Magnetic steering assembly for a toy vehicle

Information

  • Patent Grant
  • 6350173
  • Patent Number
    6,350,173
  • Date Filed
    Wednesday, December 8, 1999
    24 years ago
  • Date Issued
    Tuesday, February 26, 2002
    22 years ago
  • Inventors
  • Original Assignees
  • Examiners
    • Ackun, Jr.; Jacob K.
    • Fernstrom; Kurt
    Agents
    • Merchant & Gould P.C.
Abstract
The invention relates to a toy vehicle having steerable wheels, to a steering mechanism for such a vehicle, and to a steering module incorporated in the steering mechanism. The steering module includes a coil having a first end and a second end with a central axis extending between the first and second ends thereof, a slide bar disposed adjacent the first end of the coil and mounted for movement along a substantially linear axis generally perpendicular to the central axis of the coil, and first and second magnets mounted on the slide bar and moveable therewith along the substantially linear axis. The first and second magnets each include a north pole and a south pole, with the north pole of the first magnet facing the first end of the coil and the south pole of the second magnet facing the first end of the coil. The steering mechanism is compact in size with few parts. Further, the steering module is adaptable for use with toy cars of very small size, and the module can be installed at a variety of positions on the toy vehicle.
Description




FIELD




The invention relates generally to toy vehicles, and more particularly to toy vehicles having steerable wheels in order to enable control of the direction of travel of the toy vehicle. The invention has potential application on numerous types of toy vehicles, including toy cars, toy trains, toy trucks and the like. The invention is preferably used on toy vehicles that are radio-controlled, although the invention can be used on any toy vehicle having wheels that can be steered on command by an operator of the vehicle.




BACKGROUND




In the toy vehicle art, there is a need to keep the toy vehicle relatively simple in design with fewer parts, as well as to reduce the size and weight of the toy vehicle and to reduce costs. This is particularly important in toy vehicles having steerable wheels, since the steering mechanism for steering the wheels must be incorporated onto the toy vehicle. Any steering mechanism design that is able to reduce parts and simply design, as well as reduce vehicle size, weight and costs, would be beneficial.




Numerous toy vehicle steering mechanisms for steering toy vehicles are known from the prior art, as illustrated by U.S. Pat. No. 4,163,341; U.S. Pat. No. 4,571,213; U.S. Pat. No. 4,471,566; U.S. Pat. No. 4,898,562; U.S. Pat. No. 4,854,909; U.S. Pat. No. 4,563,162; U.S. Pat. No. 4,816,795; U.S. Pat. No. 3,579,906; and JP 4-135591. While these known mechanisms are generally satisfactory for their intended purpose, there is a continuing need for an improved steering mechanism that saves space, thereby reducing vehicle size, and that saves costs, both in the steering mechanism itself and in the toy vehicle in which the steering mechanism is used.




SUMMARY




An improved steering mechanism for a toy vehicle is provided, particularly a toy vehicle having wheels that are steerable by an operator of the toy vehicle through suitable commands input by the operator. The steering mechanism uses a minimum number of parts and simple, relatively cheap materials. The steering mechanism has a relatively small size, thereby reducing the size of the vehicle, and can be installed at a variety of locations and positions on the vehicle. Further, the design of the steering mechanism improves the steering action on the wheels. Moreover, the small size and improved steering action permits the steering mechanism to be incorporated into very small toy vehicles.




As defined by the claims appended hereto, in one embodiment in accordance with the principles of the invention, a toy vehicle is provided that includes a chassis, first and second wheels pivotally mounted to the chassis, and a steering mechanism mounted on the chassis and operatively connected to the first and second wheels for steering the wheels. The steering mechanism includes a steering module having a coil disposed on the chassis, with the coil having a first end and a second end with a central axis extending between the first and second ends thereof. In addition, the steering module has a first slide bar disposed adjacent the first end of the coil and mounted for movement along a first substantially linear axis generally perpendicular to the central axis of the coil. The first slide bar has a first end operatively connected to the first wheel and a second end operatively connected to the second wheel whereby movement of the first slide bar along the first substantially linear axis results in pivoting movement of the first and second wheels. In addition, first and second magnets are mounted on the first slide bar and are moveable therewith along the first substantially linear axis. The first and second magnets each include a north pole and a south pole, with the north pole of the first magnet facing the first end of the coil and the south pole of the second magnet facing the first end of the coil.




