JP2004342248A - Optical head device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical head device capable of easily adjusting the resistance for adjusting the output of the laser light and a manufacturing method of the optical head device. <P>SOLUTION: In the optical head device 1, a resistor circuit 10 for adjusting the laser output includes a variable resistor 11 for adjusting the output of a laser light source and a fixed resistor 12 of 0 Ω connected in series with the variable resistor 11. When the resistance of the resistor circuit 10 is set beyond the adjustment range of the variable resistor 11, the variable resistor 11 is kept unchanged and the fixed resistor 12 is replaced with another one resistor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical head device used for reproducing an optical recording disk such as a CD and a DVD. More specifically, the present invention relates to an output adjustment of light emitted from a light source in an optical head device.
[0002]
[Prior art]
2. Description of the Related Art In an optical head device used for reproducing an optical recording disk such as a CD or a DVD, a laser beam is emitted from a light source toward an optical recording medium, and the laser beam reflected by the optical recording medium is received by a signal detecting light receiving element. Thus, information reproduction of the optical recording medium is performed.
[0003]
In order to properly perform information reproduction and the like on an optical recording medium, the output level of a signal included in the return light reflected by the optical recording medium is set to a specified value while the output of the laser light emitted from the light source is always kept constant. . Therefore, in the optical head device, the output value of the laser light from the laser light source is adjusted by adjusting the resistance value of the variable resistor of the output adjustment circuit. At that time, the variable resistor is attached to an adjustable position on the device frame (for example, see Patent Document 1).
[0004]
Here, in order to keep the output of the laser light constant, it is common to monitor the light emitted from the laser light source and feed back this monitoring result to the laser light source. Depending on the case, a resistance value higher than the maximum resistance value of the variable resistor may be required. In such a case, conventionally, the variable resistor is replaced with a variable resistor having a higher rating. For example, when the maximum resistance cannot be adjusted with a variable resistor of 4.7 kΩ, the laser output is adjusted by replacing the variable resistor with a maximum resistance of 6.8 kΩ.
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-207762
[Problems to be solved by the invention]
However, in the conventional method of replacing the variable resistor with another variable resistor when the laser output cannot be adjusted by the previously mounted variable resistor, the variable resistor that has been mounted until then is reduced in terms of reliability. Since it cannot be reused, it has to be discarded even though it is expensive, and there is a problem that extra parts cost is required. However, if a variable resistor having a large maximum resistance value is mounted from the beginning, there is a problem that it is difficult to make small adjustments. That is, if the variable resistor has a maximum resistance of 3300Ω, the resistance change when the knob is rotated by １ ／ of the whole is 1100Ω, but if the variable resistor has a maximum resistance of 4700Ω, the knob is turned. The resistance change when rotating the knob 1/3 of the whole is 1567Ω, and if the maximum resistance value is 6800Ω, the resistance change when the knob is rotated 1/3 of the whole becomes 2267Ω. . Therefore, as the variable resistor to be mounted in advance, a variable resistor having the smallest possible maximum resistance is preferable, and only when this variable resistor cannot be used, a method of replacing the variable resistor with a large maximum resistance value must be adopted. I do not get it.
[0007]
In addition, the variable resistor is larger in size than the fixed resistor, and the mounting place is limited. Therefore, even if the resistance value can be adjusted (knob adjustment), the variable resistor may be placed at a position where replacement is difficult. is there. For example, as shown in FIG. 5, when the variable resistor 101 is mounted on the substrate 102 and the substrate 102 is attached to the device frame 103 of the optical head device, the variable resistor 101 It may be located on the bottom side of the part 104. In this case, if a driver is inserted through the opening 104, the knob 101a of the variable resistor 101 can be rotated to adjust the resistance value. However, it is difficult to replace the variable resistor 101 through the opening 104. In such a case, since the substrate 102 is once removed from the device frame 103 and the variable resistor 101 is replaced, there is a problem that considerable work is required.
[0008]
In view of the above problems, an object of the present invention is to propose an optical head device that can easily adjust a resistance value for adjusting an output of a laser beam, and a method of manufacturing the optical head device. It is in.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, according to the present invention, a laser light source that emits outgoing light toward an optical recording medium, receives light reflected by the optical recording medium, and detects recording information of the optical recording medium. In an optical head device having a signal detection light-receiving element and an output adjustment circuit including a variable resistor for adjusting an output level of laser light from the laser light source, the output adjustment circuit includes: On the other hand, a series or parallel fixed resistor is mounted so as to be replaceable.
