GB2428094A

GB2428094A - A controller for an input device, an input device, and a method of using an input device

Info

Publication number: GB2428094A
Application number: GB0513972A
Authority: GB
Inventors: Thomas Matthew Wynne-Powell
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2005-07-08
Filing date: 2005-07-08
Publication date: 2007-01-17
Also published as: GB0513972D0

Abstract

A controller (15) for an input device (13) is adapted to discriminate between at least first and second users on the basis of a user identification signal received from at least one of the users. In one example, the controller is adapted to receive an input signal comprising one of a first user identification signal V1(t) and a second user identification signal V2(t), and to discriminate between the first and second users on the basis of whether the input signal comprises the first user identification signal or the second user identification signal. A position controller also detects the position of the input signal on the display (13) which may be a touch screen. Alternatively, a signal from the input device may be detected passing through one or the other user to a detector circuit. The input device and controller may be used in a car dashboard, computer screen or any other user controlled touch screen.

Description

A controller for a position-sensitive input device, a position-sensitive

input device, and a method of using a position-sensitive input device The present invention relates to a controller for an input device, in particular to a controller for a touch-sensitive input device or a position-sensitive input device. It also relates to an input device, and to a method of operating an input device.

One example of an input device is a touch-sensitive input device. A touchsensitive input device has, in general terms, a sensor surface and means for determining when a touch is made to the sensor surface. The input device generates a signal, such as an electrical signal, when a touch is detected. The touch may be the touch of a user's finger, or it may be the touch of a stylus or other object.

A touch sensitive input device may further be a position-sensitive input device such as, for example, a touch panel. A touch panel has, in general terms, a sensor surface and means for determining the position of a touch on the sensor surface. The touch may again be the touch of a user's finger, or it may be the touch of a stylus or other object.

A touch sensitive input device generates co-ordinates that represent the position of the touch, and outputs them.

Such an input device can be used to control another device such as, for example, a display device or a computer - when the input device generates co-ordinates representing the position of a touch, in the case of a position sensitive input device, these co-ordinates are used to control the operation of the display device or computer in some way. In the case of a computer, as an example, if the input device generates co- ordinates that correspond to the position of an icon displayed on the display screen of the computer, the computer would then open the application identified by that icon. In other applications, an input device such as a touch panel may have virtual buttons (or "soft buttons"). If, following a touch by a user, the input device generates co-ordinates that correspond to the position of one of the virtual buttons, the input device would then control its associated device to perform the action corresponding to the "button" selected by the user, in the same way as if the user had selected the action by pushing a physical button on a keyboard.

One application of a position sensitive input device is to control a display, for example a display in a motor vehicle. Many motor vehicles now contain a display in the central console. The display may also function as an input device, to allow a user to control the operation of various sub-systems such as the radio, heating, ventilation and air- conditioning (HVAC), a navigation interface, and a digital video disc (DVD) player. A user may interact with these systems either by using soft buttons surrounding the screen of the display, or by using a touch panel overlaying the display. With increasing concerns about driver distraction many of these systems are now disabled while the car is in motion, so that the driver cannot control these systems. This is generally done by disabling the input device controlling the systems, so that it does not respond to any input from a user. However, this has the disadvantage that the input device will not respond to any input from a front seat passenger so that the front seat passenger is also unable to operate the systems. This is a particular disadvantage where a motor vehicle has a dual view display which provides different images to each of the occupants (for example by displaying a navigation display to the driver and an entertainment program to passengers), since disabling the input device means that the passenger cannot then change the image displayed to them.

A further disadvantage of the inability of conventional input devices to distinguish between users occurs when they are used to control a device whose desired operation depends on the user. In the example of a display in a motor vehicle, a conventional input device cannot distinguish between an input from the driver and an input from a front seat passenger - so, if it is desired to allow either user to control the view that they see on the display, independently of the view seen by the other user, it is necessary to provide separate input devices for each user.

US patent No. 5 365 461 describes a touch panel that can discriminate between operation by human touch and an inanimate object. This addresses the problem that, when a user writes on a touch panel using a stylus, it is important that the user's hand does not touch the touch panel at the same time, since this would cause an error in the estimated position of the stylus.

Figure 1 shows the touch panel 1 of US 5 365 461. The touch panel has a sensor surface 2, which a user 3 may touch either with their hand 4 or with a stylus 5. Current detectors 6-9 detect the current flowing out of each of the four corners of the sensor surface, and the output from each current detector is fed to a converter and controller 10 which determines the position of the touch on the sensor surface and outputs the determined position.

The panel further has a voltage source 11 that generates an a.c. voltage and feeds this to a switch 12. In one time frame switch 12 is in position "a" as shown in figure 1, and in this time frame the a.c. voltage is applied to the sensor surface I via the current detectors. When a user's hand 4 touches the sensor surface, a small amount of a.c.

current is coupled to ground through the equivalent capacitance CB of the user. This flow of a.c. current is detected by the current detectors 6-9, and is included in the output signals sent from the current detectors 6-9 to the controller 10. In another time frame the switch 12 is switched to position "b", so that in this time frame, when the stylus 5 touches the sensor surface, an a.c. current can flow to ground via the stylus 5, the sensor surface 2, the current detectors 6-9 and the terminal "b" of the switch 12. This flow of a.c. current is again detected by the current detectors 6-9 and is included in the output signals sent from the current detectors 6-9 to the controller 10. Thus, it is possible to determine whether the user's hand 4 or the stylus 5 is touching the sensor surface if an a.c. current flows at a time when the switch 12 is set to position "a" the user's hand 4 is touching the sensor surface 2, whereas if an a.c. current flows at a time when the switch 12 is set to position "b" the stylus 5 is touching the sensor surface 2.

