EP2203801A1

EP2203801A1 - Touch screen and method of use

Info

Publication number: EP2203801A1
Application number: EP08805443A
Authority: EP
Inventors: Jukka Ojala
Original assignee: Screentec Oy
Current assignee: Screentec Oy
Priority date: 2007-09-19
Filing date: 2008-09-19
Publication date: 2010-07-07
Also published as: FI7881U1; EP2203801A4; WO2009037383A1; FIU20070372U0; FI20105412A

Abstract

A touch screen according to the invention comprises a display unit (102), which has been connected to an electric device, and the image of the display unit is guided by the electric device. With the help of the touch screen the user can feed information to the device and control it using the user interface. The touch screen is equipped with one or several EMF film sensors (101, 104, 108, 110), which are in contact with the protective element (103) covering the display unit and EMF film sensors at least partly, and the EMF film sensors are connected to the control unit (107). In the method in question a pressure is directed at a spot on the protective element using a finger or another touching tool. The pressure applied to a spot on the protective element presses the EMF film sensors with forces, which are comparable to the spot where the pressure is applied to. The pressure on the EMF film sensors creates an electric response in the film sensors, which response is comparable to the pressure applied to the sensors. The control unit reads the electric responses of the film sensors and based on the responses, estimates the spot or force, or both, in the protective element onto which the pressure has been applied to, and reports it to the electric device. The electric device operates according to pre-set instructions based on the values given by the control unit.

Description

Touch Screen and Method of Use

The present invention relates to a touch screen, which comprises a display unit connected to an electric device, the image of the display unit being guided by the electric device, and by means of which touch screen the user can feed information to the device and control it by way of a user interface.

The touch screens can detect which part of the screen has been touched, and the information is transmitted to the device into which the touch screens have been connected, after which the device operates based on the part touched and according to pre-set instructions. The display identifies a touch based on, for instance, force, changes in electrical characteristics, or based on infra-red radiation. Touch screens are useful in situations in which other types of user interfaces would not be practical, would take up too much space, or would be subject to breaking or getting dirty. A problem with touch screens is the accuracy of the displays, i.e. how precisely they can determine the place onto which the user touches, as well as speed, i.e. how fast the display can react to repeated touching; and mechanical durability.

Touch screens and other information feeding appliances based on touching use Electromechanical Film (EMF) as one of the means for detecting touching. An EMF film is a permanently charged thin plastic film covered from both sides with layers, which conduct electricity. Outside pressure being applied to the film can be detected as a voltage signal produced by the film. A change of thickness of already a few micrometers is enough to produce a detectable voltage signal. In addition to this, the magnitude of the voltage signal can be used to assess the force applied to the film. The film has been described in patent publication Fl 76225.

Patent publication Fl 97577 presents a keyboard realized with an EMF film. In this publication, the said film has been covered with a suitably thick and stiff material, which protects the EMF film, and into which material a keyboard has been formed. A conductive pattern has been printed onto the EMF film to form electrodes at the place where the keys are situated on the cover plate. When the cover plate is pressed at the point of a key, the plate bends slightly and presses the EMF film, producing a detectable signal. The device connected to the keyboard identifies from which spot on the EMF film the signal from a corresponding key on the keyboard is sent, and subsequently acts according to pre-determined rules. This pub- lication also presents a touch screen in which the cover plate is a liquid crystal display or comprises one.

Patent publication EP 0817110 presents a touch screen used in a mobile terminal, realized by placing EMF film onto the entire area of the touch screen.

Patent publications US 2003/0214485 and US 2006/0284856 present the use of power sensors for detecting the touched location. In these publications, the spot at which the touch screen is touched is determined according to the signals coming from different sensors.

Realizing a touch screen using EMF film is rather difficult, since it is difficult to buil- d a precise touch screen due to the characteristics of a display placed on top of the film. In this case, the locations of the buttons on the touch screen, or more precisely the locations that activate the desired operation of the device connected to the touch screen, must be large enough and sufficiently far apart from each other to avoid pressing the wrong key. In addition to the aforementioned, the char- acteristics of the EMF film restrict the minimizing of small touch screens.