As further defined by the claims appended hereto, in a second embodiment in accordance with the principles of the invention, a steering mechanism is provided for a toy vehicle having first and second wheels. The steering mechanism comprises a steering module including a coil having a first end and a second end with a central axis extending between the first and second ends thereof, and a slide bar disposed adjacent the first end of the coil and mounted for movement along a first substantially linear axis generally perpendicular to the central axis of the coil. The slide bar has a first end operatively connected to the first wheel and a second end operatively connected to the second wheel whereby movement of the slide bar along the first substantially linear axis results in a steering action on the first and second wheels. In addition, first and second magnets are mounted on the slide bar and are moveable therewith along the first substantially linear axis. The first and second magnets each include a north pole and a south pole, with the north pole of the first magnet facing the first end of the coil and the south pole of the second magnet facing the first end of the coil.




As further defined by the claims appended hereto, in a third embodiment in accordance with the principles of the invention, a steering module for a toy vehicle is provided. The steering module includes a coil having a first end and a second end with a central axis extending between the first and second ends thereof, a slide bar disposed adjacent the first end of the coil and mounted for movement along a substantially linear axis generally perpendicular to the central axis of the coil, and first and second magnets mounted on the slide bar and moveable therewith along the substantially linear axis. The first and second magnets each include a north pole and a south pole, with the north pole of the first magnet facing the first end of the coil and the south pole of the second magnet facing the first end of the coil.




A variety of additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective view of the front end of a toy vehicle incorporating the steering mechanism of the invention.





FIG. 2

is a perspective view of the steering module utilized in the steering mechanism.





FIG. 3

is an exploded view illustrating components of the steering module.





FIG. 4

depicts other elements of the steering mechanism.





FIG. 5

is a schematic depicting the interaction of the coil and the magnets of the steering module.





FIG. 6

is a perspective view of the front end of a toy vehicle incorporating an alternative embodiment of a steering mechanism.





FIG. 7

is a perspective view of the steering module utilized in the steering mechanism of FIG.


6


.





FIG. 8

illustrates an alternative orientation of the steering module.





FIG. 9

illustrates the position of the steering module relative to a rotation axis of the wheels.





FIG. 10

illustrates a variation in which the actuating bar and the first slide bar are combined into a single, one-piece unit.





FIG. 11

illustrates a variation of the biasing mechanism.











DETAILED DESCRIPTION




The invention relates to a toy vehicle having steerable wheels, to a steering mechanism for such a vehicle, and to a steering module incorporated in the steering mechanism. The design of the steering module is simple with few parts, thereby permitting a reduction in the size and weight of the steering mechanism and of the toy vehicle itself Further, the steering module is adaptable for use with toy cars of very small size, and the module can be installed at a variety of positions on the toy vehicle.




With reference now to the figures, one implementation of a toy vehicle


10


utilizing a steering mechanism


12


with a steering module


14


of the invention is illustrated. Only the front end of the toy vehicle


10


is illustrated in the figures, it being understood that the rear end of the vehicle includes an additional set of wheels. The toy vehicle


10


is preferably of the type whose rear wheels are driven by an electric motor (not shown) suitably positioned on the vehicle. Power for running the motor is provided by a power source


16


, such as one or more batteries, positioned on the vehicle. The vehicle is preferably operated by a suitable wireless control system of a type generally known in the art.




Referring now to

FIGS. 1 and 4

, the toy vehicle


10


includes a chassis


18


with a front end


20


. Projecting from each side of the chassis


18


are tabs


22




a


,


22




b


each formed with a respective hole


24




a


,


24




b


therein. Right and left wheel assemblies


26




a


,


26




b


are mounted to the tabs


22




a


,


22




b


to permit pivoting movement of each wheel assembly. The wheel assemblies


26




a


,


26




b


are identical and therefore only the wheel assembly


26




a


will be described in detail.




The wheel assembly


26




a


includes a spindle


28


and a wheel


30


that is rotatably mounted on the spindle


28


. The spindle


28


includes pins


32


extending from the top and bottom thereof, with the bottom pin


32


being rotatably disposed within the hole


24




a


to enable the spindle


28


, and thus the wheel assembly, to pivot about a generally vertical axis. Extending rearwardly from the spindle


28


is an arm


34


with a vertical pin


36


adjacent the end thereof, the purpose of which will be described below.