The magnitudes of the current flowing through the current detectors 6-9 will depend on the position of the touch of the stylus 5 or user's hand 4. Measurement of the magnitudes of the four currents thus allows the position of a touch to be determined.

If there are two or more users, every time one of the users touches the sensor surface with their hand an a.c. current will (in a time frame when the switch 12 is set to position "a") flow to ground via the user who is touching the sensor surface. The touch panel of US 5 365 461 cannot, therefore, discriminate between touches by two different users.

US patent No. 6 498 590 discloses a touch surface formed of a plurality of touch sensitive pads arranged in rows and columns. The pads act as antennae and, when touched, couple a signal to a user. Each antenna may be driven with a signal of a different frequency so that the user who has made a particular touch can be identified.

A first aspect of the present invention provides a controller for a user input device, the controller having first means for detecting a user input to the device and second means independent of the first means for determining whether an input was made by a user in one of at least first and second groups of users. When a user makes an input to the input device, the controller can determine which of the possible users has made the input.

The first means for detecting the user input and the second means for determining the identity of the user making the input are independent. Thus, the input device may be used to make user inputs even if the second means should fail. Furthermore, it is possible to retro-fit the user identification means of the invention to a pre-existing input- device.

The second means may be adapted to discriminate between at least a user in a first group of users and a user in a second group of users on the basis of a user identification signal received from users in at least one of the groups.

Alternatively, the second means is adapted to discriminate between at least a user in a first group of users and a user in a second group of users on the basis of a signal coupled from the user input device to a user. Where the invention is applied to, for example, a touch-sensitive input device, a user identification signal may be applied to the device for coupling to a user who makes a touch, to determine the identity of a user making the touch.

The controller may be adapted to output the signal for coupling to the user via the user input device.

The controller may be adapted to receive a returned user identification signal from a user in one of the first and second groups of users, and to determine from which of the first and second groups of users the returned user identification signal was received. As indicated above, a user identification signal is output to the user input device and, when a user touches the input device, the signal is coupled to the user. The signal is then returned from the user to the controller, for example via capacitive coupling from the user to an aerial located in close proximity to the user and thence from the aerial to the controller. When the returned signal is received at the controller, the controller is then able to determine via which user (or from which group of users) the signal has been returned.

The controller may be adapted to process a user input in accordance with a determination of which user made the input. Where the controller is used to control another device, such as a display, computer, etc., the way in which the controller controls the other device can thus depend on which user makes an input to the input device.

The controller may be adapted to send an output signal in response to a user input, the output signal being dependent on the position of the user input and on a determination of which user made the input. As an example, when a controller of the invention is used to control a host system connected to a display in a motor vehicle, an input may be made by either the driver of the vehicle or by a front seat passenger. If the controller determines that the passenger has made an input, the controller can instruct the host system to control the display in the usual way in accordance with the input made by the passenger. In this case, the output signal sent by the controller to the host system would, in the case of a position-sensitive input device, be determined by the position of the user input on the position-sensitive input device, in conventional manner. If, however, the controller determines that the driver has made a particular input, the controller can "ignore" the input by sending no control signal (or, if the controller continuously sends a control signal to the host system, by sending an unchanged control signal) to the host system or by sending an enable/disable signal, so that the driver's input has no effect on the operation of the display. Thus, the display has effectively been disabled as far as the driver of the vehicle is concerned, as desired for safety reasons. The display may alternatively be partially disabled as far as the driver is concerned, so that the driver cannot control certain functions but can control other functions.

A controller of the invention also has applications outside the automotive environment.

For example, it could be used with a point-of-sale (POS) system to provide discrimination between an input from a salesperson and an input from a customer.

Alternatively, it could be used for a device such as a combined printer/copier/facsimile where more than one user may simultaneously operate the interface.

The controller may be adapted to send an output signal in response to a user input, the destination of the output signal being dependent on a determination of which user made the input. This may be of benefit in, for example a P05 system in a public house, bar or fast-food establishment where staff enter customer's orders into a touch panel or other position-sensitive input device. Conventionally, a member of staff must "key in" before they can enter a customer's order and then "key out", and another member of staff cannot enter an order until the first member of staff has keyed out. However, a controller of the invention would automatically key-in each member of staff. In this case, if the input "portion of chips" is made, the controller would determine which member of staff had made this input and add the cost of a portion of chips to the bill for the customer being served by that member of staff.

The controller may be adapted to store the result of a determination of which user made an input, or to send the result of a determination ofwhich user made an input for storage elsewhere. This is of use in application where two or more users may use a position- sensitive device and it is important to keep a record of which user made an input. As an example, a controller of the invention could be used in an aircraft, in which the flight- deck crew enter commands or other data using a touch panel or other position-sensitive input device. The controller of the invention would make it possible to discriminate between operation by the pilot or by the co-pilot for data recording purposes.

The controller may be adapted to receive an input signal comprising one of at least a first user identification signal and a second user identification signal, and to discriminate between the first and second users on the basis of whether the input signal comprises the first user identification signal or the second user identification signal. (If there are more than two users, or more than two sets of users, third, fourth etc identification signals may be used as necessary.) The controller may be adapted to receive, as the input signal, a composite of a position information signal and one of at least first and second user identification signals.

The first and second user identification signals may be different timevarying signals.

They may be different alternating signals, for example different sinusoidal signals.

The first user identification signal may have at least one of: a different frequency from the second user identification signal, a different phase from the second user identification signal, a different amplitude from the second user identification signal or a different waveform from the second user identification signal.

The first and second user identification signals may be time-multiplexed.

One of the first and second user identification signals may be zero. Alternatively, one of the first and second user identification signals may be a d.c. signal with constant amplitude.