Power sensors are expensive as compared to EMF film. They also take up more space, which is of importance for instance in the case of portable communication devices. They also tend to break easily, which means that they must be protected. Further, this results in the touch screen realized by them becoming larger in size and more expensive.

The aim of the invention is to bring forth a new type of touch screen, with which drawbacks and disadvantages associated with known technology can be remarkably reduced.

The aims according to the invention can be reached with a touch screen charac- terized by what has been presented in the independent claims. Some preferred embodiments have been presented in the dependent claims

The touch screen according to the invention comprises a display unit, which has been connected to an electric device controlling the image of the display unit. One or several EMF film sensors have been attached on top of the display unit or onto the case or frame surrounding the display unit, and a protective element wholly or partly transparent or translucent has been placed on top of these film sensors and the display unit. The EMF film sensors are essentially smaller than the display unit. The protective element touches the EMF film sensors. The characteristics of the film sensors, small size and sensitivity, make it possible to place the protective element in the way described above. When pressure is applied to a certain spot on the protective element, i.e. it is touched, different pressures are directed at different film sensors because the distances from the touched spot to the different film sensors vary, and the film sensors give different electric responses. The film sensors are connected to a device, which reads the responses from the film sensors. Using simple mathematical operations and using the responses from the film sensors, the device calculates the spot onto which the pressure on the protective element has been directed. After the device has identified the spot onto which the pressure has been applied on the protective element, it operates according to preset commands, which have been determined for implementation when a touch has been detected on the spot in question. By comparing the magnitude of the electric responses sent by the EMF film sensors the device or its control unit can calculate the force of the touch. In this way it can differentiate the spots touched, and the forces by which the protective element has been touched.

The EMF film sensors have been connected to a control unit, which has been arranged to read the electric responses given by the film sensors, and based on the- m to estimate the place or force, or both, of the touch on the protective element. The control unit sends the information concerning the touch to an electric device, which performs the tasks according to instructions based on the touch information. If for instance the display unit has a picture of a keyboard, the electric device performs the task corresponding to the pushing of the spot of the key in question.

In an advantageous embodiment of the apparatus according to the invention the protective element is a sheet or a film. In another advantageous embodiment the protective element is in contact with the display unit. The EMF film sensors are at the surface of the display unit. In another advantageous embodiment of the apparatus according to the invention, the EMF film sensors are on the periphery of the display unit. Advantageously there are four film sensors and they are located in the vicinity of the corners of the display unit. The material of the protective element is chosen in such a way, that it is durable and easy to clean. The EMF film sensors can be placed in such a way, that they do not disturb the image on the display unit.

In another advantageous embodiment the EMF film sensors are located on the frame or case, which surrounds the display unit at least partly. The protective element may be in contact with the said frame and the EMF film sensors. In that case the protective element need not be in contact with the display unit. Advantageously, the protective element of the apparatus according to the invention is designed or coloured. With the help of the said design or colouring, the protective element can be equipped with, for instance, keys or symbols. Furthermore, in an advantageous embodiment, the display unit underneath provides the markings in the protective element with lights of different colours.

There is a method according to the invention for operating the touch screen. The touch screen comprises of a display unit, which is connected to an electric device, the image on the display unit being guided by the electric device. With the help of the touch screen the user can feed information to the device and control it by way of the user interface. The touch screen has one or several EMF film sensors in the touch screen and they are connected to a protective element covering the display unit and the EMF film sensors, at least partly, and the said EMF film sensors are connected to the control unit.

In the method, a pressure is applied to a spot on the protective element, either with a finger or with a touching tool. The pressure applied to a spot on the protective element presses the EMF film sensors with forces, which are comparable to the spot where the pressure is applied to. The pressure on the EMF film sensors creates an electric response in the film sensors, which response is comparable to the pressure applied to the sensors. The control unit reads the electric responses of the film sensors and based on the responses, estimates the spot onto which the pressure has been directed on the protective element, and reports it to the electric device. The electric device operates according to pre-set instructions based on the spot given by the control unit.

In another advantageous embodiment of the method, the EMF film sensors and control unit detect the force by which a spot on the protective element has been touched, and the electric device operates according to pre-set instructions based on the spot and force or only the force given by the control unit. In this way, operations regardless of the spot on the touch screen can be programmed onto the touch screen. For instance, two stronger strokes may be arranged to cut off the electric device, and this can be done regardless of the spot which is stroked. Also operations, which combine the force and spot of the touch may be used.

