WO2007017485A2

WO2007017485A2 - Touchscreen

Info

Publication number: WO2007017485A2
Application number: PCT/EP2006/065102
Authority: WO
Inventors: Jens FÜRST; Debora Henseler
Original assignee: Siemens Aktiengesellschaft
Priority date: 2005-08-11
Filing date: 2006-08-07
Publication date: 2007-02-15
Also published as: EP1913461A2; WO2007017485A3

Abstract

The invention relates to a touchscreen (1, 30, 40, 53), comprising a display surface (8, 52, 62), a structured first electrode (3, 43, 55) with an extensive surface area comprising several first sub-electrodes (4), a second electrode (7, 47, 57) with an extensive surface area and at least one first active layer (6, 36, 46, 56) that is situated between the first electrode (3, 43, 55) and second electrode (7, 47, 57). The first sub-electrodes (4) of the first electrode (3, 43, 55) are controlled in such a way that they co-operate with the second electrode (7, 47, 57) and the first active layer (6, 36, 56) that is situated between said electrodes in order to display an image on the display surface (8, 52, 62). In addition, the touchscreen (1, 30, 40, 53) comprises organic photodetectors that are integrated into said screen (1, 30, 40, 50) and at least one second active layer (6, 36, 50, 60) consisting of an organic material. When the display surface (8, 52, 62) is touched, a signal, which is assigned to the point of contact on said surface (8, 52, 62), is generated in the organic photodetectors.

Description

touch screen

The invention relates to a touch screen.

A touch screen includes a display panel, such as an LCD panel, and a touch-sensitive sensor panel. When touched, the sensor field responds, for example, to trigger a selected action or application. Touch screens become u. a. used for private and industrial applications as a relatively simple and fast input option. The touch screen may e.g. with a finger, as u. a. at ATMs, or served by a pen, as is the case with some PDAs.

The display panel and the touch-sensitive sensor field are usually produced as separate components and mechanically connected to one another. The sensor array typically relies on a conventional display panel-like display, such as a display panel. an LCD, CRT or plasma screen, and is deposited on a separate substrate. From US 2002/0171610 Al and US 2002/0186208 Al also touch screens are known in which the sensor array and the display panel are constructed on a common planar substrate. The one planar side of the substrate is in this case provided with the display panel and the other planar side of the substrate is provided with the sensor field. Resistive, capacitive and optical sensor fields are examples of well-known sensor fields.

At the 2003 SID conference, a 2.4 x 2.4 inch TFT LCD screen with embedded 60x60 a-Si photodetector array was also presented (see Willem den Boer et al.

"Active Matrix LCD with Integrated Optical Touch Screen", SID International Symposium Digest of Technical Papers, May 2003, Vol. 34, Issue 1, pages 1494-1497). WO 03/043294 A1 also discloses a multifunctional communication device with mechanical, acoustic, visual input and output means as well as transmitting and receiving devices for communication with other communication devices. The visual input / output means is designed as a unit which can be rolled out of the communication device, can be pulled out, folded and / or folded.

Object of the present invention is to provide conditions for a touch screen can be performed as thin as possible.

The object of the invention is achieved by a touch screen comprising a display surface, a structured planar first electrode comprising a plurality of first partial electrodes, a planar second electrode, and at least one first active layer disposed between the first and second electrodes, wherein the first partial electrodes first electrodes are driven so as to cooperate with the second electrode and the first active layer disposed therebetween, thereby displaying an image on the display surface, and organic photodetectors integrated with the touch screen having at least one second active layer of an organic material in which a signal associated with the touch location of the display surface is applied to the organic photodetectors when the display surface is touched. The term "image" is to be understood in the broadest sense, so under an "image" in particular also displayed letters, numbers and

Sign understood, so any type of information to be displayed on the display surface.

In particular, mobile devices, such as portable phones or PDAs, on the one hand always smaller, but should also have a relatively large display panel on the other hand. Roll-up or foldable display panels are therefore under development. Such display fields should be as thin as possible and if possible also be flexible. Suitable bendable or flexible display panels include polymer electronic components, display elements based on electrochromic materials, electrophoretic display elements, possibly also LCDs, but above all display elements based on organic materials, such as organic LEDs. Organic LEDs are self-luminous, which is why a backlight can be dispensed with. Electrochromic displays are readable like "electronic paper" because of their color change, and they also do not require backlighting, so that such a display panel can also be used as a touch screen, the sensor array should also be flexible or flexible Organic photodetectors are as flexible or flexible as organic According to the invention, the touch screen according to the invention therefore comprises organic photodetectors as touch-sensitive elements, which are also integrated in the touch screen. By integrating the photodetectors in the touch screen, it is possible to make the touch screen only slightly thicker than a display device without touch-sensitive elements ,

