Abstract:
A keyboard device and a personal computer including a housing member made slidable, so that a membrane switch is not slid. Such a structure, designed to make the keyboard device and the personal computer thinner, makes it possible to provide very reliable, cheap, thin keyboard devices and personal computers which allow an electrical circuit in the personal computer and the membrane switch to be easily connected. Accordingly, the keyboard device and the personal computer having the above-described structure overcome the problems produced in conventional keyboard devices and personal computers using conventional keyboard devices. These were made thinner by making the membrane switch slide, which has resulted in a complicated electrical connection between an electrical circuit in the personal computer and the membrane switch, increased costs, and lack of electrical reliability.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a keyboard device suitable for use in, for example, a notebook personal computer which needs to be thin. In addition, the present invention relates to a personal computer employing the aforementioned keyboard device. 
     2. Description of the Related Art 
     One type of personal computer includes a rotatable cover above the computer body. A keyboard device is incorporated in the computer body, and a display device is incorporated in the rotatable cover. When the personal computer is in use, the cover with a display device incorporated therein is opened, whereas when the personal computer is not in use, the cover is closed so that the keyboard device is covered from above it. In the personal computer of the type described above, in order to make the keyboard device thinner, the key switches of the keyboard device are formed, as shown in FIGS. 10 and 11. 
     Each key switch has a boat-shaped key top  58 , two retainer portions  58  disposed at the back side of each key top  58 , two retainer portions  58   c  each with a slide groove  58   b , and a key top supporting structure L disposed below each key top  58 . Each key top supporting structure L comprises a first lever portion  56  and a second lever portion  57 , with the first lever portion and the second lever portion being combined so as to form a cross. One end of each first lever portion  56  is rotatably retained by the retainer portions  58   a  of the key top  58  associated thereto. One end of each second lever portion  57  is slidably inserted into the slide grooves  58   b  in the retainer portions  58   c  of the key top  58  associated thereto. 
     Below the key top supporting structures L is disposed a key top supporting member  55  with a slide groove  55   b  for slidably retaining the other end of the first lever portions  56 , and a retainer portion  55   a  for rotatably retaining the other end of the second lever portions. 
     A membrane switch  54  is disposed below the key top supporting member  55  so as to be slidable on a flat supporting substrate  60  and between the key top supporting member  55  and the supporting substrate  60 . The membrane switch  54  is a laminated structure including, from bottom to top, a protective sheet  54   a , a stationary contact sheet  54   b , a spacer sheet  54   c , a movable contact sheet  54   d , and a protective sheet  54   e . These sheets are integrally bonded together. At a hole  54   f  in the spacer sheet  54   c , a contact  54   g  on the sheet  54   d  and a contact  54   h  on the sheet  54   d  oppose each other. 
     A dome-shaped resilient member  59  with a protrusion  59   a  used for operating a switch is provided below each key top supporting structure L, such that the top portion thereof opposes its associated key top supporting structure L and the bottom portion is mounted to the membrane sheet  54 . 
     Accordingly, the keyboard device is constructed as described above. 
     As shown in FIGS. 12 and 13, the personal computer includes a cam projection  515   a  and a spring member  517 . The cam projection  515   a  is provided at the front side of the cover  515  with a display device (not shown). The spring member  517  is disposed between the membrane switch  54  of the keyboard device mounted within a body  513  and a side wall  516  of the body  513 . 
     In addition, when the personal computer having the above-described structure is ordinarily used by opening the cover  515  and operating the keyboard device  512 , the key top supporting structures L are raised and supported by their corresponding resilient members  59  at their highest positions, as shown in FIG.  10 . When an operator pushes a dome-shaped key top  58  downward against the resilient force of the resilient member  59  associated thereto, the inwardly projecting portion  59   a  of the associated resilient member  59  pushes the protective sheet  54   e  and the sheet  54   d  of the membrane switch  54 , causing the contact  54   h  to come into contact with the contact  54   g , whereby the switch is set in an on state. 
     Thereafter, releasing the key top  58  causes the resilient member  59  to return back to its original state due to its resiliency, and the associated supporting structure L and key top  58  to be restored back to its original state, causing the contact  54   h  to separate from the contact  54   g , whereby the switch is set in an off state. 
     Accordingly, contact switching is performed. 
