Compact electronic apparatus and method of assembling the same

Abstract: A personal computer comprises a housing having a bottom wall. A plurality of functional components (30, 40, 50, 60) are arranged side by side on the bottom wall of the housing. A fixture plate (105) is arranged on top of the functional components (30, 40, 50, 60) and secured to the functional components and the bottom wall by means of screws. The functional components are held between the fixture plate and the bottom wall.

Description: This invention relates to a compact portable electronic apparatus such as a book shaped personal computer or a word processor and, more particularly, to a compact portable electronic apparatus as defined in the preamble portion of claim 1 comprising a housing preferably of synthetic resin containing therein various functional components such as a floppy disc drive, hard disc drive, and the like, and a method of assembling the same. Recently, there are known book or notebook-shaped portable computers having a flat box like base unit on which a keyboard and a display unit with a flat display panel are mounted. A portable computer of the above identified type normally comprises a synthetic resin housing that provides a frame for a base unit and contains therein various functional components such as a floppy disk drive and/or a hard disc drive along with circuit board carrying thereon various circuit components. These functional components are normally supplied in the form of modules and placed in positions on the bottom wall of the housing, where they are then secured by means of screws to the bottom wall. Upon assembling the conventional portable computers of this type, however, each of the functional components placed on the bottom wall is required to be independently secured by screws to the bottom wall. Thus, the attachment of the components is very troublesome, and thus, the assembling of the computer takes large time periods. Further, the bottom wall of such a housing has a rather complicated profile because bosses for receiving screws should be provided on the bottom wall at positions on which functional components are placed. These bosses inevitably reduce the space inside the housing that can otherwise be used to accommodate components. In recent portable computers, it is desired that the housing is reduced in size in order to improve the portability of the computer. However, if the mounting space in the housing is reduced by the bosses, it is necessary to increase the size of the housing so as to increase the mounting space thereof, which opposes the requirement for providing a compact computer. In addition to the various functional components, the housing of a portable computer contains therein a circuit board on which various circuit components are mounted. This circuit board normally has a rectangular shape substantially corresponding to the size of the bottom wall of the housing. So the space on the bottom wall is substantially occupied by the circuit board. In order to improve the portability of the recent computers, it is required to reduce the length and the width of the housing. Thus, the mounting space in the housing tends to be further reduced in size, and forces the circuit board to be made further smaller. For solving this problem, there is proposed an arrangement wherein a single relatively large circuit board is divided into a plurality of small parts, and the divided board are arranged in the housing with being overlapped with one another and connected to one another by means of flexible connecting boards. Some of the circuit components carried by the circuit boards generate high frequency noises during operation. Such high frequency noises can interfere with wired as well as wireless telecommunications when leak out of the housing. Therefore, in conventional portable computers, the inner surface of the housing of is normally coated with a conductive layer typically by plating so as to provide the housing with an electromagnetic shield effect. The circuit boards and other electronic components of the computer are enclosed with the conductive layer. With such an arrangement, however, the circuit boards are apt to move relative to each other as they are connected together by flexible connecting boards, making the mutual connection of the boards unstable. This means that, when securing one of the circuit boards to the housing, it may accidentally shake the other circuit boards connected to it, causing them to hit and damage the conductive layer on the inner surface of the housing with their corners and edges and/or the components carried on them until eventually the conductive layer partly comes off from the cabinet and loses its electromagnetic shield effect. In order to avoid such problem, it is necessary to carefully assemble the circuit board in the housing, thereby making the assembly troublesome. Additionally, the housing needs to be provided with a large number of bosses for screws for securing a plurality of circuit boards to the housing in a multilayered manner. Such additional bosses make the housing even more rugged and the efficiency of assembling a portable computer by using such a large number of screws to be driven into a rugged housing is inevitably low. In a portable computer of the type under consideration, if a user desires to use an application software and/or an application device, it is often required to modify the computer by arranging additional components on the circuit substrates and/or replacing some of the existing components with improved ones in accordance with the application software and/or the application devices to be used. The multilayer arrangement of a plurality of circuit boards as described above then needs to be so devised as to facilitate such addition and/or replacement of circuit components without interfering with the circuit boards. A compact portable computer with the features of the preamble portion of claim 1 is described in IEEE SPECTRUM, vol. 28, no. 5, May 1991, NEW YORK, pages 37-41. In view of the above described circumstances, it is therefore an object of the present invention to provide a portable electronic apparatus and a method of assembling the same, wherein a plurality of functional components can be easily placed in and fixed to the housing with a single operation to facilitate the overall assembling operation. It is another aspect of the invention to provide a portable electronic apparatus wherein a housing has a simple profile that allows functional components to be installed in a highly space saving manner without enlarging the dimensions of the housing. It is still another aspect of the invention to provide a portable electronic apparatus wherein synthetic resin components and metal components of the housing can be easily separated from each other so that it may be effectively disposed as waste without damaging the environment as its recyclable components can be completely recovered once its service life is over. It is a further aspect of a preferred embodiment of the invention to provide a portable electronic apparatus which can securely shield noise generated from electronic parts on circuit boards which are