The controller may be adapted to output a user identification signal for coupling to a user via the position-sensitive input device.

The controller may be adapted to receive a returned user identification signal from one of the first and second users, and to determine from which of the first and second users the returned user identification signal was received.

The controller may be adapted to receive a position information signal from the device.

The controller may comprise a programmable data processor.

A second aspect of the invention provides a position sensitive input device comprising a controller of the first aspect.

The input device may be a touch-sensitive input device, or it may be a position-sensitive input device. It may comprise a touch panel.

The device may further comprise means for generating the first user identification signal and the second user identification signal.

The device may further comprise means for coupling the first user identification signal and the second user identification signal to the first user and the second user respectively.

A third aspect of the invention provides a computer-readable medium comprising a program for the data processor of a controller of the second aspect.

A fourth aspect of the invention provides a method of operating a user input device, the method comprising detecting a user input; and substantially simultaneously with the detection of the user input, determining whether the user input was made by a user in one of at least first and second groups of users.

The method may comprise discriminating between at least a user in a first group of users and a user in a second group of users on the basis of a user identification signal received from users in at least one of the groups.

The method may comprise coupling a signal from the position-sensitive input device to a user.

The method may comprise receiving a returned user identification signal from one of the first and second users, and determining from which of the first and second users the returned user identification signal was received.

The method may further comprise processing a user input in accordance with a determination of which user made the input.

The method may further comprise sending an output signal in response to a user input, the output signal being dependent on a determination of which user made the input.

The method may further comprise sending an output signal in response to a user input, the destination of the output signal being dependent on a determination of which user made the input.

The method may further comprise storing the result of a determination of which user made an input.

The method may further comprise sending the result of a determination of which user made an input for storage.

The method may comprise the further step of coupling a user identification signal to one of a first user and a second user.

The method may further comprise coupling a first user identification signal to a first user and coupling a second user identification signal to a second user.

The method may further comprise discriminating between the first user and the second user on the basis of whether a signal generated by the position-sensitive input device comprises the first user identification signal or the second user identification signal.

The method may further comprise generating, as an input signal, a composite of a position information signal and one of first and second user identification signals.

The method may further comprise coupling the first user identification signal and the second user identification signal to the first user and the second user respectively.

The first and second user identification signals may be time-multiplexed.

The method may further comprise coupling a user identification signal from the position-sensitive input device to a user.

The method may further comprise receiving a returned user identification signal from one of the first and second users, and determining from which of the first and second users the returned user identification signal was received.

Preferred embodiments of the present invention will be described by way of illustrative examples, with reference to the accompanying figures in which: Figure 1 is a schematic illustration of a conventional touch panel; Figure 2 shows an input device according to a first embodiment of the present invention; Figure 3 is a block diagram of the input device of figure 2; Figure 4 shows an input device according to a second embodiment of the present invention; Figure 5 is a block diagram of the input device of figure 4; Figure 6 shows an input device according to a third embodiment of the present invention; and Figure 7 is a block schematic diagram of an input device of the invention.

The invention will be described with reference to a position-sensitive input device, in particular a touch panel. However, the invention is not limited to a touch panel, nor even to a position sensitive input device. For example, the invention may be applied to any input device that generates an output signal when a user makes an input. For example, the invention may be applied to a mechanical input device such a press-button or a switch where a user makes an input by mechanically causing electrical contacts to change their state.

Figure 2 shows an input device 15 according to the present invention that is controlling (ie, is acting as input device for) a host system that is controlling a further device 13. In this embodiment the device that is being controlled is shown as a display device for illustrative purposes, but the input device of the present invention is not limited to controlling a display device.

The position-sensitive input device 15 comprises a sensor surface 14. The sensor surface may be any known sensor surface, and the details of the construction of the sensor surface 14 are not relevant to the invention. As an example, the position- sensitive input device of the present invention may be a surface capacitance type, a projected capacitance type, a four-wire resistive type, a five-wire resistive type, or any other known type. In figure 2, the sensor surface is shown as a surface capacitive sensor surface, in which the current output from each of the four corners of the sensor surface is fed to current detectors similar to the current detector 6-9 of figure 1, but this is again for illustrative purposes only.

The position-sensitive input device 15 of figure 2 is intended for operation by two or more sets of users, with one user 21 being shown in figure 2. The position-sensitive input device of the invention comprises two or more voltage generating circuits 22, 22' for generating different time-varying voltages Vj(t), V2(t). Figure 2 assumes, for illustrative purposes, that the display is intended for operation by two sets of users, and the input device 15 is therefore provided with two time-varying voltage generating circuits 22, 22', and the foregoing description will describe operation of the device with reference to there being two sets of users. However, the device is not restricted to use with only two sets of users, nor is it restricted to having only two time-varying voltage generating circuits. An input device of the present invention may in general have n time-varying voltage generating circuits, where n is an integer greater than or equal to 2, and be used with n sets of users (or even with n+1 sets of users as explained below).

For simplicity the invention will be described with reference to a device in which each set of users contains just one user, and the foregoing description will generally refer to a "first user" and a "second user" rather than to a "user of the first set of users" and "a user of the second set of users". However, the invention may be applied to sets having more than one user. The sets are not required to have the same number of users as one another.

The position controller 20 of figure 2 is a conventional touch panel controller. It contains a voltage source 18 (see figure 3) that generates a conventional touch panel signal V. When a user touches the sensor surface 14 a current flows to earth through the user. (In practice, the voltage source 18 may generate an a.c. voltage so that the currents flow alternately to and from earth.) This current flow gives rise to currents flowing through the four corners of the sensor surface 14, and these are detected by a touch panel controller 19 (see figure 3) that may, for example, contain four current detectors similar to the current detectors 6-9 shown in figure 1.