A touch screen according to the invention can be used to replace a traditional keyboard, or as an addition to various electric devices. An embodiment of the invention, which is used to create small, light, and durable touch screens, makes it pos- sible to use it in portable devices, such as telephones, PDA devices, laptops, port- able music players, and game devices. A touch screen according to the invention also functions in large displays. The invention in question can also be used to realize drawing or writing on the touch screen, and for scrolling the image of the display into various directions. Also different combinations of touching are possible. Such combinations could be for instance combinations of short and long touches.

An advantage of the invention is that the solution does not require the display unit, which makes it possible to make the display unit sturdy, leading to a better image. The protective element for its part also protects the sensitive display unit from scratching, getting dirty, and from other types of damage. A solution according to the invention also improves the exactness of the touch screen. This makes it possible to use the invention in automates or in other types of public use.

Another advantage of the invention is that it requires less wiring than an EMF film solution placed under the display, meaning that the entity is easier to produce.

Still another advantage of the invention is the fact that film sensors made of EMF film are extremely sensitive, meaning that actual mechanical movement of the protective element is not needed and the durability of the entire touch screen is thus improved remarkably.

Yet another advantage of the invention is that it enables building a small touch screen, which can be used in portable electric devices.

In the following the invention will be described in detail. The description refers to the enclosed drawings, in which

Fig. 1 shows an example of an advantageous embodiment of the invention viewed from above,

Fig. 2 shows an example of an advantageous embodiment of the invention viewed from the side,

Fig. 3 shows an example of a flowchart of the method according to the invention, and

Fig. 4 shows an example of another advantageous embodiment of the invention viewed from the side.

Fig. 1 shows an example of a touch screen according to the invention viewed from above. Display unit 102 can be, for example, the display of a cell phone, the dis- play of a PDA, a display connected with various automates, or the display of a PC. Display unit 102 obtains its driving power, and the information needed for displaying an image or the like, from the electric device to which it has been connected. The said device as well as connecting and fastening mechanisms has been left out of the picture. The four EMF film sensors 101 , 104, 108 and 110 have been produced from thin EMF film. The thickness of the EMF film sensors is approximately some tens of micrometers. The EMF film sensors in this embodiment have been placed on top of the display unit. The connecting devices, which conduct electricity, 105, 106, 109 and 111 connect the EMF film sensors to the control unit 107.

Protective element 103 is placed on top of the display unit 102. The placing is done is such a way, that the protective element is in practise in contact with the display unit. The protective element may also be placed in such a way, that its periphery touch the casing or frame surrounding the display unit. The EMF film sen- sors are left between the protective element and the casing or frame surrounding the display unit. The EMF film sensors 101 , 104, 108 and 110 left between the protective element and the frame or the display unit, are so thin that a placement described above is possible. The protective element is in whole or partly of transparent or translucent material, which makes it possible to see an image or light from the display unit underneath. When a pressure is applied to a spot on the protective element, it presses each EMF film sensor at slightly different forces, depending on where the force is aimed at. As a result of the pressure, each of the EMF film sensors sends a voltage signal, which can be detected at the control unit 107 transmitted by the connecting devices 105, 106, 109 and 111.

Control unit 107 represents a configuration used for handling the voltage signals given by the EMF film sensors 101 , 104, 108 and 110, and to transmit the given information ahead. The configuration may be an independent unit, or it uses the resources of the device onto which the touch screen has been connected. If needed, the control unit strengthens the signals given by the EMF film sensors. Since protective element 103 directs forces of varying strength to the EMF film sensors, unless the force entering the protective element is not in the centre of symmetry of the EMF film sensors, each EMF film sensor sends a different signal. Using simple mathematical operations the control unit can calculate from the signals sent by the EMF film sensors the spot on the protective element at which the force has been applied. The control unit sends the information ahead to the device onto which the control unit and the display unit have been connected, and after receiving the information the said device performs a certain operation according to pre-set instructions. This operation can be, for instance, displaying a certain symbol onto the display unit, or the starting of an operation performed by the device.

