Active capacitive control stylus

A data transfer device comprising: a body; a tip coupled to the body, wherein the tip has a dielectric constant value suitable for interacting with a capacitive touch screen of a separate device; a control unit mounted to the body; and an electronic switch mounted to the body and operatively coupled to the control unit, wherein the switch is disposed to connect the tip to a ground source when the switch is in a closed configuration and to break the connection between the tip and the ground source when the switch is in an open configuration.

BACKGROUND OF THE INVENTION

This invention relates generally to devices for transferring data through a capacitive touch screen. In recent years capacitive sensing technology has been integrated and employed in many electronic applications and devices. The capacitive sensor is replacing conventional mechanical switches and buttons used to input data and control operating machines, computer systems, games, and electronic portable devices. Touch screens on phones and other handheld devices are exemplary in their use of capacitive sensing technology. Using finger touches on the sensor screen to input data is very convenient; however as currently implemented a user can only input one value at a time with a touch. Such input is limited to the speeds at which a human can reasonably input via screen touches. To input a series of values such as a phone number or address, a user must perform several touches on different screen regions to input the information. On-screen keyboards are commonly implemented as a general-purpose input mechanism. However, current methods of transferring data through a capacitive touch screen are limited by their reliance on visual feedback and sequential input.

SUMMARY

Disclosed herein is a data transfer device comprising: a body; a tip coupled to the body, wherein the tip has a dielectric constant value suitable for interacting with a capacitive touch screen of a separate device; a control unit mounted to the body; and an electronic switch mounted to the body and operatively coupled to the control unit, wherein the switch is disposed to connect the tip to a ground source when the switch is in a closed configuration and to break the connection between the tip and the ground source when the switch is in an open configuration.

Also disclosed is a method for transferring data to a capacitive touch screen comprising the following steps: bringing a tip having a dielectric constant value suitable for interacting with the capacitive touch screen into contact with the capacitive touch screen, wherein the tip is isolated from a ground source, but for an electronic switch; and rapidly switching the electronic switch with a microcontroller such that serial data is transferred into the capacitive touch screen.

Another embodiment of the data transfer device comprises: a body; a control unit mounted within the body; a tip operatively coupled to the control unit, wherein the tip has a dielectric constant value substantially similar to that of a human finger; an input button mounted to the body and operatively coupled to the control unit; a display mounted to the body and operatively coupled to the control unit; and an electronic switch mounted to the body and operatively coupled to the control unit, wherein the switch is disposed to connect the tip to a ground source when the switch is in a closed configuration and to break the connection between the tip and the ground source when the switch is in an open configuration.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1is an illustration of a data transfer device10. As shown inFIG. 1, the data transfer device10comprises a body12, a tip14, a control unit16, and an electronic switch18. The tip14, which is coupled to the body12, has a dielectric constant value that is suitable for interacting with a capacitive touch screen of a separate device such as the one shown inFIGS. 2a-2b. The control unit16and the electronic switch18are both mounted to the body12. The switch18is operatively coupled to the control unit16such that the control unit16controls the opening and closing of the switch18. The switch18is disposed to connect the tip14to a ground source20when the switch18is in a closed configuration and to break the connection between the tip14and the ground source20when the switch18is in an open configuration. In other words, the tip14is electrically isolated from the ground source20, but for the switch18. The data transfer device10may be used to transfer data to a capacitive touch screen by bringing the tip14into contact with the capacitive touch screen and rapidly switching the electronic switch with a microcontroller such that serial data is transferred into the capacitive touch screen.

The body12may be any size or shape capable of supporting the tip14, the electronic switch18and the control unit16. For example, the body12may be, but is not limited to, a cylindrical housing such as the one shown inFIGS. 2a-2b, a glove such as that shown inFIG. 14, or a rectangular prism, such as the one shown inFIG. 15. The body12may be conductive or non-conductive. For example, in one embodiment, the body12may be in the shape of a hand-held stylus and made out of conductive material such that a user's hand26is the ground source20.

