
[Prior art]
As is well known, for example, in an optical disk apparatus that records and reproduces data on an optical disk such as a CD (Compact Disk) -RW (Re Writable) or a CD-R (Recordable), Adjustment of the amount of laser light used when writing data and adjustment of the amount of laser light used when reading data from the optical disc are performed. In addition, tracking servo and focus servo are performed on the objective lens of the optical head based on the reflected light from the optical disk.
[0003]
Specifically, from the laser light emitting element of the optical head, a recording laser beam having a light amount corresponding to the writing of data to the optical disc, and a reproducing laser beam having a light amount corresponding to the reading of data from the optical disc, Generate alternately. Then, during the generation period of the recording laser beam, the light amount of the recording laser beam is controlled based on the reflected light amount from the optical disk.
[0004]
Further, during the generation period of the reproduction laser light, the light amount of the reproduction laser light is controlled based on the amount of light reflected from the optical disk, and a tracking error signal and a focus error signal are generated based on the reflection light from the optical disk. Thus, tracking servo and focus servo are performed on the objective lens of the optical head.
[0005]
In this case, the optical head only photoelectrically converts the reflected light from the optical disk and outputs it to the outside, and the photoelectrically converted electric signal is supplied to a signal processing circuit built in the optical disk device. Signal processing is performed. For example, during the generation period of the recording laser light, an electrical signal corresponding to the amount of the recording laser light reflected by the optical disk is output from the optical head.
[0006]
At this time, the signal processing circuit samples and holds the input electric signal, generates a control signal for controlling the amount of laser light generated by the laser light emitting element of the optical head based on the signal, and returns it to the optical head. To do. Accordingly, the optical head generates laser light from the laser light emitting element based on the input control signal, and the light amount control of the recording laser light is performed here.
[0007]
Further, during the generation period of the reproduction laser beam, an electrical signal corresponding to the amount of the reproduction laser beam reflected by the optical disc is output from the optical head and supplied to the signal processing circuit. At this time, the signal processing circuit samples and holds the input electric signal, generates a control signal for controlling the amount of laser light generated by the laser light emitting element of the optical head based on the signal, and returns it to the optical head. To do. For this reason, the optical head generates laser light from the laser light emitting element based on the inputted control signal, and the light amount control of the reproduction laser light is performed here.
[0008]
On the other hand, in the generation period of the reproducing laser, the signal processing circuit generates a tracking error signal and a focus error signal for the objective lens of the optical head based on the electric signal supplied from the optical head and sampled and held. Have returned to. Thus, the optical head controls the objective lens in the tracking direction and the focus direction based on the input tracking error signal and focus error signal, and tracking servo and focus servo are performed here. The signal processing circuit also generates a wobble signal at the same time.
[0009]
By the way, the optical head is supported in the optical disk apparatus so as to be movable in the radial direction of the optical disk. Therefore, the electrical connection between the optical head and the optical disk apparatus is made through a flexible cable. That is, a printed wiring board in which a laser light emitting element, a photoelectric conversion element, and the like are installed in an optical head is connected to a main printed wiring board in which the signal processing circuit is configured in an optical disk device via a flexible cable. It has become.
[0010]
For this reason, as described above, the electrical signal output from the optical head during each generation period of the recording laser beam and the reproducing laser beam is input to the signal processing circuit of the main printed wiring board through the flexible cable. The sample will be held. In this case, the slew rate of the electric signal transmitted through the flexible cable is limited due to the influence of the stray capacitance of the flexible cable.
[0011]
On the other hand, the time that can be sampled is shortened due to the increase in the data recording speed for the optical disc. For this reason, it is now difficult to perform sampling itself.
[0012]
As known examples in which the effect of stray capacitance in the data transmission path is suppressed to increase the speed of data transfer, for example, Japanese Patent Laid-Open Nos. 10-188206, 11-16112, and 11 There are some which are shown by -273012 gazette.
[0013]
However, in these publications, there is nothing about solving the problem when the output of the optical head is transmitted to the signal processing circuit via the flexible cable and sampled and held by the signal processing circuit. It is not described.
[0014]
[Problems to be solved by the invention]
Therefore, the present invention has been made in consideration of the above circumstances, and enables high-speed sample and hold without being affected by the stray capacitance of the data transmission path, and has high reliability in the laser light quantity and the servo of the objective lens. It is an object of the present invention to provide an extremely good optical disk device and optical head device that can be realized.