Fig. 2 shows an example of the structure of a touch screen according to the inven- tion, when the case in Fig. 1 is observed from the side. The picture does not show the device onto which the touch screen has been connected, and for reasons of clarity it also does not show the connecting devices and control unit. The display unit 202 and the protective element 203 on top of it are connected to each other.

Between them are the EMF film sensors 201 and 204. The two other EMF film sensors are not shown in this picture. The thickness of the EMF film sensors has been exaggerated in the picture for reasons of clarity.

Fig. 3 shows, by way of example, a flow chart of a method according to the invention. The use of the touch screen is started 301. At this stage the touch screen is switched onto a receiving mode. A pressure is applied to a spot on the protective element covering the display unit 302, i.e. it is touched with a touch tool. The touch tool may be a finger or a pointer of some sort, with which touching is possible. When pressure is applied to the protective element, pressures are also applied to the EMF film sensors 303 underneath. The magnitudes of the pressures applied to the EMF film sensors are comparable to the spot at which the protective element has been touched. The EMF film sensors 304 give electric responses, the magnitudes of which are comparable to the pressures applied to them. The EMF film sensors have been electrically connected to the control unit, which is advantageously a processor or similar component capable of calculations. The control unit receives the electric responses sent by the EMF film sensors 305. Based on the electric responses sent by different film sensors, the control unit estimates the spot, which has been touched on the protective element 306. This is carried out by comparing the electric responses and by making calculations based on these. Based on the electric responses, the control unit can also estimate the force of the touch applied to the protective element. The control unit reports the spot it esti- mates as being touched to the electric device 307. The electric device acts according to the information sent by the control unit and according to its own instructions 308. For instance, the electric device has presented the icons of several programmes on the display unit. When the protective element has been touched in a pre-determined way from above an icon as presented above, the said touch being, for example, a simple touch, a touch lasting for a required time, a double touch, or a touch with a certain force, the electric device receives information about the touch from the control unit, and the electric device starts the programme related with the icon in question. The electric device can then move on to wait for more touches onto protective element 309. In case more electric responses are sent from the film sensors, the control unit 305 receives them. In case no more electric responses are detected, the electric device can, for example, switch the touch screen into a dormant state or switch it off 310. The control unit may also estimate the force by which the protective element has been touched. Also this touching force can be used in controlling the electric device 308.

Fig. 4 shows, by way of example, the structure of a touch screen according to the invention, when it is observed from the side. The picture does not show the device onto which the touch screen has been connected, and for reasons of clarity it also does not show the connecting devices and control unit. The display unit 402 and the protective element 403 on top of it are slightly apart from each other. The display unit is surrounded by casing structure 405. The casing structure protects or supports the display unit. EMF film sensors 401 and 404 are between the casing structure and the protective element. Possible other EMF film sensors are not shown in this picture. The thickness of the EMF film sensors has been exaggerated in the picture for reasons of clarity. In this embodiment the protective element need not be in contact with the display unit.

A solution according to the invention for the display unit is able to register and detect at least six to eight flicks per second. This makes it possible to use a touch screen according to the invention for example in portable telephones, PDA devices, and game devices, which require a quick use of the keyboard. The invention also makes possible drawing by way of touching, and the scrolling of the image on the screen, i.e. moving the image by way of touching.

The protective element may be designed in the shape of a keyboard, which makes a non-mechanical keyboard possible, and also enables different lighting of different keys from the display unit underneath. Many different embodiments may be realized using the invention, such as automates or vending machines.

The number and location of the film sensors can be altered according to the needs of an application.

Some advantageous embodiments of the apparatus according to the invention have been described above. The invention is not restricted to the solutions de-

RECTlFlED SHEET (RULE 91) scribed above, instead the scope of the invention can be applied in numerous ways, to the extent allowed by the claims.