According to a preferred embodiment of the touch screen according to the invention, the planar first electrode additionally comprises second partial electrodes, the first active layer arranged between the first and second electrodes is an active layer of an organic material and the organic photodetectors comprise the second partial electrodes of the first electrode, thus upon touching the display surface, a signal associated with the touch location of the display surface is applied to the second sub-electrodes. Thus, the touch screen according to the invention essentially comprises a pair of electrodes with at least one active layer of organic material interposed therebetween. The first electrode is structured and comprises the first partial electrodes. These are driven so that an image to be displayed with the touch screen appears on the display surface. A partial electrode of the first partial electrodes with subsequent organic active layer, the first active layer, and second electrode thus substantially corresponds to an organic LED. Each of these organic LEDs is in turn associated with a pixel of the displayed image.

Organic materials for the first active layer are, for example, polyfluorenes, polyspirofluorenes, polyphenylenevinylenes or organic molecules such as Alq3. Polymers comprising organic active layers can e.g. by spin-coating, knife coating, screen printing, ink jet printing or similar printing techniques applied to the first electrode. Small organic molecules comprising first active layers can be processed by vapor deposition.

The second sub-electrodes are associated with the organic photodetectors. A partial electrode of the second partial electrodes with subsequent second active layer and second electrode essentially corresponds to an organic photodiode. Thus, it is envisaged that not all pixels of the touch screen are intended for image reproduction, but some of the pixels, namely the pixels associated with the second sub-electrodes, as touch-sensitive elements, i. used as photodetectors.

The readout of the individual organic photodiodes is preferably carried out in the reverse direction of the photodiodes. As a result, the intensity with which the individual organic photodiodes are illuminated determines their diode currents. Touches e.g. an operator the display surface, then the corresponding photodiodes are covered. Through the corresponding photodiodes only a negligible electric current flows.

According to a variant of the touch screen according to the invention, the first active layer and the second active one Layer an according to the structured first electrode structured active layer of organic material.

If the touch screen according to the invention comprises the active layer of organic material structured in accordance with the structured first electrode, it is possible, on the one hand, for the active layer in the area in which it is used to display the image, to have the most suitable material for the image display and, on the other hand, for the active layer in the region in which it is designed as a photodiode, to use a material which is as suitable as possible for a photodiode. Cheap materials for a photodiode include a blend of a good hole transporter and a good electron acceptor and transporter, such as polythiophene in admixture with excipient derivatives. This embodiment is particularly suitable when the first active layer is e.g. is applied by ink jet printing or vapor deposition through masks structured.

The partial electrodes of the first electrode can be operated in particular in the so-called active matrix or passive matrix control. The first electrode is structured in a matrix-like manner in such a case and comprises rows and columns.

With a passive-matrix control, the individual lines are sequentially illuminated by multiplexing during a specific time period assigned to an image cycle. There is no "stagnant" image, but each line shines only a fraction of the time, but relatively bright. Both the first and second electrodes are striped and perpendicular to each other, some of the pixels, for example, certain columns and / or rows , the second sub-electrodes are the first

Assigned electrode, ie some of the rows and / or columns are not used for image display, but are designed as photodiodes. If the touch screen according to the invention comprises the active layer comprising the first active layer and the second active layer, then it is also possible for the active layer to have the property both of displaying an image and of being used as part of a photodiode. Then a time window between two image cycles can be provided. During the image cycle, both the pixels assigned to the first sub-electrodes and to the second sub-electrodes of the first electrode can then be used for imaging. During the time window, the pixels assigned to the second sub-electrodes are then used as photodiodes.

In an active-matrix drive, each of the sub-electrodes of the first electrode is driven or read out with one or more transistors. During an image cycle, all sub-electrodes intended for image display can then be activated. The same transistors are also preferably used to read those sub-electrodes associated with the photodiodes. In this type of driving, it is also possible to use the partial electrodes associated with the photodiodes, i. the second sub-electrodes, both for image display and to use as a photodiode.

In particular, when the second sub-electrodes are not used for image display, it is provided to make the area of the second sub-electrodes smaller than the area of the first sub-electrodes. It is then possible to use fewer pixels for the photodiodes than for image display.

According to a further embodiment of the touch screen according to the invention, the first active layer and the second active layer are only an unstructured active layer of the same organic material. This active layer must be usable both for image display and for a photodiode. Examples of such an organic material are poly-phenylene-vinylenes (PPVs). Such a touch screen can be manufactured relatively inexpensively.

Because active layers of an organic material are relatively flexible, it is provided according to a particularly preferred variant of the touch screen according to the invention, the first electrode, the second electrode, the first active layer, the second active layer and the display surface of a flexible and / or flexible To produce material. Such a touchscreen can then be foldable or rollable in particular.

