CASSETTE TYPE MAGNETIC BUBBLE MEMORY

Abstract: A cassette type magnetic bubble memory comprising : a bubble memory device (1) including a bubble chip and lead terminals ; a connector (2) having contacts for electrically connecting the bubble memory device to an outside unit ; thin flexible printed substrates (3, 4) for electrically connect­ ing the contacts of the connector to the lead terminals of the bubble memory device ; and a cassette case (5, 6, 7) for accomodating therein the bubble memory device, connector, and printed substrates. The cassette case has inner walls of which same parts (26a, 26b, 27a, 27b, 29) are in contact with at least some parts of an outer face of the bubble memory device to retain the device in the cassette case so that the majority of the outer face of the device is spaced from the majority of the inner walls of the cassette case. The bubble memory device and the connector are arranged at the same horizontal level with respect to the longitudinal inserting direction of the cassette case.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cassette type bubble memory device, hereinafter referred to simply as a "cassette memory". Along with integrated circuit (IC) memories and floppy disks, bubble memory devices have come into increased use in recent years. Bubble memory devices have the following advantages: nonvolatile information storage; enabling easy rewriting; a solid chip construction without any mechanically movable parts; enhancing the reliability of the device; and small size and high density enabling mounting the bubble memory devices on printed circuit boards. Such devices have been recently found to be particularly useful as file memories or program loaders in the field of numerical control (NC) machines, industrial robots, terminal units for manufacturing control point-of-sale (POS) systems, office automation (OA) machines, and so on. In order to make such bubble memory devices easily carriable in the same manner as floppy disks or cassette tapes, a cassette memory has been proposed and applied in which a device is accommodated in a case which can be inserted into a bubble memory control unit. This kind of cassette memory must be small in size (thickness, width, and length) and light in weight so as to be easily carried by a person who operates these machines or units. 2. Description of the Related Art As well known in this field of art, a bubble memory device comprises a shield case of soft magnetic metal for accommodating therein a bubble memory chip, bias magnets, rectifiers, X and Y drive coils for generating rotating magnetic field for driving bubbles, and, if applicable, release coils for erasing the information stored in the bubble chips. As also well known, a memory system including a bubble memory device requires a direct peripheral circuit, also referred to as a "linear circuit", for directly driving and controlling the device with analog signals and an indirect peripheral circuit for controlling the direct peripheral circuit with digital signals of a transistor-transistor-logic (TTL) level in accordance with instructions for writing or reading of information from a host system. The direct peripheral circuit includes a coil drive circuit for driving and controlling the bubble memory chips by supplying a predetermined current, i.e., analog signals, to the drive coils or memory chips, a function drive circuit, and a sense amplifying circuit for amplifying the sensed output voltage of a few mV voltage level from a detector in the bubble memory chips and converting it into TTL level. The indirect peripheral circuit includes a bubble control circuit for controlling the drive of the bubble memory chips by inputting various control digital signals to the direct peripheral circuit in accordance with the instructions for writing or reading information from the host system and outputting the digital sensed signals from the direct pheripheral circuit (sense amplifier circuit) to the host system. One prior art cassette memory, such as disclosed in Japanese Unexamined Utility Model Publications (Kokai) Nos. 56-56098 and 56-56099, is constructed with the bubble memory device and outside lead connector both mounted on a solid printed substrate (a printed substrate with no flexibility) and accommodated in a plastic or metal case. The printed substrate may be provided with a direct peripheral circuit (sense amplifier circuit) as well as the memory device. The cassette memory thus constructed can be detachably inserted into a receiving connector of a magnetic bubble memory control