The tip14may be of any size, shape, or material that is capable of interacting with a capacitive touch screen. For example, the tip14may be made of an elastic material which has dielectric characteristics about the same as a human finger and provides a soft touch on the capacitive touch screen. In another embodiment, the tip14may be metallic. Other examples of the tip14shape include, but are not limited to: a paintbrush tip, a marker tip, a ball-point pen tip, a pointed tip, and a rounded tip. Some of these shapes are depicted inFIG. 13. Those having ordinary skill in the art will realize that there are many possible sizes and shapes for the tip14that would be compatible with a capacitive touch screen.

The electronic switch18may be any switch capable of being rapidly controlled by the control unit16. Suitable examples of the electronic switch18include, but are not limited to, an electro-mechanical switch, a solid-state switch, and a micro-electro-mechanical system (MEMS) switch.

FIG. 2shows a perspective view of one embodiment of the data transfer device10transferring data through a capacitive touch screen22of a separate device24. The separate device may be any machine with a capacitive touch screen22such as, for example, a cellular phone, a computer, a personal digital assistant, or a machine operator control panel. In this embodiment, the body12is shaped such that a user may hold the data transfer device10in his/her hand26.

FIGS. 3a-3bshow the operational principle behind a typical capacitive touch screen22. A typical capacitive touch screen22comprises at least one capacitive sensor element28and a ground plane30, both of which are typically capacitive pads laid out on a substrate32. The capacitive sensor elements28and the ground plane30are usually covered by a protective layer34. As shown inFIG. 3a, the two capacitive pads form a capacitor, denoted as Cpad. The circuits on the right ofFIGS. 3a-3bare electrical representations of the layouts to the circuits' left. InFIG. 3b, the finger-touch on the protective layer34forms a gap between the finger-tip and the capacitive sensor element28, which forms another capacitor named Cfinger. The ground plane30of a capacitive touch screen22is often connected to Ground via a user's hand(s)26and body. As shown inFIG. 3a, when there is no finger touch, the total capacitance Ctotal=Cpad. As shown inFIG. 3b, when there is finger touch, the total capacitance Ctotal=Cpad+Cfinger. An additional electronic circuit can measure the difference in capacitance in the two situations, though only about 10 to 100 pF, and interpret it as two different signal levels such as ON/OFF.

FIGS. 4a-4bdescribe the operation of one embodiment of the data transfer device10. As shown inFIG. 4a, the finger(s) or hand26of the user is not directly in contact with the protective layer34, but via the electronic switch18. In this embodiment, the body12is conductive. When a user's finger(s) touch the body12, the body12connects to one side of the electronic switch18. The other side of the electronic switch18is connected to the tip14, which is also conductive. The tip14and the capacitive sensor element28form a capacitance named Cstylus. As shown inFIG. 4a, when the switch18is opened, the total capacitance Ctotal=Cpad. When the switch18is closed, as shown inFIG. 4b, the total capacitance Ctotal=Cpad+Cstylus.

FIG. 5ais a plot of an example electrical signal generated by the data transfer device10as the control unit16controls the switch18. Logic level ‘0’ and ‘1’ represent two signal voltage levels that the control unit16may generate. Signal ‘0’ drives the switch18to open and signal ‘1’ drives the switch18to close. This logic may be reversed for some applications in order to save power and to simplify protocol design. When the switch18is open, the total capacitance Ctotal=Cpad. When the switch18is closed the total capacitance Ctotal=Cpad+Cstylus. From the different values of capacitance, the capacitive touch screen22can measure the difference, which the device24can interpret as serial data input.

