Title of Invention

"AN IMPROVED TOUCH SENSITIVE INPUT DEVICE FOR COMPUTERS"

Abstract

The present invention relates to an improved touch sensitive input device for computers for public usage in outdoor locations such as villages, slums, roadside etc. which is able to work under stressful environmental conditions and also withstands handling by more than one person at a time. The device under the present invention enables a user to navigate through a graphical user interface by touching the surfaces. The device has no moving parts, is intuitive and is user friendly. The device under the present invention addresses limitations of standard input devices such as mouse and keyboard, which are non-intuitive and hinder the progress of a new computer user. It also addresses the limitation of input devices such as touch pads, which are too fragile and expensive to be used in public computer kiosks, as they get easily damaged by fingernails. The device provided by the present invention in rugged and lasts longer under rough use, as the surfaces are metallic and almost indestructible.

Full Text

FIELD OF INVENTION The present invention provides for an improved touch sensitive input device for computers to control the movement of the cursor on the display screen. The said 'input device' is so designed that there are no parts involving the mechanical movement in the device. The device is made of metal and is affixed. It is rugged, intuitive and touch sensitive. It provides for six discrete metallic buttons, four buttons controlling the direction movement of the cursor. The other two buttons provide the same functionality as left click and right click of a conventional input device, albeit without requiring press of button. A mere touch is sufficient in all the six case. These six metallic buttons put on a copper laminated printed circuit board, are connected to an electronic circuit, which is capable of sensing the touch of any of these buttons. Due to the presence of the large amount of water in the human body, the touch of the user's finger raises the capacitance between the metallic disc and the corresponding pad of the laminated copper on the printed circuit board. The change in capacitance is detected by the circuits and this generates a data packet containing binary data for the movement of the cursor. The circuit is connected to a computer interface circuit, which enables the translation of signals voltage levels and communication protocols in a manner that the device can communicate with standard input/output ports of the computer. Thus the device allows the movement of the cursor on the display screen, while it is suitable to be used in outdoor locations such as villages, slums, roadsides etc., in a wide range of rough usage and environmental conditions, being rugged, intuitive and touch sensitive: Deployment of computers for public user in outdoor locations such as villages, slums, roadsides etc. requires input devices, which should be able to work under a wide range of rough usage and environmental conditions. The standard keyboard and mouse used in the offices or homes do not last very long in this environment. Moreover the non-intuitiveness of a standard computer mouse hinders the progress! of new computer users. They cannot figure out for themselves the correlation between the movement of standard computer mouse and cursor on the computer screen. There are input devices such as touch pad where this correlation is clearer, but these devices are too fragile and expensive to be used in public computer kiosks. Similarly touch screen are intuitive but too expensive and prone to scratches. The design of the input device provided by the present invention is such that the new users find it easier to use and it can be deployed and used in an outdoor, multi-user environment being much more rugged and without any moving parts. PRIOR ART The known and conventional input devices such as Mouse, Trackball, Joystick, Touch-screen and Touch-pad etc. are generally designed for use indoors and by limited number of users. Once deployed in outdbor environment for public use each one these demonstrate several shortcomings. These are usually not rugged enough to handle rough usage. Touch pads get scratched easily. Touch screens are expensive, prone to damage by nails and dust and need recalibratibns sometimes. Joysticks have springs and other mechanical part, which get damaged due to rough usage. A standard mouse is not very intuitive for a new user. Also a standard mouse requires free horizontal surface area to operate. Trackball have moving parts, which are prone to damage due to dust accumulation and rough usage in a public computer kiosk. Therefore need for a rugged and intuitive pointing device was felt. This is the object of the present invention. The known and conventional input devices are-US Patent number US 5,831597 titled "Computer input device for use in conjunction with a mouse input device" discloses a mouse pad like surface with integrated touch sensor which can have pre-selected functionality. The mouse functioning is similar to a standard mouse. US Patent number US 6,535,200, titled "Capacitive position sensor" discloses mouse pointer on top of a normal keyboard. A resistive sheet needs to spread over the keyboard to get the mouse pointer feature. This design is neither intuitive nor rugged enough for use in public computer kiosks. US 6,204,839 discloses a capacitive sensing keyboard and pointing device. However this input device is meant for portable notebook computer and not suitable for outdoor use. Also it does not have six-button design. US 5,959,612 titled "Capacitive sensing keyboard and pointing device" discloses a pointing device for computer which has no moving parts. However its principle of operation is quite different and uses ultrasound for sensing the presence or absence of user's finger. Even the presence of object other than human finger can affect ultrasound based sensing. German patent DE 4312672 titled "Apparatus and method for a contact-less mouse-compatible PC pointer input device" discloses a contact-less pointing device for computer. This invention, though using capacitive sensing and six pads, there are significant distinctions such as: > This prior art patent is forced to use six odd shaped sensitive regions. Our invention uses six circular sensitive areas. > In order to use the said prior art invention the user needs to bring his/her finger towards one of the said six pads. He/She is not required to touch them to use it. One critical shortcoming of this prior art invention is that human finger (or any other body part used) should be right above the sensitive region. This requires that user should keep the finger horizontal (if the device is mounted vertically) in front of one of the six pads and ensure other fingers, palm or wrist of that hand are not in sensitive region of any other pad. Otherwise conflicting signals (e.g. both move-up and move-down) may get generated. This problem is even more severe if the said invention is mounted horizontally. This can lead to a situation where actual direction of cursor movement on the computer screen is different from