Extending upwardly from the chassis


18


are a pair of support posts


38


each having a threaded hole, and a pair of right angle members


40


. Further, a pair of rails


42


are disposed on the top surface of the chassis


18


at the sides thereof, and extend forwardly from a central portion


44


of the vehicle


10


to adjacent the support posts


38


. As shown in

FIG. 1

, a cover


46


is provided in order to retain the wheels assemblies


26




a


,


26




b


, the steering mechanism


12


and the steering module


14


in place on the chassis


18


. The cover


46


includes a pair of caps


48


that are designed to fit over, and rotatably support, the top pins


32


on the spindles


28


. The cover


46


also has a pair of apertures


50


that align with the threaded holes in the support posts


38


whereby the cover


46


can be fastened to the chassis


18


using screws. A pair of bosses


52


are provided at the rear end of the cover


46


that cooperate with corresponding bosses


54


provided on the central portion


44


of the vehicle to permit attachment of the rear end of the cover.




As shown in

FIG. 4

, an actuating bar


56


is positioned on top of the rails


42


between the right angle member


40


and the central portion


44


. The actuating bar


56


, together with the steering module


14


to be later described, form the steering mechanism


12


of the invention. As indicated by the arrows in

FIG. 4

, the actuating bar


56


is slideably disposed on the chassis


18


for sliding movement to the left and to the right along a generally linear axis. The actuating bar


56


includes tabs


58


that project from the sides of the chassis


18


, with each tab


58


including a hole


59


therein to receive the respective pin


36


on the spindle arm


34


, as best seen in FIG.


1


. Thus, as the actuating bar


56


moves to the right and the left, the movement is transmitted through the spindle arms


34


to the spindle


28


thereby causing the wheels


30


to steer to the right and the left.




Returning to

FIG. 1

, it is the steering module


14


that causes the actuating bar


56


to move to the right and left. The steering module


14


is positioned between a pair of tabs


60


projecting upward from the actuating bar


56


whereby movement of a portion of the steering module


14


to the right and to the left, shown by the arrows in

FIG. 1

, is transmitted to the actuating bar


56


. As mentioned above, the steering module


14


and the actuating bar


56


form the steering mechanism


12


of the toy vehicle.





FIGS. 2 and 3

illustrate the steering module


14


in detail. The module


14


includes a generally rectangular frame


62


, which as shown in

FIG. 1

, cooperates with the right angle members


40


and the central portion


44


whereby the frame


62


is fixed on the chassis


18


. The frame


62


is preferably made from plastic in order to reduce vehicle weight and costs. The frame


62


includes a generally hollow central area


64


that receives therein a coil


66


. The coil


66


has a first end


68


and a second end


70


with an axis A—A extending between the ends


68


,


70


through the center of the coil. The coil


66


is sized to fit snugly within the hollow area


64


to thereby retain the coil within the frame


62


.




The bottom of the frame


62


includes a cut-out section


72


in opposite side walls thereof in order to receive a first slide bar


74


. The slide bar


74


, which is preferably made from plastic to reduce weight and costs, includes rails


76


cut on each side thereof that cooperate with rails


78


formed on opposite walls of the frame


62


, whereby the slide bar


74


is slideable to the right and left relative to the frame. Mounted on the slide bar


74


, at spaced locations thereon, are a pair of magnetic disks


80


,


82


.




The top of the frame


62


also includes a cut-out section


84


in opposite side walls thereof that receive a second slide bar


86


. The second slide bar


86


, like the first slide bar


74


, is preferably made from plastic to weight and costs. Extending downward from opposite ends of the slide bar


86


are connecting arms


88


, each of which is provided with notches


90


at the ends thereof and a central slot


92


. The ends of the first slide bar


74


are provided with a pair of spaced notches


94


between which is a tab


96


. As shown in

FIG. 2

, the ends of the connecting arms


88


are designed to engage with the ends of the first slide bar


74


, with the tab


96


fitting into the slot


92


and the notches


90


,


94


cooperating with each other, whereby the first and second slide bars


74


,


86


are connected together so as to move in unison to the right and the left.