FIG. 5bis a block diagram of an example embodiment of the control unit16. The control unit16comprises a microcontroller36and a switch driver38. The microcontroller36generates and sends On/Off electrical signals to control the switch driver38to close and open the electronic switch18in a desired temporal pattern. A user can input data or select data to send through the tip14to the separate device24via an input button40. The data transferred from the tip14into the capacitive touch screen22of the separate device24may comprise instructions to the separate device24. When such a device24controls a graphical display such as a liquid crystal display (LCD), portions of displayed content may be manipulated according to the received instructions when the tip14passes over the capacitive touch screen22. It is understood by one having ordinary skill in the art that the device24may comprise a display screen and a capacitive touch screen which co-reference one another.

The input button40may also be used to allow the user to select the operating mode of the data transfer device10and may also be used to select a data base stored in the control unit16. In a stylus mode of operation the control unit16is disposed to maintain the electronic switch18in the closed configuration. Alternatively, in a data transfer mode the control unit16is disposed to transfer data to the separate device24by rapid actuation of the electronic switch18while the tip14remains in contact with the capacitive touch screen22. In yet another embodiment, the control unit16may be configured to transfer data to the separate device24both by rapid actuation of the electronic switch18as well as the movement of the tip14over the protective layer34of the capacitive touch screen22. For example, if a user desired to draw a line on a capacitive touch screen, the data transfer device10is capable of simultaneously transferring multiple characteristics of the desired line to the separate device24. For example, the location of the tip14on the capacitive touch screen22could determine the location of the line, the speed of movement of the tip14over the capacitive touch screen22could determine the opacity of the line, acceleration of the tip14could determine whether the drawn line endpoints are rough or smooth in displayed texture, and the serial data transferred through the tip by rapid actuation of the switch18could determine other line characteristics such as, but not limited to, the color, hue, saturation, and line-type. In a copy mode, the tip14could be dragged across text to inform the device24that a user desires to highlight or copy the text. The serially-transferred data could provide instructions to the separate device24to both visually highlight and copy the highlighted text—all in one stroke.

The control unit16may also comprise a display42, which provides the user with a view of the operational status of the data transfer device10and representations of data before, during, and/or after the data is sent to the switch driver38. In connection with the line-drawing example provided above, the display42may be used to display the current color of the stroke and the input button40may be configured to allow the user to select the color and width of the stroke from a menu. The control unit16may comprise a memory store comprising a data base of text, numbers, figures, pictures, templates, maps, etc. for a user to choose from.

The control unit16may further comprise motion and orientation sensors44, which measure motion and orientation of the data transfer device10. The control unit16may be configured to interpret the output from the motion and orientation sensors44as control commands such as up, down, turn, in, and out, which can subsequently be transferred to the separate device24. In this manner, the data transfer device10could be used as a multiple-axis joystick, as shown inFIG. 7. Suitable examples of the motion and orientation sensors44include, but are not limited to: 3-dimensional magnetic sensors, 3-dimensional acceleration sensors, and 3-dimensional gyroscopes.

The control unit16may also comprise a haptic feedback module46, which provides tactile feedback to the finger and hand of the user—indicating operation control status. The control unit16may also be equipped with a transceiver48, which may provide an interface between multiple data transfer devices10or between a data transfer device10and a personal computer for the update of internal memory data and the transfer of data. The transceiver48can be wired or wireless. The control unit16may also comprise a power unit50that supplies power for all the electronic components of the data transfer device10. In one embodiment, the power unit50comprises a charger, a battery and a regulator. As an alternative to the embodiment discussed above where the user's hand acts as the ground source20, the power unit50may provide the ground source20. Also shown inFIG. 5bis a switch control signal51, which is sent from the switch driver38to the electronic switch18.

FIG. 6ais a perspective view of another embodiment of the data transfer device10showing the display42and the input button40mounted on the body12. A user may use the input button40and display42to select data from a list, shown on the display42, which would then be transferred through the tip14while the tip14rests on the capacitive touch screen22. The data will then be retrieved and interpreted by the capacitive sensor element28.FIG. 6bis an internal view of the data transfer device10depicted inFIG. 6adepicting the electronic switch18and the control unit16mounted within the body12.

