GB2286034A

GB2286034A - Magnetic computer mouse

Info

Publication number: GB2286034A
Application number: GB9401765A
Authority: GB
Inventors: Terence Keith Gibbs; Graham Luck; Peter J Robertson
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1994-01-31
Filing date: 1994-01-31
Publication date: 1995-08-02
Also published as: GB9401765D0

Abstract

A variable magnetic field between the mouse 300 and a ferrous surface 310 provides a down force that stabilises the position of the mouse. The mouse 300 may contain an electromagnetic coil 306 and the strength of the down force may be continuously controlled by an operator, via a trigger control 104 which varies the current through the coil 306. In an alternative embodiment, the magnetic field is provided by a permanent magnet. The magnetic field may, alternatively, be provided by the work surface and the mouse may include a ferrous plane. The mouse 300 to be used for display cursor control in environments where high levels of vibration and rapid motional changes make a conventional mouse unusable. <IMAGE>

Description

MOUSE FOR USE WITH A COMPUTER Field of the Invention The present invention relates to the control of pointers and cursors on a display screen, used in conjunction with computers or computer based equipment. More specifically, the invention relates to a mouse for use in environments where vibration and rapid changes in attitude make use of a conventional mouse difficult or impossible.

Backaround of the Invention A mouse is a device that a computer user moves on a flat surface to position a pointer on a display screen. The mouse has established itself, amongst computer users, as the most widely accepted method of pointing to display objects and other nominated areas displayed on a screen, and as a means of selecting the desired function from a number of functions displayed on a screen. Objects, nominated areas and selections are displayed on a display screen and as a mouse is moved across a flat surface, a pointer displayed on the screen follows the movement of the mouse. By depressing a button located oii the mouse, an object, nominated area or function displayed on the screen may be selected.

A mouse has the disadvantage of being unsuitable for use in a mobile environment. The laptop computer user needs a device that will work, like the laptop computer, on his lap, including whilst seated in a moving car, train or plane. The military computer operator has yet greater demands imposed by the environmetlt in which he must work. The rotary winged aircraft (helicopter) environment is probably the most hostile of these environments, with its rapid changes in direction and high vibration rendering the use of a mouse impractical.

Other devices available for use as pointing devices on a computer include keyboard cursor controls, a touch screen, a track ball or a joy stick. Keyboard cursor controls utilise keys on a keyboard that a computer user presses to move a cursor or a pointer around a display screen. Typically, the keys are labelled with a down arrow, a left arrow, a right arrow and an up arrow. A touch screen is a display device that allows a computer user to interact with a computer system by touching an area on its display screen. Co-ordinate data is generated when a pointing device (such as a finger) approaches or contacts the surface of the display screen. A track ball (or control ball) is a ball, rotatable about its centre, that is used as an input device.A joystick is a lever that can pivot in all directions and is used to locate a pointer on the screen by pivoting the lever away from its rest position.

Use of keyboard cursor controls requires accurate positioning of fingers for control. Movement of the pointer and selection of items using keyboard cursor controls is slow in operation. Ease of operator use has fuelled the search for a more productive solution.

The ideal solution would have a "direct" relationship between the pointer and its control device, like the mouse. The touch screen conceptually appears ideal, in directness. Several technologies of touch screen have been developed, all with their own individual problems. It does have acceptance for some market sectors. In practice, hours of use with hand and arm raised, pointing at the screen, lead to operator fatigue. The pointing accuracy is inferior to that of the track ball and mouse, especially in a moving, vibrating environment.

Because of the above mentioned problems, the keyboard cursor controls and the touch screen, when used in a helicopter, give inferior performance to the mouse. The drawback with a mouse, when used in a helicopter, is the tendency to fall off the table or flat surface on which it is being used.

Options currently used in aircraft and helicopters and in portable and laptop computers include the track ball and joystick. Both need a special design for aircraft use. The movable parts are strengthened to withstand the loads imposed on them. These loads include vibration and rapid motional changes to which the strengthening makes the track ball and the joystick resistant. Unfortunately, under these circumstances, the joystick or the track ball becomes so unwieldy to move that it becomes clumsy for the operator to control. The user-friendliness associated with the track ball and joystick are lost, because of the strengthening. None of the alternatives fully satisfy the demand for user-friendliness and pointing efficiency, combined with the capability of coping with the loads in the helicopter environment.

Ease of access to select buttons is a further consideration. With some devices this needs use of both hands, or such access to buttons or the like may be awkward whilst moving the control. As described above, the desirability of a solution that combines directness of control with ease of access of the select button would be desirable and is not fulfilled by the common solutions used at present. The mouse has both of the desired features, plus the advantage of familiarity. It has the advantage of right or left handed use (versus a fixed track ball or stiff joystick) and can readily plug into another work station providing a better reversionary mode than the stiff joystick or the like, with simpler maintenance and replacement. Unfortunately, it is not suitable in its current form for high vibration or moving applications.

Suitable however, because of its freedom of movement, this free movement could cause spurious pointer motion due to vibration or could cause the mouse to fall off the operating surface completely.

