JP2012094212A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for reducing the number of terminals, which become interfaces with an optical disk device, in the three-wavelength type optical pickup of the optical disk device which generates and processes both of a red laser beam and a blue laser beam.SOLUTION: Terminals are shared by the PC output of an ACU detecting whether or not an optical pickup is positioned at a prescribed position when an optical device is powered on or reset and the output of an FMIC detecting the power of a generated laser beam; or the terminals are shared by the PS output of an ACU and the output of an OEIC converting the catoptric light of the optical disk into an electric signal.

Description

  The present invention relates to an optical pickup, and more particularly to an optical pickup with a reduced number of terminals of electrical contacts.

In the field of optical disc devices, in addition to conventional CDs (Compact Discs) and DVDs (Digital Versatile Discs), devices using BDs (Blu-ray Discs) with higher recording capacities as recording media are increasing. For this reason, an optical pickup capable of functioning with respect to all these recording media has been developed as an optical pickup for writing information data on a recording medium using a laser beam and reading information data from the recording medium. This pickup is required to be processed by emitting one of CD laser light, DVD laser light, and BD laser light having different wavelengths depending on the recording medium.
Patent Document 1 discloses a configuration example of an optical disc apparatus equipped with an optical pickup.

JP 2003-317280 A

In the optical pickup, one of the items to be considered when using three laser beams for the above-mentioned circumstances is an electrical contact for transmitting and receiving power and signals between the optical pickup and the optical disk apparatus on which the optical pickup is mounted. There are a number of terminals. Compared to optical pickups that use only red laser light of CD laser light and DVD laser light, optical pickups that use both red / blue laser light increase the number of built-in components, and the number of electrical contact terminals also increases. Easy to increase. If an optical pickup requires a large number of terminals, it will not be possible to meet the demands for downsizing and thinning of the device, and other peripheral parts will need to be changed. As a result, there is a problem that management problems occur and the cost of the apparatus increases.
In view of the above problems, an object of the present invention is to provide an optical pickup in which the number of terminals of electrical contacts is reduced.

In order to solve the above problems, the present invention is an optical pickup that irradiates an optical recording medium with generated laser light, and converts reflected light from the optical recording medium into an electrical signal.
A laser light source that generates the laser light, a collimator lens that collimates the laser light source, a mechanism unit that moves the collimator lens, and whether or not the mechanism unit is at a predetermined initial position. An ACU (Auto Collimator Lens Driver Unit) having a position sensor that outputs a light beam, an objective lens that irradiates the optical recording medium with light from the collimator lens, and the laser light emitted through the objective lens. A photoelectric converter (OEIC: Optical Electronic Integrated Circuit) that receives reflected light through the objective lens and the collimator lens, converts it into an electrical signal of information data recorded on the optical recording medium, and outputs the signal. A laser light sensor for detecting the power of the laser light generated by the laser light source and outputting a detection signal; a detection signal output by the position sensor of the ACU; Is characterized by having a terminal detection signal output from the laser light sensor is output by sharing the signal lines.

Further, the present invention is an optical pickup that irradiates an optical recording medium with generated laser light and converts reflected light from the optical recording medium of the laser light into an electric signal,
A laser light source that generates the laser light, a collimator lens that collimates the laser light source, a mechanism unit that moves the collimator lens, and whether or not the mechanism unit is at a predetermined initial position. An ACU (Auto Collimator Lens Driver Unit) having a position sensor that outputs a light beam, an objective lens that irradiates the optical recording medium with light from the collimator lens, and the laser light emitted through the objective lens. A photoelectric converter (OEIC: Optical Electronic Integrated Circuit) that receives reflected light through the objective lens and the collimator lens, converts it into an electrical signal of information data recorded on the optical recording medium, and outputs the signal. A laser light sensor for detecting the power of the laser light generated by the laser light source and outputting a detection signal; a detection signal output by the position sensor of the ACU; It is characterized by having a terminal electrical signal information data photoelectric converter output is outputted by sharing the signal lines.