FIG. 7is a perspective view of an embodiment of the data transfer device10showing the range motion of the data transfer device10. While holding the tip14on the capacitive touch screen22, a user can change the orientation of the body12in the following directions: X, Y, Z, and angle alpha. The control unit16is configure to receive the outputs from the orientation and motion sensors44and to convert that orientation information into control commands for controlling items or actions on the separate device24. The orientation sensors44are disposed to generate acceleration data representing accelerations of the data transfer device10in X, Y, Z directions as well as rotation of the data transfer device10about a center axis A-A of the data transfer device10. A motion gesture can be performed in air or on the other surfaces with the data transfer device10, and the control unit16captures the gesture. The gesture is then transferred to the capacitive touch screen22.

FIG. 8is an illustration showing two wirelessly linked data transfer devices10aand10b. The transceiver48in each data transfer device10allows the data transfer devices10aand10bto communicate with each other at a distance. Although the data transfer devices10aand10bare shown inFIG. 8to be wirelessly connected, it is to be understood that a wireless link is merely one embodiment and that the link between different data transfer devices10may be wired or wireless. Users of separate data transfer devices10aand10bmay desire to link their data transfer devices in order to share information or synchronize control and actions on different separate devices24aand24bor other equipment.

FIGS. 9a-9bare illustrations of another embodiment of the data transfer device10wherein the tip14includes a trackball sensor52. In this embodiment, the tip14is mounted on a detachable head54. The data transfer device10with an integrated trackball sensor52on its tip14is capable of tracking and recording hand-writing56on a surface58as well as sending the recorded data to the separate device24through the capacitive touch screen22as discussed above. The control unit16may be configured to analyze and recognize alphanumeric and symbolic characters from the data generated by the trackball sensor52.

FIG. 10ashows a data transfer device10configured with a demultiplexing electronic switch60to switch data from a serial bus switch control signal62generated by the control unit16across individual electrically isolated segments64of a segmented tip66. The segmented tip in this embodiment could be used to detect finger grasping position or as a control surface for active manipulation of the switched data streams. Note that the segmented tip66can be segmented such that each segment64is electrically isolated and that each segment64is equal in area. The segmented tip66could be made flexible such that pressure would cause a greater number of segments64to contact the surface of the capacitive touch screen22, allowing pressure applied by the user to be used as a control parameter.FIG. 10bshows an alternate embodiment of the data transfer device10configured with a multiplexing electronic switch68to switch data from a parallel bus switch control signal70generated by the control unit16across a non-segmented tip14.FIG. 10cshows another embodiment of the data transfer device10where the control unit16is configured to generate multiple switch control signals51, each of which activates a different segment64of the segmented tip66.

FIGS. 11a-11billustrate another embodiment of the data transfer device10. In this embodiment, the body12comprises first and second ends74and76respectively. The tip14is coupled to the first end74and the second end76comprises an electronic and mechanical interface78disposed to engage an accessory device80. The electronic and mechanical interface78is disposed to electrically couple the accessory device80to the control unit16and to mechanically couple the accessory device80to the second end76of the body12. The accessory device80shown inFIGS. 11a-11bis a chemical and temperature sensor82. The chemical and temperature sensor82is configured to sample, monitor, and capture temperature and chemical characteristics of a chemical solution84held in the container86. The control unit16can record and store output data from the chemical and temperature sensor82. The stored output data can be later transferred to the separate device24for further processing and analyzing. The chemical and temperature sensor82may also operate in an open-air sensing environment in which environmental contaminants or environmental characteristics are tracked. The data transfer device10can be used as a probe to interrogate a surface, container, or region by placing the data transfer device10directly upon a surface or by attaching the data transfer device10to an extended shaft to reach a surface or region.