In operation, the output voltage from a first voltage generating circuit 22 is coupled into one user 21. The output from a second voltage generating circuit 22' is coupled to a second user 21'. As a result, when one of the users touches the sensor surface 14, the respective timevarying voltage is coupled to the sensor surface. It will be assumed that the first and second generating circuits 22,22' generate first and second time-varying voltages V1(t), V2(t) that are distinguishable from one another in some way (as described below). The first and second timevarying voltages Vi(t), V2(t) may be coupled to first and second users 21, 21' by any suitable means. Figure 2 shows, for illustrative purposes, the first and second time-varying voltages being coupled to the first and second users by means of respective aerials 27, 27' disposed in the seats of the first user and the second user respectively. These aerials need not be extra elements placed inside the seats, instead the aerial may make use of the infrastructure of the seat.

For instance, the conductive frame in a car seat may be used as an aerial when used in an automotive environment.

The foregoing description will refer to a user "touching" the sensor surface. It is, however, to be understood that it is not necessary for a part of the user, such as their finger, to come into physical contact with the sensor surface 14 in order to make an input in to the device. For example, in many touch-sensitive input devices the occurrence of a touch, and possibly the determination of the position of a touch, may be determined via capacitive coupling of the user to the touch panel. The term "touch" as used herein is not limited to a user making physical contact to the sensor surface 14 but also includes a part of a user (such as a finger) coming into sufficiently close proximity to the sensor surface 14 that a transfer of electrical signal between the user and the sensor surface may occur.

In the input device of figure 2, the position of a touch on the sensor surface is determined from measurements of the output current from a number of positions around the periphery of the sensor surface measuring. Figure 2 shows an input device in which the sensor surface is rectangular and the output current from each corner of the sensor surface is used in the determination of the position of a touch, but the invention is not limited to this arrangement.

When a user touches the sensor surface 14, the output currents from the sensor surface each contain a component arising from the touch panel signal generated by voltage source 18. These components of the output currents are fed to respective current sensors (not shown in figure 2). The current sensors correspond to the current sensors 6-9 in figure 1, and are located in position controller 20. The touch panel components of the output currents from the sensor surface are fed to the position controller 20 over a bus line 17 which in practice may comprise four parallel leads to allow each individual output current to be input to the position controller. For example, the frequency of the touch panel signal from voltage generator 18 may be made different from the frequency of either of the time-varying voltages V1, V2, and a suitable band pass filter may be provided in the bus line 17 such that only the components of the output currents arising from the touch panel signal generated by voltage source 18 are fed to the touch panel control 19. The position controller 20 determines the position of the touch, in any known manner. For example, the x- and y- coordinates of the touch may be determined according to: =(i +/4)-(/3 +/3) + 2 +/3 +14 (i1+i2)-(i3 +/4) + l + 13 + 14 In these equations, the current h. . .i4 denote the outputs from each of the current sensors 16-19 respectively. As can be seen from the above description, the position controller 20 is

generally conventional in operation. The position controller is not limited to the particular position controller described, and an input device of the invention may have any suitable position controller.

In the input device 15, the current flowing from each of the four corners of the sensor surface 14 are also fed to first and second current sensors 16, 16' connected to one or more of the leads in the bus line 17. The currents are fed to the first current sensor 16 via a filter 23 that passes the first time-varying voltage V1(t) and blocks or substantially blocks the second time-varying voltage V2(t), and are fed to the second current sensor 16' via a second filter 23' that passes the second time-varying voltage V2(t) but blocks or substantially blocks the first time-varying voltage V1(t). Thus, when a user touches the sensor surface 14, the currents flowing from the four corners of the sensor surface are also applied to the first and second current sensors 16, 16', via the first and second filters respectively. The first and second filters 23,23' also block, or substantially block, the touch panel signal If a user 21,21 touches the sensor surface 14, one of the first or second time-varying voltages V1(t), V2(t) will be coupled to the sensor surface 14. The output currents from the sensor surface will thus contain, in addition to the component arising from the touch panel signal from voltage generator 18, a component derived from the first or second time varying voltage depending on which user touched the sensor surface. The component of the current output from the corners of the sensor surface that is derived from the first or second time varying voltage, as appropriate, is passed to the first or second current detector 16,16', but is blocked from passing along the bus line 17 to the position controller 20.

If the first user touches the sensor surface the output currents from the sensor surface 14 will contain a component derived from the first ac voltage V1(t), and these components will be passed by the first filter 23 but will be blocked by the second filter 23'. Thus, the first current sensor 16 will receive a non-zero input, and so will provide a non-zero output to a user detector 29. However, the second current sensor 16' will receive zero or substantially zero input, and so will provide a substantially zero output signal to the user detector 29. Conversely, if the second user touches the sensor surface 14, the second current sensor 16' will receive a non-zero input and so will provide a non-zero output to the user detector 29, whereas the first current sensor 16 will receive substantially zero input and so will provide zero output to the user detector 29. The user detector 29 can thus determine, from the signals received from the first and second current sensors, whether the first user 21 or the second user 21' is touching the sensor surface 14.

The user detector 29 may comprise a circuit for detecting the amplitudes of the two signals received on the channels from the first current sensor and the second current sensor 16'. It may further comprise a logic circuit for determining from the amplitudes of the signals on the two input channels which user is touching the panel.

In the input device of figure 2 the determination of the position of a touch on the sensor surface 14 is separated from the determination of the identity of the user who made the touch. The determination of the position of the touch is made by the position controller in a conventional manner as stated above, the four currents flowing from the four corners of the sensor surface 14 are input to the position controller in a conventional manner. This is illustrated schematically in figure 3, which is a block flow diagram shown operation of the input device 15 of figure 2. The component of the output currents from the sensor surface 14 that are derived from the first or second time varying voltage V1 or V2 (figure 3 shows the first user 21 touching the sensor surface) provide an input to the user detector 29 (via the currents detector 16,16' of figure 2).