unit provided with direct and indirect peripheral circuits. In this cassette memory, the printed substrate usually has a thickness of 0.8 to 1.6 mm. The lead terminals of the device are formed with a "stand off" so as to position the device about 1 mm above the printed substrate and thus improve soldering when dipping in solder. The total thickness of the known cassette memory, including the thickness of the printed substrate, the space between the device and the printed substrate, the height of the bubble device, and the thickness of the cassette case, is about 20 mm. Another magnetic bubble memory cassette having a similar arrangement is disclosed in EP-A-0 106 474, the cassette case being provided with inner walls to retain the bubble memory device in the cassette case by contact with the printed substrate on which the bubble memory device is mounted. Still, another cassette memory has been proposed wherein a printed substrate is formed with an opening. The bubble memory device is situated within the opening to obtain a thin cassette memory having a thickness of about 10 mm. In this case, however, the printed substrate has to horizontally extend from the peripheral side of the device. SUMMARY OF THE INVENTION An object of the present invention is to provide a cassette type magnetic bubble memory smaller in size and lighter in weight and thus easier in handling than conventional memories. This object is attained by a magnetic bubble memory cassette comprising a bubble memory device including a bubble chip and lead terminals; a connector having contacts for electrically connecting the bubble memory device to an outside unit; printed substrate means for electrically connecting the contacts of the connector to the lead terminals of the bubble memory device; and a cassette case for accommodating therein the bubble memory device, the connector, and the printed substrate means, the cassette case having inner walls to retain the memory device in the cassette case, wherein, according to the invention: at least some parts of the inner walls of the cassette case are in contact with at least some parts of primary outer faces of the bubble memory device to retain the memory device in the cassette case while leaving a majority of the primary outer faces of the device being spaced from the majority of the inner walls of the cassette case; the connector is arranged in front of the bubble memory device with respect to the longitudinal direction of insertion of the cassette case; the bubble memory device has front and rear end faces, with respect to the direction of insertion of the cassette case, on which end faces the lead terminals are arranged; the printed substrate means comprises a pair of respectively shorter and longer flexible printed circuit substrates which overlap at their one ends where the connector is mounted; the lead terminals on the front end face and the lead terminals on the rear end face are connected to the contacts of the connector via the shorter and longer flexible printed substrates respectively; and the longer flexible printed substrate extends along and over one of the primary outer faces of the bubble memory device. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an exploded perspective view of a cassette type magnetic bubble memory according to the present invention; Figures 2A to 2E are views of the cassette memory shown in figure 1, illustrating the connection between a bubble memory device and a connector, wherein figure 2A is a plan view thereof, and figures 2B to 2E are views taken along lines or seen from arrows indicated by B, C, D, and E, respectively, in figure 2A; Figures 3A to 3F are views of the cassette memory shown in figure 1, illustrating the assembled status thereof, wherein figure 3A is a plan view thereof, figure 3B is a bottom view thereof, and figures 3C to 3F are views seen from arrows C, D, E, and F, respectively, in figure 3A; Fig. 4 is a schematic perspective view illustrating use of a cassette memory according to the present invention; Fig. 5 is an enlarged perspective view of a memory control unit shown in Fig. 4; Fig. 6 is a perspective view of another embodiment of a cassette memory according to the present invention; and Fig. 7 is a longitudinal cross-sectional view of the cassette memory shown in Fig. 6. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to Figs. 1 to 3, a cassette memory of the present invention includes a bubble memory device 1, an outer leading connector 2, flexible printed circuit substrates 3 and 4, a cassette case 5 consisting of an upped case half 6 and a lower case half 7 made of plastic, a metal plate 8 serving as a shield, and ground terminals 9. The bubble memory device 1 includes a shield case 10, in which a bubble memory chip (not shown) and the related elements are accommodated, and an inner supporting piece 11 (Fig. 2E), supporting a plurality of lead terminals 12a and 12b protruding from the openings at the respective ends of the shield case 10 to constitute a dual-in-line (DIP) type terminal arrangement. The lead terminals 12a and 12b are each bent in an L-shape at the ends thereof so as not to protrude from the shield case 10. The shield case 10 may have attached on its outer faces sheets 13 a sheet indicating the Nos. of inferior loops of the bubble memory chip. The connector 2 includes a plastic piece 14 accommodating therein a plurality of female contacts 15 (Fig. 2D) each having an end protruding toward the inner side of the mold 14 as a terminal 16 (Fig. 2B). The plastic piece 14 is formed integrally with projections 17 at the respective side walls thereof. The flexible printed substrates 3 and 4 are made of thin and flexible substrates, as known in the art, formed therein with conductive patterns. One of the substrates, i.e., substrate 3, connects the connector terminals 16 to the lead terminals 12a of the device 1 at the side facing to the connector 2. The other substrate 4 connects the connecting terminals 16 to the other connecting terminals 12b of the device at the side opposite the connector 2. The printed substrates 3 and 4 are overlapped at their one ends on an insulative plate 19 and adhered to the insulative plate 19, as shown in Fig. 2B. The other ends of the substrates 3 and 4 are extended and connected to the respective lead terminals 12a and 12b. The ends of the printed substrates 3 and 4 and the insulative plate 19 are previously formed with holes into which the connecting terminals 16 are inserted. The conductive patterns located at these ends are exposed from the insulative sheet for to allow the terminals to be electrically connected to the conductive patterns during solder dipping. The conductive patterns at the sides of the printed substrate 4 are formed as ground patterns 20 (Fig. 2A) having ear-shaped exposed terminals 22 at the respective ends 21 thereof. The terminals 22 are connected through lead lines 23 to the ground terminals 9. The upper and lower case halves 6 and 7 of the cassette case 5 are both substantially U-shaped in cross-section, so that the device 1 and the connector 2 are supported and secured in predetermined positions between the upper and lower case halves 6 and 7 by attaching and fixing them with respect to each other. Consequently, the upper and lower case halves 6 and 7 are provided in their inside areas with portions 24a and 24b for securing the device 1 and portions 25a and 25b for securing the connector 2. The securing portions 24a and 24b include projections 26a and 26b (each of the upper and lower case halves has four such projections 26), contacting four corners of the shield case 10 of the device 1, and longitudinal projections 27a and 27b (each of the upper and lower case halves has two such projections 27), contacting upper and lower faces of the shield case 10 of the device 1. These projections 26 and 27 are formed integrally with the upper and lower case halves 6 and 7. The securing portions 24a and 24b also include openings 28a and 28b at the majority of areas corresponding to the front and back faces of the device 1. The securing portion 25b of the lower case half 7 is formed at each of its sides with a pair of projections 29, between which a projection 17 provided at each side end of the connector 2 is inserted. In addition, the molded body 14 of the connector 2 is also fixed between the upper and lower case halves 6 and 7 in the securing section 25. One of the upper and lower case halves 6 and 7 has also a projecting flap 30 formed along the periphery of the abutting face thereof and used for adhering the two case halves. The metal plate 8, made of, for example, a steel strip, is bent into a substantially U-shaped section, the outer faces thereof being able to be attached with a memo sheet 31 or another sheet 32 for indicating, for instance, the type of the device. The metal plate 8 is also provided at the ends thereof with grounding projections 33 and screw holes 34 for detachably mounting the metal plate 8 onto the case 5 by means of screws 38. The steps for assembly of the cassette case according to the present invention will now be described in detail. First, the bubble memory