KR900006953B1 - Attaching method and apparatus for optical detector - Google Patents

Abstract

The method automatically laser beam spot of laser pick-up for compact disk player (CDP) to the center of detector. The apparatus includes automatic power control APC regularly controlling the source of electric power, laser diode (1) radiating laser according to APC, grating (2) splitting laser in to three beams, beam spliter (3) for outputing polarized light, collimator lens (4) for outputing parallel light, objective lens (5) disk (6), and concave lens (7) and cylindrical lens (8) for projecting reflected light of (3) to detector (9).

Description

Attachment method of photodetector for laser pickup and its device

1 is a structural diagram of a laser pickup.

2 shows the shape of a laser spot on a photodetector.

3 is a laser pickup-photodetector attachment device according to the present invention.

4 is a control circuit diagram of FIG.

5 is an operation flowchart according to the present invention.

* Explanation of symbols for main parts of the drawings

l: Base 2: Y-axis fixing plate

3: Y axis stage 4: X axis adjusting motor

5: X-axis fixing plate 6: X-axis stage

7: X axis adjustment motor 8, 8 ': Z axis fixing plate

9: Z axis stage 10: Z axis adjusting motor

11: detector key holder 12: detector substrate

13: laser pickup mount 14: laser pickup

15: objective lens and standard lens 16: holding knob

17: fixed knob 18: objective lens and standard lens holder

19: laser radiation hole 10a-10d: 1-4 current / voltage voltage transformer

20a: analogue / digital converter 30a: central processing unit,

40a-40c: 1-3 motor drive.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for attaching a photodetector for a laser pick-up and a device thereof, and more particularly to a laser beam spot of a laser pickup for a compact disk player (hereinafter referred to as a CDP). A method and apparatus for automatically attaching to a CDP set by automatically matching the center of the (Detector).

In general, a laser pickup device reads information on a disc in a non-contact manner by using a laser beam in a CDP or a video disk player, and automatically adjusts power automatically as shown in FIG. An automatic power control circuit (hereinafter referred to as an APC), a semiconductor laser (1) for firing a semiconductor laser by a power source by the control of the APC, and a launch from the semiconductor laser (1). A diffraction grating 2 for dividing the laser beam into three beams (one main beam and two auxiliary beams) and a laser beam emitted from the diffraction grating 2 are polarized and simultaneously reflected. A polarizing prism 3 that rotates by 90 ° and outputs the same; a parallelimaging lens 4 that outputs laser light output from the polarizing prism 3 as parallel light; and the parallel light lens 4 in An objective lens 5 for imaging parallel rays output as light rays on a disk 6 with a beam spot, and splitting the reflected light rotated by 90 ° from the polarizing prism 3 It consists of a concave lens 7 and a cylindrical lens 8 for incident on the detector 9.

In the process of reproducing and reproducing the information stored in the compact disc by the laser pickup configured as described above, the APC adjusts the power supply voltage to a randomly set voltage and outputs the semiconductor laser 1 to the semiconductor laser ( In 1), a high-performance semiconductor laser (wavelength 78nm) having a predetermined light source is generated and is emitted to the diffraction grating 2. At this time, the laser light emitted from the semiconductor laser 1 is diffracted by the diffraction grating 2 and is divided into three beams (one main beam and two auxiliary beams) and is flatly polarized by the polarization prism 3, By the parallel light lens 4, it becomes parallel light and enters the objective lens 5.

The counter lens 5 forms a laser beam radiated in parallel from the parallel light lens 4 on the disc 6 as a beam spot.

On the other hand, the beam spot formed on the disk 6 is reflected and is incident on the polarizing prism 3 through the objective lens 5 and the parallel optical lens 4.

At this time, the beam splitter 3 is reflected by an intrinsic feature and the incident path is rotated by 90 degrees, and is incident to the light splitting detector 9 through the concave lens 7 and the cylindrical lens 8. .