Further, like the first slide bar


74


, the second slide bar


86


is also provided with a pair of magnetic disks


98


,


100


mounted at spaced locations thereon. The slide bars


74


,


86


and magnetic disks


80


,


82


,


98


,


100


are positioned such that the disk


80


is generally vertically aligned with the disk


98


, and the disk


82


is generally vertically aligned with the disk


100


. Although the magnets


80


,


82


,


98


,


1




00


have been described as being discs, it is to be realized that other shapes could be used for the magnets as well.




As shown in

FIG. 5

, each of the magnets


80


,


82


,


98


,


100


includes a north pole and a south pole. For the slide bar


74


, the magnets


80


,


82


are arranged such that the north pole of the magnet


80


faces the end


68


of the coil


66


while the south pole of the magnet


82


faces the end


68


. Likewise, for the slide bar


86


, the magnets


98


,


100


are arranged such that the south pole of the magnet


98


faces the end


70


of the coil


66


, while the north pole of the magnet


100


faces the end


70


.




By controlling the direction of current through the coil


66


, thereby controlling its polarity, the slide bars


74


,


86


can be forced to the right or to the left due to attraction and repulsion of the respective magnets. For instance, as shown in

FIG. 5

, when current is directed through the coil


66


such that the N-polarity points upward, the magnets


80


,


98


are attracted in the direction of arrow A while the magnets


82


,


100


are repulsed in the direction of arrow A, thereby causing the slide bars


74


,


86


to shift resulting in a steering action on the wheels. When the current is reversed such that the N-polarity points downward, the magnets


80


,


98


are repulsed in the direction of dashed arrow B while the magnets


82


,


100


are attracted in the direction of dashed arrow B, thereby causing the slide bars


74


,


86


to shift resulting in a steering action on the wheels. Circuitry for controlling the direction of current flow through the coil


66


is known in the art and need not be described herein. The electricity for the current flow is provided by the power source


16


.




A biasing mechanism


102


is also provided in order to bias the slide bars


74


,


86


to a central position once current flow through the coil


66


is stopped. As shown in

FIGS. 2 and 3

, a pin


104


projects from the slide bar


74


through a cut-out


106


provided in the frame


62


. A pair of spring arms


108


,


110


are disposed on either side of the pin


104


for biasing the slide bar


74


back to its central position after sliding either left or right. The spring arms


108


,


110


preferably form the opposite ends of the same single piece of flexible wire that is suitably fixed to the frame


62


. However, the spring arms could be from separate wire elements that are each fixed to the frame.




The embodiment described thus far and shown in

FIGS. 1-5

has utilized a pair of slide bars


74


,


86


. The use of two slide bars and their corresponding magnets provides the maximum amount of steering force. However, when a smaller steering force will suffice, it is possible to utilize the steering module


14


with only a single slide bar. Referring to

FIGS. 6 and 7

, it is seen that the second slide bar


86


of the steering module


14


has been removed, and only the first slide bar


74


is present. This embodiment permits use of the steering module on smaller toy vehicles and those toy vehicles that require a smaller amount of steering force.




In addition, the invention thus far described has had the core


66


of the steering module


14


oriented such that the axis A—A thereof extends generally vertically relative to the vehicle. However, it is to be realized that the steering module


14


could be oriented in such a manner that the axis A—A of the core


66


extends generally forward and aft of the toy vehicle. Such an orientation is illustrated in FIG.


8


. The actuating bar


56


would have to be suitably modified in order to actuated by the slide bar. The embodiment illustrated in

FIG. 8

could also be used with the second slide bar as well.




One of the advantages provided by the steering module


14


and steering mechanism


12


described herein is that they are compact and take up very little space on the vehicle. Therefore, the vehicle size can be reduced. To illustrate the compact nature of the invention, reference should be made to

FIG. 9

, which show the front wheels


30


, each of which is rotatable about a respective rotation axis forming a common axis B—B. As

FIG. 9

schematically illustrates, the actuating bar


56


and the slide bars


74


,


86


and the coil


66


of the steering module


14


, are positioned entirely to the rear of the axis B—B. Likewise, in keeping with the flexible nature of the invention,

FIG. 9

illustrates in dashed lines that the actuating bar, slide bars and coil can be positioned entirely in front of the axis B—B. Thus, the steering mechanism


12


takes up very little fore and aft space, and it can be positioned at different locations depending upon the space that is available on the toy vehicle.