arranged in a housing in a multilayered manner, and wherein the circuit boards can be easily installed in the housing, thereby facilitating the assembly of the apparatus. In order to achieve the above objects, a portable electronic apparatus according to the present invention comprises the features of claim 1. The invention also provides the method of claim 12. Preferred embodiments of the apparatus are defined in the sub-claims. With a portable electronic apparatus having an above described configuration, the functional components can be removed from the housing in a single operation of unscrewing the fixture plate. Therefore, the synthetic resin housing can be easily separated from the metal fixture plate and the functional components having metal parts when the service life of the apparatus is over and the apparatus is to be disposed as waste so that any recyclable parts of the apparatus may be recovered as resources. With the method of assembling a portable electronic apparatus, a plurality of functional components can be secured to their respective proper positions only by the operations of laying a fixture plate on top of the functional components and securing the fixture plate to the housing and the functional components by means of screws once the components are placed in position on the bottom wall of the housing, the functional components do not need to be individually secured to the bottom wall as in the case of conventional assembling methods. So the overall operation of assembling functional components and other components into a portable electronic apparatus is remarkably simplified and therefore can be carried out in an effective and efficient manner. With the arrangement according to a preferred embodiment, once the circuit substrates are secured to the respective receiving portions of the shield members and the shield members are superposed with each other, the circuit boards are automatically laid one above another to form a multilayer structure and surrounded by the shield members. Thus, the circuit boards that are mutually and electrically connected by means of flexible connecting board are arranged one above another like so many shelves to form a unit with the shield members surrounding them before they are mounted on the housing so that they may be housed in the housing without losing their safe and stable posture. Since the layered circuit boards are surrounded by the shield members, no additional conductive layers are required to be arranged inside the housing to electromagnetically shield them. Additionally, since the shield members formed of a metal are by far mechanically stronger than a conventional conductive layer prepared by plating, they are least likely to he damaged during assembling the circuit boards into a portable electronic apparatus and, therefore capable of effectively contain within them any noises that may be generated by the components of the apparatus. Since the circuit boards mutually and electrically connected by means of a flexible connecting board are housed in the housing as a unit along with the shield members, it may be apparent that the housing only needs to be provided with means for rigidly holding either one of the shield members. This means that the housing may have a simplified inside configuration as compared with a conventional housing provided with means for rigidly holding a plurality of circuit boards. This fact and the fact that the circuit boards form a unit with the physically strong shield members can greatly simplify the operation of assembling the circuit boards into a portable electronic apparatus. Preferably, more than two of the circuit boards may be arranged on one of the shield members in two layers. Thus, there will be formed three layers of circuit boards that are surrounded by the shield members by simply interposing the shield members together. Accordingly, three circuit boards superposed with each other can be easily assembled in a limited space of the housing. This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Figs. 1 through 13 illustrates a portable electronic apparatus according to an embodiment of the present invention, in which: Fig. 1 is a schematic perspective view of the apparatus, having its display unit swung open; Fig. 2 is an exploded perspective view of the housing; Fig. 3 is a perspective view showing a bottom case in which functional components such as a FDD and a HDD are mounted; Fig. 4 is a sectional view of a base unit, illustrating the positional relationship of a shield plates, a board unit and the HDD of the apparatus; Fig. 5 is a perspective view of the computer having its display unit held in the closed position; Fig. 6 is an exploded perspective view illustrating an area connecting the display unit and the base unit; Fig. 7 is a perspective view showing a battery storage section of the bottom; Fig. 8A is a sectional view showing a state wherein a battery pack is stored in the battery storage section; Fig. 8B is a sectional view taken along line A-A of Fig. 8A; Fig. 9 is an exploded perspective view of a pair of shield members securely holding thereon respective circuit boards; Fig. 10 is an exploded perspective view of a first shield member; Fig. 11 is a plan view showing a plurality of circuit boards; Fig. 12 is a perspective view showing a shield plate and a liquid crystal display supported in a recess of the shield plate; and Fig. 13 is an enlarged sectional view of an area of the shield plate where the liquid crystal display is anchored. Now, the present invention will be described with reference to the accompanying drawings that illustrate a preferred embodiment of the invention. Fig. 1 shows a portable computer 1 sized to A4. The computer 1 comprises a flat box-shaped base unit 2 and a flat panel type display unit 3. Housing 4 of the base unit 2 that defines the profile of the base unit 2 is divided into a bottom case 5 having a top opening and a top cover 6 for concealing the top opening of the bottom case 5. The bottom case 5 and top cover 6 are formed of a synthetic resin material such as ABS resin. As illustrated in Fig. 4, the bottom case 5 has a flat bottom wall 5a and a peripheral wall 5b extending from the bottom wall 5a. The top cover 6 has a substantially flat top wall 6a and a peripheral wall 6b extending from the top wall 6a. The outer surface of the peripheral wall 6b of the top cover 6 is coplanarly aligned with that of the peripheral wall 5b of the bottom case 5 and the peripheral walls 5b and 6b jointly define the front, side and rear ends of the housing 4. As shown in Figs. 2 and 4, the top cover 6 is provided on its top wall 6a with a large opening that serves as a keyboard outlet 7, which substantially occupies the entire area of the front half of the top wall 6a. The top wall 6a has a projecting portion 8 arranged at its rear end. The projecting portion 8 extends between the opposite sides of the top cover 6 and has on its underside and near the opposite ends a pair of grooves serving as stem bearing portions 10a, 10b and a pair of cut off areas 11a, lib arranged adjacent to the respective stem bearing portions 10a, 10b. As seen from Figs. 1 and 4, a keyboard unit 13 is