Device with a touchscreen

Abstract

Device comprising a force touchscreen, which includes an area bounded by a circumference, several segments defined in the area, a support structure, several force sensors attached to the support structure carrying the force touchscreen, each force sensor being configured to generate a signal in response to pressure on a segment on the screen, and a computer to which the signals from the force sensor are supplied.

Description

Background(Capacitive) touch screens have become common since the introduction of the original iPhone by Apple.Today (approximately 2024) touch screens are ubiquitous and are used, for example, to control:ATMHeimsicherheitssystemenAccounting OperationsVending MachinesAccess ControllersThis is the case in various kitchen / household appliances (coffee machines, frits, hot air frits, etc.)Personal care productsFitness ArmbandsSmart watchesGPS devicesAlthough capacitive touch technology provides excellent resolution and easy-to-use interface, capacitive touch screens also have some disadvantages. They are quite expensive because transparent connections (indium tin oxide - ITO) are required and, of course, wiring cables and connectors for the connections to all nodes. Capacitive touch switches / touch screens are also very sensitive to water or any liquids that can cause severe degradation of functionality.A wet screen is hardly operable and not ideal. Even operation with a common glove may be a problem.SUMMARY OF THE INVENTIONIn accordance with this invention, there is provided a touch screen device without capacitive or resistive sensing that uses inductive sensing force sensing technology, i.e., a force applied to the screen by the user is measured or detected using a method to measure or detect a change in inductance related to the pressure of the user applied to a selected location or segment on the screen.That is, a user may still press a particular segment of the screen, although the screen is not equipped with capacitive or resistive sensing, and the force measurement device or system connected to the screen surface may identify the location of the press using inductive (or other) force sensing measurements.Typically, for a square or rectangular screen, sensors may be located in the four corners of the screen and, using the measured information about a force from the four corners, the position of the user applied force on the screen surface may be calculated using triangulation techniques or using information from the four (or more) sensors.For example, consider a coffee maker having a touch screen display offering six choices: top left, top right, center left, center right, bottom left, bottom right. In accordance with this invention, force sensors (inductive) can be used to resolve user selection (pressing with a finger on a selected segment) on the screen without requiring capacitive sensing in resolving the position of the pressing operation.Using force sensors, 6, 9, 12, or even more positions may be determined using triangulation or by using four force sensors. Since this invention relies purely on force measurements, the system is immune to interfering with water or other liquids such as beer, oil, soups etc. Even gloves of the user do not affect decisions or performance in any way.In another embodiment, the screen may be an opaque covering layer, i.e., the choices are printed and a segment to which a pressure is applied by a user may be determined using the force sensors. This is a low-cost user input system based on a screen or an operating panel compared to capacitive sensing.Although the system cannot keep track of the resolution of a capacitive touch screen or touch pad, a force sensing user interface is preferable in view of wet environments (kitchens, showers) and costs as compared. For example, conductive structures (e.g., ITO) are not required on a glass over an LCD display device. The force-based select pad also does not exhibit wear as occurs with resistive touch screens.Inactive regions may be created between the selection segments to ensure accurate selections and margin for errors.The method in accordance with this invention enables discrimination according to the level of pressure applied to the screen by the user. Therefore, it is possible to indicate preselection of a specific segment under light pressure, but not make a final selection before applying more pressure that satisfies a minimum pressure level.Another popular function found in capacitive touch solutions is wiping hand movements such as left, right, up or down. This can easily be simulated on a force contact surface without capacitive / resistive touch functions. This function can be used, for example, to select a second screen.When force sensing is performed using inductive measurements, example implementations may include a conductive object or a ferrite object adjacent to an inductive coil (e.g., on a printed circuit board) that moves closer to such a coil and affects the inductance of the coil, or may include a conductive object or a ferrite object that moves into a hole in a center (a core) of an inductive device.In another embodiment, a decision to accept a command (a press / user actuation) may be advertised using light, sound, or haptic feedback, such as may be found in other user interface solutions.Since only a limited number of choices are intended, a template may be placed on the stiff surface to guide the user's finger. This will help prevent pressure spots on a boundary between two segments. This construction can help prevent ambiguous selections on screens of a displaying type or a non-displaying type.For non-display screen applications, a printed text membrane may be employed under or on a rigid surface. This can be used to designate the functions associated with each segment.In another embodiment, true buttons may be provided that are fitted into a frame. When a button is pressed, the button applies pressure to a solid surface (e.g., glass and a planar steel plate) beneath. The force sensors in the four corners of the screen may be used to determine which button has been pressed. Thus, no electromechanical contact is required and the solid surface can be used to completely seal the electronics underneath. This is good for outdoor keypads, for example.In accordance with this invention, haptic, light, sound, or other feedback may be provided to the user when the touch screen is operated. Apertures for light with logos or text can be provided in the templates.A color or type of light (flickering or weak) may be provided to indicate to the user which segment will be activated when a pressure lower than a required selection level is applied. If sufficient pressure is applied to make the selection decision, another indication may be given. This can likewise be done by means of haptics or sound.In another embodiment with combined capacitive sensing and inductive force sensing in a redundant method (dual / cross testing), a situation may arise with false or corrupted capacitive sensing due to liquids on the screen or for some other reason in which the selection of capacitive sensing and inductive sensing do not match. In this case, the inductive sensing may be used alone for certain selections. As an additional safety measure, it may be necessary to press a series (or otherwise) of the selection segments to verify that the inductive selections are accurate and can be trusted without correlating with the