On the other hand, the light splitting detector 9 separately detects the light incident through the polarizing prism 3, the concave lens 7, and the cylindrical lens 8, converts the light into an electrical signal, and outputs it to a CDP servo (not shown) on the disk. Play back information.

2 is a plan view of the light splitting detector 9 of FIG. 1 and a laser spot diagram on the detector.

FIG. 2A is a case where the position of the objective lens 5 from the disk 6 of FIG. 1 is shorter than the focal length of the objective lens, and b is the position of the objective lens 5 from the disk 6. C is farther than the focal length and c is the focal point of the objective lens 5.

Therefore, in the case of the a and b degrees, the distance between the objective lens 5 and the disk 6 is not accurate, so it can be seen that the focus is not accurately rounded up. As a result, the light splitting detection element 9 accurately detects the disk 6. The information on the image could not be read.

On the other hand, considering the deflection or vibration during rotation of the disk 6, it can be seen that the focusing error (Focusing Error) further increases, which causes the initial attachment of the light splitting detector (9).

In the conventional method of attaching the light splitting detector as described above, the attachment position of the light splitting detector is manually adjusted by using a measuring instrument such as an oscilloscope while moving the stage which can move the light splitting detector in a predetermined direction. It took a lot of time and it was very difficult to get the correct position.

Accordingly, it is an object of the present invention to provide a method for automatically adjusting the laser beam spot of a light splitting detector to be attached to a laser pickup.

Another object of the present invention is to provide an apparatus capable of automatically adjusting the laser beam spot of the light splitting detector to be attached to the laser pickup.

Another object of the present invention is to provide a control circuit for controlling an apparatus for automatically adjusting the laser beam spot of the light splitting detector accurately.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 3 is a schematic diagram of a laser splitting detector attachment apparatus for laser pickup according to the present invention, wherein a Y-axis fixing plate 2 is formed on one side of the attachment base 1, and an X-axis fixing plate is formed on the Y-axis fixing plate 2. The Y-axis stage (3) to which the (5) is attached is slide coupled to the Y-axis direction, and the Y-axis stage 3 is attached to the base 1 to move the Y-axis stage. The X-axis stage 6 is screwed with the attached Y-axis adjusting motor 4 and the X-axis fixing plate 8 'is attached to the upper axis of the X-axis fixing plate 5 so as to move in the X-axis direction. To the X-axis fixing plate (5) by screwing the X-axis adjusting motor (7) to the X-axis stage (6), and the Z-axis fixing plate (8 ') attached to the X-axis stage (6) The Z-axis fixing plate 8 is attached to the detector, and the detector substrate holder 11 is formed on the Z-axis fixing plate 8 to move in the Z-axis direction. Z-stage stage (9) is slide-bonded and screw-coupled with Z-axis adjusting motor (10) attached to Z-axis fixing plate (8 '). A mounting 13 is attached, and a laser pickup 14 having a laser beam boss hole 19 is mounted on the upper side of the laser pickup mounting base 13, and a standard mirror and an object are mounted on the main portion of the laser pickup 14. An objective lens and a standard mirror holder 18 including a lens 15 and a holding knife 16 for adjusting the holding of the standard mirror and the objective lens 15 and a fixing knob 17 for fixing the holding. ) Is attached to the image axis of the base 1 in one direction of the standard mirror and the objective lens 15.

4 and 3, a light splitting detector 100 which is incident on the dividing planes A, B, C, and D and converts and outputs a laser spot beam into an electrical signal, and the dividing plane A 1, 2, 3, which converts the current conversion signal of each divided plane into a voltage by inputting the current conversion signal outputted from B, C, and D through the lines AL, BL, CL, and DL. 4 Analog-to-digital converter (A), which converts and outputs a voltage signal output from the current-voltage converter 10a-10d and the first-4 current voltage converters 10a-10d into a digital signal. / D converter) 20a and a digital processing unit for inputting a digital output from the A / D converter 20a and outputting first, second and third step driving data for controlling the system by a built-in program. 30a and the first, second, and third step digital data output from the CPU 30a are buffered. Y, X, Z step motors (Step-) driven by output of the first, second and third motor drives 40a-40c and the respective outputs of the first, second and third motor drives 40a-40c. Motor (4,7,10) and the Y, X, Z-axis stage (3, which slides by the step driving of the respective step motors (4,7,10) to move the light splitting detector 100). 6,9).