  According to the present invention, it is possible to provide an optical pickup with a reduced number of terminals of electrical contacts, and there is an effect that it is possible to contribute to realizing a preferable optical disc apparatus for manufacturers and users.

1 is a block diagram of an optical disc apparatus equipped with an optical pickup in one embodiment. FIG. It is a block diagram of the optical pick-up in one Example. It is a circuit diagram which shows the conventional photosensor periphery. It is a circuit diagram which shows the photosensor periphery in one Example. It is another block diagram of the optical pick-up in one Example.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of an optical disc apparatus equipped with an optical pickup 3 in one embodiment. The optical disc 1 that is a recording medium may be any of CD, DVD, and BD. Of course, any one of a write-once type capable of recording only once such as BD-R and DVD-R, and a rewritable type such as BD-RE and DVD-RAM may be used. The mounted optical disk 1 is rotationally driven by a disk motor 2 at a predetermined rotational speed (for example, a rotational speed at a predetermined linear speed at a position where data is recorded / reproduced). A disk motor control signal for this purpose is generated by a servo unit 6B included in a DSP (Digital Signal Processor) 6 and supplied to the disk motor 2. In order for the servo unit 6B to generate the disk motor control signal, a rotation speed detection circuit 2A is provided, and a signal indicating the rotation speed of the disk motor 2 generated by the rotation speed detection circuit 2A is supplied to the DSP 6. ing.

  Next, the operation of the signal circuit unit will be described. First, at the time of data recording, recording data is supplied from an external host device (not shown) to the recording signal processing unit 5A via an interface (hereinafter abbreviated as IF) 6C. The recording signal processing unit 5A adds an error correction code with a predetermined amount of data as one error correction block, and performs a modulation process for encoding according to the generation probability of the code to generate a recording signal. The generated recording signal is supplied to the optical pickup 3, and the optical pickup 3 generates laser light in accordance with the supplied recording signal. The laser beam is applied to the recording track of the optical disc 1 through the objective lens 301, and the signal is recorded on the recording track.

In FIG. 1, only the objective lens 301 is shown as a component inside the optical pickup 3, but a more detailed configuration will be described later.
The optical pickup 3 is mounted on a sled mechanism, and moves in the radial direction of the optical disc 1 as the sled motor 4 rotates to record and reproduce data at a predetermined track position. A thread motor control signal for this purpose is generated by the servo unit 6B and supplied to the thread motor 4. As will be described later, the optical pickup 3 generates a control signal indicating whether or not the optical pickup 3 is at a predetermined initial position in the radial direction on the optical disc 1, and supplies the control signal to the servo unit 6B. Thus, for example, when the power is turned on, the servo unit 6B performs control so that the optical pickup 3 is located at the predetermined initial position.

  The objective lens 301 is mounted on a tracking actuator and a focus actuator (not shown in FIG. 1) using electromagnetic force. The tracking actuator control signal generated by the servo unit 6B is supplied to the tracking actuator, and based on this, the objective lens 301 is directed in the radial direction with respect to the optical disc 1 so that the laser beam correctly traces on a predetermined recording track of the optical disc 1. The position in the (tracking direction) is finely adjusted. Further, the focus actuator is supplied with the focus actuator control signal generated by the servo unit 6B, and based on this, the objective lens 301 causes the objective lens 301 to focus on the optical disc 1 so that the laser beam is correctly focused on a predetermined recording track of the optical disc 1. The position in the vertical direction (focus direction) is finely adjusted.

  As will be described later, the optical pickup 3 has a front monitor IC (hereinafter sometimes abbreviated as FMIC) for detecting the power of laser light generated by the optical pickup 3. The power value of the laser beam detected by the FMIC is supplied to the servo unit 6B, and the servo unit 6B controls the optical pickup 3 so that the laser beam power is always a predetermined value regardless of variations in the light source and temperature characteristics. To do.

