JPS642266Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] The invention is based on the above-described method by irradiating a laser beam emitted from a semiconductor laser onto an optical disk on which information signals such as audio signals and video signals are recorded, for example, using pits. Regarding an optical pickup used in an optical disk player that reads and reproduces information signals, particularly in an optical pickup that has a semiconductor laser built into the pickup body, an electric device including an adjusting means for adjusting the output of the laser beam emitted from the semiconductor laser is used. A circuit board is provided integrally with the pickup main body.

[Background technology and problems]

Due to the characteristics of semiconductor lasers used in optical disk players and the like as described above, the laser output, which is the output of the emitted laser beam, changes significantly depending on temperature and aging, or depending on the supplied power supply voltage. Therefore, when using a semiconductor laser for the optical pickup of an optical disc player, a part of the laser beam emitted from the semiconductor laser is monitored with a certain coupling, and a sharp contrast can be obtained by monitoring this laser beam. An APC (Auto Power Control) circuit is essential as a means to adjust the laser output according to the output. In addition, since semiconductor lasers have large variations in characteristics from product to product, when used in an optical disk player built into an optical pickup, it is necessary to determine the voltage level to obtain the optimum laser output for driving the semiconductor laser, and the laser for a predetermined drive voltage. The output has significantly different characteristics. Therefore, A. to adjust the laser output of the semiconductor laser.
The PC circuit needs to be significantly variably adjusted for each semiconductor laser used.

By the way, in the optical disc player proposed earlier, the above laser output is adjusted.
The APC circuit is separate from the optical pickup with a built-in semiconductor laser, and is provided as a unit with a circuit board and the like that constitute a signal reproducing circuit block, etc., on the player main body side. Therefore, it becomes necessary to adjust the APC circuit, which is integrated with other circuits in the player body, to correspond to the optical pickup installed in the player, making it impossible to maintain the versatility of the APC circuit for optical pickups. . This makes it difficult to ensure compatibility of the optical pickup with one optical disc player, making it difficult to provide after-sales service such as replacing the optical pickup as necessary. Furthermore, during the assembly process of the optical disc player, it is necessary to adjust the APC circuit in accordance with the optical pickup to be attached, resulting in a significant decrease in assembly efficiency.

[Purpose and general purpose of the invention]

Therefore, the present invention was proposed with the aim of solving the drawbacks of the conventional ones as described above, and in particular, an electric circuit board including means for adjusting laser output in consideration of the characteristics of semiconductor lasers. is provided in the pick-up body in which the semiconductor laser is built-in, and means for adjusting the laser output is adjusted for each optical pick-up in accordance with the built-in semiconductor laser, and the adjustment is made when it is attached to the player body. It was designed to eliminate it. The present invention was proposed for the purpose of facilitating the replacement of optical pickups for each optical disk player, thereby improving serviceability and assembling efficiency.

[Example of idea]

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

The optical pickup 1 according to the present invention includes a laser block 2 containing optical components as shown in FIG.
A two-axis drive device 4 for displacing an objective lens (described later) in two directions, a tracking direction and a focusing direction, is fixedly mounted on the upper surface of the laser block 2 via a positioning ring 3, and a two-axis drive device 4 is mounted on one side of the laser block 2. An electric circuit board 11 on which a circuit for adjusting the output of a semiconductor laser 12 built in the semiconductor laser 2 is mounted is integrally attached thereto.

The laser block 2 includes a semiconductor laser 12 that emits a laser beam and various optical components. The internal mechanism of the laser block 2 will be schematically explained with reference to FIG.
Of the laser beams emitted from the front side (upper side in the figure), the laser beams emitted from the front side (upper side in the figure) are controlled to be parallel beams by the collimating lens 13, and the polarization is modulated by the wavelength plate 14, and the laser beams emitted from the front side (upper side in the figure) are controlled by the collimator lens 13, and the polarization is modulated by the wavelength plate 14. The recording surface of an optical disk (not shown) is irradiated through an objective lens 7 attached to the movable part 6. Further, the laser beam reflected from the recording surface is polarized again by the wavelength plate 14, and due to the difference in polarization direction, the laser beam is sent to the beam splitter 15.
The light is reflected in the right angle direction, focused by the cylindrical lens 16, and exposed by the photodetector 17.