     As shown in FIGS. 11 and 13, lowering the cover  515  onto the keyboard device  512  causes the cam projection  515   a  to engage the left end of the membrane switch  54  of the keyboard device, causing the membrane switch  54  to move to the right against the spring force of the spring member  517 . This causes the membrane switch  54  to slide in sliding contact between the supporting substrate  60  and the key top supporting member  55 , and the resilient members  59  to move in the same direction and move out from below their corresponding key top supporting structures L. Disengagement of the resilient members  59  from below their corresponding key top supporting structure L causes the key top supporting structures L to be lowered due to its own weight, causing the key tops  58  to be lowered downward. This reduces the thickness of the entire keyboard device  512 . 
     When the cover  515  is opened, the cam projection  515   a  disengages the membrane switch  54 , whereby the spring member  517  causes the membrane switch  54  to slide in sliding contact between the supporting substrate  60  and the key top supporting member  55 , and move back to its original position. Since, as a result of the sliding movement of the membrane switch  54 , the resilient members  59  slide back to the bottom portion of their corresponding key top supporting structures L in sliding contact therewith, the key top supporting structures L are pushed back upward by their respective resilient members  59 , which in turn causes the corresponding key tops  58  to rise upward and horizontally in order to be supported at their highest positions. 
     Thereafter, operations, such as those described above, are repeated to perform contact switching. 
     In such conventional keyboard devices and personal computers employing the aforementioned conventional keyboard devices, since the membrane switch  54  is slid, the electrical connecting structure between the electrical circuit in the personal computer and the sliding membrane switch  54  is complicated, which not only leads to high costs but also to lack of electrical reliability. 
     In addition, since the resilient member  59  is slid along its associated key top supporting structure L, the resilient member  59  has a shorter life. Moreover, since the resilient member cannot move smoothly, it cannot be operated with ease. 
     SUMMARY OF THE INVENTION 
     In order to overcome the above-described problems, according to a first aspect of the present invention, there is provided a keyboard device comprising: a key top; a first lever portion having one end slidably retained by a housing member and the other end rotatably retained at a back side of the key top; a second lever portion having one end rotatably retained by a supporting member disposed below the housing member and the other end slidably retained at the back side of the key top; and a membrane switch disposed between the housing member and the supporting member; wherein the first lever portion and the second lever portion are combined through a shaft member into the shape of a cross; wherein the supporting member and the membrane switch are affixed together; and wherein the housing member is slidably retained, with the sliding movement of the housing member causing the first lever portion and the second lever portion combined into the shape of a cross to be raised and lowered. 
     Although not exclusive, the keyboard device may further comprise a switch operating resilient member provided at a back surface of the key top. 
     Although not exclusive, the keyboard device may further comprise a spring member for pushing the one end of the first lever portion in an inward direction. 
     According to a second aspect of the present invention, there is provided a keyboard device comprising a key top; a first lever portion having one end slidably retained by a housing member and the other end rotatably retained at a back side of the key top; a second lever portion having one end rotatably retained by a supporting member disposed below the housing member and the other end slidably retained at the back side of the key top; and a membrane switch disposed between the housing member and the supporting member; wherein the first lever portion and the second lever portion are combined through a shaft member into the shape of a cross; wherein the housing member is affixed to the membrane switch; and wherein the supporting member is slidably retained, with the sliding movement of the supporting member causing the first lever portion and the second lever portion combined into the shape of a cross to be raised and lowered. 
     According to a third aspect of the present invention, there is provided a personal computer comprising any one of the aforementioned keyboard devices. 
     According to a fourth aspect of the present invention, there is provided a personal computer comprising a keyboard device including a plurality of arranged key switches, each key switch including a key top; a first lever portion having one end slidably retained by a housing member and the other end rotatably retained at a back side of the key top corresponding thereto; a second lever portion having one end rotatably retained by a supporting member disposed below the housing member and the other end slidably retained at the back side of the key top corresponding thereto; and a membrane switch disposed between the housing member and the supporting member; wherein the first lever portion and the second lever portion are combined through a shaft member into the shape of a cross; wherein the supporting member and the membrane switch are affixed together; and wherein the housing member is slidably retained, with the sliding movement of the housing member causing the first lever portion and the second lever portion combined into the shape of a cross to be raised and lowered; and wherein the personal computer further comprises a rotatable cover with a display device incorporated therein; wherein the housing member slides in response to an opening or a closing operation of the cover. 