disposed in the front half area of the housing 4. The keyboard unit 13 has a keyboard body 14 formed of synthetic resin and having a rectangular plate shape adapted to fit in the keyboard outlet 7. The keyboard body 14 has a flat upper surface and a flat lower surface and a number of keys 15 are arranged on the upper surface. An aluminum reinforcement plate 17 is laid under the lower surface of the keyboard body 14 with a film 16 inserted therebetween. On the film 16 is printed a circuit pattern in order to transmit switching signals generated by depressing keys. The reinforcement plate 17 is rectangular and has a length and a width same with those of the keyboard body 14. The reinforcement plate 17 serves to increase the strength of the keyboard body 14 and, at the same time, prevent switching noises generated by key operations from leaking outside the housing 4. The keys 15 of the keyboard unit 13 are exposed through the keyboard outlet 7 of the housing 4, and the reinforcement plate 17 faces inside the housing 4. As seen from Figs. 1 and 6, the display unit 3 comprises a thin box-shaped housing 20 and a liquid crystal display 21. The housing 20 is divided into a front panel 20a and a rear panel 20b. The front panel 20a is provided with a display opening 22, through which the liquid crystal display 21 is exposed. The housing 20 is provided at its opposite sides with a pair of horizontal stems 24, 25 projecting therefrom. As shown in Fig. 6, the stem 24 is formed by combining a front stem half 24a integrally formed with the front panel 20a and a rear stem half 24b integrally formed with the rear panel 20b. The other stem 25 is also configured in a similar manner. The stems 24 and 25 are received by the respective stem bearing portions 10a and 10b and connected to the bottom case 5 of the housing 4 via respective hinges 26. Each of the hinges 26 comprises a hinge shaft 27 projecting sideways from the stems 24 or 25. As shown in Fig. 6, the hinge shaft 27 of the hinge 26 for the stem 24 is rigidly held at an end by a bracket (not shown) buried in the stem 24 and connected at the opposite end to another bracket 28, which is rotatable around the axis of the hinge shaft 27, with a wave washer 29 interposed therebetween. The wave washer 29 gives rise to frictional resistance between the bracket 28 and the hinge shaft 27 to inhibit free rotation of the hinge shaft 27, and the bracket 28 is inserted into the bottom case 5 from above and rigidly secured to it. The above description also applies to the hinge shaft 27 for the stem 25. Thus, the hinge shafts 27 provide pivots for rotary movement of the display unit 3 so that it may be rotatable to take a first position where it covers the keyboard unit 13, a second position where it stands up behind the keyboard unit 13 to expose the liquid crystal display 21 and a third position where the liquid crystal display 21 is found almost lying flat and opposite to the keyboard unit 13 with respect to the hinge shafts 27. In the first position as illustrated in Fig. 5, the outer surface of the housing 20 of the display unit 3 is coplanarly aligned with that of the housing 4 including the projecting portion 8 to make the computer 1 appear like a flat book that can be conveniently carried by hand. When the display unit 3 is brought to its third position, the top cover 6 becomes removable from the top of the bottom case 5. Under this condition, the hinges 26 are concealed by the projecting portion 8 of the top cover 6 and, if seen from outside, the stems 24, 25 appear to be located in the respective stem bearings 10a, 10b. As indicated in Fig. 3, a floppy disc drive (hereinafter referred to as FDD) 30, a hard disc drive (hereinafter referred to as HDD) 40 and a battery pack 50 are arranged in the above mentioned order from right to left in the front half of the bottom case 5 as so many functional components. Each of the FDD 30, the HDD 40 and the battery pack 50 is of modular design and located below the keyboard unit 13. The FDD 30 comes in a metal casing 31, which is provided on its front end with an aperture 32 through which a floppy disc can be inserted into and ejected from the casing 31 and a push button 33 that triggers ejection of a floppy disc when it is depressed. The casing 31 is also provided on its side ends with respective metal brackets 34a, 34b having respective lugs 35a, 35b, 36a, 36b extending upward from the top of the casing 31. The FDD 30 is disposed on the bottom wall 5a with the aperture 32 and the push button 33 facing the front end of the bottom case 5 and exposed to the outside through an access opening 37 cut through the front wall of the bottom case 5 near its right side end. As shown in Figs. 3 and 4, the HDD 40 also comes in a metal housing 41 that contains magnetic discs and heads hermetically sealed therein. A circuit board 42 is arranged on the top of the housing 41 and various circuit components are mounted on the circuit board 42 to form a control circuit and a drive circuit for the HDD 40. The housing 41 is arranged on the bottom wall 5a side by side with the FDD 30 and carries on its lateral wall a metal bracket 44, which by turn comprises a pair of fixtures 45a, 45b that are rigidly secured to respective upright bosses 46, 46 projecting from the bottom wall 5a by means of screws 47, 47. The battery pack 50 is rechargeable and serves as power source when the computer 1 is used without any commercial power supply. The battery pack 50 has a flat and rectangular synthetic resin case 51, which contains therein a plurality of rechargeable batteries and is arranged on the bottom wall 5a of the bottom case 5. As shown in Figs. 3 and 7, the bottom wall 5a of the bottom case 5 carries thereon a pair of guide walls 52a, 52a standing there to guide the sides of the case 51 and defining a batter storage section 53 within the bottom case 5. The battery storage section 53 is located to the left of the bottom case 5 and accessible through a battery insertion opening 54 cut through the front wall of the bottom case 5 near its left side end. Thus, a battery pack 50 may be inserted into and ejected from the battery storage section 53 through the insertion opening on the front side of the housing 4. As illustrated in Fig. 7, the battery access opening 54 includes a bottom opening 54a cut through the bottom wall 5a of the bottom case 5. The front edge of the bottom wall 5a defining the rear end of the bottom opening 54a is found behind the front wall of the bottom case 5. As shown in Fig. 8A, the case 51 of the battery pack 50 has a downward ridge 55 extending along the front end and between the opposite side ends of the case 51. The downward ridge 55 makes part of the bottom wall 5a of the bottom case 5 when the battery pack 50 is inserted into the battery storage section 53 and serves as a hook for receiving a finger tip when the battery pack 50 is pulled out of the battery storage section 53. As illustrated in Figs. 8A and 8B, the battery storage section 53 is provided along its rear end with a pair of upwardly projecting stoppers 56a, 56b. As a battery pack 50 is inserted into the battery storage section 53, its front end eventually abuts the stoppers 