Next, the operation during data reproduction will be described.
An OEIC (not shown in FIG. 1) included in the optical pickup 3 detects the reflected light from the optical disk 1 of the laser beam, detects a data signal recorded on the optical disk 1, and converts it into an electrical signal. The detected data signal is supplied to the reproduction signal processing unit 5B. The reproduction signal processing unit 5B performs arithmetic processing on the data signal to generate, for example, a DPD (Differential Phase Detecting) signal for tracking control, a DPP (Differential Push-Pull) signal, and a DAD (Differential Astigmatism Detection) signal for focus control. And supplied to the servo section 6B included in the DSP 6. The servo unit 6B generates tracking servo signals and focus servo signals based on the supplied DPD signal, DPP signal, and DAD signal, that is, the previous tracking actuator control signal and focus actuator control signal, and supplies them to the optical pickup 3. The tracking operation and focus operation described above are controlled.

  The reproduction signal processing unit 5B equalizes the frequency characteristics of amplitude and phase when data is recorded / reproduced with respect to the optical disc 1, and supplies the equalized data to the decoder unit 6A included in the DSP 6. The decoder unit 6A performs a reproduction process of the data signal recorded on the optical disc 1. For example, the original information signal is decoded by performing a decompression process opposite to the data compression process performed on the information signal before recording on the optical disc 1. Note that the recording signal processing unit 5A and the reproduction signal processing unit 5B may be integrated on the same semiconductor chip. These may be integrated on the same semiconductor chip as the DSP 6. Further, the DSP 6 may include an encoder unit that performs an operation substantially reverse to that of the decoder unit 6A. For example, when data that has not been subjected to data compression is supplied to the IF 6C as recording data, the data may be recorded on the optical disc 1 after being compressed by the encoder unit.

The operation of the optical disk apparatus described above is performed based on a control signal generated by the control unit 7 including, for example, a microcomputer. Note that the controller 7 may also be integrated on the same semiconductor chip as the DSP 6.
In addition, for example, an operation command from the user is supplied to the control unit 7 via an IF 6C from a host device (not shown).

Next, the optical pickup 3 will be described in more detail.
FIG. 2 is a block diagram of the optical pickup 3 in one embodiment. In the drawing, the optical path of the laser beam is represented by a solid line, a broken line, and a dotted line. Each line shows the optical path of CD laser light, the optical path of DVD laser light, and the optical path of BD laser light. That is, FIG. 2 shows a three-wavelength optical pickup. The function of the objective lens 301 is as described above with reference to FIG. The signal line shown in the lower part of the optical pickup 3 in FIG. 1 is connected to the terminal 311. Although only the signal lines used in the description of the present embodiment are described here, in practice, many lines including a power source, a ground, and a control signal are connected, and the terminal 311 has, for example, 45 pins. is doing.

  A focus actuator control signal generated by the servo unit 6B is supplied from the terminal 311 to the focus actuator 302A, and based on this, the objective lens 301 causes the laser beam to pass through a predetermined recording track of the optical disc 1 (not shown in FIG. 2). The position in the vertical direction (focus direction) with respect to the optical disc 1 is finely adjusted so as to focus correctly upward. The tracking actuator 302B is supplied with the tracking actuator control signal generated by the servo unit 6B from the terminal 311. Based on the tracking actuator control signal, the objective lens 301 causes the laser beam to correctly trace on a predetermined recording track of the optical disk 1. The position in the radial direction (tracking direction) with respect to 1 is finely adjusted. In the drawing, a bidirectional arrow around the objective lens 301 indicates a schematic moving direction of the objective lens 301 driven by the actuators 302A and 302B.

  Further, the recording signal described above is supplied from a terminal 311 to an LDD (Laser Diode Driver) 303. The LDD 303 power-amplifies the supplied recording signal and supplies the amplified recording signal to an LD (Laser Diode) 304. The LD 304 emits a built-in CD laser light source, DVD laser light source, or BD laser light source according to the type of the optical disc 1, and sends the generated laser light to the beam splitter 307. In this embodiment, the case where three laser light sources are provided in the same housing is shown. However, as described above, the light sources of CD laser, DVD laser, and BD laser may be provided separately.

