JPS60251527A - Method for adjusting fitting position of quartered sensor - Google Patents

Abstract

PURPOSE:To visually display the direction and quantity of center deviation so as to easily confirm the completion of adjustment, by adjusting the oriented position of a quartered sensor so that the light receiving output levels of areas facing to each other at both ends of an objective lens which is forcedly vibrated can be made equal to each other. CONSTITUTION:This invention utilizes a principle that, when the irradiated shape of a beam is completely extended in X-direction, the difference in light receiving output of an area provided in Y-direction becomes larger and the center deviation in Y-direction becomes distinct. Therefore, holding circuits 31 and 32 compare light receiving outputs of the 1st and 3rd areas 11a and 11c when the beam is completely extended in Y-direction. The 1st comparator circuit 37 which inputs the 1st and 2nd sample and hold outputs operates the 1st adjusting means 33 and adjust the position in Y-direction of a quartered sensor 11 by generating the 1st comparator output proportional to the center deviation in Y-direction and controlling the 1st driving circuit 39. The same operation is made for X-direction. A display means 41 which inputs both comparator outputs visually displays the direction and quantity of the center deviation and, therefore, completion of adjustment can be confirmed easily.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a method for adjusting the mounting position of a quarter centimeter used in an optical disc player.

←) Conventional technology Optical video disc players and compact disc players condense a laser beam onto the bits of a recording track formed on a disc record, then condense the reflected beam onto a sensor and convert the received light output into a reproduction signal. It is said that

In these optical disc players, it is necessary to focus a laser beam on the bits of the disc record during playback, and the objective lens must be moved to a focused position following the displacement of the disc record.

Therefore, many conventional optical disc players employ the focus control method disclosed in detail in Hikari No. 55-57722. As shown in Fig. 4, this focus control method focuses the light from a laser light source (1) onto a track (6) of a video disc (5) using a condenser lens (4), and collects the reflected light. The light separated by the beam splitter (3) and collected through the cylindrical lens (7) is received by the four-split sensor 111) shown in FIG. (11b
) (11a) are inputted to separate adder circuits σ2 and (131), the summed outputs are inputted to a differential amplifier [41], and the drive circuit is operated based on the differential outputs to collect the light. This is to move the lens to the focused position.Although the figure shows only two lenses due to the principle, 1Usually, a magnifying lens is placed in front of the laser light source.
An objective lens is placed on the disk record surface, and a condenser lens is placed between the beam splitter and the cylindrical lens. In addition, the cylindrical lens (7) shown in Figure 1 forms an angle of 45 degrees with the tracking direction, and when tracking is lost, the right area (11a
) (11dl and the left area (11b) 11o) there is a difference in the received light output level. Using this principle, tracking control is also possible by displacing the tracking mirror so that the center of the focused spot of the reflected beam coincides with the center of the quarter centimeter 11D.

Therefore, in order to perform accurate focus control and tracking control, it is necessary to specify the mounting position of the 4-split sensor so that the center of the focused spot and the center of the 4-split sensor coincide, but conventionally, the objective lens It was a tedious task to make installation adjustments while watching the output waveforms of the four developing oscilloscopes so that the photoelectric conversion outputs of the opposing areas would match among the photoelectric conversion outputs of each area through forced vibration.

(c) Object of the Invention In view of the above-mentioned points, the present invention proposes a method for attaching and adjusting quarter-centimeter parts, which facilitates and speeds up the attachment and adjustment work.

B) Structure of the Invention The present invention is characterized in that the mounting positions of the quarter centimeters are adjusted so that the received light output level of the opposing areas at both ends of the objective lens subjected to forced vibration are equalized.

(E) Embodiment The present invention will be described below with reference to an embodiment illustrating the present invention. Second
The figure shows the 4-division centimeters adjusted in this example.
Built-in pickup C) and semiconductor laser (1)
The laser beam emitted from
The racking mirror 1221 and the objective lens (2 East) are used to condense and irradiate the laser and one lens outside the pickup (P).In the adjustment of this embodiment, instead of the disc record, the reflective mirror @ is placed at the beam irradiation position. In order to arrange the laser beam, the laser beam is reflected through the reflective mirror (G).The reflected beam is transmitted through the objective lens Q1, the tracking mirror (22), and the beam splitter (3).
By entering the beam and changing the optical path, the beam is condensed and irradiated onto the condenser lens (old 4-split sensor by the 2IO cylindrical lens (7)).