The touch panel voltage signal V voltage from the voltage generator 18 enables the position of the touch to be determined.

Since determination of the position of a touch on the sensor surface 14 is separated from the determination of the identity of the user who made the touch, a failure of a component used in the identification of the user for example failure of one of the voltage sources 21,21' - has no effect on the capability of the device to determine the location of a touch. Moreover, since determination of the position of a touch on the sensor surface 14 is separated from the determination of the identity of the user who made the touch, it is possible to apply the invention to a pre-existing conventional input device.

The output from the position controller 20 and the output from the user detector 29 may be passed to a host system that controls the device 13. The host system thus receives the co-ordinates of the position of a touch on the sensor surface 14 (from the position controller 20), and the identity of the user who has made that touch (from the user detector 29). The host system may then control an associated device 13 (here shown as a display for illustration) in accordance with the co-ordinates of the touch, and in accordance with the information concerning the identity of the user who has made the touch, for example in accordance with any of the methods described above.

The position controller 20 provides the coordinates of the position at which a user has touched the sensor surface 14. These coordinates are fed to the host system, which can process the output from the position controller 20 to determine the action required. For example, the host system can determine an action that corresponds to the coordinates at which the determined user touched the sensor surface, for example using a look-up table or similar. If it is found that the co-ordinates at which the user touched the surface correspond to the instruction "increase brightness", as an example, the host system can then instruct the display 13 to increase the brightness of a displayed image. This can be achieved in any conventional way.

The host system is, however, able to provide more advanced processing of the user input, because of the possibility of determining which user has made the input. As an example, the way in which the host system controls the display 13 may depend not only on the location at which the user touches the sensor surface but also on the identity of the user who touched the sensor surface. An input made at a particular position on the sensor surface 14 by the first user would be processed in a different manner to an input made by the second user at the same position on the sensor surface 14 - that is, a touch by the first user at a position on the sensor surface could lead to the host system sending a first instruction to the display, but a touch by the second user at the same point on the display could lead to the controller sending a second, different instruction to the display.

As an example, the position sensitive input device 15 might be the position-sensitive input device of a display provided in a motor vehicle, and the first and second users might be the driver and front seat passenger of the motor vehicle, respectively. In this example, the host system might not send any control signal (or, if the host system continuously sends a control signal to the display, send an unchanged control signal) as a consequence of an input made, if a particular input is determined to have been made by the driver. The host system would thus "ignore" an input made by the driver, so that the display is effectively disabled as far as the driver of the vehicle is concerned. (The host system may alternatively be arranged to ignore only some inputs from the driver, but not others, so that the display is partially disabled as far as the driver of the vehicle is concerned.) ilowever, if an input is made by the front seat passenger, the host system would instruct the display 13 in the normal manner based on the position on the sensor surface where the touch from the front seat passenger occurs. The front seat passenger can thus operate the display 13 as normal.

Additionally or alternatively, a record of which user entered a particular command may be sent by the user detector 29 for storage in an external storage means, for example located in the host system or associated with the host system. Additionally or alternatively this information may be stored in the user detector 29 or in a memory associated with the user detector 29. . This provides a record of which command was entered by which user, and this may be of value for data recording purposes.

In an embodiment in which the host system records the identity of the user who makes a particular input, the host system may control the device 13 in the same way regardless of which user makes an input. Where the position sensitive input device is provided in the cockpit of an aircrafl to enable the pilot and co-pilot to enter commands, for example, an input corresponding to "bank left" would always result in the host system instructing the control surfaces of the aircraft to operate so as to turn the aircraft to the left. However, the host system would store, or send for storage, a record of whether the "bank left" command was entered by the pilot or co-pilot.

The host system may additionally or alternatively process an input signal received from the sensor surface by choosing the destination for an output command based on the identity of the user who made the input. An example of this would be where the position-sensitive input device was part of a point of sale system and was used by staff to enter customer's orders. The invention would allow two (or more) members of staff to enter orders from two customers simultaneously, with orders entered by one stall being sent to the bill for one customer and orders from the second member of staff being sent to a bill for a second customer. The host system could maintain (for example in a memory) files corresponding to orders from two customers who were being served at the same time but by different members of staff, and use the identity of the member of staff who enters a an order item to determine to which file the item is sent. For example, if one of the members of staff touches the position of the sensor surface that corresponds to an order of "a portion of chips", the host system would determine which member of staff had entered that order, and would add the price of a portion of chips to the file being kept for the customer being served by that member of staff.

A further application of the present invention is in controlling a multiple-view display.

One example of a multiple-view display is a dual-view display, which displays first and second independent images in two different directions so that one observer can see one image and a second observer can see a second image. The ability of an input device of the present invention to determine which user has made an input means that it is particularly suitable for controlling a dual-view display. When a user makes an input to the input device, the controller can determine which user made the input, and instruct the dual-view display to control the view visible to that user in accordance with the input made by the user. This avoids the need to have two separate sets of controls for a dual-view display, one set for each observer.

The present invention is not, however, limited to use with multiple-view displays. It may be applied to a standard display, in which the information about the user who has made an input can be used to disable or modify functions relating to the control of the display. For example, when applied to a vehicle display, the driver can be restricted wholly or partially from operating the display - for example the driver may be restricted from entering new waypoints into the vehicles' navigation system - while still allowing the passenger to operate all features of the display.