[0010]
In the present invention, a laser light source that emits outgoing light toward an optical recording medium, a light receiving element for receiving light reflected by the optical recording medium and detecting recording information on the optical recording medium, An output adjustment circuit having a variable resistor for adjusting the output level of the laser light from the laser light source, wherein the output adjustment circuit is connected in series with the variable resistor in advance. Alternatively, a fixed resistor having a fixed resistance value is electrically connected in parallel, and when adjusting the output level beyond the resistance adjustment range of the variable resistor, the fixed resistor is replaced with a fixed resistor having another resistance value. It is characterized by replacement.
[0011]
In the present invention, the output level of the laser beam from the laser light source is adjusted by adjusting the variable resistor. However, if the output level exceeds the adjustable range of the variable resistor, the variable resistor is not replaced and is mounted in advance. After replacing the fixed resistor that has been set, adjust again with the variable resistor. Therefore, even if the replaced fixed resistor is discarded, the manufacturing cost can be reduced because the fixed resistor is cheaper than the variable resistor. Further, since the variable resistor does not need to be replaced with a variable resistor having a large maximum resistance value, it is possible to easily adjust the resistance value by turning the knob. Further, since the fixed resistor is smaller in size than the variable resistor, it is easy to arrange the fixed resistor at a replaceable position.
[0012]
In the present invention, it is preferable that a resistor having a resistance value of 0Ω is electrically connected in series to the variable resistor as the fixed resistor used in advance in the output adjustment circuit. As long as it is a 0Ω resistor, for example, an inexpensive member such as a lead wire can be used instead of the 0Ω resistor.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an optical head device to which the present invention is applied will be described with reference to the drawings.
[0014]
(overall structure)
FIG. 1 is a schematic configuration diagram mainly showing an optical system of the optical head device of the present embodiment. As shown in FIG. 1, an optical head device 1 performs information recording and information reproduction on an optical recording disk 5 (optical recording medium) such as a CD or a DVD, and a laser beam emitted from a laser light source 2 emits a laser beam. After being reflected by the half mirror 3, the light is collimated by the collimator lens 6, and then condensed by the objective lens 4 to focus on the information recording surface of the optical recording disk 5. The position of the objective lens 4 in the tracking direction and the focusing direction is servo-controlled by the objective lens driving mechanism 40.
[0015]
The return light reflected by the optical recording disk 5 passes through the objective lens 4, the collimator lens 6, and the half mirror 3, and enters the signal detection light-receiving element 7. The drive control device 100 performs information reproduction processing based on the amount of light received by the signal detection light-receiving element 7 and controls the drive of the objective lens drive mechanism 40 to servo-control the position of the objective lens 4 in the tracking direction and the focusing direction. I do. The drive control device 100 also controls the drive of the laser light source 2.
[0016]
(Drive control of laser light source 2)
In the drive control of the laser light source 2 by the drive control device 100, the laser light emitted from the laser light source 2 is monitored by the monitoring light receiving element 8, and the intensity of the emitted laser light is controlled based on the monitoring result. It is done by doing. For this reason, the drive control device 100 serves as a laser output adjustment circuit that controls the intensity of the laser beam from the laser light source 2 based on the monitoring result of the monitoring light-receiving element 8 (AUTOMATIC LASER POWER CONTROL CIRCUIT / (Hereinafter, referred to as an ALPC circuit).
[0017]
(Configuration of automatic laser controller)
FIG. 2 is an explanatory diagram showing a configuration of the ALPC circuit 9 that monitors laser light emitted from the laser light source 2 and controls output of the laser light source 2 based on the monitoring result. FIG. 3 is a side view schematically illustrating an arrangement state of the variable resistor 11 and the fixed resistor 12 in the optical head device 1.
[0018]
As shown in FIG. 2, the automatic laser output control circuit 9 has a control circuit 90 and a resistance circuit 10 having a variable resistor 11.
[0019]
The control circuit 90 has a terminal 97 for supplying a drive current to the laser light source 2, a terminal 95 for supplying a common potential, and a voltage generated when an output current of the monitoring light receiving element 8 flows through the variable resistor 11 and the resistors 12 and 93. Are connected to a comparator 96, and a terminal 92 for flowing the output current of the monitoring light-receiving element 8 to the ground potential GND through the variable resistor 11, the resistors 12, and 93. Output of various currents and voltages and signal input are performed via 92, 95, and 97. Although a description of each element is omitted in the control circuit 90, a comparator 96 for comparing a reference voltage Vref with a monitoring result of the monitoring light-receiving element 8 input via a terminal 91, and an output from the comparator 96 , A transistor 98 for controlling a drive current supplied from the terminal 97 to the laser light source 2, a protection resistor 93, a variable resistor 94, and the like.