device 1 is connected to the connector 2 by means of the flexible printed substrates 3 and 4, provided at their one ends with the insulative plate 19. The other ends of these printed substrates 3 and 4 are inserted into the spaces defined between the supporting piece 11 and the lead terminals 12a and 12b, at the side adjacent to the connector 2 and the opposite side, respectively, as shown in Figs. 2E and 2C. The spaces are the same as the thickness of the printed substrates 3 and 4, so that the latter are held only by inserting them into the spaces. Then, the leading terminals 12a and 12b are electrically connected by soldering to the signal conducting patterns 18 (Fig. 2A) or the ground patterns 20 of the printed substrates 3 and 4. On the other hand, the connecting terminals 16 of the connector 2 are inserted through the insulative plate 19 into the holes at the one ends of the printed substrates 3 and 4. Thus, as shown in Figs. 2A to 2E, one printed substrate 3 connects the connector 2 to the lead terminals 12a of the device 1 adjacent to the connector 2. On the other hand, the other printed substrate 4 extends along and over the bottom surface of the device 1 and connects the connector 2 to the lead terminals 12b of the device opposite to the connector 2. Then, the ground terminals 9 are attached to the device 1. Thus, an assembly including the device 1, the connector 2, and the printed substrates 3 and 4 can be accommodated in the cassette case 5 by enclosing these inside elements with the upper and lower case halves 6 and 7. Consequently, the device 1 is located in the securing section 24b such that the four corners and the upper and lower walls of the device 1 are supported and embraced by the projections 26b and 27b, respectively. Then, the connector 2 is, on the other hand, placed on the securing section 25a such that the projections 17 of the connector 2 are supported and embraced between the projections 29 of the lower case half 7. The ground terminals 9 are inserted into slits 37 at the step portions 36 providing case guide slots 35 (Fig. 3C) at the respective sides of the cassette case 5. The portion of each ground terminal 9 which is to be connected to the lead line 23 is positioned inside the case 5. The face of the terminal 9 is exposed in the step portion of the guide grooves 35 (Fig. 3C), such that the ground terminal 9 is connected to the ground of the bubble memory control unit or cassette body (not shown) before the connector 2 is connected to the corresponding connector in the cassette body, when the cassette case 5 is inserted into the cassette body (not shown). Then, the upper and lower case halves 6 and 7 are attached and fixed with respect to each other by hot melting the peripheral flap 30 with the help of ultrasonic welding, so that the device and the connector 2 are fixed with the cassette case 5. Then, the U-shaped metal plate 8 is fitted to the cassette case 5 such that the plate 8 covers the upper and lower openings 28a and 28b and embraces the case halves 6 and 7. The metal plate 8 is then fixed to the cassette case 5 by means of screws 38. In this state, the metal plate 8 is located on the outside of the longitudinal projections 27a and 27b to define spaces between the upper and lower faces of the device 1 and the metal plate 8 corresponding to the thickness of the longitudinal projections 27a and 27b. The metal plate 8 also serves as a handling portion for an operator who handles this cassette memory. The upper and lower case halves 6 and 7 are provided with recesses 39 as shown in Fig. 1 for guiding the metal cover plate 8 so it does not come out from the surfaces of the cassette case 5. Also, the upper case half 6 is provided with a transverse slot 40 (Fig. 1) which is engaged with a retaining member (not shown) in the cassette body to prevent the cassette memory from coming out while the memory is inserted into the cassette body. Finally, the sheets 31 and 32 are attached to the surfaces of the metal cover plate 8 so as to cover the screw heads, although the latter are seen in Figs. 3A and 3B. Thus, a cassette memory as shown in Figs. 3A to 3F is assembled. Figure 4 illustrates an example of use of a cassette memory according to the present invention, wherein the cassette memory in question is indicated by reference numeral 50. A host system 60 is a small sized portable word processor including a display 61, and a keyboard, printer, and so on (not illustrated). A bubble memory control unit 70 controls the reading and writing in the device 1 of the cassette memory 50 in accordance