US Patent 4,868,549 describes a magnetic feedback mouse that uses an electromagnet inside a standard mechanical or optical mouse to provide tactile feedback under computer control. In order to overcome the difficulty of positioning the mouse precisely with respect to screen objects, the magnetic feedback mouse alters the apparent texture of the flat surface by selective energising of its electromagnet. Such selective energising is controlled by software. The energising can occur at grid lines to allow precise positioning, or in a text processing application can occur only when the mouse is pointing to words. It does not address the problems of spurious pointer movement due to vibration or of the mouse falling off the operating surface because it does not provide any resistance to movement of the mouse parallel to the surface over which the mouse is moved.

Disclosure of the Invention This invention describes a means of overcoming this disadvantage of the mouse in order that its inherent advantages become available to the mobile user.

Accordingly the invention provides a mouse for use with a computer having a means for providing a magnetic force between the mouse and a ferrous substantially planar surface, the mouse being moveable parallel to the surface, wherein the magnetic force provides resistance to said moving of the mouse.

The magnetic force may be provided by a fixed magnet, but in a preferred embodiment, the magnetic force is controlled by a user of the mouse, preferably by means of a downforce control located on the mouse.

This allows the user to reduce or remove the down force when the mouse is in use, but still retain the advantage of the downforce retaining the mouse in position despite vibration or motional changes when the mouse is not in use. The control of the magnetic force is preferably provided by an electromagnet located in the mouse together with the ferrous plane and is controlled by controlling the current flowing in the electromagnet.

In a preferred embodiment the means for controlling the current in the electromagnet is a switch mode control means, so that the power dissipated in the small area of the mouse is minimised.

Also provided by the invention is a system for controlling a pointer on a display screen attached to a computer, the system comprising: a ferrous substantially planar surface; a mouse for use with the computer having a means for providing a magnetic force between the mouse and the surface, the mouse being moveable parallel to the surface; and means, located on the mouse to allow user control of the magnetic force; wherein the magnetic force provides resistance to said moving of the mouse.

Brief Description of the Drawings Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an isometric drawing of a prior art mouse; Figure 2 shows a ball used for motion detection in a prior art mouse such as that of figure 1; and Figure 3 is an exploded isometric drawing of a mouse according to the invention; Figure 4 shows an electromagnetic coil used in a mouse such as that of figure 3; Figure 5 is a schematic diagram of an electronic control circuit for use in the mouse of figure 3.

Detailed DescriDtion of the Invention A mouse can be used as the basis on which to provide a solution to the problems described above. The mouse needs, like the track ball and joystick, to be restrained and stable when not in use, but unlike the track ball and joystick, easy for the operator to move when in use.

Figure 1 shows a typical prior art mouse 100, with motion detection ball (200 in figure 2), selection button 102 and additional button 104.

If two buttons are required for the normal functions on the mouse, a third button is added as the additional button 104. The mouse 100 is connected to a computer system via a connecting lead 106 and a connector 108, which connects to a suitable connector in the computer system.

Figure 2 shows a motion detection ball withdrawn from the prior art mouse 100 of figure 1. The motion detection ball rotates as the mouse 100 is moved across a flat surface by the user. Mechanical, optical or other means are used to detect the rotation of the ball 200 and signals are sent via connecting lead 106 and connector 108 to the computer system.

Although not shown in Figure 1, an optical mouse, whose motion is detected from a grid of lines on the work surface, can equally be used as can any other arrangement of motion sensors used in a mouse.

Figure 3 shows a mouse 300 including an electromagnetic restraining function according to the present invention. The mouse consists of a cover and button assembly 302 which has a selection button 102 as in a conventional mouse. The second button present in a conventional mouse is used as a downforce trigger control. The purpose of the downforce trigger control will be described later. In an alternative embodiment the second button remains available for use with the mouse and a further button is added. The cover and button assembly 302 is attached to a base 312 which in the present embodiment has a motion detection ball 200 and rollers or wheels 314, 316 to detect movement of the ball 200. The features described above will be well known to those familiar with the construction of a conventional mouse.An electromagnetic coil assembly 306 within the mouse provides an electromagnetic attraction between the mouse 300 and a ferrous plane 310 which is used as a work surface. The strength of the attraction is under operator control, making the mouse 300 suitable for use in a range of moving environments.

Figure 4 shows an electromagnetic coil assembly 306 which has an inductive coil 402 is wound around a ferrous core 404. The core 404 is shaped in an inverted U configuration to concentrate the magnetic field down towards the base. The magnetic field induced in the core 404 of the coil assembly 306 causes a magnetic flux to flow. A ferrous metal placed near the open section of the 'U' will be attracted to the coil assembly 306, completing the magnetic circuit. The force of attraction is proportional to the number of turns of wire on the coil 402 and to the current flowing in the coil 402. This force may, therefore be controlled by control of the current. When the mouse 300 is not in use, the force between the mouse 300 and plane 310 should be high, tethering the mouse 300 to the work surface 310 at its last used point, as the operator's hand moves away.

