Disk cartridge

Abstract: A generally square disk cartridge (3) for a recording disk (4) includes at least one air filter (10) in a corner (9) of the cartridge (3) and a circular rib (13) adjacent the disk (4) and between the disk (4) and filter (10). The cartridge (3) may also include a radial rib (12) connected to the circular rib (13) to enhance air flow to the filter (10). Air filters (10) may be located in each of the corners (9) of the cartridge (3) with associated circular (13) and radial (12) ribs to induce air flow to each.

Description: Background of the Invention 1. Field of the Invention This invention relates to disk cartridges which contain a recording/playback disk which is contained in such a way that the disk is free to rotate. 2. Description of the Prior Art A disk cartridge which contains a recording/playback disk contained in such a way in the cartridge that the disk is free to rotate, and recording and playback are accomplished by inserting a head into the cartridge while rotating the disk at high speed within the cartridge, is disclosed in U.S. Patent No. 4,459,628. However, in the above-mentioned patent, no form of dust prevention in the cartridge has been provided, and therefore, when a disk is rotated at high speed (for example 3600 rpm), air flow induced by the rotation causes dust in the cartridge to become disturbed, some of which becomes trapped between the disk and the head, which leads to problems such as dropouts and damage to the disk and head. JP-A-59,207,471 on which the preamble of claim 1 is based describes a magnetic disk cartridge with a perforate spoiler concentric to the outer periphery of the disk. An air discharge hole is drilled in the side plate of the casing and a dust proof filter is set in the hole in order to eliminate the disturbance of the air current within the cartridge, whereby dust is prevented from entering the cartridge. US-A-4,369,475 discloses a sealed disk drive with a filter member mounted on the inner surface of a bottom support member in a peripheral position thereof. An air guide, formed as an arcuate guide directs air flow created by a spinning disk through the filter. Radial obstructions on the inner surface of the bottom support member cause the air pressure below the disk to be increased relative to ambient so that inward leakage of air past faulty or worn seals is prevented. JP-A-6,104,280 discloses an optical disk cartridge with a dust proof filter, which does not contact the optical disk, and which is situated at the outer peripheral part of the optical disk with a space formed at the near side to the case of the filter to reduce flow resistance. Summary of the Invention According to the present invention there is provided a generally square disk cartridge adapted to contain a circular recording/playback disk in such a way that the disk is free to rotate, including an air filter disposed beyond the outer circumference of the said disk characterised in that:- said air filter is disposed in at least one corner of said generally square disk cartridge; and a circular rib is provided adjacent said outer circumference of said disk and between said disk and said filter, said circular rib being adapted to guide air flow induced by rotation of said disk (4) to said air filter; and a radial rib extends outwardly from substantially the center of said cartridge to connect with said circular rib at the end of said circular rib first encountered in the direction of rotation of said disk. In the disk cartridge of the present invention, an air filter is provided near the outer circumference of the cartridge and a rib for inducing the air in the cartridge to flow toward the air filter, is incorporated on the inner surface of the cartridge. When the disk is rotated at high speed within the cartridge, airflow induced by the rotation of the disk is directed toward the air filters by the ribs, and dust contained in the air is effectively removed by the air filters. Brief Description of the Drawings The novel features and advantages of the present invention will become more apparent to those skilled in the art upon consideration of the following detailed description which refers to the accompanying drawings, wherein: Figure 1 is a cross-sectional plan view of one embodiment of a cartridge of the present invention taken generally along the line I-I of Figure 2; Figure 2 is a cross-sectional elevational view of the cartridge of Figure 1 taken generally balong the line II-II of Figure 1; Figure 3 is a a cross-sectional plan view illustrating a second embodiment of the present invention shown in a manner similar to that of Figure 1; and Figures 4 and 5 are partial and enlarged cross-sectional views of recording disks which may be contained within the cartridge of the present invention. Description of the Preferred Embodiment As shown in Figures 1 and 2, cartridge 3 consists of upper and lower halves (1 and 2) made of a synthetic resin, and a recording/playback disk 4 which is contained in cartridge 3 in such a way that the disk is free to rotate. A turntable insertion hole 5 is provided at the center of the lower half 2 of the cartridge, and a pair of head insertion slots 6, formed in the upper and lower halves 1 and 2, are designed to be closed by a U-shaped shutter 7. Three air filters 10 are provided at the three corners 9, which are near the outer circumference of disk 4 in cartridge 3. Three pairs of ribs 11, which direct the airflow within the cartridge toward the air filters 10, are incorporated into the inner surface of cartridge 3. These ribs 11 consist of radial ribs 12, which stretch from the turntable insertion hole toward the outer circumference of the disk 4, and circular ribs 13, which stretch from the outer ends of the radial ribs 12 along the outer circumference of the disk 4 (disk rotation is in the direction of arrow a), and are incorporated into the upper and lower halves 1 and 2 and 1a and 2a. Radial ribs 12 are formed at a height of H₁ to provide a space 14 between the upper 4a and the lower 4b surfaces of disk 4 and the cartridge 3, and circular ribs 13 are formed at a height of H₂ to connect the inner surfaces 1a and 2a of the cartridge 3. Space 15, which leads to the before mentioned corners 9, is formed between the circular rib 13 and the outer wall 3a of cartridge 3. When the disk cartridge is inserted into the disk player (not shown), spindle 17 of turntable 16 is inserted through turntable hole 5 into the spindle insertion hole 18 in the center of disk 4, and as disk 4 is chucked on turntable 16, shutter 7 opens and a pair of recording/playback heads (not shown) are positioned on the upper 4a and lower 4b surfaces of the disk 4. Then, disk 4 is rotated at a high speed (for example 3600 rpm) in the direction of arrow a by turntable 16, and recording/playback of disk 4 is carried out within cartridge 3. At this time, airflow is induced in cartridge 3 by the high speed rotation of disk 4, and air is guided in the direction of the arrows b and c by ribs 11 and directed through air filters 10. Dust contained in the air is effectively removed by the air filters 10, which prevents trapping of dust between the upper and lower surfaces (recording surfaces) 4a and 4b of disk 4 and the heads in the cartridge. Also, rectification of air flow is accomplished, which prevents head oscillation and provides a uniform heat distribution for the upper and lower surfaces 4a and 4b of disk 4 by directing airflow in the cartridge by means of ribs 11. Figure 3 shows a variation of rib 11. Radial rib 12 forms a smooth circular curve starting at the center circumference of turntable insertion hole 5 and spreading toward the outer circumference of disk 4 to form a smooth curve in the direction of disk rotation (arrow a direction). In the case of the above-mentioned example, air current induction in the direction of arrow b is found to be improved, and the airflow into air filter 10 increases, and as a result, the degree of rectification of air current is increased. It should be noted that disk 4 used in the above-mentioned practical example is made by laminating a sheet comprised of a synthetic resin film, with a magnetic coating on both sides of a disk 4 made of materials such as synthetic resins or light metals under tension. That is, in the case of the structure shown in Figure 4, the base support surfaces 22a and 22b, and false support surfaces 23a and 23b are provided on both sides of the inner and outer circumferences 20a-20b of disk substrate 20, and grooves 24a-24b are formed between them. A pair of sheets 21a-21b are applied to false surfaces 23a and 23b with an adhesive. In the case of the structure shown in Figure 5, a neck G is provided on 23a and 23b for the base surfaces 22a and 22b and false surfaces 23a and 23b are parallel with the base surface 22a and 22b. A pair of sheets 21 are applied in the same manner as in Figure 4. Ring grooves 24a and 24b provide a clearance groove for adhesives thus maintaining the flatness of sheet 21. Practical examples of this model were mentioned with the figures described above; however, the model is not limited to the above-mentioned examples, and variations based on the technology of this model are possible. In particular, it should be recognized that fewer than three filters and channels could be employed, down to a minimum of one, and four filters could be employed, one in each corner of the cartridge. The design is applicable to disk cartridges for various types of disks other than SSR disks. As mentioned above, air current induced by high speed disk rotation in the cartridge is directed into air filters, and dust in the air current is effectively removed by the air filter in the disk cartridge. Therefore, dropouts and head and disk damage caused by dust trapped between the head and disk can be prevented, and improvements in recording/playback and the life of the head and disk can be obtained. Also, the ribs on the inner surface of the cartridge increase the rigidity of the cartridge, and therefore, compatibility and reliability of the cartridge for disk players is increased. When airflow in the cartridge is turbulent, oscillations tend to form in the floating head and it beats on the recording surface which becomes uneven and results in off-track recording. However, in the case of the disk cartridge of this model, the air current is rectified by directing the air current with ribs, and therefore, oscillation of the head can be prevented. A uniform heat distribution on the recording surface can also be obtained.