A further application of the present invention is as an input device for a vehicle's climate control system that provides separate climate control for the driver and for the front seat passenger. Currently, it would be necessary to provide two control panels, one for the driver and one for the front seat passenger. It would, however, be possible to control such a climate control system using a single input device of the present invention - if a command to change the setting of a climate control system is entered, the input device can determine whether that command was entered by the driver or by the front seat passenger, and can then instruct the driver's climate control system or the passenger's climate control system accordingly.

The first and second time-varying voltages may be coupled to the first and second users in any suitable way. Figure 2 shows one way of coupling the voltages to the users which is suitable where the users will be at fixed locations that are separated from one another. The voltages are coupled to the users by means of respective aerials, for example conductive plates 27,27', provided in the vicinity of the expected positions of the first and second users. For example, the first and second users will be sitting at positions that are known in advance, the aerials 27, 27' can be placed at the positions at which it is known that the first and second users will sit. This is particularly convenient where the first and second users are the driver and front seat passenger of a motor vehicle, since it is known that they will be sitting in the driver's seat of the vehicle and the front passenger seat of the vehicle respectively. The aerials 27, 27' may then be disposed within the driver's seat and the front passenger seat of the vehicle, respectively. The first time-varying voltage is capacitively coupled to the first user via the first aerial, and the second time-varying voltage is coupled to the second user via the second aerial 27'.

Figure 4 shows an input device 30 according to a further embodiment of the present invention. This is again generally similar to the device of figure 2, and components common to the device of figure 2 will not be described again.

In the embodiment of figure 4, a separate "user identification signal" is generated by voltage generating circuit 41 (see figure 5) and is applied to the sensor surface 14. The identity of a user who touches the sensor surface 14 is determined from whether the user identification signal flows to earth through the first user or through the second user. As in the previous embodiment, the touch panel voltage V11, is generated by a voltage source 18, for example located in the position controller 20, and is fed to the sensor surface by a bus line 17. The user identification signal is distinguishable from the touch panel signal in some suitable manner, for example using different digital codes or different wavelengths.

When a user 21, 21' touches the sensor surface, the user identification signal is coupled to that user, and is then further coupled to a respective current sensor 32, 32'. For example, the signal may be coupled from the user to the respective current sensor by capacitive coupling to an aerial 27, 27'such as a conductive plate.

The output from each current sensor is input to the user detector 29.

Figure 4 shows the second user 21' touching the sensor surface 14, while the first user 21 is not touching the sensor surface. In this case, no signal will be coupled to the first current sensor 32 via the first user, and the input to the user detector 29 from the first current sensor will be zero. However, a current will flow to the second current sensor 32, via the second user 21', and the second current sensor 32' will therefore provide a non-zero signal to the user detector 29. The user detector 29 can determine, by comparing the signal received from the first current sensor 32 to the signal received from the second current sensor 32', which of the first and second users is touching the sensor surface 14.

The output currents from positions on the periphery of the sensor surface, for example from each of the four corners of the sensor surface 14, are input to the position controller 20. When a user touches the sensor surface 14, the position controller determines the coordinates of the touch, in any suitable manner. The position controller outputs the determined coordinates of the touch, for example to a host system (not shown). The host system also receives a signal from the user detector 29 indicating which user has made the touch. The host system may then control an associated device 13 (here shown as a display for illustration) in accordance with the co- ordinates of the touch, and in accordance with the information concerning the identity of the user who has made the touch, for example in accordance with any of the methods described above.

Figure 5 is a block schematic diagram of the input device 30 of figure 4.

In the embodiment of figures 2 and 3 above, the first and second timevarying voltages are preferably alternating voltages. In a preferred embodiment, the first time-varying voltage is an a.c. voltage having frequency f1, and the second time-varying voltage is an a.c. voltage having frequency f2, where f1!= f2. Each first filter 23 may then be a band pass filter that passes voltages of frequency f1, while blocking or substantially blocking a.c. voltages having frequency f2. Each second filter is similarly a band pass filter that passes an a.c. voltage having frequency f2 with little or no attenuation while blocking or substantially blocking an a.c. voltage having frequency f1 The embodiment of figures 2 and 3 is not, however, limited to the first and second-time- varying voltages being discriminated from one another by their frequency. The two time-varying voltages may additionally or alternatively be distinguished from one another in any of the following ways: They may be distinguished by waveform, by using two or more signals having different waveforms (for example, digital signals having different binary values). In this case, discrimination between the signals is made from the detected waveforms.

The two signals may be distinguished by their phase - the signals may have the same waveform, but have different phases from one another. In this case, the signals are distinguished from one another by the phase of the signals output from the sensor surface.

The signals may be distinguished by their amplitude. The two signals may have the same waveform, but have different amplitudes from one another. In this case, the discrimination between the two users is made on the basis of the amplitude of the signals output from the sensor surface.

The signals may be distinguished from one another using a time-multiplex method. In this method, the two (or more) time-varying voltages are sent sequentially to each of the users 21, 21', for example in sequential time frames. A determination of which user has made an input is made on the basis of the time at which a non-zero output signal is obtained from the sensor surface 14.

Alternatively, the two signals may be distinguished from one another by any of the above methods combined.

In principle, however, all that is necessary in the embodiment of figures 2 and 3 is that the touch panel signal Vu,, the first time-varying voltage and the second time-varying voltages can be distinguished from one another. It would be possible for one of the first and second timevarying voltages of figures 2 and 3 to be replaced by a constant d.c.

voltage, for example, if the touch panel signal V is an alternating signal. Thus, discrimination between the first user and the second user (or between the first and second sets of users) would be achieved by determining whether the received user identification signal was a timevarying signal or a d.c. signal.

Similarly, in the embodiment of figures 4 and 5 the user identification signal generated by the generating circuit 41 may in principle be a d.c. signal.