On the other hand, a laser beam is also emitted from the backside (lower side in the figure) of the semiconductor laser 12. Here, by detecting this backside laser beam with the PIN diode 40 shown in FIG. 3 attached to the lower side of the semiconductor laser 12 in FIG. The output of the side laser beam is adjusted by an APC circuit. The APC circuit used here is an electric circuit with the following configuration.

In Figure 3 showing the circuit configuration of the APC circuit,
The semiconductor laser 12 and the PIN diode 40 that detects the output of the semiconductor laser 12 are built into the laser block 2 described above, and each of the semiconductor laser 12 and the PIN diode 40 is connected to the ground terminal 41 of the APC circuit 8. The cathode is connected, the anode of the semiconductor laser 12 is connected to the drive power output terminal 42, and the anode of the PIN diode 40 is connected to the detection input terminal 43.

As shown in FIG. 3, the APC circuit 8 in this embodiment has an emitter connected to a +5V drive power input terminal 44 via a current control resistor 47, and a collector connected to the drive power output terminal 42 via a choke coil 48. A first PNP transistor 49 connected to the PIN diode 40 is provided as a series control element, and the operation of the PNP transistor 49 is controlled by the PIN diode 40.
By controlling according to the detection of the above first
The APC operation is performed so that the output of the semiconductor laser 12 driven via the PNP transistor 49 is constant. That is, the above PIN diode 40
The detection output is applied to the base of an NPN transistor 50 for level fluctuation detection via the detection input terminal 43, and the collector output of the NPN transistor 50 is applied to the second PNP transistor 5 for signal amplification.
1 to the base of the first PNP transistor 49. the above
The emitter bias of the NPN transistor 50 is determined by two Zener diodes 52 and 53 connected in series between the -12V power supply terminal 45 and the ground terminal 41, and the base thereof is connected to a variable resistor. It is connected to the -12V power supply terminal 45 via the variable resistor 54, and the base bias can be varied by variably setting the resistance value of the variable resistor 54. Therefore, the output of the semiconductor laser 12 connected to the APC circuit 8 can be variably adjusted to an appropriate value by the variable resistor 54. In FIG. 3, a diode 55 connected between the drive power output terminal 42 and the ground terminal 41 of the APC circuit 8 is for protecting the semiconductor laser 12 from electrostatic damage. Further, a third PNP transistor whose collector is connected to the base of the first PNP transistor 49 as the series control element is
The PNP transistor 56 is for switching the operation of the APC circuit 8, that is, driving and stopping the semiconductor laser 12. When a control voltage of, for example, +5V is applied to the base via the control input terminal 46, it becomes an OFF operating state. , the APC circuit 8 is activated, and when the control voltage is OV, it is in the ON operation state and serves to stop the operation of the APC circuit 8 by keeping the first PNP transistor 49 in the OFF operation state.

The above-mentioned APC circuit is mounted on an electric circuit board 11 and attached to the upper surface of a mounting plate 18 that is integrally provided at the bottom 2A of one side of the laser block 2. Therefore, the laser output of the semiconductor laser 12 built into the laser block 2 can be adjusted by the optical pickup 1 alone, eliminating the need for adjustment when installing it to the player body (not shown), greatly improving assembly efficiency. improves. Furthermore, even when the optical pickup 1 attached to the player body is replaced, the laser output of each optical pickup 1 is adjusted appropriately, making it easy to replace and improving serviceability. I can do it.

Further, one side portion 2B of the laser block 2 is provided with bearing holes 19 and 20 into which two rod-shaped feed guides of a feed mechanism provided on the player body (not shown) are inserted. Therefore, the optical pick-up 1 is guided by the feed guide by the feed mechanism of the player main body and is moved in the radial direction of the optical disk to trace the disk surface. The configuration of the guide mechanism, which is a combination of the bearing holes 19 and 20 through which these guides are inserted, makes it possible to irradiate the disk surface with a laser beam at right angles with high precision.

On the other hand, the two-axis drive device 4 is composed of a fixed part 5 that constitutes a magnetic circuit part that constitutes a magnetic gap, and a movable part 6 that is displaceably attached to the fixed part 5.