[0020]
On the other hand, the resistance circuit 10 is a circuit for matching the output signal level from the monitoring light receiving element 8 with the signal level in the control circuit 90. When the resistance value of the resistance circuit 10 is changed, As a result of the change in the input voltage, the drive current supplied to the laser light source 2 also changes. For example, when the resistance value of the resistance circuit 10 is reduced, the level of the drive current supplied to the laser light source 2 increases, and the output level of the laser light increases. On the other hand, when the resistance value of the resistance circuit 10 is increased, the level of the drive current supplied to the laser light source 2 is reduced, and the output level of the laser light is reduced.
[0021]
In the optical head device 1, the resistance value of the resistance circuit 10 is adjusted by turning the knob of the variable resistor 11 used in the resistance circuit 10 after the optical head device 1 is assembled. For this reason, after assembling the optical head device 1, the resistance circuit 10 is arranged at a position in the device frame of the optical head device 1 operable from outside so that the knob of the variable resistor 11 can be adjusted. .
[0022]
For example, as schematically shown in FIG. 3, the flexible substrate 14 on which the variable resistor 11 is mounted is mounted on the device frame 13 such that the variable resistor 11 is located on the side of the optical head device 1. Further, the variable resistor 94 (see FIG. 2) of the control circuit 90 and the connector 99 are also mounted on the flexible board 14, and the other flexible board 15 drawn out from the slit 131 is electrically connected thereto. I have.
[0023]
In this embodiment, as shown in FIGS. 2 and 3, the resistor circuit 10 includes a variable resistor 11 and a fixed resistor 12 having a resistance value of 0Ω directly connected to the variable resistor 11. In the present embodiment, the total resistance of the resistor circuit 10 is a combined resistance of the resistance of the variable resistor 11 and the resistance of the fixed resistor 12.
[0024]
In the resistance circuit 10 configured as described above, after assembling the optical head device 1, the knob 110 of the variable resistor 11 is turned by turning the knob 110 of the variable resistor 11 so that the laser output from the laser light source 2 becomes a predetermined level. By changing the resistance value, the total resistance value of the resistance circuit 10 is adjusted.
[0025]
At this time, if the output level from the laser light source 2 cannot be adjusted unless the combined resistance value of the resistor circuit 10 is set to be larger than the resistance adjustment range of the variable resistor 11, the variable resistor 11 is not replaced and is fixed. The resistor 12 is replaced with a fixed resistor having another resistance value. As a result, for example, when the maximum resistance value of the variable resistor 11 is 3300Ω and the resistance value of the fixed resistor 12 originally mounted is 0Ω, the adjustable range of the combined resistance value of the resistance circuit 10 is 0Ω to 3300Ω. However, when the fixed resistor 12 of 0Ω is replaced with the fixed resistor 12 of 470Ω, the adjustable range of the combined resistance value of the resistor circuit 10 becomes 470Ω to 3770Ω. Therefore, the combined resistance value of the resistance circuit 10 can be adjusted to the target value.
[0026]
(Effect of this embodiment)
As described above, in this embodiment, even when the variable resistor 11 exceeds the adjustable range, the variable resistor 11 is not replaced and the fixed resistor 12 is replaced, so that the inexpensive fixed resistor 12 can be discarded. Even if there is, there is no need to discard the expensive variable resistor 11. Therefore, according to this embodiment, the manufacturing cost can be reduced.
[0027]
Further, since the variable resistor 11 does not need to be replaced with a variable resistor having a large maximum resistance value, it is possible to easily set a small resistance value by turning the knob 110. That is, if the variable resistor 11 has a maximum resistance value of 3300Ω, the resistance change when the knob 110 is rotated by １ ／ of the full rotation angle is as small as 1100Ω, but the maximum resistance value is as large as 4700Ω or 6800Ω. When the knob is turned, the resistance change becomes large as 1567Ω or 2267Ω even when the knob is similarly rotated by １ ／ of the full rotation angle, and it is difficult to make small adjustments. However, in the present embodiment, since it is not necessary to replace the variable resistor 11 with a variable resistor having a large maximum resistance value, it is possible to easily make small adjustments.
[0028]
Further, in the present embodiment, both the fixed resistor 12 and the variable resistor 11 are laid out so as to be exposed on the side surface of the device frame 13. However, since the fixed resistor 12 is smaller in size than the variable resistor 11, the fixed resistor 12 is fixed. It is also possible to adopt a layout in which only 12 can be replaced.
[0029]
Further, in the present embodiment, since a resistor having a resistance value of 0Ω is used as the fixed resistor 12 to be used in advance, the fixed resistor 12 is not limited to a 0Ω resistance element, and may be an inexpensive member such as a lead wire. .