[0015]
[Means for Solving the Problems]
The optical disc apparatus according to the present invention is intended for recording or reproducing data by irradiating an optical disc with laser light. And an optical head for irradiating the optical disk with laser light, and a sample-hold means provided inside the optical head for sample-holding an output of a photoelectric conversion element for receiving the laser light irradiated from the laser light-emitting element and reflected by the optical disk; The output of the sample hold means is input via a cable, a predetermined control signal is generated based on the output of the sample hold means, and is supplied to the optical head via the cable. And a signal processing means for generating a signal indicating the timing for sampling and holding the output .
[0016]
Further, the optical head device according to the present invention is intended for a device that irradiates an optical disk with laser light generated from a laser light emitting element through an objective lens, converts the reflected light into an electric signal by a photoelectric conversion element, and outputs the electric signal. It is said. Then, based on a timing signal given from the outside of the optical head device, a sample-and-hold means for sampling and holding an electric signal output from the photoelectric conversion element is incorporated.
[0017]
According to the configuration as described above, since the sample hold means for sampling and outputting the output signal of the optical head is installed inside the optical head, it is affected by the stray capacitance of the data transmission path. For example, the laser light quantity and the servo of the objective lens can be realized with high reliability.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows an optical disk recording / reproducing apparatus described in this embodiment. That is, reference numeral 11 denotes an optical disk such as a CD-RW or CD-R, and data is written and read by the optical head 12.
[0019]
The optical head 12 is configured to irradiate the optical disk 11 with laser light generated by a laser diode 13 via an optical system 14 and an objective lens 15. The laser light reflected by the optical disk 11 travels backward through the objective lens 15 and is received by the photodiode 16 via the optical system 14 and converted into an electrical signal corresponding to the light quantity.
[0020]
The electrical signal output from the photodiode 16 is subjected to current / voltage conversion by the I / V converter 17 and then directly fixed to the optical disc recording / reproducing apparatus via a flexible cable (not shown). 18 is supplied to the signal processing circuit formed in 18.
[0021]
The output of the I / V converter 17 is supplied to a signal processing circuit formed on the main printed wiring board 18 via a switch 19a and a holder 19b constituting the sample hold circuit 19. Further, the output of the I / V converter 17 is supplied to a signal processing circuit formed on the main printed wiring board 18 via a switch 20a and a holder 20b constituting the sample hold circuit 20.
[0022]
Here, the switches 19a and 20a constituting the sample hold circuits 19 and 20 are independently turned on based on a switching signal supplied from the signal processing circuit of the main printed wiring board 18 through a flexible cable. And controlled to an off state.
[0023]
The optical head 12 is provided with a laser driver 21 for driving the laser diode 13. The laser driver 21 controls the light emission amount of the laser diode 13 based on a drive signal supplied from the signal processing circuit of the main printed wiring board 18 via a flexible cable.
[0024]
Further, the optical head 12 is provided with an actuator unit 22 for driving the objective lens 15 in the tracking direction and the focusing direction, respectively. The actuator unit 22 drives the objective lens 15 in the tracking direction and the focus direction, respectively, based on a drive signal supplied from the signal processing circuit of the main printed wiring board 18 via a flexible cable.
[0025]
Here, the main printed wiring board 18 was recorded on the optical disk 11 as an amplifier 23 for amplifying the electrical signal output from the I / V converter 17 as a signal processing circuit, and the output of the amplifier 23. A signal reproduction circuit 24 for restoring the original data is formed.
[0026]
Further, a tracking error signal and a focus error signal are generated from the signal sampled and held by the sample hold circuit 19 as a signal processing circuit on the main printed wiring board 18 and output to the actuator unit 22 of the optical head 12. A servo circuit 25 is formed. At this time, the wobble signal is also reproduced at the same time.
[0027]
Further, the main printed wiring board 18 generates a signal for controlling the light emission amount of the laser diode 13 from the signal sampled and held by the sample hold circuit 20 as a signal processing circuit. A laser servo circuit 26 that outputs to the driver 21 is formed.
[0028]
Here, the main printed wiring board 18 is provided with a microcomputer 27 as a signal processing circuit for comprehensively controlling the operation of the optical disk recording / reproducing apparatus. The signal reproducing circuit 24 is also provided with the microcomputer. Based on the control of No. 27, data restoration processing is performed.
[0029]
When the recording operation is executed, the microcomputer 27 controls the laser servo circuit 26 to alternately generate a recording laser beam and a reproducing laser beam from the laser diode 13 to the laser driver 21. It is controlled to let you.
[0030]
The main printed wiring board 18 is formed with a switching signal generating circuit 28 as a signal processing circuit. Based on the control of the microcomputer 27, the switching signal generation circuit 28 generates a switching signal for turning on the switch 20a during the generation period of the recording laser beam and the reproducing laser beam. As a result, the output of the I / V converter 17 is sampled and held and guided to the laser servo circuit 26.