capacitive measurement.In the same way, capacitive sensing may be used to verify the validity of an inductive touch measurement. Incorrect detection can result, for example, from fast or strong movements. It would be particularly cost effective to use few capacitive electrodes on a printed circuit board under a non-display area designed to enable inductive touch selections in accordance with this invention. Or a single layer of ITO may be disposed on a glass layer and connected to a capacitive sensor. This capacitive measurement may then detect a touch or a spatial proximity (i.e., detect the presence of a human itself through gloves, etc.) that will confirm that the force sensing results from a touch on the screen. Since the position does not depend on the capacitive measurement, it is more resistant to effects of liquids on the screen.The elements used for inductive force sensing (i.e., the inductive components) may be used to provide the force for haptic actuation. The inductive component can be used to generate an electromagnet that can draw an object in its direction or repel a magnetized object. The pulling action is similar to what can be found in a magnetic switch. To avoid too high power supply requirements to the power supply, a supply capacitor may be disposed near the inductive device and the sharp increase in current may be drawn out of the capacitor as the current is switched therethrough for haptic actuation. This may provide a very cost effective solution for haptic implementation, as the inductive components used for the inductive measurements are used for two tasks.The integrity of a selection can be improved by the use of software. For example, multiple thresholds may be used to decide on a preselection (which may also be indicated to the user by haptics or light) with a lower pressure level, and then a higher pressure level is used to make the final selection. The final selection may also be indicated to the user with, for example, specific haptics, light, or other indicia.In another embodiment of the invention, the software may be adaptive (AI) and so adjust the decision levels in accordance with noise levels and other measurement information and user feedback. This will improve selection integrity over time.If the options from which to choose are on a grid with a considerable margin for errors, the software AI can also compensate for any drift over time or over temperature or even offsets caused by mechanical changes. That is, for example, when the software detects that the user inputs are constantly offset to the right at a higher temperature, it may adjust in accordance with the temperature in the future.Additionally, an elapsed time (time period) may be used to improve the quality and integrity of selections. A surge or sudden jerk of a product including the touch screen may cause force measurements similar to user activation. However, if a user is required to press the touch screen or the touch panel for a prolonged period of time, it is unlikely that a shock of any kind might result in such signals. And, when capacitive approximation or touch is taken into account, the integrity of the touch selection is very high.The force sensing touch screen may also be implemented using other (not just inductive) force measurements.Brief Description of the DrawingsFIG. 1 shows a screen divided into segments with inactive zones; FIG. 2 ashows a conventional (stack) construction; FIG. 2 b illustrates a variation of the construction of an inductive force sensor; FIGS. 3a,b depict forces measured when a user presses into two specific segments; FIGS. 4 a, b, c show various designs for implementing force sensors and haptics in combination; FIG. 5 shows a non-display panel having a covering layer that maps choices and a grid to assist in preventing ambiguous selections, where the grid is over inactive zones and includes an opening for light in each selection zone; and Figures 6a,b show a non-displaying inductive touch screen with mechanical buttons designed to press at specific points on the inductive touch screen.DETAILED DESCRIPTION OF THE INVENTIONThis description is exemplary of embodiments of the invention that clarify certain concepts and implementations of the invention, and is not intended to limit the scope of the invention. Many products and applications not described herein may fall within the scope of what is covered.In Figure 1, a touch screen (101), such as a touch screen found in many coffee machines, is shown, with selection segments indicated. When a user presses the segment indicating "slat" (102), the force applied to the screen by the user is measured and by combining the relative measured forces from all force sensors used with the screen, the position of the pressing operation can be calculated.The darker areas 103 are inactive areas and can be used to improve selection accuracy, i.e., when the user presses between "slat" 102 and "americano" 104 in the inactive zone, no selection is made. There may optionally be an indication of invalid selection feedback to the user. As can be seen, the inactive zones 103 are virtual areas and need not appear differently on the display in any way. As a preselection indication, the display may change appearance during a light press operation to inform the user of the selection made when, for example, more force is applied or when more time is allowed to elapse, with one force being applied. The user can actually slide a finger under light pressure from one segment to the next segment, indicating the corresponding segment as the finger slides over it.In FIG. 2 a, an exemplary construction is shown, wherein a display screen 201 is covered on the top side (for strength and protection) with a glass 202 and inductive components 203 are arranged in four corners of the screen. The inductance is changed when an element 206 (conductive or ferrite) fixed to the glass moves to the center of a coil 203. A spring 204 supports the glass and is configured so as not to force the display screen out of the product housing 209. The only screen / glass support points 202 are at the four corners where a force exerted by the user is counteracted by the springs, but there is a small movement which brings the elements 206 closer to the inductive components. Depending on the position of the pressing operation, the various corners experience various displacements that can be measured and used to calculate the position of the pressing operation.A flexible sealing ring 216 may be used to seal the bottom surface 211 or even the sides of the top layer 202, but this must be such that a user's pressing action still results in the glass moving under the pressure exerted by the user, i.e. compressing such a sealing ring or other sealing mechanism.The coils 203 may be part of a printed circuit board 207. The display is connected to the printed circuit board by a ribbon cable or flexible printed circuit board 208. Stop elements 205 are mounted on a base 210 of the product and may be located around the whole unit. A space 211 between the stop members 205 and the glass 202 may be filled with a compressible material or an adhesive that may help seal the inside against the outside and hold the display screen in place.In Figure 2b, the housing 209 is shaped to provide the stop function. The only spring action is provided by the compressible material 212 between the housing 209 and the glass 202.The change in inductance is induced by an element 