The fixing part 5 constituting the magnetic circuit part includes a mounting board 21 that serves as a mounting plate to the laser block 2;
It is composed of a magnet 22, first yokes 23, 24, second yokes 25, 26, which are integrally provided on the mounting board 21, and a support shaft 27 which is erected on the mounting board 21. The mounting board 21 has a pair of substantially fan-shaped first yokes 23 and 24 formed opposite to each other, and has notches 28 and 2 formed between the first yokes 23 and 24.
An optical window 30 is provided that communicates with one of the notches 28 of the semiconductor laser 9 and allows the laser beam from the semiconductor laser to pass therethrough. Further, the first yoke 23,
A ring-shaped magnet 22 is fitted to the bottom of the outer periphery of the magnet 24, and a pair of second yokes 25 and 26 are attached to the upper surface of the magnet 22. The second yokes 25 and 26 are integrally provided on the ring-shaped yoke attachment part 31, and each of the second yokes 25 and 26 has a length that is one quarter of the circumference of the yoke attachment part 3. formed and arranged opposite each other. Therefore, cutouts 32 and 33 are formed between the second yokes 25 and 26. These second yokes 25, 26 and notches 32, 33 are connected to the first yokes 23, 24.
and the notches 28 and 29, respectively, to form a magnetic circuit section. Further, a support shaft 27 is vertically installed in the center of the mounting board 21. Further, a damper holder 35 provided with a damper 34 made of an elastic material is provided with a pair of leg pieces 35a, 35.
b are mounted on the upper end surfaces 23A, 23B of the first yokes 23, 24 formed on the mounting board 21, respectively, and are installed on the lower surface of the movable part 6, which will be described later, at the center 34A of the damper 34. By inserting and fixing a pin (not shown), the movable part 6 is urged, and the center of the optical axis of the objective lens 7 attached to the movable part 6 is positioned.

On the other hand, the movable part 6 having a bearing hole 36 is inserted into the support shaft 27. The movable part 6 is supported so as to be rotatable about the support shaft 27.
The movable portion 6 is adapted to slide and displace in the axial direction of the support shaft 27. An objective lens 7 is attached to the movable portion 6 at a position 6A which is eccentric with respect to the axial center of the movable portion 6.
Further, a cylindrical portion 37 is attached integrally to the lower side of the movable portion 6 in FIG.

A focusing drive coil (not shown) is wound around the outer peripheral surface of the cylindrical part 37 along its circumferential direction, and a tracking drive coil (not shown) consisting of four coils wound in a rectangular shape and connected to each other. A coil is glued onto the focus drive coil. The cylindrical part 37 is connected to the first yokes 23, 24 and the second yoke 2 of the fixed part 6.
5 and 26, and supplies a servo current to the focus drive coil and the tracking drive coil to drive the movable part 6 in the focus direction or the tracking direction. By displacing the objective lens 7, tracking servo and focus servo are performed for the recording track of the laser beam.

The above-mentioned two-axis drive device 4 is covered with a cover 38 in which an objective lens through hole 39 is formed.

The two-axis drive device 4 has a positioning ring 3 that aligns the optical axis of the laser beam of the semiconductor laser 12 built into the laser block 2 with the center of the objective lens 7 attached to the movable part 6 of the two-axis drive device 4. The laser block 2 is fixedly placed on the upper surface of the laser block 2, with the laser block 2 aligned with the laser block 2 with high precision.

In the embodiment described above, since the output of the semiconductor laser 12 built in the optical pickup 1 can be adjusted only by the optical pickup 1, the workability of the adjustment work is good and the efficiency of the assembly work to the player body is improved. is greatly improved. Further, even when the optical pickup 1 is replaced, by adjusting the output of the semiconductor laser 12 in advance, the replacement work becomes extremely easy, and serviceability for the user is improved.

[Effect of idea]

As is clear from the above-described embodiments, the present invention provides an electric circuit board that includes means for adjusting the output of a laser beam emitted from a semiconductor laser built into the pickup body and is integrally provided with the pickup body. This not only improves assembly efficiency by eliminating adjustments during installation to the player body, but also facilitates the replacement of optical pickups for each optical disc player, thereby improving serviceability. Become.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing the optical pickup according to the present invention, Fig. 2 is a partially cutaway perspective view, Fig. 3 is a circuit diagram of the APC circuit, and Fig. 4 is an exploded perspective view of the two-axis drive device. It is. 1...Optical pickup, 8...APC circuit,
11... Electric circuit board, 12... Semiconductor laser.

Claims (1)

[Scope of utility model registration request] An electric circuit board including means for detecting a portion of the laser beam emitted from a semiconductor laser built into the pickup body and adjusting the output of the laser beam in accordance with the detection output is integrally provided in the pickup body. An optical pick-up.