56a, 56b so that the battery pack 50 is held in position within the battery storage section 53. On the other hand, the case 51 is provided along its front end with positive and negative power supply terminals 57a, 57b connected to the batteries housed in the case 51 and a pair of connector terminals 58a, 58b connected to a safety fuse and a temperature sensor (not shown). As shown in Fig. 3, a board unit 60 that operates as one of functional components is housed in the rear half of the bottom case 5 and located behind the FDD 30, the HDD 40 and the battery pack 50 as it extends all the way between the opposite side ends of the bottom case 5. The board unit 60 of the embodiment comprises, as shown in Figs. 9 and 11, first through fifth circuit boards 61a through 61e and a shield frame 62 holding and surrounding the circuit boards 61a through 61e arranged in mutually separated three layers laid along the height of the housing 4. The circuit boards 61a through 61e are prepared by cutting a single rigid board base and have appropriate respective dimensions. Each of the boards carries on its upper and lower surfaces given circuit patterns (not shown) formed by printing. As shown in Fig. 11, the circuit boards 61a through 61e are divided into two groups. The first through third circuit boards 61a through 61c are arranged on a side by side basis along the transversal direction of the bottom case 5 to form a first board group 63, while the fourth and fifth circuit boards 61d and 61e are arranged in a similar manner to form a second board group 64. The first circuit board 61a and the second circuit board 61b are electrically connected with each other via a first flexible connecting board 65a, whereas the first circuit board 61a and the third circuit boards 61c are electrically connected with each other via a second flexible connecting board 65b. Similarly, the fourth circuit board 61d and the fifth circuit board 61e are electrically connected with each other via a third flexible connecting board 65c, whereas the first circuit board 61 and the fourth circuit board 61d are electrically connected with each other via a fourth flexible connecting board 65d. Thus, while the circuit boards 61a through 61e are separated from one another, they are electrically mutually connected. The circuit boards 61a through 61e carry on their upper and lower surfaces a number of circuit components 66, which are connected to the respective circuit patterns. The circuit components 66 include those that generate and emit high frequency noises as well as heat. Particularly, since the third circuit board 61c in this embodiment constitutes a power supply board, most of the circuit components arranged on it can generate heat at a considerable rate. The shield frame 62 comprises a first shield plate 68, a second shield plate 69 and a connector board 70 disposed between the shield plates 68 and 69. Each of the shield plates 68 and 69 and the connector board 70 is made of a metal plate having an electromagnetic shield effect. As illustrated in Figs. 4, 9 and 10, the first shield plate 68 comprises as integral parts thereof an oblong base plate section 71 to be directly placed on the bottom wall 5a of the bottom case 5 and an upright section 72 standing from some of the edges of the base plate section 71. The base plate section 71 is provided with first support portions 73 for supporting the first circuit board 61a, second support portions 74 for supporting the second circuit board 61b and third support portions 75 for supporting the third circuit board 61c. These support portions 73, 74 and 75 are formed by partly cutting the base plate section 71 to produce curved slits and bending the cut areas upward along the lines connecting the opposite ends of the respective slits. The first and second support portions 73 and 74 have a substantially equal height, whereas the third support portions 75 is higher than the other two support portions 73 and 74. The first and second circuit boards 61a and 61b are supported respectively by the front ends of the first and second support portions 73 and 74 and secured thereto by means of screws. Note that the base plate section 71 covers the undersides of the first and second circuit boards 61a and 61b and some of the circuit components 66 are arranged between the base plate section 71 and the circuit board 61a or 61b. As seen from Fig. 9, the second connecting board 65b connecting the first circuit board 61a and the third circuit board 61c is bent to show a turned U-shaped cross section so that the third circuit board 61c may be located above the first and second circuit boards 61a and 61b. Moreover, the third circuit board 61c is supported by the front end of the third support portions 75 and secured thereto by means of a screw at an end opposite to the end where it is connected to the connector board 65b. Thus, it may be understood that the three circuit boards 61a through 61c are arranged on the first shield plate 68 in two layers. The base plate section 71 of the first shield plate 68 has a right side extension 71a extending from the side of the base plate section 71 located opposing to the second circuit board 61b. The extension 71a is found behind the FDD 30 and covered by a metal plate cover 80 as illustrated in Fig. 10. The cover 80 comprises a partition 81 disposed above the extension 71a and lugs 82 arranged on the four corners of the cover 80. The lugs 82 are respectively placed on the corners of the extension 71a and the front ends of the second support portions 74 and secured thereto by means of screws 83. As shown in Figs. 3 and 9, the second shield plate 69 comprises as integral parts thereof an oblong base plate section 85 transversally extending on the housing 4 and an upright section 86 standing from an edge of the base plate section 85. The base plate section 85 is provided with first support portions 87 for supporting the fourth circuit board 61d and second support portions 88 for supporting the fifth circuit board 61e. The fourth circuit board 61d and the fifth circuit board 61e are respectively secured to the front ends of the first support portions 87 and the front ends of the second support portions 88 by means of screws. When, as illustrated in Fig. 9, the circuit boards 61a through 61e are respectively secured to the first and second shield plates 68 and 69, the shield plates 68 and 69 are connected to each other via the fourth connecting board 65d. Then, the shield plates 68 and 69 are put together on a one on the other basis, i.e., superposed with each other, the fourth connecting board 65d being bent to show a turned U-shaped cross section. Under this condition, the shield plates 68 and 69 are rigidly secured to each other by means of screws (not shown). Now, the base plate section 71 of the shield plate 68 and the base plate section 85 of the shield plate 69 are oppositely located and the circuit boards 61d and 61e secured to the base plate section 85 are located above the circuit boards 61a through 61c arranged on the base plate section 71. Thus, the circuit boards 61a through 61e are arranged in three layers in the housing 4. Note that, in this embodiment, the third circuit board 