Claims: A generally square disk cartridge (3) adapted to contain a circular recording/playback disk (4) in such a way that the disk (4) is free to rotate, including an air filter (10) disposed beyond the outer circumference of the said disk (4) characterised in that:- said air filter is disposed in at least one corner (9) of said generally square disk cartridge (3); and a circular rib (13) is provided adjacent said outer circumference of said disk (4) and between said disk (4) and said filter (10), said circular rib being adapted to guide air flow induced by rotation of said disk (4) to said air filter (10); and a radial rib (12) extends outwardly from substantially the center of said cartridge to connect with said circular rib (13) at the end of said circular rib first encountered in the direction of rotation of said disk (4). A disk cartridge (3) according to claim 1 wherein said circular (13) and said radial (12) rib form a smooth curve which is convex with respect to the direction of rotation of said disk (4). A disk cartridge (3) according to claim 1 or 2 wherein said radial rib (12) comprises two portions, one disposed between each side of said disk (4) and said cartridge (3). A disk cartridge (3) according to claim 1 including three filters (10) each disposed in a respective corner (9) of said cartridge (3), three circular ribs (13) each disposed adjacent said disk (4) and between said disk (4) and one of said filters (10) with a separation between each of said circular ribs (13), and three radial ribs (12) each extending from substantially the center of said cartridge (3) to connect one with each of said circular ribs (13) at the ends of said ribs first encountered in the direction of rotation of said disk (4). A disk cartridge (3) according to claim 4 wherein said circular rib (13) and their associated radial ribs (12) form smooth curves which are convex with respect to the direction of rotation of said disk (4).

Inventors: LEONARD VURNEN J C O MINNESOTA, LEONARD, VURNEN J. C/O MINNESOTA MINING AND
Applicants: MINNESOTA MINING & MFG, SONY CORP, MINNESOTA MINING AND MANUFACTURING COMPANY, SONY CORPORATION
Application year: 1989
Main classification: G11B23
IPC codes: G11B23, G11B33