[0031]
Further, the switching signal generation circuit 28 generates a switching signal for turning on the switch 19a during the generation period of the reproduction laser beam based on the control of the microcomputer 27. As a result, the output of the I / V converter 17 is sampled and held and guided to the servo circuit 25.
[0032]
That is, during execution of the recording operation, the output of the I / V converter 17 is different between the generation period A of the recording laser beam and the generation period B of the reproduction laser beam, as shown in FIG. Indicates the level.
[0033]
Then, in the generation period A of the recording laser beam, as shown in FIG. 2B, the output of the I / V converter 17 is sampled and held, and based on the sample-held signal, the recording laser beam is output. Light amount control is performed. Further, in the generation period B of the reproduction laser beam, as shown in FIG. 2C, the output of the I / V converter 17 is sample-held, and based on the sample-held signal, the reproduction laser beam Light amount control is performed.
[0034]
According to the above-described embodiment, the sample-and-hold circuits 19 and 20 for sample-holding the output signal from the I / V converter 17 are installed in the optical head 12, and the sample-and-hold signal is transmitted to the flexible cable. Since the signal is transmitted to the main printed wiring board 18 through the signal line and the recording waveform component is removed, the sample hold can be performed at high speed without being affected by the stray capacitance of the flexible cable. The laser light quantity and the servo of the objective lens 15 can be realized with high reliability.
[0035]
The present invention is not limited to the above-described embodiment, and can be variously modified and implemented without departing from the scope of the invention.
[0036]
【The invention's effect】
As described above in detail, according to the present invention, high-speed sample-holding is possible without being affected by the stray capacitance of the data transmission path, and the laser light quantity and objective lens servo can be realized with high reliability. Therefore, it is possible to provide an extremely good optical disk apparatus and optical head apparatus that can perform the above-described process.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an outline of an optical disc recording / reproducing apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining that the output of the optical head is sampled and held in a recording period and a reproduction period in the embodiment.
[Explanation of symbols]
11 ... Optical disc,
12 ... Optical head,
13 ... Laser diode,
14 ... optical system,
15 ... Objective lens,
16 ... photodiode,
17 ... I / V converter,
18 ... main printed wiring board,
19: Sample hold circuit,
20 ... Sample and hold circuit,
21 ... Laser driver,
22 ... Actuator part,
23 ... Amplifier,
24. Signal reproduction circuit,
25 ... Servo circuit,
26 ... Laser servo circuit,
27 ... Microcomputer,
28: A switching signal generating circuit.

Claims (6)

In an optical disc apparatus for recording or reproducing data by irradiating an optical disc with laser light,
An optical head for irradiating the optical disk with the laser beam;
A sample-and-hold means provided inside the optical head for sample-holding an output of a photoelectric conversion element that receives laser light emitted from a laser light-emitting element and reflected by an optical disc;
The output of the sample hold means is input via a cable, a predetermined control signal is generated based on the output of the sample hold means, and is supplied to the optical head via the cable. An optical disc apparatus comprising: signal processing means for generating a signal indicating timing for sample-holding the output of the photoelectric conversion element . The signal processing means alternates between a first period in which the laser light emitting element generates a laser beam having a light amount corresponding to recording and a second period in which a laser beam having a light amount corresponding to reproduction is generated. 2. The optical disc apparatus according to claim 1, wherein the optical disk device is controlled to generate a signal indicating a timing at which the output of the photoelectric conversion element is sample-held by the sample-hold means in each of the first and second periods . 2. The optical disc apparatus according to claim 1 , wherein the signal processing means generates a control signal for controlling the amount of laser light generated by the laser light emitting element based on the output of the sample hold means . Said signal processing means on the basis of the output of the sample and hold means, according to claim 1, wherein generating a control signal for controlling the objective lens provided in the optical head in the tracking and focusing directions Optical disk device. In an optical head device that irradiates an optical disk with laser light generated from a laser light emitting element through an objective lens, converts the reflected light into an electrical signal by a photoelectric conversion element, and outputs the electric signal.
An optical head device comprising sample hold means for sample-holding an electric signal output from the photoelectric conversion element based on a timing signal given from the outside of the optical head device. The sample hold means includes
A first sample and hold circuit that samples and holds an electrical signal output from the photoelectric conversion element to generate a control signal for controlling the amount of laser light generated by the laser light emitting element outside the optical head device. When,
A second sample-and-hold circuit that samples and holds an electric signal output from the photoelectric conversion element in order to generate a control signal for controlling the objective lens in a tracking and focusing direction outside the optical head device; 6. The optical head device according to claim 5, wherein:

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