213 which is fixedly attached to the glass 202 and which moves closer to the induction coil 203 when pressure is applied to the glass 202, such as when a user wants to select a function by touching the glass.The appended drawings are not to scale, and the dimensions in the drawings have been chosen to clearly demonstrate the concepts and implementations of the invention. For example, in practice, the spring 204 will be much stronger to limit movement under user actuation. The pre-stop clearance 211 will be much smaller than shown.In Fig. 3a, a screen according to this invention designed with 3 × 2 segments is shown. Pressure is applied by an object at the upper left position. The relative forces measured at the four corners are shown.In Figure 3b the same screen and the measured forces are shown when pressed at the middle right position.This is exemplary and although many more positions may be shown, the concept is clear. The position of the pressing operation is calculated using the forces measured at the support points. If there are only two support points, there is only information to determine the position in one dimension. Triangulation can be used for three carrier points. For more than 4 points, mathematics will be more complex, but may be worth achieving increased accuracy. A mechanism such as a suitably programmed processor or computer 300 may readily determine the position on the screen at which a force was applied using the force measured from the respective screen corners.The seal ring 216 may also introduce an effect wherein a press operation with a certain amount of pressure in the center of the screen causes a change in the measured inductance in all four corner sensors, but these changes will not add up to the same press motion / inductance change as when the same specific force is applied to the right over one sensor. However, this effect can be calibrated out with a stable / consistent flexibility in the sealing ring to compensate for this effect.In Figures 4a, b and c the construction of a combined haptic generator and inductive force sensor is shown. An induction coil 401 is fabricated on a printed circuit board, which may be multi-layered. On one side, a magnetically permeable member 402 is disposed adjacent to the coil 401. The construction is such that pressure on the circuit board or coil 401 will move it closer to the element 402. The resulting change in the distance between element 402 and coil 401 is reflected in the measured inductance of the coil, i.e., for a particular design, the applied force can be calculated from the change in inductance.In Figure 4a, when current is passed through the inductor 401, the printed circuit board and the inductor 401 may be magnetically drawn towards the element 402. With a sufficient magnetically generated force, the printed circuit board and the coil 401 can generate a haptic effect. A spring 404 will urge the element 402 away from the printed circuit board and the coil 401.In a variation of the implementation of FIG. 4 a, the element 402 may be permanently magnetized. When current is passed through the inductor 401, the printed circuit board and the inductor 401 may be magnetically drawn towards the element 402. Or by reversing the direction of current through coil 401, the printed circuit board and coil 401 may be magnetically urged away from element 402.In Figures 4b and 4c, a member 403 which is permanently magnetized is mechanically attached to the printed circuit board and coil 401. The printed circuit board, coil 401, and member 403 are urged away from the fixed member 402 by a spring 404 or by a compressible material. When current is conducted in one direction through the induction coil 401, the element 403 may be magnetically attracted toward the fixed element 402. Conversely, when current is applied such that it counteracts the permanent magnetic field, the element 403 will be urged away from the stationary element 402 by the spring 404 and the opposing magnetic field generated by the coil 401. With sufficient force / mass, element 403 may generate a haptic effect. The unit will also have a natural frequency depending on the spring.Elements 403 and 402 are interchangeable in Figure 4b.In a variation of the embodiments of Figures 4b and 4c, the element 403 comprises a magnetically permeable material. By using a magnetizable material (low coercive force) as the element 402 and inducing a large instantaneous excitation, the magnetizable material 402 (low coercive force) can be semipermanently magnetized. The effect of this is that the spool 401, and the printed circuit board and element 403, can be drawn semi-permanently closer to the element 402, tensioning the spring 404 or compressible material used in place of the spring.In a further modification of the embodiments from FIGS. 4 band 4 c, the element 403 is a permanent magnet. By using a magnetizable material (low coercive force) in the element 402 and inducing a large instantaneous excitation, the magnetizable material 402 (low coercive force) can be semipermanently magnetized. The polarity of magnetization may be controlled by the direction of current flowing through the coil 401. The effect of this is that the coil 401, and the printed circuit board and element 403, may be semi-permanently drawn closer to the element 402 or repelled from the fixed element 402, tensioning or relaxing the spring 404 or compressible material (when used).FIG. 5 shows a non-display touch panel 500 with a template 502 comprising a covering glass layer and a layer of printed material designating the functions associated with each location on the touch panel. The printed layer may be above or below the glass layer and does not affect the movement of the glass layer under pressure. The template 502, which is 3-dimensional with high areas 503 between selection areas or segments, may be placed over the glass layer to clearly guide a user to the various selections. A central region 501 in each segment is open (i.e., without material). Thus, the user will press directly on the touch panel when pressing in the proper position. The inactive areas 503 / 502 are implemented to ensure that any touch that does not occur in an opening 501 is ignored.In Figure 6a, mechanical buttons 601 are arranged in a frame 600. When a button is pressed by a user, it simply presses down on the top fixed layer. This is illustrated in Figure 6b where the button structure 601 is located in the frame 600 with a spring 603 pushing the button outwards. A downward user pressing action 602 on the button 601 overcoming the force of the spring 603 causes the element 601 to press on the force touch layer 604 and act on a selected segment of the screen corresponding to a button. Because the user can now apply only force to the top layer (i.e., through the buttons rather than directly with a finger), adaptive algorithms can be more easily implemented to compensate for drift over time or other factors affecting the position derived from the measured inductive devices in the corners. No ohmic contacts are still required.The button construction is exemplary and merely illustrates a concept of the invention. With the embodiment in FIGS. 6 a, 6 b, an activating force may be applied only at very specific positions on the force-contact layer 604, which may seal the rest of the product.By using the correct materials, the present invention provides an ideal solution for keypads exposed to all elements.

