JPH0233295Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a focus lens unit for an optical information reading device.

Optical video discs have recesses called pits arranged on the disc surface to form concentric or spiral tracks.
Video information is recorded by the length and interval of these pits.

Information is read from the video disk by making light incident on a video track consisting of pits on the disk and demodulating the reflected light which is modulated depending on the presence or absence of the pits. At this time, the disk is rotated at high speed by a predetermined driving device, but since the entire recording surface of the disk is not flat, vertical movement of the recording surface due to rotation is unavoidable. Therefore, in order to always accurately focus the light on the track of the video disk, a focus lens unit is provided which is movable in the direction perpendicular to the recording surface of the disk, and this unit is also adapted to move up and down the disk. A focus servo device is provided for follow-up movement.

Here, since it is necessary to always converge the light onto the video track over the maximum range in which the disk moves up and down, the movement range of the focus lens unit must be designed to be somewhat large. As a result, if for some reason the focus servo device is unable to adequately control the movement of the focus lens unit, the unit and disk may collide, resulting in damage to the disk. .

The present invention has been made in view of the above, and it is an object of the present invention to provide a focus lens unit for an optical information reading device that does not damage the disk even if it collides with the disk.

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

FIG. 1 is a sectional view of a first embodiment of the present invention. In the figure, a focus lens 1 for converging irradiated light onto an information recording surface of a disk (not shown) is held by a cylindrical holding member 2. This holding member 2 is movable in the direction perpendicular to the recording surface of the disk (in the vertical direction in the figure) in order to always accurately focus the light that has passed through the focus lens 1 on the track of the disk. The movement is controlled by the device to follow the vertical movement of the disk.

A protective pad 3 made of a rubber-like elastic material or the like is provided at the tip of the holding member 2 so as to protrude from the tip.
is installed. This protection pad 3 is in a state where the focus servo device cannot sufficiently control the movement of the holding member 2 for some reason.
This is to protect the disk from damage when the holding member 2 collides with the disk. A low friction layer 4 is provided on the surface of the protective pad 3 that comes into contact with the disk in order to suppress heat generation due to contact with the high speed rotating disk.

Here, in the event of an actual collision, there may be a case where the disk cannot be sufficiently protected only by the cushioning effect of the protective pad 3, which is unique to the elastic body. In addition, protective parts 3
If the protective pad 3 is deformed or the installation condition is poor, the contact area of the protective pad 3 during a collision will become very small and local stress will occur, making it impossible to obtain the original cushioning effect of the protective pad 3 or lowering the low friction layer 4. There are problems such as accelerated wear.

Therefore, in this embodiment, an annular groove 5 is formed in the inner bottom of the protective pad 3, and the protective pad 3 is attached to the tip of the holding member 2. Therefore, the tip of the holding member 2 and the groove 5 define a completely sealed air chamber 6. As a result, the protective pad 3 has a buffering effect inherent to an elastic body and is easily deformed against mechanical stress, so that the contact area in the event of a collision is expanded and local stress can be reduced. Moreover, since the air chamber 6 is completely sealed, it also functions as an air cushion.

FIG. 2 is a sectional view of a second embodiment of the present invention, in which parts equivalent to those in FIG. 1 are designated by the same reference numerals. In the figure, the structure is the same as that in FIG. 1 except that a through hole 7 with an extremely small diameter is formed in the protective pad 3 to communicate the air chamber 6 with the outside air. In this way, by forming the through hole 7 with a small diameter, a braking effect can be obtained due to the viscous resistance of the air in the air chamber 6 that is discharged to the outside through the through hole 7 in the event of a collision.

Note that the shape of the protective pad 3 and the connection structure with the holding member 2 are not limited to the above embodiments, and various configurations can be considered.

As detailed above, according to the present invention, even if the focus lens unit collides with the disk for some reason, the disk can be reliably protected. Furthermore, even if the protective pad 3 is deformed or the attachment condition is poor, the stress on the abutment surface during a collision becomes almost uniform, so the life of the low friction layer 4 is extended. Furthermore, according to the present invention, the air chamber can be formed by the protective pad with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a first embodiment of the present invention;
FIG. 2 is a sectional view of a second embodiment of the present invention. Explanation of symbols of main parts, 1... Focus lens, 2... Holding member, 3... Protective part, 6...
air chamber.

Claims (1)

[Scope of utility model registration request] A focus of an optical information reading device that includes a focus lens for converging irradiated light onto an information recording surface of a disk and a holding member that holds the focus lens, and is movable in a direction perpendicular to the information recording surface. The lens unit includes a protective pat provided at the distal end of the holding member so as to protrude from the distal end, the protective pat is provided with a groove, and a groove is provided at the distal end and is perpendicular to the movable direction. A focus lens unit for an optical information reading device, wherein an air chamber is formed by the surface and the groove, and a tip of the protective pad that contacts the information recording surface is a substantially flat surface.