FIG. 10

illustrates a variation in which the actuating bar


56


and the first slide bar


74


are combined into an integral, one-piece unit, in which the slide bar


74


′ is provided with tabs


58


′ at both ends. Thus, in this version, the steering mechanism is comprised of only the steering module itself, as the actuating bar has essentially been eliminated. This design further reduces size, weight and costs of the toy vehicle.





FIG. 11

illustrates a variation utilizing a biasing mechanism


102


′ in which the spring arms


108


′,


110


′ are separate wire elements fixed to respective mounting elements


112


,


114


on the frame


62


.




The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.



Claims
  • 1. A toy vehicle, comprising:a chassis; first and second wheels pivotally mounted to the chassis; and a steering mechanism mounted on the chassis and operatively connected to the fist and second wheels for steering the wheels, the steering mechanism including a steering module having; a) a coil disposed on the chassis, the coil having a first end and a second end with a central axis extending between the first and second ends thereof; b) a first slide bar disposed adjacent the first end of the coil mounted so as to be moveable perpendicular to the central axis of the coil, the first slide bar having a first end operatively connected to the first wheel and a second end operatively connected to the second wheel whereby movement of the first slide bar results in pivoting movement of the first and second wheels; c) first and second magnets mounted on the first slide bar and moveable therewith perpendicular to the central axis of the coil, the first and second magnets each including a north pole and a south pole, the north pole of the first magnet facing the first end of the coil and the south pole of the second magnet facing the first end of the coil; wherein the steering mechanism further includes an actuating bar mounted on the chassis for movement perpendicular to the central axis of the coil, the actuating bar are operatively having a first end operatively connected to the first wheel and a second end operatively connected to the second wheel, and the first slide bar and the actuating bar are operatively engaged whereby movement of the first slide bar causes movement of the actuating bar perpendicular to the central axis of the coil; and wherein the wheels are each rotatable about a respective rotation axis, and wherein the coil, the first slide bar and the first and second magnets are all disposed either entirely forward or entirely rearward of the rotation axes.
  • 2. The toy vehicle according to claim 1, wherein the wheels are front wheels of the toy vehicle.
  • 3. The toy vehicle according to claim 1, further including a biasing mechanism engaged with the first slide bar biasing the first slide bar to a central position.
  • 4. A toy vehicle, comprising:a chassis; first and second wheels pivotally mounted to the chassis; and a steering mechanism mounted on the chassis and operatively connected to the first and second wheels for steering the wheels, the steering mechanism including a steering module having: a) a coil disposed on the chassis, the coil having a first end and a second end with a central axis extending between the first and second ends thereof; b) a first slide bar disposed adjacent the first end of the coil and mounted so as to be movable perpendicular to the central axis of the coil, the first slide bar having a first end operatively connected to the first wheel and a second end operatively connected to the second wheel whereby movement of the first slide bar results in pivoting movement of the first and second wheels; c) first and second magnets mounted on the first slide bar and moveable therewith perpendicular to the central axis of the coil, the first and second magnets each including a north pole and a south pole, the north pole of the first magnet facing the first end of the coil and the south pole of the second magnet facing the first end of the coil; d) a second slide bar disposed adjacent the second end of the coil, the second slide bar being connected to the first slide bar for movement therewith; and e) third and fourth magnets mounted on the second slide bar and moveable therewith, the third and fourth magnets each including a north pole and a south pole, the north pole of the third magnet facing the second end of the coil and the south pole of the fourth magnet facing the second end of the coil; and wherein the wheels are each rotatable about a respective rotation axis, and wherein the coil, the first slide bar and the first and second magnets are all disposed either entirely forward or entirely rearward of the rotation axes.
  • 5. The toy vehicle according to claim 4, wherein the steering mechanism further includes a frame fixed to the chassis, the coil being disposed within the frame, and the first and second slide bars are slideably supported by the frame.