61c dedicated to power supply and hence apt to emit heat at an enhanced rate is disposed between the first circuit board 61a and the fourth circuit board 61d. When the shield plates 68 and 69 are put together on a one on the other basis, the upright sections 72 and 86 are arranged side by side to provide the left side wall and the rear wall of the shield frame 62. The upright sections 72 and 86 are provided with a plurality of connector access apertures 92 that allows lead wires of various connectors to pass therethrough. As shown in Figs. 3 and 4, the connecting board 70 is disposed between front end of the base plate section 71 and that of the base plate section 85 and secured to the base plate sections 71 and 85 by means of screws. The connecting board 70 provides the front wall of the shield frame 62 and the fourth circuit board 61d is partly supported on the top of the connecting board 70. Near the left side end of the connecting board 70, there is formed an slot 94 through which the front end of the battery pack 50 is introduced. The battery pack 50 is held under an area of the base plate section 85 located above the slot 94. The board unit 60 comprising the circuit boards 61a through 61e and the shield frame 62 is loaded on the bottom wall 5a of the bottom case 5. Then, as shown in Figs. 3 and 4, lugs 95a extending from the connecting board 70 and a lug 95b arranged at the front right corner of the second shield plate 69 are fitted to respective bosses 46 erected on the bottom wall 5a of the bottom case 5 by means of screws. Note that the lug 95b is secured to the corresponding boss 46 as it is placed on the case 31 of the FDD 30, whereas the lugs 95a are respectively secured to the bosses 46 with anchoring members 46b of the HDD 40. As seen from Figs. 6 and 9, anchoring members 96a and 96b are formed at the respective ends of the upright sections 72 and 86 that provide rear wall for the shield frame 62 and the brackets 28 of the hinges 26 are respectively secured to the anchoring members 96a and 96b by means of screws. Thus, the shield frame 62 is designed to support the display unit 3 too. As shown in Figs. 2 and 3, a pair of synthetic resin covers 98a, 98b are secured to respective rear end areas of the upper surface of the shield frame 62. These covers 98a, 98b are so designed as to conceal the openings of the stem bearing portions 10a, 10b from under when the top cover 6 is fitted onto the bottom case 5 and provide bottoms for the respective stem bearing portions 10a, 10b. As shown in Fig. 3, of the circuit boards 61a through 61e arranged in three layers, the fourth circuit board 61d located on the top layer is provided with a spare zone 101 for receiving thereon one or more than one additional circuit components 100 such as a keyboard controller to be installed in order to upgrade the portable computer. The spare zone 101 is located at the middle of the board unit 60 in the longitudinal direction of the unit 60 and will be filled with circuit patterns. The base plate section 85 of the second shield plate 69 that covers the fourth circuit board 61d from above is provided with a cut out area 102 at a position facing at least the spare zone 101 and most of the upper surface of the fourth circuit board 61d including the spare zone 101 is upwardly exposed through the cut out area 102. On the other hand, the upper surfaces of the FDD 30, the HDD 40 and the battery pack 50 are covered by a metal shield plate 105 that also operates as a fixture plate. The shield plate 105 comprises, as illustrated in Figs. 2 through 4 and 12, a flat and rectangular main section 105a realized in a form that corresponds to the plan view of the front half of the bottom case 5. The main section 105a is provided along its edges with a plurality of lugs 106. The shield plate 105 is then secured to the lugs 35a, 35b, 36a, 36b, while the lugs 106 are secured by screws 47 to the corresponding bosses 46 on the bottom wall 5a of the bottom case 5. Of the lugs 106, those arranged at the rear corners of the main section 105a are laid on the respective lugs 95a, 95b of the shield frame 62 on the bosses 46 so that the shield frame 62 and the shield plate 105 are electrically connected with each other. Thus, once the lugs 106 of the shield plate 105 are secured to the bosses 46 by screws, the FDD 30, the HDD 40 and the battery pack 50 are clamped by the shield plate 105 and the bottom wall 5a and consequently firmly fixed to the bottom case 5. As shown in Fig. 4, the main section 105a of the shield plate 105 is located below the keyboard unit 13, and the reinforcement plate 17 of the keyboard unit 13 is located opposing to the shield plate 105 with a narrow clearance therebetween. A pair of metal plate springs 107a and 107b are arranged near the respective side edges and on the upper surface of the shield plate 105. Each of the plate springs 107a, 107b are equipped with a plurality of resiliently deformable contact pieces 108, which are held in contact with the reinforcement plate 17 of the keyboard unit 13 so that the shield plate 105 and the reinforcement plate 17 are electrically connected with each other. As illustrated in Fig. 12, the shield plate 105 has as integral part thereof an extension 110 extending from the rear end of the main section 105a toward the board unit 60. The extension 110 has a shape corresponding to that of the cut out area 102 and covers the cut out area 102 and the fourth circuit board 61d that carries thereon the spare zone 101. The extension 110 has at its front end a connecting portion 111 as integral part thereof, and the connecting portion 111 is secured to the rear end of the shield frame 62 by means of screws. Thus, the extension 110 may not lift unintentionally, and the board unit 60 is held between the extension 110 and the bottom wall 5a of the bottom case 5. As seen from Figs. 4 and 12, the extension 110 is located close to the rear half of the top wall 6a of the top cover 6 and has a transversely extending recess 112 for receiving a reflection type liquid crystal display 113, which is designed to display various operating conditions of the computer 1. The liquid crystal display 113 has an oblong rectangular plan view. While it is held immovable relative to the recess 112 in the transverse direction of the housing 4, its position is adjustable forwardly or rearwardly within a given limit. More specifically, the recess 112 has a width slightly greater than that of the liquid crystal display, and oppositely arranged pairs of engaging members 114a, 114b and 115a, 115b are projecting toward the corresponding ones from the front and rear edges of the recess. As shown in Fig. 13 in enlarged dimensions, the front and rear sides of the liquid crystal display 113 are separated from the respective engaging members 114a, 114b and 115a, 115b by narrow clearances 116 so that the liquid crystal display 113 may be shifted forwardly or backwardly within the limit. The top surface of the liquid crystal display 113 is found above the upper surface of the extension 110. An oblong display window 117 is formed through the rear half of the top wall 6a of the top cover 6 to expose the liquid crystal display 113. A