5 is an attachment flow diagram of the light splitting detector according to the present invention, in which step (a) of determining whether the light-receiving element substrate touches the upper surface of the laser pickup 14 at start-up, (a), and (B) to drive the Z-axis motor 10 in the lower axis direction when it is not in contact with each other, and in the dividing planes A, B, C, D of the light receiving element 100 when the judgment of step (a) (C) determining whether the detected and converted current signals are (A + B)-(C + D) = 0, and when the determination of the (C) process is not 0, the converted signal is (A + B). (D) process of searching for-(C + D) > 0, and (e) process of driving the X-axis adjusting motor 7 in the (+) direction when the judgment of process (d) is less than 0 And (f) driving the X-axis adjusting motor 7 to the (-) side when the judgment of step (d) is greater than zero, and each division of the photodetector 100 when the judgment of the step (C) is zero. (G) searching whether the current conversion amount of the surface is (A + D)-(B + C) = 0, and (g) If the stage is not 0 (A + D)-(B + C)> (h) process of searching whether or not, and if the judgment of the (h) process is less than 0, the Y-axis adjusting motor (4) ( (I) process of driving in the side direction and (j) process of driving the Y-axis adjusting motor 4 in the (-) direction when it is larger than 0, and a substrate on which the light receiving element is mounted when (g) process is 0. Step (K) of attaching 19 to the laser pickup 19 and step (e) of driving the Z-axis adjusting motor 10 upward after the step (K) is performed.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 3 to 5. On the upper side of the laser pickup mounting base 13 attached to the upper shaft of the base 1 of FIG. 3, the laser pickup 14 configured as shown in FIG. 1 is mounted (at this time, the objective lens 5 and the disc 6 and The photodetector element 9 is the laser pickup portion in the removed state), and the objective portion of the laser pickup 14 is adjusted with the objective lens, the holding lens 16 of the standard lens and the standard lens holder 18, and the focusing object is long. Insert the standard mirror 15, which can be used as a lens and disk, and adjust the fixing knob 17 to fix the objective lens and the standard lens 15.

In addition, as described above, the laser pickup 14 is mounted on the upper side of the laser mounting unit 13, and then the detector substrate 12 having the light splitting detector 100 is held by the detector substrate holder 11 having the data Taper. (Holding) and inputting data indicating that the detector substrate 12 has reached the upper portion of the laser radiation hole 19 of the laser pickup 14 through the input port Port B of the CPU 30a of FIG. (5) executes the program of FIG. 5, and the CPU 30 performing the FIG. 5 shows whether the detector substrate 12 has touched the laser beam radiation hole 19 of the laser pickup 14. Step drive outputs the drive data in the lower axis direction to the output terminal (0D3) until it makes a judgment as in the same procedure.

At this time, the third motor drive 40c inputting the step motor driving data output from the CPU 30a buffers the step motor driving data to drive the Z-axis adjusting step motor 10 in the lower axis direction, thereby driving the Z-axis adjusting motor. The Z-axis stage 9 screwed with the shaft of 10 is slid down from the Z-axis fixing plate 8.

Accordingly, the detector holder 11 mounted on the Z-axis stage 9 is also moved so that the detector substrate 12 comes into contact with the upper surface of the laser beam radiation hole 19 of the laser pickup 14.

When the detector substrate 12 touches the upper portion of the laser pickup 14 and the Z-axis adjustment step motor 10 does not rotate, the CPU 30a determines that the detector engine 12 touches the upper portion of the laser pickup 14. Then, the data input to the input port (Port A) is analyzed and judged.