  • 6. A steering mechanism for a toy vehicle having first and second wheels, the steering mechanism comprising:a steering module including a coil having a first end and a second end with a central axis extending between the first and second ends thereof; a first slide bar disposed adjacent the first end of the coil and mounted so as to be movable perpendicular to the central axis of the coil, the first slide bar having a first end operatively connected to the first wheel and a second end operatively connected to the second wheel whereby movement of the first slide bar results in a steering action on the first and second wheels; first and second magnets mounted on the first slide bar and moveable therewith perpendicular to the central axis of the coil, the first and second magnets each including a north pole and a south pole, the north pole of the first magnet facing the first end of the coil and the south pole of the second magnet facing the first end of the coil; an actuating bar mounted for movement perpendicular to the central axis of the coil, the actuating bar having a first end operatively connected to the first wheel and a second end operatively connected to the second wheel, and the first slide bar and the actuating bar are operatively engaged whereby movement of the first slide bar causes movement of the actuating bar perpendicular to the central axis of the coil; and wherein the wheels are each rotatable about a respective rotation axis, and wherein the coil, the first slide bar and the first and second magnets are all disposed either entirely forward or entirely rearward of the rotation axes.
  • 7. The steering mechanism according to claim 6, wherein the first and second wheels are front wheels of the toy vehicle.
  • 8. The steering mechanism according to claim 6, further including a biasing mechanism engaged with the first slide bar and the second slide bar biasing the first slide bar to a central position.
  • 9. A steering mechanism for a toy vehicle having first and second wheels, the steering mechanism comprising:a steering module including a coil having a first end and a second end with a central axis extending between the first and second ends thereof; a first slide bar disposed adjacent the first end of the coil and mounted so as to be movable perpendicular to the central axis of the coil, the first slide bar having a first end operatively connected to the first wheel and a second end operatively connected to the second wheel whereby movement of the first slide bar results in a steering action on the first and second wheels; first and second magnets mounted on the first slide bar and moveable therewith perpendicular to the central axis of the coil, the first and second magnets each including a north pole and a south pole, the north pole of the first magnet facing the first end of the coil and the south pole of the second magnet facing the first end of the coil; a second slide bar disposed adjacent the second end of the coil, the second slide bar being connected to the first slide bar for movement therewith; and third and fourth magnets mounted on the second slide bar and moveable therewith, the third and fourth magnets each including a north pole and a south pole, the north pole of the third magnet facing the second end of the coil and the south pole of the fourth magnet facing the second end of the coil, wherein the wheels are each rotatable about a respective rotation axis, and wherein the coil, the first slide bar and the first and second magnets are all disposed either entirely forward or entirely rearward of the rotation axes.
  • 10. The steering mechanism according to claim 9, further including a frame fixed to the toy vehicle, the coil being disposed within the frame, and the first and second slide bars are slideably supported by the frame.
  • 11. A steering module for a toy vehicle, comprising:a coil having a first end and a second end with a central axis extending between the first and second ends thereof; a frame, said coil being disposed within said frame; a first slide bar disposed adjacent the first end of the coil and slidably supported on said frame for movement perpendicular to the central axis of the coil; first and second magnets mounted on the first slide bar and moveable therewith perpendicular to the central axis of the coil, the first and second magnets each including a north pole and a south pole, the north pole of the first magnet facing the first end of the coil and the south pole of the second magnet facing the first end of the coil; a second slide bar disposed adjacent the second end of the coil and slidably supported by said frame, the second slide bar being connected to the first slide bar for movement therewith; and third and fourth magnets mounted on the second slide bar and moveable therewith, the third and fourth magnets each including a north pole and a south pole, the north pole of the third magnet facing the second end of the coil and the south pole of the fourth magnet facing the second end of the coil.
  • 12. The steering module according to claim 11, further including a biasing mechanism engaged with the first slide bar biasing the first slide bar to a central position.
US Referenced Citations (10)
Number Name Date Kind
3579906 La Forge May 1971 A
4163341 Jones Aug 1979 A
4471566 Ishimoto Sep 1984 A
4563162 Ishimoto Jan 1986 A
4571213 Ishimoto Feb 1986 A
4816795 Suto Mar 1989 A
4854909 Ishimoto Aug 1989 A
4881917 Suzuki et al. Nov 1989 A
4898562 Ishimoto Feb 1990 A
5851134 Chiu Dec 1998 A
Foreign Referenced Citations (2)
Number Date Country
4-135591 May 1992 JP
404135591 May 1992 JP