intended direction. British patent GB 2354572 titled "Touch- or proximity-sensitive switch for a computer pointing device" discloses a mouse for computer. This mouse sends movement signal to computer in response to touch or proximity of the finger. The touch sensitive is, however achieved by means of a switch or interruption of light. This is entirely different from principle used in our invention. A switch-based touch switch is prone to mechanical failure. A light-based interruption switch is prone to misbehavior once the dust accumulation takes place. A capacitance-based touch switch is immune to such problems. PCT patent WO0154111 titled "Capacitive Pointing Stick" uses force sensing capacitor and springs. Thus it has moving parts and therefdre liable to mechanical failure. The present invention addresses all the limitations of the known and conventional input devices. SUMMARY OF THE INVENTION The present invention provides for an improved input pointing device to control the movement of the cursor on the display screen of computers, which has three key features- > There are no moving parts. > Senses capacitance to detect presence or absence of user's finger > Six discrete metallic touch points to insure intuitive usage (four buttons are mapped on up, down, left and right directions and remaining two are equivalent of right and left click of mouse) This invention is a pointing device for computer to control the cursor on the display screen. The known and conventional input devices either use a mechanical movement or are too fragile to be used in a computer deployed for outdoor, public use. Also in many of these devices a continuous movement of the device itself is needed to achieve the corresponding movement of cursor on the screen. The present invention takes care of all these problems. The invention consists of six metallic buttons (as shown in Fig.A). Four of these buttons correspond to the four directions of the movement (Point 1 is to move Up, Point 2 is to move Down, Point 3 is to move Left & Point 4 is to move Right). The other two buttons have application dependant functionality (Point 5 is for left click and Point 6 is for right click). Each of these buttons is solid metallic disc of the circular shape as shown in Fig. C. Each of the six metallic discs (17) is put on a printed circuit (19) as shown in Fig. D. There is a thin layer of dielectric (18) between the said discs and the printed circuit board. Once the user's finger touches the metallic disc, the capacitance (30) between the discs and the corresponding circular pad of laminated copper on the printed circuit board goes up. This is due to the presence of the large amount of water in the human body, which causes the metal disc to go almost ground potential. This change in the capacitance is detected by the circuits (7), (8), (9), (10), (11), and (12) as shown in Fig.A. The capacitance change detection circuits work in the manner as shown in Fig. B. a common square wave oscillator (26 in Fig.B) feeds into each six circuits. When the disc is not touched by the user's finger, its capacitance (30) is very low (typically few fico Farads). The said square wave is therefore able to charge and discharge this capacitance rapidly. This wave then charges another capacitor. The circuit (27) behaves in a manner as shown in Fig. B. If the user is not touching the metallic disc, then it passes the incoming square wave as it is. However, if the user is touching the metallic disc, the capacitance (30) rises and a waveform as shown in Fig. F is generated at the output of (27). The behavior of the circuit (28) can be summarized in the following words - a) if the input is square wave then its output is binary state A. b) if the input is as shown in Fig. F then its output is binary state B. Thus the said binary state A corresponds to the "no touch" situation and the said binary state B corresponds to the "touched" state of the said metallic button. The role of the circuit (29) is to inhibit square wave oscillator (26), briefly, when user's fingers gets off one of the buttons. This eliminates the switch bounce problem. The said binary signals are then fed into a micro-controller based circuit (13). In the preferred embodiments this is either 89C2051 or PIC16F74 based circuit. This circuit receives the six inputs from the capacitance change detection circuit. Based on these inputs, the circuit (13) creates data packets to be sent to the computer via a computer interface circuit (14). The said computer interface circuit is connected to the said data packet generation circuitry computer. In the preferred embodiments it is either a RS232 level translator or a small microcontroller (if the device is connected to PS/2 or USB port of the computer). Thus if, for instance, a user touches the move-up button, binary signal (20) changes its state. This state is recognized by the micro controller based circuit (13). It then creates a data packet such that the computer interprets that as move-up command for its cursor, which is displayed on the computer display screen. The solid metallic button (17) is mounted slightly below the surface of upper printed circuit board as shown Fig. D at point (31) so as to minimize the chance of unintended touching of any button and thus causing unintended cursor movement. STATEMENT OF INVENTION: Improved touch sensitive input device for computers characterised in that it comprises computer interface circuit, enabling translation of signals, voltage level, electronic circuit having capacitance (30), oscillator (26), six metallic touch buttons. WE CLAIM :- 1. Improved touch sensitive input device for computers characterised in that; moving it comprises computer interface circuit, enabling translation of signals, voltage level, electronic circuit having capacitance (30), oscillator (26), six metallic touch buttons. 2. Improved touch sensitive input device for computer as claimed in Claim 1, wherein each of six buttons is solid metallic disc of circular shape mounted ifi slight depression. 3. Improved touch sensitive input device for computer as claimed in Claim 1, wherein 1 to 4 buttons correspond to movement (up, down, left & right). 4. Improved touch sensitive input device for computer as claimed in Claim 11, wherein buttons 5 & 6 correspond to left and right click respectively. 5. Improved touch sensitive input device for computer as claimed in Claim | providing for electronic circuit capable of detecting the touch of user's finger by sensing the change in capacitance and generating data packets at periodic intervals. 6. Improved touch sensitive input device for computer substantially as herein described with reference to the description and as illustrated in the accompanying drawings.

Documents:

317-del-2003-abstract.pdf

317-del-2003-claims.pdf

317-del-2003-complete specification granted.pdf

317-del-2003-correspondence-others.pdf

317-del-2003-correspondence-po.pdf

317-del-2003-description (complete).pdf

317-del-2003-drawings.pdf

317-DEL-2003-Form-1.pdf

317-del-2003-form-13.pdf

317-del-2003-form-19.pdf

317-del-2003-form-2.pdf

317-del-2003-form-3.pdf

317-del-2003-form-5.pdf

317-del-2003-petition-138.pdf