     According to a fifth aspect of the present invention, there is provided a personal computer comprising a keyboard device including a plurality of arranged key switches, each key switch including a key top; a first lever portion having one end slidably retained by a housing member and the other end rotatably retained by a back side of the key top corresponding thereto; a second lever portion having one end rotatably retained by a supporting member disposed below the housing member and the other end slidably retained by the back side of the key top corresponding thereto; and a membrane switch disposed between the housing member and the supporting member; wherein the first lever portion and the second lever portion are combined through a shaft member into the shape of a cross; wherein the housing member and the membrane switch are affixed together; and wherein the supporting member is slidably retained, with the sliding movement of the supporting member causing the first lever portion and the lever portion combined into the shape of a cross to be raised and lowered; and wherein the personal computer further comprises a rotatable cover with a display device incorporated therein; wherein the supporting member slides in response to an opening or closing operation of the cover. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a personal computer with a keyboard device incorporated therein in accordance with the present invention. 
     FIG. 2 is a sectional side view of the main portion of the personal computer with the keyboard device incorporated therein in accordance with the present invention. 
     FIG. 3 is a plan view showing a portion of the keyboard device in accordance with the present invention. 
     FIG. 4 is a sectional view taken along line  4 — 4  of FIG.  3 . 
     FIG. 5 is a perspective view of the first lever portion of the keyboard device in accordance with the present invention. 
     FIG. 6 is a perspective view of the second lever portion of the keyboard device in accordance with the present invention. 
     FIG. 7 is a sectional view showing the main portion of the keyboard device in accordance with the present invention. 
     FIG. 8 is a view illustrating the operation of the keyboard device in accordance with the present invention. 
     FIG. 9 is a view illustrating the operation of the keyboard device in accordance with the present invention. 
     FIG. 10 is a sectional view showing a portion of a conventional keyboard device. 
     FIG. 11 is a view illustrating the operation of the conventional keyboard device. 
     FIG. 12 is a sectional side view of the main portion of a conventional personal computer. 
     FIG. 13 is a view illustrating the operation of the conventional personal computer. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A description will now be given of an embodiment of a personal computer with a keyboard device incorporated therein in accordance with the present invention, with reference to FIGS. 1 to  9 . FIG. 1 is a view showing a personal computer with a keyboard device incorporated therein in accordance with the present invention. The personal computer comprises a computer body formed by incorporation of a keyboard device  12  with a plurality of key switches S disposed in each row, and a cover  15  with a display device  14  incorporated therein so as to be rotatable at the body  13 . When in use, the cover  15  with the display device  14  is opened in order to allow operation of the keyboard device  12  for displaying information on the display of the display device  14 . When not in use, the cover  15  is closed by rotating the cover  15  onto the keyboard device  12 , whereby the keyboard device  12  is covered from above by the cover  15 . 
     In FIGS. 3 and 4, each of the key switches S is made of synthetic resin, and has a boat-shaped key top  8 . At the back side of each key top  8  are disposed in a row two retainer portions  8   a  and two L-shaped retainer portions  8   c  each with a slide groove  8   b . At about the center of a back side  8   d  of each key top  8  is provided a relatively thin, radially-extending base portion  8   e . A protrusion  8   f  is provided at the center of each base  8   e . A resilient member  9  is affixed to each protrusion  8   f , and pushes a membrane switch  4  by the lowering of the associated key top  8 . Each resilient member  9 , being a hanging bell shaped member, includes a protrusion  9   a  at the center thereof which deforms resiliently when it comes into contact with the membrane switch  4 , and pushes the membrane switch  4  for operation. Since each resilient member  9  deforms resiliently, an overstroke pushing force can be exerted onto the membrane switch  4 , when a contact moves beyond its on state position. 
     Each key switch S has a key top supporting structure K having a first lever portion  6  (shown in FIG. 5) made of synthetic resin, and a second lever  7  (shown in FIG. 6) also made of synthetic resin. 
     Each first lever portion  6  is substantially square-shaped, and has a rod-shaped retainer portion  6   a  at one end thereof which is rotatably retained by the retainer portions  8   a  of its associated key top  8 , circular protrusions  6   b  at the other end thereof, an opening  6   c  at the center thereof for receiving the resilient member  9  associated thereto, and shaft members  6   d  between the two ends which protrude outward. 
     Each second lever portion  7  is substantially C-shaped, and has circular protrusions  7   a  at one end thereof which are slidably inserted into the slide grooves  8   b  of the retainer portions  8   c  of the associated key top  8 , circular protrusions  7   b  at the other end thereof, and openings  7   c  between the associated circular protrusions  7   a  and  7   b . The shaft members  6   d  of each of the first lever portions  6  are slidably inserted into their corresponding openings  7   c , whereby each key top supporting structure K is formed as a result of combining the first lever portions  6  and the second lever portions  7  so that they form a cross shape. 