The combination of magnetic force and friction between the mouse 300 and the work surface 310 is sufficient to hold the mouse in place, despite the vibrations and rapid movement associated with helicopters, ships, cars, planes and the like. Hhen the operator's hand is placed on the mouse 300, a finger rests over the downforce trigger control 104 that controls the current and thus the magnetic force. Increasing depression of the downforce trigger control 104 reduces the force and so the friction between the mouse 300 and the ferrous plane 310. The control law between the finger pressure on the downforce trigger control 104 and the restriction to movement is arranged such that at full depression, the mouse 300 is unrestricted in movement. When the trigger 104 is fully released, the restriction to movement is sufficient to restrain the mouse 300.In a preferred embodiment, the restriction to movement is no more than necessary to restrain the mouse 300.

Under ambient conditions of low vibration, the operator may choose to fully depress the trigger 104 during use, giving swift movement and accurate control. Under ambient conditions of high vibration and erratic motional changes, the operator may choose to use partial finger pressure on the trigger 104, using the magnetic force and friction to steady the mouse 300 to retain the necessary control accuracy. Under ambient conditions where extreme vibration and rapid changes of attitude persist, the operator may choose to use no trigger 104 pressure at all, having the design maximum current and magnetic force available to control the mouse 300 stability.

Whilst the practical application of the invention described here employs an electromagnetic coil assembly 306 in the mouse 300, the electromagnetic restraining force could equally be provided by the work surface with the mouse having a ferrous plane within or attached to it.

Whilst the mouse shown in figure 3 employs a motion detection ball 200 and electromechanical linkage for motion detection, this invention applies equally to optical mice, whose motion is detected from a grid of lines on the work surface, or to any other arrangement of motion sensors.

Electronic Control The interface between the trigger 104 and the coil assembly 306 requires electronic control. A transducer at the trigger 104 produces a small electrical signal. The transducer may be a resistive potentiometer 502 coupled mechanically to the trigger 104. The small electrical signal from the transducer is compared to a reference voltage created by, for example, a zener diode 504, to generate a difference signal. The difference signal is amplified by an integrated circuit operational amplifier 506, as shown in the schematic diagram of figure 5. The amplified signal can be fed directly to a power output stage 508, employing bipolar transistors, or similar, to control the current 510 flowing in the coil 402. Variation of the current flowing in the coil 402, will cause the magnetic force between the mouse and the ferrous surface, and hence the friction between the mouse 300 and the working surface 310, to vary.

In another embodiment switch mode techniques of control of the current 310 are used to minimise heat dissipation in the small area of the mouse enclosure 302, 312.

Stray Field Control The tethered mouse 300 is intended for use on a ferrous plane 310 where stray field will be reduced due to the flow of the magnetic flux in the plane 310. However, magnetic fields can cause disturbance on some aircraft equipment, including CRT based displays that rely on magnetism to control the beam deflection. To further reduce this stray field, in a preferred embodiment, a Mu-metal shield 304 is fitted around the coil assembly 306. The Mu-metal ensures that the stray magnetic field does not disturb displays or other avionic equipment, whilst concentrating the field towards the ferrous plane 310.

In another embodiment, for ease of construction, a fixed magnet is used in place of the electromagnetic coil assembly. The fixed magnet provides the down force necessary to restrain the mouse, when not in use, or under conditions of high vibration and rapid motional changes.

Although this embodiment has none of the control function of the mouse 300 described above, it still has the ability to remain in a stable position whilst under the influence of both rapid movement and variable vibration. A fixed, maximum down force is provided which is easy to control, with no loss in accuracy of movement. However tests have shown that use of such an embodiment by a computer user for long periods of time is tiring, due to the friction between the mouse and work surface.

This disadvantage is overcome by the use of the downforce trigger control which has been described above.

Claims

1. A mouse for use with a computer having a means for providing a magnetic force between the mouse and a ferrous substantially planar surface, the mouse being moveable parallel to the surface, wherein the magnetic force provides resistance to said moving of the mouse.

2. A mouse as claimed in claim 1 wherein the magnetic force may be controlled by a user of the mouse.

3. A mouse as claimed in claim 2 wherein the user controls the magnetic force by means of a downforce control located on the mouse.

4. A mouse as claimed in any preceding claim further comprising a shield for substantially preventing stray magnetic fields being emitted from the mouse.

5. A mouse as claimed in any one of claims 2 to 4 wherein the magnetic force is provided by an electromagnet located in the mouse acting on said surface and the force is controlled by controlling the current flowing in the electromagnet.

6. A mouse as claimed in claim 5 wherein the means for controlling the current in the electromagnet is a switch mode control means.

7. A system for controlling a pointer on a display screen attached to a computer, the system comprising: a ferrous substantially planar surface; a mouse for use with the computer having a means for providing a magnetic force between the mouse and the surface, the mouse being moveable parallel to the surface; and means, located on the mouse to allow user control of the magnetic force; wherein the magnetic force provides resistance to said moving of the mouse.