As a further example, in the description of figures 2 and 3, a timevarying voltage has been applied to each user (or, more generally, to users in each set of users). In principle, however, it is possible for one user (or one set of users) not to receive a time- varying voltage. As an example in which there are two possible users (or sets of users), a first-time varying voltage may be coupled to the first user (or to each user in the first set of users) but no time-varying may be coupled to the second user (or to any of the users in the second set of users). If a touch is detected but no time-varying voltage is detected at the same time, this would indicate that the second user (or a user from the second set of users) is touching the sensor surface. Conversely, if a touch is detected and the first time-varying voltage is also detected, this indicates that the first user (or a user from the first set of users) has touched the sensor surface.

In the embodiments described above, the time-varying voltage(s) have been coupled to or from each user by means of a conductive plate or other aerial. The invention is not, however, limited to coupling the signal to or from the user by capacitive conduction, and it would be possible to couple the time-varying voltages to or from the users by direct conduction or by free-space conduction.

As a further alternative, the embodiment of figures 2 and 3 could be embodied by providing each user with a portable device that generates a respective time-varying voltage. This would be particularly advantageous in an application where the users are likely to be moving around rather than remaining at one defined location such as, for example, a point of sale system. Alternatively, the signal generating devices could be integrated with an item of clothing, such as a shoe of the user.

The devices of the invention may be able to define a default user (or default set of users). if a touch is detected and it is not possible to determine the identity of the user who has made the touch (for example, if no user identification signal is determined, or if two or more user identification signals are detected), the device would then assume that the touch has been made by the default user (or by a user from the default set of users).

The default user or set of users can be defined by, for example, a mechanical switch on the device to be controlled, or it can be defined in software that controls operation of the device.

In modifications of the embodiment of figures 2 and 3, a single timevarying voltage signal may be transmitted by means of a directional aerial. The separation between the users means that the time-varying signal received at one user will be different from the signal received at another user - for example, the amplitude of the signal received at a user will be lower as the distance of that user from the aerial increases. Thus, in a case where the users will be at well-defined location, it is possible to use a single directional aerial to couple one signal to all users, rather than using a separate aerial to couple a separate signal to each user.

The description of the invention as applied to a motor vehicle has referred to discrimination between the driver and a front seat passenger. The invention may however be applied to discrimination between any two (or more) occupants of a motor vehicle, including the driver, front seat passenger(s) and rear seat passenger(s). For example, the invention could be used to discriminate between two rear seat passengers, for example to control a climate control system that provides separate climate control for two rear seat passengers.

Figure 6 shows a further input device according to the present invention. In this device, one or more aerials 27 transmitting time-varying waveforms are disposed at a distance from an input device 33. A signal will be induced in each user operating the input device, and the phase of the signal induced in a user will be dependent on the distance between the user and the aerial 27. Thus, the horizontal position of the user relative to the input device 33 can be detected by measuring the phase of the signal induced in the input device when the user touches the input device. This can be done by means of a phase detector 35 that receives one input from the input device 33 and receives a second input from a signal generator 34 that provides the signal to be radiated from aerial 27.

In an application in which the lateral position of each user relative to the input device is known, as in a motor vehicle for example, knowledge of the lateral position of the user relative to the display enables the identity of the user who has made a particular input to be determined.

This embodiment may also be used to give the position of the user who has made a touch, rather than identify the exact user who made a touch. In this embodiment, the user controller 29 would output the position of a user who made a touch rather than outputting the identity of a user. An example of an application of this is in a photo booth where the user must align their head with the camera - when a user touches the screen (or a button), the system could provide audio-feedback as to whether the user was in the correct position for a photograph to be taken.

An alternative application is for a 3-D display that requires observer head tracking. The aerial could be located to one side of a display monitor and the detector connected to a conductive contact on the user's mouse. Then a component of the signal detected at the mouse would be dependent on the users horizontal head position, and the information thus obtained about the horizontal position of the user's head can be fed to an observer tracking device to control the viewing windows of the display accordingly.

A controller of the invention may be implemented as a programmable apparatus 34, and Figure 7 is a schematic block diagram of such a programmable apparatus. The apparatus comprises a programmable data processor 35 with a programme memory 36, for instance in the form of a read-only memory (ROM), storing a programme for controlling the data processor 35 to perform any of the processing methods described above. The apparatus further comprises non-volatile read/write memory 37 for storing, for example, any data which must be retained in the absence of power supply. This information might for example include a look-up table that relates positions on the position sensitive input device to particular commands. A "working" or scratch pad memory for the data processor is provided by a random access memory (RAM) 38. An input interface 39 is provided, for instance for receiving the outputs from the position controllers 20,20' and the user controller 29. An output interface 40 is provided, for instance for outputting controls to a device 13 associated with the position-sensitive input device, for outputting information relating to which user made a particular input, or, in the case of figure 4, for outputting the time-varying voltage signal to the sensor surface. Information relating to, for example, a default user may be supplied via the input interface 39, or may alternatively be retrieved from a machine-readable data store 41.

The programme for operating the system and for performing any of the methods described hereinbefore is stored in the programme memory 36, which may be embodied as a semi-conductor memory, for instance of the well-known ROM type. However, the programme may be stored in any other suitable storage medium, such as magnetic data carrier 36a, such as a "floppy disk", or CD-ROM 36b.