In this case, the laser pickup 14 having the same configuration as that of FIG. 1 emits a laser from the internal laser diode 1, and the laser pickup 14 emits a laser in the same path as that of FIG. 1 described above. Reflected by the objective lens and the standard mirror 15 acting as the disk 6, and rotated 90 degrees by the polarizing prism 3, the hole 19 through the concave lens 7 and the cylindrical lens 8 Radiated).

Therefore, the laser beam emitted from the laser beam radiation hole 19 forms a spot on the light receiving surface of the light splitting detector 100 mounted on the detector substrate 12.

The light splitting detector 100, which enters the laser emitted from the radiation hole 19 of the laser pickup 14, is formed on each of the divided surfaces A, B, C, and D (first upper limit to fourth upper limit). When the amount of light is converted into an electrical signal and divided into a signal of current, the output lines AL, BL, CL and DL of the first, second, third and fourth current-voltage converters A, B, C and D (10a-10d). Are printed respectively.

In addition, the first, second, third and fourth current-to-voltage converters 10a-10d convert the amount of current converted from the respective divisions A, B, C, and D of the light splitting detector 100 into a voltage to convert the current into voltage A. It outputs to / D converter 20a, and inputs it into the input port Port A of the CPU 30a.

The CPU 30a, which inputs a signal which is converted into a current from the respective divisions A, B, C, and D of the light splitting detector 100 by the input port, as digital data, is inputted by a built-in program. As shown in (C), it is determined whether the ratio of the light quantity of (A + B)-(C + D) received at the dividing planes A, B, C, and D of the light splitting detector 100 is zero.

That is, it is checked whether the amount of laser light received by the dividing planes A and B is the same as the amount of laser light received by the dividing planes C and D. Search in the next step (g).

If the ratio of the amount of light retrieved in step (c) is not zero, it is determined whether the amount of light received from the diamines A, B, C, and D is (AB)-(C + D)> 0. If the value is greater than 0 and the judgment value is greater than 0, the laser beam is determined to be swept between the dividing planes A and B, and the data capable of driving the X-axis adjusting motor 7 in the (-) direction is shown in FIG. 5 (f). The process outputs to the second motor drive 40b.

The motor drive 40b which inputs the step motor driving signal output from the CPU 30 buffers it and outputs it to the X-axis step motor 7 to output the X-axis step adjustment motor 7 to the detector substrate 12 of FIG. ) Is moved in the negative (-) direction, which is the X axis, so that the laser beam is moved stepwise on the (-) axis as shown in FIG. Therefore, an image is formed from the dividing plane AB of the light splitting detector 100 of FIG. 4 to the dividing planes C and D planes. If the determination value is less than 0, it is determined that the light split detector 100 is inclined in the (+) axis direction and the data capable of driving the X-axis motor 7 in the (+) direction is transferred to the second motor drive 40b. After outputting, the stepwise driving of the light splitting detector 100 with the (+) axis is performed, and the above-described process of FIG. 5C is searched.

Therefore, when the light receiving amounts of the divided surfaces C and D are large, the X-axis motor 7 is driven by the (+) axis so that the laser beam radiated from the beam radiation hole 19 is positioned at the center of the photodetector 100.

In this way, the X-axis step adjustment motor 7 is moved in the (-) or (+) direction until the values of the light splitting planes A + B and (C + D) of the light splitting detector 100 are the same. At this time, the CPU 30a stops outputting the (-) (+) movement drive data of the X-axis stem adjustment motor 7 outputted to the output terminal 0D2. In the process of FIG. 5G, the CPU 30a inputs the output of the A / D converter 20a so that the received light quantity values of the light splitting surfaces A, B, C, D of the light splitting detector 100 are ( Search for A + D)-(B + C) = 0. When the determined value in FIG. 5 (g) is not 0, the CPU 30a outputs (A + D)-(B + C)> in the process of FIG. 5 (h). If it is greater than 0 by searching for 0, it is determined that the light receiving amount of the dividing planes A and D of the light splitting detector l00 is larger than the light receiving light of the dividing planes B and C. Then, the Y-axis stage 3 of FIG. Outputs the step movement data that can move to the side to the output terminal (0Dl).