with word processing control signals for (drafting, deletion, correction) from the host system 60. Figure 5 is an enlarged perspective view of the memory control unit 70, which includes in its housing 71 various circuits. One of the corners of the housing 71 is formed by a detachable cover 72. Inside the cover 72 within the housing there is a connector (not illustrated). A cassette memory 50 is inserted into the housing 71 so that the connector of the cassette memory is connected to the connector in the housing 71. The cover 72 is attached to the housing 71 so that a projection 73 thereof engages with a switch (not shown) for confirming that the cover 72 is closed. The system also includes a connecting cable 80 and an AC power connecting cable 90. In this system, the bubble memory 50 is used as an outside memory. Therefore, the memory control unit 70 includes direct and indirect peripheral circuits, as mentioned above, as well as a DC battery (not shown) and DC/DC converter for powering the direct and indirect peripheral circuits. In this system, the control signals for word processing and actual word data are input via the cable 80 into the memory control unit 70, which controls and drives the device 1 in accordance with the above-mentioned control signals to write the word data in the device, or to read out the recorded data in the device and to transmit the data to the host system 60. The memory control unit 70 can be driven by AC power, if the cable 90 is used. Figure 6 is a perspective view illustrating a second embodiment of cassette memory according to the present invention, which is adapted for use for a 4 Mega-bit bubble memory chip. Figure 7 is longitudinal cross-sectional view of this second embodiment. In this embodiment, a bubble memory device 1 is connected to a connector 2 by means of two flexible printed substrates 3 and 4 in the same manner as the first embodiment. However, the longer flexible printed substrate 4 is provided, on its face opposite to the bubble memory device 1, with mini-flat IC's 100, which are so-called function IC's, such as sense selectors or function selectors, for adapting the same common connector 2 for different capacities of bubble memory devices. Therefore, if this bubble memory device is used for a 4 Mega-bit memory and if the bubble memory device in the first embodiment is for a one Mega-bit memory, the same connector 2 can be interchangeably used. A cassette case 105 consists of upper and lower case halves 106 and 107 made of such as of plastic. The upper case half 106 is substantially the same size as the upper case half 6 (Fig. 1) in the first embodiment, except it has no central opening 28 (Fig. 1) and is instead provided with a central portion made of steel plate 101. The lower case half 107 has a larger depth than the lower case 7 (Fig. 1) in the first embodiment in order to accommodate therein the mini-flat IC's 100 as mentioned above. The lower case half 107 has no opening 28 (Fig. 1), either. In the cassette case 105 is provided a substantially U-shaped thin metal plate 111 for ground connection, which is arranged along the inner wall of the cassette case 105 so as to cover the bubble memory device 1, the mini-flat IC's 100, and the flexible printed substrates 3 and 4. The upper and lower cassette case halves 106 and 107 are provided, on the inner faces thereof adjacent to a connector opening 102, with conductive metal coatings 103 and 104 which are electrically connected to the respective ends of the metal plate 111 by means of connecting lines 113 and 114. This metal plate 111 has a pair of ear-shaped projections (not shown in the drawings) at both sides thereof adjacent to the ear-shaped exposed terminals 21 (Figs. 2A and 2B) of the flexible printed substrate 4. These projections are in contact with the exposed terminals 21 of the flexible substrate 4 to be electrically connected to the ground terminals 9 (Fig. 1 and Fig. 6). The connector 2 and cassette guide grooves 35 are quite the same in size and arrangement as those of the cassette case 5 in the first embodiment, so this cassette case 105 is insertable into the memory control unit 70 (Fig. 5) in the same manner as the cassette case 5. In this second embodiment, static electricity transmitted from the operator's hand can be easily discharged through the steel plate 101, the thin metal plate 111, connecting lines 104, and the metal coating portions 103 to the outside of the cassette case 105. Therefore, the inner bubble memory device 1 or information stored therein is not affected by such static electricity.