  The laser beam sent to the beam splitter 307 is reflected toward the collimating lens 306 by the reflecting surface of the beam splitter 307. The collimating lens 307 changes the laser light from diverging light to parallel light, and then travels substantially parallel to the optical axis up to the objective lens 301. The laser light that has passed through the collimating lens 301 is totally reflected by a total reflection mirror (rise mirror) 305, the traveling direction is changed, and the laser light is supplied to the objective lens 301. The laser beam that has passed through the objective lens 301 is focused on the recording track of the optical disc 1 and writes a recording signal on the recording track.

  The laser light reflected from the optical disk 1 is collected by the objective lens 301, reflected by the total reflection mirror 305, and further supplied to the OEIC 308 through the collimator lens 306 and the beam splitter 307. As described above, the OEIC 308 is a photodetector, which converts the laser light into an electrical signal, and the electrical signal is supplied from the terminal 311 to the reproduction signal processing unit 5B.

When writing or reading information data on a BD recording medium with increased storage capacity, a mechanism unit 309A of an ACU (Auto Collimator Lens Drive Unit) 309 moves the collimator lens 306 in accordance with a control signal from the terminal 311. Thus, the quality (aberration) of the BD laser beam is corrected. The PS (photo sensor) 309B is a position sensor, and detects whether or not the collimating lens 306 is at a predetermined initial position and outputs a detection signal. For example, when the power is turned on or the apparatus is reset, control is performed so that the collimating lens 306 is set to a predetermined initial position.
An FMIC (Front Monitor Integrated Circuit) 310 is a laser light sensor, and detects the power of the laser light generated by the optical pickup 3. The laser beam power value detected by the FMIC 310 is supplied to the servo unit 6B, and the servo unit 6B controls the LDD 303 so that the laser beam power is always a predetermined value regardless of variations in light sources and temperature characteristics. Here, the FMIC 310 is arranged at a position for detecting the power of the light using the laser light leaked from the reflection surface of the beam splitter 307 out of the laser light generated by the LD 304, but this is an example. There is also an arrangement method. For example, it may be arranged obliquely in front of the LD 304, and a part of the laser beam generated by the LD 304 may be directly received to detect the light power.

  One of the features of the embodiment of FIG. 2 is that the output of PS309B and the output of FMIC 310 share the signal line and are output from the same terminal. This will be described with reference to FIGS. 3 and 4. FIG. The terminal 311Z in FIG. 3 and the terminal 311 in FIG. 4 are components corresponding to the terminal 311 in FIG. 2, but a power supply and ground terminal are added, and signals other than the output of the PS309A and the output of the FMIC 310 are described. It is omitted.

FIG. 3 is a circuit diagram showing the periphery of a conventional photosensor (ACU PS) 309B. The PS 309B includes a photodetector 3091 including a light emitting diode and a phototransistor. In the photodetector 3091, the impedance between the collector and the emitter in the phototransistor changes depending on whether or not the light generated by the light emitting diode in the drawing is supplied to the phototransistor. When the optical pickup 3 is located at the predetermined initial position, the optical disc device has a light shielding plate that blocks, for example, between a light emitting diode and a phototransistor. Thereby, a control signal indicating whether or not the optical pickup 3 is located at the predetermined initial position is supplied to the PS output terminal of the conventional terminal 311Z. The resistors R1 and R2 in the figure have a high resistance value of about several tens of k ohms.
Conventionally, as shown in FIG. 3, a detection signal of the power of laser light by an FMIC (Front Monitor Integrated Circuit) 310 is supplied to an FM output terminal which is a terminal different from the PS output terminal.