     As shown in FIGS. 3,  4 , and  7 , below each key top supporting structure K is disposed a housing member  5  made of synthetic resin. Each includes a slot  5   a , a retainer portion  5   c  disposed away from its associated slot  5   a  and including one slide groove  5   b , and a circular hole  5   d  formed between the retainer portion  5   c  and the slot  5   a  associated thereto and allowing the associated resilient member to move in and out of the circular hole  5   d . Although the housing member  5  is described as being made of synthetic resin, when a metallic plate is used, the heat is dissipated more effectively from the central processing unit (CPU) in the personal computer. The protrusions  6   b  of each first lever portion  6  are supported by their corresponding retainer portions  5   c  so as to be slidable into the slide groove  5   b  corresponding thereto. A spring member  10  is provided in each slide groove  5   b  for pushing the protrusions  6   b  of any one of the first lever portions  6  in the direction of its associated hole  5   d , that is towards the interior of its associated key top. The spring member  10  is preferably a coil spring or a leaf spring. 
     Below the housing members  5  is disposed a membrane switch composed of an upper flexible sheet (not shown) with stationary contacts and a lower flexible sheet (not shown) with movable contacts. At the hole  5   d  in each of the housing members  5 , the stationary contacts (not shown) and their corresponding movable contacts (not shown) oppose each other. As shown in FIG. 7, the membrane switch  4  includes an opening  4   a  formed in correspondence with both edges of the slot  5   a  of its associated housing member  5 . Below the membrane switch  4  is disposed a supporting plate  2  formed of, for example, a metallic plate, with a retainer  2   a , extending through the associated opening  4   a  of the membrane switch  4  and inserted into the slot  5   a  of the associated housing member  5 , being formed at the surface of the supporting plate  2 . Each retainer portion  2   a  has a hole for rotatably retaining the protrusions  7   b  of its associated second lever portion  7 . When the retainer portions  2   a  are formed by molding so as to protrude from the supporting plate  2 , the retainer portions  2   a  can be produced with ease. 
     As shown in FIGS. 2 and 9, a rack  5   e  is provided at the right end portion of the housing members  5 . The rack  5   e  engages a gear  11  provided at the cover  15 . The rotation of the cover  15  causes the housing members  5  to be slidably retained. 
     A description will now be given of the rising and lowering of the key tops  8  caused by rotation of the cover  15 , with reference to FIGS. 2,  4 ,  8 , and  9 . 
     When a personal computer is ordinarily operated using the keyboard device  12  after the cover  15  is opened, the biasing force of each spring member  10  keeps each key top supporting structure K in an X shape, and causes each key top  8  to be supported at its highest position, as shown in FIG.  4 . When the operator pushes any key top  8  against the biasing force of the associated spring member  10 , with the shaft members  6   d  (refer to FIGS. 3 and 5) associated thereto as center, the ends  6   a  and  7   b  of the first and second lever portions  6  and  7  of the associated key top supporting structure K rotates at the retainer portions  8   a  and  2   a , respectively, causing the end  6   b  of the associated first lever portion  6  to push against the spring member  10  while sliding into the associated slide groove  5   b , and the end  7   a  of the associated second lever portion  7  to slide into the slide grooves  8   b . When this occurs, the lowering of the associated key top supporting structure starts, as a result of which the key top  8  is also lowered. FIG. 8 shows a key top  8  which has been lowered. 
     When the key top  8  is at the lowest position, the associated first lever portion  6  moves into the substantially C-shaped space in the associated second lever portion  7 , whereby the associated key top supporting structure K is completely lowered. When any of the key tops  8  is lowered downward, the pusher member  9  associated thereto moves straight down and pushes the membrane switch  4 , causing the circuit contacts to contact each other, thereby turning on the switch. Thereafter, releasing the pressed key top  8  causes the biasing force of the associated spring member  10  to push back the key top  8 , the key top supporting structure K and the resilient member  9  to their initial positions or positions prior to pressing of the key top  8 . The membrane switch  4  pushed by the associated resilient member  9  is restored back to its original condition due to its own restoring force, causing the contacts to separate from each other, thereby turning off the switch. 
     Accordingly, contact switching is performed. 