Claims

An apparatus comprising a force touch screen comprising an area bounded by a perimeter, a plurality of segments defined in the area, a support structure, a plurality of force sensors attached to the support structure supporting the force touch screen, each force sensor configured to generate a signal in response to a pressure on a segment on the screen, and a computer to which the signals are provided from the force sensor.The apparatus of claim 1, wherein each force sensor comprises an inductive force sensor.Device according to claim 1 or 2, comprising a timer for measuring the duration of a time interval between two successive touches of the screen.The device of claim 2 or 3, including a plurality of biasing elements each associated with an inductive force sensor to generate a haptic signal.The apparatus of any of claims 2 to 4, including a plurality of buttons arranged to correspond to respective segments on the force touch screen, each button, when pressed, applying a force to the associated segment.An apparatus comprising a touch screen comprising an area surrounded by a perimeter, wherein the screen comprises a plurality of segments in the area, each segment designating a particular selection option available to a user, a support structure, a plurality of spaced apart inductive force sensors attached to the support structure and supporting the touch panel, and wherein each force sensor generates a signal representative of the force generated by a user touching a selected segment.The apparatus of claim 6, wherein the screen further comprises a display.The device according to claim 6 or 7, wherein a displacement of the screen is determined using inductive measurements from the force sensing structures used to determine the positions of the user's pressing operation and also to generate a haptic signal that can be perceived by the user touching the force touch screen.A touch screen device comprising a touch screen having a plurality of segments each indicating a particular selection option, a support structure, a plurality of spaced apart force sensors attached to the support structure responsive to movement of the touch screen resulting from a touch selection on the touch screen by a user, each sensor generating a respective signal representative of the force applied thereby to the sensor, and a mechanism for detecting the position of the touch on the touch screen and thus the particular selected segment from the force measurements of the sensors.

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