Incidentally, the signal output to the PS output terminal in FIG. 3 is not used when recording / reproducing data, for example, although it is necessary when the power is turned on or the device is reset as described above. In the latter case, the impedance of the PS output terminal is almost determined by the resistor R1, which is a high impedance.
On the other hand, the signal output to the FM output terminal in FIG. 3 is not used when the power is turned on or when the apparatus is reset. For example, if the output of the FMIC 310 is output by an open collector (drain), it is easy to increase the output impedance when not in use.

  FIG. 4 is a circuit diagram showing the periphery of the photosensor in one embodiment, and corresponds to the embodiment of FIG. 2 described above. Paying attention to the fact that the output of PS309B and the output of FMIC 310 are not used at the same time, and the output impedance when not in use can be set high, both output the same signal line and terminal at terminal 311 It is characterized by that. As a result, an optical pickup with a reduced number of electrical contacts can be provided. In addition, the optical pickup using a three-wavelength laser functions so as not to increase the number of terminals as compared with the conventional one, so that conventional parts can be used, and the cost of the apparatus can be eliminated.

  FIG. 5 is another block diagram of the optical pickup in one embodiment. First, the output signal of the FMIC 310 is not used when the power is turned on or when the device is reset, but the output signal of the OEIC 308 is the same. Therefore, unlike FIG. 2, FIG. 5 shows an example in which the signal line and the terminal 311 are shared by the OEIC 308 and the PS 309B. This embodiment also has the same effect as FIG.

  The embodiments described so far are merely examples, and do not limit the present invention. For example, the block diagrams of the optical pickup 3 shown in FIGS. 2 and 5 are examples, and the present invention is not limited to the optical pickup having these configurations. Further, the optical disc apparatus to which the optical pickup of the present invention is applied may not have a data recording function but may have only a reproduction function. In addition to the examples described above, different embodiments can be considered based on the gist of the present invention, but all fall within the scope of the present invention.

  1: optical disk, 2: disk motor, 3: optical pickup, 4: thread motor, 6: DSP, 7: control unit, 301: objective lens, 303: LDD, 304: LD, 305: total reflection mirror, 306: collimator Lens, 307: Beam splitter, 308: OEIC, 309: ACU, 309A: (ACU) mechanism, 309B: (ACU) PS, 310FMIC, 311: Terminal.

Claims (3)

An optical pickup that irradiates an optical recording medium with generated laser light and converts reflected light of the laser light from the optical recording medium into an electrical signal,
A laser light source for generating the laser light;
A collimating lens for collimating the laser light source;
An ACU comprising a mechanism for moving the collimator lens and a position sensor for detecting whether the mechanism is in a predetermined initial position and outputting a detection signal;
An objective lens for irradiating the optical recording medium with light from the collimating lens;
The reflected light of the laser beam irradiated through the objective lens is received through the objective lens and the collimator lens, converted into an electrical signal of information data recorded on the optical recording medium, and output. A converter (OEIC);
A laser light sensor that detects the power of laser light generated by the laser light source and outputs a detection signal;
An optical pickup comprising: a terminal through which a detection signal output from the position sensor of the ACU and a detection signal output from the laser light sensor are output using a common signal line. An optical pickup that irradiates an optical recording medium with generated laser light and converts reflected light of the laser light from the optical recording medium into an electrical signal,
A laser light source for generating the laser light;
A collimating lens for collimating the laser light source;
An ACU comprising a mechanism for moving the collimator lens and a position sensor for detecting whether the mechanism is in a predetermined initial position and outputting a detection signal;
An objective lens for irradiating the optical recording medium with light from the collimating lens;
The reflected light of the laser beam irradiated through the objective lens is received through the objective lens and the collimator lens, converted into an electrical signal of information data recorded on the optical recording medium, and output. A converter (OEIC);
A laser light sensor that detects the power of laser light generated by the laser light source and outputs a detection signal;
An optical pickup comprising: a terminal from which a detection signal output from the position sensor of the ACU and an electrical signal of information data output from the photoelectric converter are output using a common signal line.   3. The optical pickup according to claim 1, wherein the laser light source selectively generates a plurality of laser beams having different wavelengths.

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