Claims: A magnetic bubble memory cassette comprising : a bubble memory device (1) including a bubble chip and lead terminals (12a, 12b); a connector (2) having contacts (16) for electrically connecting the bubble memory device to an outside unit; printed substrate means (3, 4) for electrically connecting the contacts of the connector to the lead terminals of the bubble memory device; and a cassette case (5) for accommodating therein the bubble memory device, the connector, and the printed substrate means, the cassette case (5) having inner walls to retain the memory device (1) in the cassette case (5), characterized in that : at least some parts of the inner walls of the cassette case (5) are in contact with at least some parts of primary outer faces of the bubble memory device to retain the memory device in the cassette case while leaving a majority of the primary outer faces of the device being spaced from the majority of the inner walls of the cassette case; the connector (2) is arranged in front of the bubble memory device (1) with respect to the longitudinal direction of insertion of the cassette case (5); the bubble memory device (1) has front and rear end faces, with respect to the direction of insertion of the cassette case, on which end faces the lead terminals (12a, 12b) are arranged; the printed substrate means comprises a pair of respectively shorter and longer flexible printed circuit substrates (3, 4) which overlap at their one ends where the connector is mounted; the lead terminals (12a) on the front end face and the lead terminals (12b) on the rear end face are connected to the contacts of the connector via the shorter and longer flexible printed substrates (3, 4), respectively; and the longer flexible printed substrate (4) extends along and over one of the primary outer faces of the bubble memory device (1). A magnetic bubble memory cassette as claimed in claim 1, wherein the cassette case (5) comprises upper and lower case halves (6, 7), each made of a plastic material, which are joined together. A magnetic bubble memory cassette as claimed in claim 2, wherein the upper and lower case halves (6, 7) have inner faces on which protruding portions (26a, 26b, 27a, 27b) are integrally formed for retaining and positioning both said bubble memory device (1) and said connector (2) within the cassette case (5) in the up-and-down, front-and-rear, and left-and-right directions. A magnetic bubble memory cassette as claimed in claim 2, wherein the upper and lower case halves (6, 7) made of a plastic material are joined together by ultrasonic welding. A magnetic bubble memory cassette as claimed in claim 2, wherein the upper and lower case halves (6, 7) made of a plastic material are joined together by adhesive. A magnetic bubble memory cassette as claimed in claim 2, wherein a sheet for indicating the Nos. of inferior loops is attached on one of the faces of the bubble memory device (1), at least one of the upper and lower halves (6, 7) having an opening (28a, 28b) through which the indicating sheet on the device is visible. A magnetic bubble memory cassette as claimed in claim 2, wherein the bubble memory device (1) has at least top and back faces, the upper and lower case halves (6, 7) have openings (28a, 28b) at positions corresponding to the top and back faces of the bubble memory device, and a metal cover plate (8) is attached to the cassette case to cover the openings, the top and back faces of the device being spaced from the metal plate. A magnetic bubble memory cassette as claimed in claim 7, wherein the metal plate for covering the openings (28a, 28b) is detachably mounted on the cassette case (5). A magnetic bubble memory cassette as claimed in claim 7, wherein the metal plate (8) is bent in a substantially U-shape to be detachably mounted on the cassette case (5) so as to grasp the upper and lower case halves (6, 7) and cover the openings (28a, 28b). A magnetic bubble memory cassette as claimed in claim 7, wherein a sheet for indicating the Nos. of inferior loops is attached on one of the faces of the bubble memory device (1), and at least one of the openings (28a, 28b) of the upper and lower case halves (6, 7) serves as an opening through which the indicating sheet on the device is visible. A magnetic bubble memory cassette as claimed in claim 1, wherein the printed circuit substrates (4, 5) have a ground pattern (20), said cassette case (5) is made of a plastic material and has a ground terminal (9) exposed on a face of the cassette case and electrically connected to a ground pattern of a printed circuit substrate. A magnetic bubble memory cassette as claimed in claim 1, wherein the cassette case (5) is provided on side faces thereof with guide grooves along which the cassette case is insertable into a bubble memory control unit, and a ground terminal (9) is formed in at least one of the guide grooves. A magnetic bubble memory cassette as claimed in claim 1, further comprising function integrated circuit elements (100) being mounted on a face of the longer flexible printed substrate (4) opposite the bubble memory device (1) so that the circuit elements are also accommodated in the cassette case (105). A magnetic bubble memory cassette as claimed in claim 13, wherein the memory device (1), the connector (2), the printed circuit substrates (3, 4), and the function elements (100) are covered by a ground metal plate (111) received in the cassette case (105). A magnetic bubble memory cassette as claimed in claim 14, wherein at least the longer printed circuit substrate (4) has a ground pattern, the cassette case (105) is made of a plastic material, and has a ground terminal on one face, and the ground metal plate (111) is electrically connected to the ground terminal and to the ground pattern of the printed circuit substrate (4).

Inventors: IMAI, SATORU, KASHIRO, KOUEI, MAEGAWA, HARUMI, SUKEDA, TOSHIAKI, TAKAI, SAKAN
Applicants: FUJITSU LIMITED
Application year: 1985
Main classification: G11C19
IPC codes: G11C19, G11C11