For adjustment, first fix the reflecting mirror (2F5 on the pickup ψ). Next, the output terminal of the oscillation circuit (c) of the adjustment device is connected to the drive coil Cη that drives the objective lens. Furthermore, each area output terminal of the 4-split sensor u1) and each sample hold circuit (29) of the adjustment device
Connect 1C3■C31)432). Although not shown, adjustment screws are arranged to displace the 4-split centimeter (the old 4-split sensor) in the X and Y directions of the arrows in Figure 1, respectively, on the support base on which Ill is attached. Each driver (33a) (3413) of the first adjusting means and the second adjusting means 1341 is attached to the g-yoko.Of course, a driving voltage is also applied to the semiconductor laser (11). The adjustment device of this embodiment is configured so that the above-mentioned electrical connection and mechanical fixation can be achieved with a single touch by simply attaching the pickup (P).

The oscillation output of the 1 oscillation circuit (■) is picked up by the adjustment device as described above.
tL) is input to the drive coil c2D, and the objective lens is forced to vibrate. This forced vibration.

When the oscillation phase is 0°, the objective lens c23 is moved farthest from the reflecting mirror (c), and when the oscillation phase is 180°, it is moved closest. Therefore, the irradiation beam shape for the 4-division centimeter ttn extends in the X direction when the oscillation phase is 0°, and extends in the Y direction when the oscillation phase is 180°. Therefore, in this embodiment, one oscillation phase is O.
When the second. The received light output levels of the fourth area (11'1) and (11d) are compared.

When the oscillation phase is 180°, the first and third areas (11a)
It is necessary to compare the received light output levels (11c) and control the first and second adjusting means (2). Therefore, in this embodiment, in order to realize sampling, the oscillation output is first input to the waveform shaping circuit C35+, and a shaped output (b) that rises at 0 and falls at 180 of one oscillation phase is derived. The sampling pulse generation circuit which receives the shaped output (1)) generates a first sampling pulse (0) in synchronization with the rising edge of the input, and a second sampling pulse in synchronization with the falling edge of the input. 1st. Second sample hold circuit I29
1cn is the second area (1ib) and '$4 area (11(
Input each light reception output of 1) and generate s1 sampling pulse (
Sampling is performed in synchronization with C). That is, in this embodiment, when the beam irradiation shape is fully extended in the X direction,
This method utilizes the principle that the difference in the received light output level between areas arranged in the Y direction becomes large, and the center shift in the Y direction becomes clear. Meanwhile, '$1 6th area (11a)
The sixth and fourth sample-and-hold circuits tqDI32i inputting each light reception output (11a) perform sampling in synchronization with the @2 sampling pulse (d). Therefore,
3rd and 49th sample hold circuit C'1ll (3Z
is the first nest 6 when the irradiation beam is fully extended in the Y direction.
The light receiving outputs of areas (i ia ) (i 1c) will be compared.

The 11th stem comparison circuit inputs the 1st and 2nd sample and hold outputs.The 11th stem comparison circuit generates a first comparison output proportional to the center shift in the θησ direction, controls the first drive circuit (3), and operates the first adjustment means (c). Adjust the position in the Y direction of 11 by 4 centimeters.

Also, 6th. The second comparison circuit inputs the fourth sample and hold output +() and outputs a second comparison output proportional to the center shift in the X direction to control the second drive circuit (A1 and operate the second adjustment means 01 , adjust the position of the 4-split upper sensor aυ in the X direction.

Furthermore, the display means f41) for inputting the 1-car comparison output visually displays the direction of center deviation and 1, making it easy to confirm the completion of the adjustment.

(f) Effects of the Invention According to the present invention, complicated adjustment work can be accomplished automatically and quickly, and the effect is great.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a circuit block diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of the configuration of the same pickup, Fig. The optical system explanatory diagram and FIG. 5 each show a circuit block diagram of the same main part.弼...Objective lens, +24...Condensing lens, (7
)...Silitrical lens, Glto...4-split sensor. Applicant Sanyo Electric Co., Ltd. Agent Patent Attorney Shizuo Sano Figure 4 Figure 5

Claims (1)

[Claims] (1) Irradiate the reflected beam that has passed through the condensing lens and cylindrical lens into four centimeters, and observe the changes in the irradiation shape as described above.
In the focus control mechanism of an optical disc player, which detects changes in the received light output level in each area of a divided sensor and keeps the distance of the objective lens to the disc record constant. A method for adjusting the mounting position of a four-division centimeter, comprising forcibly vibrating the objective lens and displacing the four-division sensor so that the received light output level of opposing areas is equal at both ends of the vibration.