transparent protective cover 118 is fitted to the display window 117. The top wall 6a has as integral part thereof on its inner surface with downwardly projecting ridges 120a and 120b extending respectively along the front and rear edges of the display window 117. As shown in Fig. 13, the ridges 120a and 120b are respectively located right above the upper front edge and the upper rear edge of the liquid crystal display 113 and oppositely chamfered to produce guide bevels 121a and 121b that provide a greater distance therebetween toward the ridgelines. The guide bevels 121a and 121b are so arranged that they respectively abut the upper front edge and the upper rear edge of the liquid crystal display 113 when the top cover 6 is properly put on the bottom case 5. As a result of the abutment, the liquid crystal display 113 is moved forward or rearward as a function of the inclination of the guide bevels 121a and 121b to offset any clearances between the display window 117 of the top cover 6 and the liquid crystal display 113. At the same time, the liquid crystal display 113 is pressed against the bottom of the recess 112 so that the display 113 may not be allowed to accidentally tilt in any directions. Then, there will be described a method of assembling the FDD 30, HDD 40, battery pack 50, and board unit 60 in the bottom case 5 with respect to the computer 1 having the above-mentioned arrangement. Firstly, an FDD 30, an HDD 40, a battery pack 50 and a board unit 60 are placed on the respective proper positions on the bottom wall 5a of the bottom case 5. Then, the lug 95b extending from the connecting board 70 of the shield frame 62 is laid on the upper surface of the metal casing 31 of the FDD 30 and the slot 94 formed near the left side of the connecting board 70 is aligned with the leading end of the battery pack 50. Now, the board unit 60 is partly superposed on the FDD 30 and the battery pack 50. Thereafter, the lug 95a extending from the connecting board 70 of the board unit 60 is secured to the corresponding boss 46 together with the fixture 45b of the HDD 40 by means of a screw 47 and the other lug 95b is secured to the other boss 46 also by means of a screw 47. Under this condition, the shield plate 105 is placed on the FDD 30, the HDD 40, the battery pack 50 and the board unit 60. Then, the main section 105a of the shield plate 105 is secured to the brackets 34a, 34b of the FDD 30 by means of screws, and the lugs 106 arranged along the edges of the main section 105a are secured to the respective bosses 46 also by means of screws. Note that one of the lugs 106 is placed on the fixture 45a and are then secured to the corresponding boss 46 together with the fixture 45a, as shown in Fig. 4. At the same time, the connector member 111 of the extension 110 of the shield plate 105 is secured to the rear end of the shield frame 62 by means of screws so that the extension 110 may not lift unintentionally. When the shield plate 105 is secured to the bosses 46 by means of screws, the FDD 30, the HDD 40, the battery pack 50 and the board unit 60 are held between the shield plate 105 and the bottom wall 5a of the bottom case 5, so that these functional components are rigidly secured to their proper positions on the bottom wall 5a. As described above, according to the embodiment of the present invention, the FDD 30, the HDD 40, the battery pack 50 and the board unit 60 of the above embodiment are securely held between the shield plate 105 and the bottom wall 5a by simply securing the shield plate 105 that carries thereon these functional components to the bosses 46 by means of screws. Thus, a plurality of functional components can be aligned and secured in a very simplified manner. Accordingly, the assembling of the computer 1 can be easily carried out without requiring the functional components 30, 40, 50 and 60 to be individually and sequentially secured by means of screws in a lengthy manner as in the case of conventional portable computers. Besides, it is not necessary to provide many bosses on the bottom wall 5a at positions individually corresponding to the functional components 30, 40, 50 and 60. Thus, the total number of bosses to be formed on the bottom wall 5a can be reduced, so that the bottom wall 5a of the bottom case 5 can be formed in a simple shape without concave or convex portions. In accordance with the reduction of the number of bosses, the bottom case 5 may show a simple structure and those spaces which are defined for arranging conventional bosses can be used as spaces for receiving components. Because more space is made available within the bottom case 5, the functional components 30, 40, 50 and 60 may be placed very close to the bottom wall 5a and any adjacent ones of the functional components 30, 40, 50 and 60 may be brought closer to each other on the bottom wall 5a to reduce the overall space required for the components. With the computer 1 having the configuration as described above, since the lugs 95b of the board unit 60 to be secured to the bosses 46 are partly placed on the casing 31 of the FDD 30, the FDD 30 may be pressed against the bottom wall 5a by way of the lugs 95b. In other words, the adjacently arranged board unit 60 and the FDD 30 can be securely fitted to the bottom wall 5a by a single operation of driving screws 47 into the bottom wall 5a, thereby reducing the total number of portions to be screwed and simplifying the assembling operation. Additionally, since the fixture 45b of the HDD 40 and the lugs 95a of the board unit 60, and the fixture 45a of the HDD 40 and the lug 106 of the shield plate 105 are commonly secured to the respective bosses 46, the total number of screws 47 and bosses 46 can be further reduced, thereby simplifying the assembling operation and increasing the mounting space in the bottom case 5. Furthermore, since the shield plate 105 is used as the fixture plate for holding the functional components 30, 40, 50 and 60 between itself and the bottom wall 5a, any high frequency noises generated by the functional components 30, 40, 50 and/or 60 during operation can be shield within the housing 4. Thus, interference of radio and telecommunications due the leakage of the high frequency noises can be prevented. Moreover, the FDD 30, the battery pack 50 and the board unit 60 can be released from the bottom case 5 by simply undoing the screws fastening the shield plate 105 to the bottom case 5 and separating the shield plate from the bottom case. The HDD 40 can also be released from the bottom case 5 by removing the shield plate 105 from the bottom case 5 and undoing a single screw fastening the fixture 45a to the bottom case 5. Thus, all the functional components 30, 40, 50 and 60 that comprise metal parts, the metal shield plate 105 and the synthetic resin bottom case 5 may be easily separated from one another. This means that, when the computer 1 lost its service life, parts formed of synthetic resin and metal parts can be easily divided each other, so that any parts can be easily recycled and can cope the problem of environmental pollution. As described earlier, the board unit 60 of the above embodiment is realized by arranging first through third