Claims

CLAIMS: 1. A controller for a user input device, the controller having

first means for detecting a user input to the device and second means independent of the first means for determining whether an input was made by a user in one of at least first and second groups of users.
2. A controller as claimed in claim 1 wherein the second means is adapted to discriminate between at least a user in a first group of users and a user in a second group of users on the basis of a user identification signal received from users in at least one of the groups.
3. A controller as claimed in claim I wherein the second means is adapted to discriminate between at least a user in a first group of users and a user in a second group of users on the basis of a signal coupled from the user input device to a user.
4. A controller as claimed in claim 3 and adapted to output the signal for coupling to the user via the user input device.
5. A controller as claimed in claim 4 and adapted to receive a returned user identification signal from a user in one of the first and second groups of users, and to determine from which of the first and second groups of users the returned user identification signal was received.
6. A controller as claimed in any preceding claim and adapted to process a user input in accordance with a determination of which group of users the user who made the input belongs to.
7. A controller as claimed in claim 6 and adapted to send an output signal in response to a user input, the output signal being dependent on a determination of which group of users the user who made the input belongs to.
8. A controller as claimed in claim 6 and adapted to send an output signal in response to a user input, the destination of the output signal being dependent on a determination of which group of users the user who made the input belongs to.
9. A controller as claimed in any preceding claim and further adapted to store the result of a determination of which group of users the user who made the input belongs to.
10. A controller as claimed in any of claims 1 to 8 and further adapted to send the result of a determination of which user made an input for storage.
11. A controller as claimed in claim 1 or 2, or in any of claims 6 to 10 when dependent from claim I or 2, and adapted to receive an input signal comprising one of at least a first user identification signal and a second user identification signal, and to discriminate between the first and second users on the basis of whether the input signal comprises the first user identification signal or the second user identification signal.
12. A controller as claimed in claim 11 and adapted to receive, as the input signal, a composite of a user input signal and one of the at least first and second user identification signals.
13. A controller as claimed in claim 12 and adapted to pass the user input component of the input signal to a selected processing means.
14. A controller as claimed in any of claims 11 to 13 wherein the first and second user identification signals are different time-varying signals.
15. A controller as claimed in claim 14 wherein the first user identification signal has a different frequency from the second user identification signal.
16. A controller as claimed in claim 14 or 15 wherein the first user identification signal has a different phase from the second user identification signal.
17. A controller as claimed in any of claims 14, 15 or 16 wherein the first user identification signal has a different amplitude from the second user identification signal.
18. A controller as claimed in any of claims 14, 15, 16 or 17 wherein the first user identification signal has a different waveform from the second user identification signal.
19. A controller as claimed in claim 14 wherein the first and second user identification signals are time-multiplexed.
20. A controller as claimed in any one of claims 14 to 19 wherein one of the first and second user identification signals is zero.
21. A controller as claimed in any preceding claim and comprising a programmable data processor.
22. A user input device comprising a controller as defined in any of claims Ito 21.
23. A user input device as claimed in claim 22 wherein the user input device is a touch-sensitive input device.
24. A user input device as claimed in any claim 22 or 23 wherein the user input device is a position-sensitive input device.
25. A user input device as claimed in claim 24 and comprising a touch panel.
26. A user input device as claimed in any of claims 22 to 25, wherein the controller is a controller as defined in any of claims 11 to 20, and wherein the device further comprises means for generating the first user identification signal and the second user identification signal.
27. A user input device as claimed in claim 26 and further comprising means for coupling the first user identification signal and the second user identification signal to the first user and the second user respectively.
28. A computer-readable medium comprising a program for the data processor of a controller as defined in claim 21.
29. A method of operating a user input device, the method comprising detecting a user input; and substantially simultaneously with the detection of the user input, determining whether the user input was made by a user in one of at least first and second groups of users.
30. A method as claimed in claim 29 and comprising discriminating between at least a user in a first group of users and a user in a second group of users on the basis of a user identification signal received from users in at least one of the groups.
31. A method as claimed in claim 29 and comprising coupling a signal from the position-sensitive input device to a user.
32. A method as claimed in claim 31 and comprising receiving a returned user identification signal from one of the first and second users, and determining from which of the first and second users the returned user identification signal was received.
33. A method as claimed in claim 29, 30, 31 or 32 and further comprising processing a user input in accordance with a determination of which group of users the user who made the input belongs to.
34. A method as claimed in claim 32 and further comprising sending an output signal in response to a user input, the output signal being dependent on a determination of which group of users the user who made the input belongs to.
35. A method as claimed in claim 33 and further comprising sending an output signal in response to a user input, the destination of the output signal being dependent on a determination of which group of users the user who made the input belongs to.
36. A method as claimed in any of claims 29 to 35 and further comprising storing the result of a determination of which group of users the user who made the input belongs to.
37. A method as claimed in any of claims 29 to 35 and further comprising sending the result of a determination of which group of users the user who made the input belongs to for storage.
38. A method as claimed in claim 29 or 30, or in any of claims 33 to 37 when dependent from claim 29 or 30, and comprising the further step of coupling a user identification signal to one of a first user and a second user.
39. A method as claimed in claim 38 and comprising coupling a first user identification signal to a first user and coupling a second user identification signal to a second user.
40. A method as claimed in claim 39 and comprising discriminating between the first user and the second user on the basis of whether a signal generated by the position- sensitive input device comprises the first user identification signal or the second user identification signal.
41. A method as claimed in claim 40 and comprising generating, as an input signal, a composite of a position information signal and at least one of first and second user identification signals.
42. A method as claimed in any of claims 39 to 41 wherein the first and second user identification signals are different time-varying signals.
43. A method as claimed in claim 42 wherein the first user identification signal has a different frequency from the second user identification signal.
44. A method as claimed in claim 42 or 43 wherein the first user identification signal has a different phase from the second user identification signal.
45. A method as claimed in claim 42, 43 or 44 wherein the first user identification signal has a different amplitude from the second user identification signal.
46. A method as claimed in claim 42, 43, 44 or 45 wherein the first user identification signal has a different waveform from the second user identification signal.
47. A method as claimed in claim 41 wherein the first and second user identification signals are time-multiplexed.