     Thereafter, bringing the cover  15  down onto the keyboard  12  from the open state shown in FIG. 2 causes the housing members  5  to slide towards the right side as a result of rotation of the gear  11  caused by rotation of the cover  15 , whereby the end  6   b  of each first lever portion  6  is pulled towards the right. Therefore, with the associated shaft members  6   d  (refer to FIGS. 3 and 5) as center, the ends  6   a  and  7   b  of each of the first and second lever portions  6  and  7 , respectively, remain retained at the retainer portions  8   a  and  2   a , respectively, whereas the end  7   a  of each second lever portion  7  slides into the slide groove  8   b  corresponding thereto. Since the retainer portions  2   a  are integrally formed with the corresponding support plates  2 , even if the housings  5  slide, the retainer portions  2   a  do not move, so that the positions of the protrusions  7   b  of the corresponding lever portions  7  do not change. On the other hand, since the retainer portions  5   c  are integrally formed with the corresponding housings  5 , if the housings  5  slide, the retainer portions  5   c  slide with the corresponding housings  5 . This causes the protrusions  6   b  of the corresponding lever portions  6  to slide. Since the protrusions  6   b  slide while the protrusions  7   b  remain at fixed locations, the lever portions  6  and  7  are lowered to lower the key tops  8 . This causes the key top supporting structures K to be lowered downward, causing the key tops  8  to be lowered downward, so that the entire keyboard device can be made thinner by decreasing the key stroke distance D (refer to FIG.  4 ). FIG. 9 is a view showing a key top  8  which has been lowered downward as a result of rotation of the cover  15 . When the cover  15  is thereafter opened, the housing members  5  slide back to their original positions as a result of the rotation of the cover  15 , causing sliding movement of the end  6   b  of each first lever portion pushed by the spring member  10  corresponding thereto. Therefore, with the shaft members  6   d  as center, the ends  6   a  and  7   b  of the first and second lever portions  6  and  7 , respectively, rotate at the retainer portions  8   a  and  2   a , respectively, whereas the end  6   b  of each first lever portion  6  due to the biasing force of the spring member  10  corresponding thereto slides while it is at their initial positions in the associated slide groove  5   b , and the end  7   a  of each second lever portion  7  slides in the slide grooves  8   b  corresponding thereto. This causes each key top supporting structure K to be rise upward, and become an X-shaped structure as it had been initially, causing each key top  8  to rise upward and horizontally. 
     Each key top  8  is supported at its highest position by keeping each key top supporting structure K in an X-shaped structure by the biasing force of each spring member  10 . 
     Although in the above-described embodiment, the housing members  5  were slid to raise and lower the key top structures upward and downward, it is obvious that the supporting member  2  may be slid for the same purpose. 
     According to the present invention, a first lever portion  1  is retained by a slidable housing member, and a second lever portion is retained by a supporting member. Therefore, since the membrane switch is not slid, it is possible to provide a highly reliable, cheap, and thin keyboard device which allows connection with an electrical circuit in a personal computer with ease. 
     In addition, according to the present invention, a resilient member, which is provided at a back surface of each key top for operating each switch, is not slid. Therefore, since the conventional problem of wearing caused by sliding in sliding contact between the key top supporting structures and resilient members does not occur, it is possible to provide a long-life, easily operable keyboard device. 
     Further, according to the present invention, spring members are disposed in the keyboard device, so that tactile feedback and an operational force are provided by the spring members, unlike the conventional case where they are provided by the resilient members themselves. Therefore, it is possible to provide a keyboard device providing a suitable operational force and good tactile feedback. 
     Still further, according to the present invention, since a first lever portion is retained by a housing member, and a second lever portion is retained by a slidable supporting member, and the membrane switch is not slid, it is possible to provide a highly reliable, cheap, and thin keyboard device, which allows connection with an electrical circuit in the personal computer with ease. 
     Still further, according to the present invention, a personal computer is constructed so that a housing member is slid, instead of the membrane switch. Therefore, it is possible to provide a highly reliable, cheap, and thin personal computer which allows connection with an electrical circuit in the personal computer with ease. 
     Still further, according to the present invention, a housing member is slid by opening and closing a cover. Therefore, it is possible to provide cheap personal computers with a simple structure, which are capable of being produced in large quantities. 
     Still further, according to the present invention, a supporting member is slid by opening and closing a cover. Therefore, it is possible to provide cheap personal computers with a simple structure, which are capable of being produced in large quantities.