The first motor drive 40a that inputs the step movement data of the Y-axis stage 3 output from the CPU 30a buffers it and drives the Y-axis stage adjusting motor 4 in the negative direction. The stage 3 is driven one step on the Y axis, and the process (9) is checked after one step drive. When it is not the result of the repetitive check of FIG. 9 (9), the CPU 30a repeatedly checks the process h) and continuously receives the amount of received light on the light splitting surface of the light splitting detector 100 (A + D)-(B + If C) is greater than zero, the Y-axis stage driving motor 4 is driven.

If the process of FIG. 5 (h) determines that the value of (A + D)-(BC) is less than 0, it is determined that the amount of light received by the dividing planes B and C is large and the light splitting detector 100 is (+) The digital data value input through the A / D converter 20a is driven by driving the Y-axis stage drive motor 4 in the (+) axis direction so as to move in the axial direction such that (A + D)-(B + C) = 0. The Y axis of the light splitting detector 100 is adjusted by driving the Y axis stage adjusting motor 4 to the (+) axis until it becomes.

At this time, the detector substrate 12 to which the photodetector 100 is attached is moved in the (+) direction of the Y axis, so that the laser emitted from the laser radiation hole 19 moves from the planes B and C to the planes A and D. It becomes like that.

When the laser beam emitted from the laser radiation hole 19 of the laser pickup 14 is imaged in the correct spot on the light split detector 100 mounted on the detector substrate 12 and adjusted as described above, the light split detector ( 100) Each current output from each side A, B, C, and D is a current of light quantity and is the first, second, third, and fourth current / voltage converters through the output lines AL, BL, CL, and DL (10a-10d). ) Is entered.

Accordingly, when the 1-4 current / voltage converters 10a-10d convert the amount of light detection current into voltage and output the voltage to the A / D converter 2a, the A / D converter 20a converts the input voltage into a digital signal. The input port Port A of the CPU 30a is input.

At this time, the CPU 30a determines whether the input data is the value received by each divided surface as shown in FIG. 5 (g) (A + D)-(B + C) = 0. It judges that it has been adjusted and stops operation in the present state.

In this way, after the pickup state of the laser connected to the light splitting detector 100 is in the state as shown in c of FIG. 2, the CPU 30a outputs the adhesive substrate 12 with the adhesive surface of the laser pickup 14. The third step driving data capable of driving the Z-axis stage driving motor 10 to the terminal 0D3 is output to the third motor drive 40C.

At this time, the third motor drive 40C outputs the third step driving data capable of driving the Z-axis stage driving motor 10 to the third motor drive 40C through the output terminal 0D3.

At this time, the three-motor drive 40C buffers the Z-axis stage adjustment data output from the CPU 30a and adjusts the Z-axis stage adjustment motor 4 by one step so that the Z-axis stage 9 is moved to the upper axis.

On the other hand, after the laser spot is precisely adjusted, the locking knob 17 is adjusted to release the locking state, and the hliding knob 16 is adjusted to adjust the objective lens and the standard mirror 15 inserted into the main portion of the laser pickup 14. Release the holding state.

The objective lens and the objective lens for the CBP pickup having the standard depth of focus are attached to the main portion of the laser pickup 14 from which the standard mirror 15 is removed, and attached to the 0DP set for use as a CDP laser pickup.

As described above, the present invention accurately adjusts the laser imaging of the light splitting detector using a central processing unit while using an objective lens and a standard lens having a large focal length instead of a disk and an optical lens when attaching the light splitting detector to the laser pickup. By attaching to the laser pickup, it is possible to improve the quality at the time of manufacturing the set and at the same time, there is a great advantage in mass production.