Claims

1. A touch screen which comprises a display unit (102; 202; 402), connected to an electric device, and in which the image of the display unit has been arranged to be controlled by the electric device, and the touch screen of which has been arranged to feed information to the device and to control the device via the user interface, characterized in that

- the touch screen has one or several EMF film sensors (101 ,104,108,110; 201 , 204; 401 , 404),

- on top of the display unit and the EMF film sensors there is a pro- tective element (103; 203; 403), which is at least partly translucent, and which has been arranged to be in contact with the EMF film sensors,

- the EMF film sensors have been arranged in such a way, that they give electric responses when a pressure is applied to the protective element, and which electric responses are comparable to the spot onto which the pressure on the protective element is directed,

- the EMF film sensors have been connected to the control unit (108), which is arranged to read the electric responses sent by the sensors, and based on the responses to estimate the spot onto which the pressure has been directed on the protective element, and

- the electric device has been arranged to operate according to pre-set instructions after the control unit has detected the spot onto which the pressure is directed to on the protective element.

2. A touch screen according to claim 1 , characterized in that the protective element (103; 203; 403) is a sheet or a film.

3. A touch screen according to one of claims 1-2, characterized in that the protective element (103; 203; 403) is in contact with the display unit (102; 202; 402).

4. A touch screen according to one of claims 1-3, characterized in that the EMF film sensors (101 ,104,108,110; 201 , 204; 401 , 404) are located on the surface of the display unit (102; 202; 402).

5. A touch screen according to one of claims 1-3, characterized in that the EMF film sensors (101 , 104, 108, 110; 201 , 204; 401 , 404) are located on the periphery of the display unit (102; 202; 402).

6. A touch screen according to one of claims 1-3, characterized in that the EMF film sensors (101 ,104,108,110; 201 , 204; 401 , 404) are located in the frame or casing (405) at least partly surrounding the display unit (102; 202; 402).

7. A touch screen according to claim 1 , characterized in that the protective element (103; 203; 403) is in contact with the casing or frame (405) essentially surrounding the display unit (102; 202; 402).

8. A touch screen according to one of claims 1-4, characterized in that there are four EMF film sensors (101 ,104,108,110; 201 , 204; 401 , 404) and they are located in the vicinity of the corners of the display unit (102; 202; 402).

9. A touch screen according to one of claims 1-5, characterized in that the touch screen is in a portable electric device.

10. A touch screen according to one of claims 1-5, characterized in that the EMF film sensors (101 ,104,108,110; 201 , 204; 401 , 404) and control unit (107) have been arranged to detect the force by which the protective element (103; 203; 403) has been touched.

11. A touch screen according to claim 10, characterized in that the electric devi- ce has been arranged to guide the display unit according to pre-set instructions, based on the spot and force or only the force of the touch applied to the protective element (103; 203; 403), and reported by the control unit (107).

12. A touch screen according to one of claims 1-6, characterized in that the material of the protective element (103; 203; 403) is durable and easy to clean.

13. A touch screen according to one of claims 1-7, characterized in that the protective element (103; 203; 403) is designed or coloured.

14. A touch screen according to claim 8, characterized in that the protective element (103; 203; 403) is equipped with designed or coloured symbols.

15. A method for using the touch screen, which touch screen comprises a dis- play unit (102; 202; 402) connected to an electric device, the image of the display unit being guided by the electric device, by means of which touch screen the user can feed information to the device using the touch screen and control it using an user interface, characterized in that:

- the touch screen comprises one or several EMF film sensors (101 ,104,108,110; 201 , 204; 401 , 404) touching the protective element (103; 203; 403) at least partly covering the display unit, and which EMF film sensors have been connected to the control unit (107),

- in the method in question, a pressure is applied to a spot on the protective element, either with a finger or with a touching tool (302),

- the pressure applied to a spot on the protective element presses the EMF film sensors with forces, which are comparable to the spot where the pressure is applied to (303),

- the pressure on the EMF film sensors creates an electric re- sponse in the film sensors, which response is comparable to the pressure applied to the sensors (304),

- the control unit reads the electric responses of the film sensors (305) and based on the responses, estimates the spot in the protective element onto which the pressure has been applied to (306), and reports it to the electric device (307), and

- the electric device operates according to pre-set instructions based on the spot given by the control unit (308).

16. A method according to claim 15, characterized in that the EMF film sensors (101 ,104,108,110; 201, 204; 401 , 404) and control unit (107) detect the force by which a spot on the protective element (103; 203; 403) has been touched, and the electric device operates according to pre-set instructions based on the spot and force, or only the force, given by the control unit.