While the accessory device80is portrayed inFIGS. 11a-11bas a chemical and temperature sensor82, it is to be understood that the accessory device80is not limited to a chemical and temperature sensor, but may be any device that is compatible with, and adds functionality to the data transfer device10. Suitable examples of the accessory device80include, but are not limited to, an environmental characteristic sensor, a connection adapter, an auxiliary power supply, a track ball, a writing implement tip, a wireless data transfer unit, a laser pointer, a microphone, a camera, a radio receiver, an infrared transmitter, a vitals sign sensor, and a light source.

FIGS. 12a-12billustrate different embodiments of the electronic and mechanical interface78. The electrical and mechanical interface78may be any interface capable of holding an accessory device80and electrically connecting the accessory device to the control unit16.FIG. 12ashows the electrical and mechanical interface78as a universal serial port (USB) plug.FIG. 12bshows the electrical and mechanical interface78as a multi-pin connector. One having ordinary skill in the art will recognize that there are many suitable embodiments of the electrical and mechanical interface78beyond those specifically mentioned above.

FIG. 13shows another embodiment of the data transfer device10where the body12comprises electrical and mechanical interfaces78on both the first and second ends74and76. The interface78on the first end74is disposed to mechanically and electrically interface with each of a plurality of interchangeable tips88. The interface78on the second end76is disposed to mechanically and electrically interface with one of a plurality of accessory devices80. In operation, the data transfer device10may comprise any desired combination of interchangeable tips88and accessory devices80.

The interchangeable tip88may be any size, shape, and material that allow the interchangeable tip88to be capable of interacting with the capacitive touch screen22. For example, in one embodiment, the interchangeable tip88may comprise bristles90substantially similar to that of a paint brush. In another embodiment, the interchangeable tip88may be a blunt tip92made of an elastic material which has dielectric characteristics about the same as a human finger and provides a soft touch on the capacitive touch screen22. In another embodiment, the interchangeable tip88may be a stylus tip94having a sharper tip than the blunt tip92. In another embodiment, the interchangeable tip88may comprise a trackball sensor52. Also shown inFIG. 13, is another embodiment of the interchangeable tip88comprising a suction cup96disposed to be coupled to the capacitive touch screen22and disposed to be electrically coupled to the electronic switch18(not shown) via the electrical and mechanical interface78. The suction cup96allows greater freedom of movement of the data transfer device10while still enabling serial data transfer through the capacitive touch screen.

FIG. 13illustrates four example embodiments of the accessory device80. In one embodiment, the accessory device80comprises at least one button98. The accessory device80may be a finger trackball99, an environmental characteristic sensor100, and/or a connection adapter102. The environmental characteristic sensor100may be any sensor disposed to sense a characteristic of the environment surrounding the data transfer device10such as the temperature, humidity, gas and/or chemical presence, audio levels and frequencies, light level, etc. The connection adapter102may be any desired electrical adapter for allowing the data transfer device10to interface with another machine.

FIG. 14shows another embodiment of the data transfer device10where the body12is in the form of a glove104. In this embodiment, a tip14may be placed at the end of one or more of the glove's fingers106. Alternatively, the glove104may be coupled to a suction cup tip96via a conductive tether108—this allows the glove104to utilize a large number of degrees of freedom while maintaining contact with the separate device24. In this embodiment, gesture data provided by the motion and orientation sensors44could be transferred into the capacitive touch screen22.

FIG. 15shows another embodiment of the data transfer device10as an interface between a separate device24with a capacitive touch screen22and a machine110. Although the machine110is shown inFIG. 15to be a laptop computer, it is to be understood that the machine110may be any machine with a digital central processing unit. In the embodiment shown inFIG. 15, the data transfer device10is plugged into a USB port of a laptop with the tip14directed outwards ready to engage the capacitive touch screen22of the separate device24.

From the above description of the data transfer device10, it is manifest that various techniques may be used for implementing the concepts of data transfer device10without departing from its scope. The described embodiments are to be considered in all respects as illustrative and not restrictive. It should also be understood that the data transfer device10is not limited to the particular embodiments described herein, but is capable of many embodiments without departing from the scope of the claims.