JPS6232352Y2 - - Google Patents

Description

[Detailed Description of the Invention] [A. Field of Industrial Application] The present invention relates to a lens position adjustment device in the optical axis direction that can be applied to a recently proposed optical pickup device for a digital audio disc player. [B Background of the Invention] FIG. 1 is a diagram showing an optical pickup device 1. As shown in FIG. The laser beam emitted from the laser diode 2 passes through a diffraction grating 3, a collimator lens 4, a polarizing beam splitter 5, a λ/4 plate 6, and an objective lens 7, and is irradiated onto a disk D. The reflected light modulated by the pit recorded on the disk D passes through the objective lens 7 and the λ/4 plate 6, and enters the polarizing beam splitter 5. The beam splitter 5 changes the optical path, and then After passing through a single lens 8 and a cylindrical lens 9, the light enters an optical sensor 10, from which an information (RF) signal, a tracking control signal, and a focus control signal are obtained. These are well-known configurations. Now, in the above-mentioned optical system, the position of each element on the optical axis must be defined fairly accurately. Typically, a laser diode 12, an optical sensor 1
In many cases, it is more convenient to adjust the position of each lens than to adjust the position of each lens. FIG. 2 is a diagram showing the positional relationship between the laser diode 2 and the collimator lens 4. The collimator lens 4 is for collimating the laser light output from the laser diode 2, but its parallelism requires considerable precision. In Figure 2, if the solid line is the precisely defined traveling direction of the laser beam, θ is ±0.02
It is desirable to keep it below 30 degrees. Now, if the focal length of the collimator lens 4 is h, the aperture radius is h, and the position of the laser diode is shifted by Z in the optical axis direction, then the formula becomes 1/+z+1/b=1/tanθ=h/b. To establish. If the commonly used values of =20 mm and h = 2.5 mm are substituted for this, and θ is set to 0.02 degrees as described above, Z = 56 x 10 ^-3 mm. In other words, the position of the collimator lens is ±56×
Fine adjustment is required within the range of 10 ^-3 mm. [C. Purpose of the present invention] It is an object of the present invention to enable fine adjustment of lenses, such as collimator lenses, constituting an optical pickup. [D] Structure of the present invention: A ring-shaped elastic body is installed between the holding frame that holds the lens and the main body of the device, and the position of the adjustment plate provided above the holding frame is adjusted using an adjustment screw. Accordingly, the elastic body is bent to adjust the position of the lens. [E Example] In the figure, the collimator lens 4 is held by a lens holding frame 11, and a ring-shaped elastic body 12 (rubber or molded from foamed resin, etc.) is attached. A hollow ring-shaped adjustment plate 13 is provided on the upper surface of the flange 11a, and at least two convex portions 13a on the lower surface thereof are in contact with the flange 11a. The support end 13b of the adjustment plate 13 is connected to the device main body 1.
The adjustment screw 14 is screwed onto the main body 1 of the device. When the adjustment screw 14 is rotated and adjusted, the convex portion 13a on the lower surface of the adjustment plate 13 comes into contact with the flange 11a of the lens holding frame 11, and the elastic body 12 is deflected, so that the direction of the optical axis of the lens 4 is adjusted. The position of is finely adjusted. After adjustment, to prevent misalignment due to vibration etc.
It is best to fix it with adhesive 15. [Effect] Since the ring-shaped elastic body is uniformly in contact with the entire outer circumference of the flange of the lens holding frame, when adjusting with the adjustment screw, the optical axis of the lens is not tilted and the optical axis direction is adjusted. You can adjust the position by moving only to

[Brief explanation of the drawing]

Fig. 1 shows a pickup, Fig. 2 shows a positional relationship between a laser diode and a collimator lens, Figs. 3 and 4 show an adjustment device according to the present invention, and Fig. 3 is a plan view. , Figure 4 is A of Figure 3.
-A' cross-sectional view. Reference numeral 1 denotes a pickup device main body, 4 a collimator lens, 11 a lens holding frame, 12 a ring-shaped elastic body, 13 an adjustment plate having a convex portion 13a, and 14 an adjustment screw.

Claims (1)

[Scope of utility model registration request] A lens, a lens holding frame for holding the lens, a ring-shaped elastic body installed between the lens holding frame and the pickup device main body, and an adjusting plate that contacts the top surface of the lens holding frame at at least two places. and an adjustment screw for screwing one end of the adjustment plate to the pick-up device main body, and by adjusting the adjustment screw, the ring-shaped elastic body is deflected via the adjustment plate, and the lens is bent. An optical pickup adjustment device configured to adjust the position in the optical axis direction.