circuit boards 61a through 61c on a first shield plate 68 in two layers, while securing fourth and fifth circuit board 61d and 61e side by side onto a second shield plate 69, and then superposing the first and second shield plates 68, 69 with each other, so that the circuit boards 61a through 61e may be arranged in three layers. So the five circuit boards 61e through 61e connected one another through the flexible connecting boards 65a to 65d are kept in a multilayered manner before they are assembled in the bottom case 5. Further, the circuit boards 61a to 61d are arranged in layers and completely surrounded by the shield plates 68 and 69, and a single board unit 60 having a shielding effect is constructed by the circuit boards and the shield plate. Thus, the housing 4 does not need to have a conductive layer for shielding noises. Since both the first shield plate 68 and the second shield plate 69 are made of a metal plate, they are by far stronger than a conductive layer prepared by plating and, therefore, least liable to be damaged when the board unit 60 is mounted on the housing 4. Consequently, high frequency noises that may be generated from any of the circuit components 66 are effectively confined within the housing 4 to thereby improve the reliability of the computer. Additionally, since the housing 4 is provided on its inner surface with no conductive layer, the operation of mounting the circuit boards 61a to 61e can be carried out without paying particular attention not to have the circuit boards collide with the housing 4 that may adversely affect the efficiency of the mounting operation. With the above-mentioned arrangement, since the circuit boards 61a to 61e form a unit with the first and second shield plates 68 and 69 and then mounted on the housing 4, the bottom case 5 only requires bosses arranged on the bottom wall 5a for securing the first shield plate 68. Thus, the housing 4 does not need to has many fixing portions to which the circuit boards are individually secured, so that the inside of the housing 4 may have a very simplified profile. Further, the circuit boards 61a to 61e are rigidly held by the shield plates 68 and 69 within the housing 4 without the fear of being shaken, and it is possible to easily carry out the operation of mounting circuit boards 61a to 61e within a limited space inside the housing 4. To upgrade the computer 1 having a configuration as described above by installing in the spare zone 101 of the board unit 60 an additional circuit component 100 such as a keyboard controller, the display unit 3 is firstly rotated to the third position, where the display unit 3 is away from the top cover 6. Under this condition, the top cover 6 and the keyboard unit 13 are removed from the bottom case 5 to expose the upper surface of the bottom case 5. Now, the shield plate 105 covering the FDD 30, the HDD 40 and the battery pack 50 and the board unit 60 come to be exposed. Then, the shield plate 105 is taken out by undoing the screws 47 securely holding the shield plate 105 to the bottom case 5. Since the shield frame 62 of the board unit 60 arranged adjacent to the shield plate 105 has a cut out area 102 for exposing the spare zone 101, and the shield plate 105 has as integral part thereof an extension 110 for concealing the spare zone 101, the spare zone 101 on the fourth circuit board 61d comes to be exposed as the shield plate 105 is moved away. Therefore, without removing the board unit 60 from the bottom case 5 or exploding the board unit 60, a circuit components 100 may installed into the spare zone 101 and the components currently installed in the spare zone 101 may be replaced by an upgraded circuit component 100. Thus, any operation of adding and/or replacing circuit component 100 can be carried out easily despite the fact that the circuit boards 61a to 61e are arranged in three layers. In the above-mentioned embodiment, the circuit components 66 on the circuit boards 61a to 61d arranged in three layers generate heat to raise the temperature of the board unit 60. Since the third circuit board 61c disposed in the middle of the layers of the circuit boards 61a to 61d is dedicated to power supply, it generates heat at a considerable rate and the generated heat may be stored around it to thereby locally raise the temperature of a particular area of the board unit 60. However, because of the fact that the shield plate 105 having a surface area substantially equal to the entire surface area of the rear half of the bottom case 5 is held in contact with the shield frame 62 of the board unit 60 and that the shield frame 105 is provided with an extension 110 that directly covers the fourth circuit board 61d, the heat generated in the board unit 60 is efficiently transmitted to the large shield plate 105. Moreover, since the shield plate 105 is held in contact with the reinforcement plate 17 that covers the entire surface area of the underside of the keyboard unit 13 by way of the plate springs 107a and 107b, the heat transmitted to the shield plate 105 is further sent to the reinforcement plate 17, where it is radiated into the atmosphere. Therefore, any heat in the board unit 60 can be effectively and efficiently transmitted to the shield plate 105 and then radiated therefrom so that the board unit 60 is protected against the danger of storing heat in a particular area thereof. Thus, although the housing 4 of the computer 1 is made of a synthetic resin material that poorly transmits heat, the board unit 60 that generates heat at an enhanced rate can be reliably cooled without requiring a particularly designed cooling mechanism such as a fan. Since a dedicated cooling mechanism is not required for the computer 1, the number of the components can be reduced and its components can be arranged within the housing 4 without the risk of overloading. Further, a problem of noise generated from a fan can be omitted. While the shield plate of the above embodiment covers only the tops of functional components such as an FDD and an HDD, it may alternatively be integrally formed with a wall section extending downward from the peripheral edge of the shield plate to conceal the functional components from above and laterally. Similarly, while the fixture plate operates also as a shield plate, the shield and fixture plates may be prepared independently. In this case the fixture plate may be made of a synthetic resin material. Components to be stored within the housing are not limited to those described above by referring to the embodiment such as a battery pack and may include expansion device such as a modem unit and hard disc drives. While the circuit boards are arranged in three layers in the above embodiment, the number of layers of circuit boards is not particularly limited to three and circuit boards may alternatively be arranged in two layers by omitting the third support member and the third circuit board or still alternative be arranged in four layers if additional circuit boards and support members are used. Finally, the present invention is not limited to book- or notebook-shaped portable computers and may be applied to other portable electronic apparatuses such as word processors.