Claims (2)

A method of attaching a photodetector for laser pickup, comprising the steps of: determining whether the substrate has touched the upper portion of the laser pickup by driving a Z-axis motor so that the substrate on which the light splitting detector is attached touches the upper portion of the laser pickup. If the determination of the first step does not reach the upper portion of the laser pickup, if the Z-axis motor is continuously lowered, the light receiving amount of each divided surface A, B, C, and D of the light splitting detector is (A + B). The second step of searching whether () + (C + D) = 0 and the division plane A of the light splitting detector when it is determined that the judgment of the second step is not (A + B)-(C + D) = 0; Search for whether the amount of light received by B, C, D is (A + B)-(C + D)> 0. When the judgment value is greater than 0, X until (A + B)-(C + D) = 0. Drive the motor of the axis one step in (-) direction, and if it is less than 0, drive the motor of the X axis one step in the (+) direction until light receiving amount is (A + B)-(C + D) = 0 A third step of judging whether the amount of received light of the detector is (A + D)-(B + C) = 0; and the light splitting when the judgment of the third step is not (A + D)-(B + C) = 0 The light receiving amount of the light splitting planes A, B, C, D of the detector is searched for (A + D)-(B + C)> 0 of the light receiving amount. Greater than the amount of received light The motor on the Y axis is driven one step in the negative direction until the light receiving amount of the lower surface A + D and the light receiving amount of (B + C) are the same, and the light receiving amount of the dividing surface A + D is the split surface (B + C). The fourth step of driving the Y-axis motor one step in the (+) direction until the light receiving amount of the split surface A + D and the light receiving amount of (B + C) are equal when the light receiving amount is less than And a fifth step of attaching the engine on which the light splitting detector is mounted on the laser pickup surface and driving the motor of the Z-axis up upon completion of the execution. A device for attaching a light splitting detector for laser pickup, comprising: inputting a change in the amount of current with respect to the amount of laser beam received at the A-mi in the light splitting detector 100 to input a light amount received at the splitting surface AD 1-4 current / voltage converter 10a-10d for changing and outputting the digital signal, and analog voltage for converting the voltage output from the 1-4 current / voltage converter 10a-10d into digital signals and outputting them as control data. A digital processing unit (20a), a central processing unit (30a) for analyzing control data input by a predetermined program embedded therein, and outputting first, second, and third step data corresponding thereto, and the central processing unit (30a) A Y-axis rigid plate 2 is formed on one side of the base 1 and a control circuit composed of 1-3 motor drives 40a-40c for inputting and driving first, second and third step data output from On the Y-axis fixing plate 2, the Y-axis stage 3 to which the X-axis fixing plate 5 is attached is Y screwed to the Y-axis stage 3 so that it can be moved to the Y-axis screwed to the Y-axis stage 3 so that it can be moved to the Y-axis by the output of the first motor drive 40a The shaft adjusting motor 4 and the X-axis fixing plate 5 are coupled to the X-axis stage 6 so as to be driven at the X-axis stage by the output of the second motor drive 40b. Screwed X-axis adjusting motor 7 and Z-axis fixing plates 8 ', 8 are attached to the upper surface of the X-axis stage 6, and Z-axis stage 9 is slide-coupled to Z-axis fixing plate 8 And a Z-axis adjusting motor 10 screwed to the Z-axis stage 9 so as to move in the Z-axis by the output of the third motor drive 40c, and a laser pickup mount mounted on one side of the base 1. A laser pickup 14 and a ray mounted on the upper side of the laser beam 13 to emit a predetermined amount of laser beams from the laser beam radiation hole 19. The objective lens and the standard mirror 15 for forming a beam for forming the focus of the laser beam on the main portion of the pickup 14, and the horizontal position of the laser pickup mount 14 mounted on the base 1 And an objective lens and a standard lens holder (18) having a nab mounted in a direction to hold and hold the objective lens and the standard lens (15).

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