[0030]
(Other embodiments)
In the above embodiment, the variable resistor 11 and the fixed resistor 12 are connected in series. However, as shown in FIG. 4, the fixed resistor 12 may be connected to the variable resistor 11 in parallel. Also in the case of such a configuration, by changing the resistance value of the variable resistor 11, the combined resistance value of the resistance circuit 10 can be adjusted and the output of the laser beam can be adjusted. That is, when it is desired to increase the output of the laser beam, the combined resistance of the resistor circuit 10 is reduced, and when it is desired to reduce the output, the combined resistance of the resistor circuit 10 is increased. Further, even when the variable resistor 11 exceeds the adjustable range, the maximum resistance value of the resistor circuit 10 can be increased by replacing the fixed resistor 12 without replacing the variable resistor 11.
[0031]
For example, if the maximum resistance value of the variable resistor 11 is 4700Ω and the resistance value of the fixed resistor 12 originally mounted is 11000Ω, the maximum value of the combined resistance value is 3293Ω, and the knob 110 of the variable resistor 11 is fully turned. The resistance change of the variable resistor 11 when it is rotated by １ ／ of the rotation angle is 1567Ω, and the change of the combined resistance is 1371Ω. When the fixed resistor 12 is replaced with a resistor having a resistance value of 20000Ω while the variable resistor 11 is kept as it is, the maximum value of the combined resistance value can be increased to 3806Ω. Also in this case, since the variable resistor 11 is the same, the resistance change when the knob 110 is rotated by 1/3 of the full rotation angle remains at 1567Ω, and the change amount of the combined resistance of the resistance circuit 10 is 1453Ω. , And before the replacement of the fixed resistor 12. Therefore, small adjustments can be easily made.
[0032]
【The invention's effect】
As described above, in the optical head device of the present invention, the output level of the laser beam from the laser light source is adjusted by adjusting the variable resistor. The variable resistor is not replaced, but the fixed resistor mounted in advance is replaced, and then the variable resistor is adjusted again. Therefore, even if the replaced fixed resistor is discarded, the manufacturing cost can be reduced because the fixed resistor is inexpensive compared to the variable resistor. Further, even when a variable resistor having a small maximum resistance value is used, it is not necessary to replace the variable resistor with a resistor having a large maximum resistance value, so that it is possible to easily adjust the resistance value by turning the knob. Further, since the fixed resistor has a smaller size than the variable resistor, it is easy to arrange the fixed resistor at a replaceable position if the fixed resistor is used.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram mainly showing an optical system of an optical head device to which the present invention is applied.
FIG. 2 is an explanatory diagram showing a configuration of an ALPC circuit that controls output of a laser light source based on a result of monitoring a laser beam emitted from the laser light source in the optical head device shown in FIG.
FIG. 3 is a side view showing an arrangement state of a variable resistor and a fixed resistor used in the optical head device shown in FIG.
4 is an explanatory diagram of a resistance circuit in which a variable resistor and a fixed resistor are connected in parallel in the optical head device shown in FIG.
FIG. 5 is an explanatory diagram showing an example of an arrangement state of a variable resistor for adjusting an output of a laser light source in the optical head device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical head device 2 Laser light source 3 Half mirror 4 Objective lens 5 Optical recording disk (optical recording medium)
7 light receiving element for signal detection 8 light receiving element for monitoring 9 ALPC circuit 10 resistor circuit 11 variable resistor 12 fixed resistor 13 device frame 14 flexible board 90 control circuit 100 drive control device 110 knob of variable resistor

Claims (4)

A laser light source that emits outgoing light toward the optical recording medium, a signal detection light-receiving element that receives light reflected by the optical recording medium and detects information recorded on the optical recording medium, An output adjustment circuit having a variable resistor for adjusting the output level of the laser light;
The optical head device, wherein in the output adjustment circuit, a serial or parallel fixed resistor is replaceably mounted on the variable resistor. 2. The optical head device according to claim 1, wherein the fixed resistor is a 0Ω resistor connected in series to the variable resistor. A laser light source that emits outgoing light toward the optical recording medium, a signal detection light-receiving element that receives light reflected by the optical recording medium and detects information recorded on the optical recording medium, An output adjusting circuit having a variable resistor for adjusting the output level of the laser light;
In the output adjustment circuit, a fixed resistor having a fixed resistance value is electrically connected in advance to the variable resistor in series or in parallel,
When adjusting the output level beyond the resistance adjustment range of the variable resistor, the fixed resistor is replaced with a fixed resistor having a different resistance value. 4. The method of manufacturing an optical head device according to claim 3, wherein a resistor having a resistance value of 0Ω is electrically connected in series to the variable resistor as the fixed resistor used in advance in the output adjustment circuit. .

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