Claims: A compact portable electronic apparatus comprising: a housing (4) having a bottom wall (5a); and a plurality of functional components (30,40,50,60) in the form of modules arranged side by side on the bottom wall (5a) of the housing (4); characterized in that : a fixture plate (105) is arranged on top of the functional components (30,40,50,60) and secured to the functional components (30,40,50,60) and the bottom wall (5a) by means of screws (47), so that the functional components (30,40,50,60) are rigidly held between the fixture plate (105) and the bottom wall (5a). The compact portable electronic apparatus according to claim 1, characterized in that said bottom wall (5a) of the housing (4) is provided with a plurality of bosses (46) for receiving the screws (47). The compact portable electronic apparatus according to claim 2, characterized in that one of two adjacent functional components (30,40,50) arranged side by side on the bottom wall (5a) is provided with a holding portion (35a,35b,36a,36b) extending to a top of the other functional component (30,40,50) and secured to one of the bosses (46) by means of a screw (47). The compact portable electronic apparatus according to claim 1, 2 or 3, characterized in that each of said functional components (30, 40, 60) is provided with a lug (45a,45b,95a,95b) secured to the housing (4) together with the fixture plate (105) by means of a screw (47). The compact portable electronic apparatus according to any one of claims 1 to 4, characterized in that said functional components (30,40) include circuit components (43) that generate noise in operation, and said fixture plate (105) is formed of metal to operate as a shield plate. The compact portable electronic apparatus according to any one of claims 1 to 4, characterized in that said housing (4) is formed of synthetic resin and said fixture plate (105) is made of metal. The compact portable electronic apparatus according to claim 6, characterized in that : a board unit (60) is arranged in the housing (4), the board unit (60) including a plurality of circuit boards (61a to 61e) superposed with each other with a space therebetween and a metal shield frame (62) surrounding the circuit boards (61a to 61e) ; said metal fixture plate (105) acts as a shield plate and covers at least upper surfaces of the functional components (30,40,50); said shield frame (62) has a cut out area (102); at least one of the circuit boards (61a to 61e) of the board unit (60) is arranged opposite to the cut out area (102) and has a spare zone (101) for selectively receiving additional circuit components (100); and the metal fixture plate (105) has as integral part thereof an extension (110) extending to cover the cut out area (102) of the shield frame (62). The compact portable electronic apparatus according to claim 7, characterized in that said shield frame (62) has a pair of shield members (68,69) opposed to each other with a space, and said plurality of circuit boards (61a to 61e) are arranged between the shield members (68,69) one above another to form a multilayer structure. The compact portable electronic apparatus according to claim 8, characterized in that flexible connecting boards (65a to 65d) are provided to electrically connect said plurality of circuit boards (61a to 61e). The compact portable electronic apparatus according to claim 8 or 9, characterized in that each of said shield members (68,69) has a plurality of receiving portions (73,74,75,87,88) arranged on a side facing the other shielding member, and each of the receiving portions securely holds thereon at least one of the circuit boards (61a to 61e). A compact portable electronic apparatus according to claim 8 or 9, characterized in that one of said shield members (68,69) has a first receiving portion (73) securely holding one of the circuit boards and a second receiving portion (75) extending beyond the first receiving portion toward the other shield member and securely holding another circuit board. A method of assembling a compact portable electronic apparatus characterized by comprising: a first step of arranging a plurality of functional components (30,40,50,60) supplied in the form of modules on a bottom wall (5a) of a housing (4); a second step of laying a fixture plate (105) on top of the functional components (30,40,50,60); and a third step of securing the fixture plate (105) to the housing (4) and the functional components (30,40,50,60) by means of screws (47) to rigidly hold the functional components (30,40,50,60) between the bottom wall (5a) of the housing (4) and the fixture plate (105).

Inventors: KONNO TOSHIKAZU, NAKAJIMA YUJI, SATO YOUJI, TAKI KINJI, KONNO, TOSHIKAZU, NAKAJIMA, YUJI, SATO, YOUJI, TAKI, KINJI, Konno, Toshikazu, c/o Intel. Property Division, Nakajima, Yuji, c/o Intel. Property Division, Sato, Youji, c/o Intel. Property Division, Taki, Kinji, c/o Intel. Property Division
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1993
Main classification: G06F1
IPC codes: G06F1