According to a further embodiment of the touch screen according to the invention, it is provided that the latter comprises a substrate having a planar first side and a planar second side, on the first side of which the first electrode is applied, the organic photodetector a structured third electrode comprising a plurality of third partial electrodes and a planar fourth electrode, between which the second active layer is arranged, wherein the third electrode is applied on the second side of the substrate or on the second electrode. According to this embodiment, the organic photodetectors are not integrated into the electrodes provided for imaging, but form a separate layer system. The third electrode and the fourth electrode, that is to say the electrodes assigned to the organic photodetectors, are made as transparent as possible, so that the image to be displayed appears through this layer system on the display surface. The electrodes associated with the photodetectors and the electrodes used for imaging have separate leads. It is also possible to make the pixels assigned to the photodetectors larger than the pixels intended for image display. In this embodiment of the touch screen according to the invention, the first active layer, that is to say that active layer which is intended for imaging, consists of an inorganic or an organic material. Thus, not only organic LEDs used for image display, but in particular also electrochromic or electrophoretic display elements, and inorganic LEDs.

In particular, electrochromic or electrophoretic display elements, but also organic display elements, e.g. Organic LEDs, can be made flexible or flexible, so it is provided according to a preferred variant of the touch screen according to the invention, the substrate, the first electrode, the second electrode, the third electrode, the fourth electrode, the first active layer, the second active layer and manufacture the display surface from a flexible and / or flexible material. Such a touchscreen can then be foldable or rollable in particular.

Embodiments of the invention are illustrated in the accompanying schematic drawings. Show it:

Fig.l a touch screen with two electrodes in partial representation,

Fig. 2 shows one of the two electrodes of the touch screen shown in FIG. 1 in partial Dar- position and

FIGS. 3 to 5 each show a further touch screen in partial representation.

1 shows a first preferred embodiment of a touch screen 1 according to the invention. The touch screen 1 comprises a substrate 2 on which a planar structured first electrode 3 is arranged. The structured first electrode 3 comprises, as shown in FIG. 2, a plurality of first partial electrodes 4 arranged in matrix form and second partial electrodes 5 shown hatched in FIG. 2. In the case of the present exemplary embodiment, the second partial electrodes 5 have a smaller area than the first partial electrodes 4 and the number of second partial electrodes 5 are substantially smaller than the number of the first partial electrodes 4.

On the planar structured first electrode 3, an organic semiconductor layer 6 is applied, which in turn is provided with a planar second electrode 7. The planar second electrode 7 is made of a relatively transparent material and is unstructured. The planar second electrode 7 is in turn provided with a transparent protective layer, which represents the display surface 8 of the touch screen 1. The protective layer may e.g. a polymer layer, an organic or inorganic multi-layer or a glass cap.

In the case of the present exemplary embodiment, the organic semiconductor layer 6 is likewise structured in accordance with the planar first electrode 3 and comprises, in those regions which are arranged above the first partial electrodes 4, an organic material suitable for image reproduction, which in the case of the present exemplary embodiment comprises poly-phenylene -Vinyene includes.

In the case of the present exemplary embodiment, thin-film transistors (not shown) are furthermore arranged in the substrate 2, of which in each case one thin-film transistor is connected to one of the first partial electrodes 4 or 5 of the planar structured first electrode 3. The thin-film transistors are in turn electrically connected to electrical leads 9 to a control device 10.

The control device 10 and the thin-film transistors connected to the first sub-electrodes 4 are designed to drive the individual first sub-electrodes 4 and the second electrode 7 such that an image to be displayed on the touch screen 1 appears on the display surface 8. The individual first Electrodes 4 associated structured portions of the organic semiconductor layer 6 in conjunction with the corresponding areas of the second electrode 7 thus each represent an organic LED, which in turn are each associated with a pixel of the image displayed on the touch screen 1.

The organic semiconductor layer 6 is embodied in the regions which adjoin the second subelectrodes 5 of the first electrode 3 such that in each case a second subelectrode 5 with adjoining organic semiconductor layer 6 and corresponding regions of the second electrode 7 forms an organic photodiode. In the present exemplary embodiment, polythiophene in the mixture with fullerene derivatives is used as the organic material.

The thin-film transistors of the substrate 2 associated with the second sub-electrodes 5 of the first electrode 3 in connection with the control device 10 are designed such that they measure the charge on the second sub-electrodes 5 that arises due to incidence of light on the touch screen 1. If an operator, not shown in the figures, for example, touches the display surface 8 with a finger, the corresponding photodiodes are covered, whereby the electric current flow in the corresponding photodiode changes. Because of the electrical signals read out from the thin film transistors associated with the second sub-electrodes 5 and applied to the second sub-electrodes 5, the control device 10 can determine the coordinates of the touch location on the display surface 8 which the operator touches.

FIG. 3 shows a further embodiment of a touch screen 30 according to the invention. The touch screen 30 shown in FIG. 3 essentially differs from the touch screen 1 shown in FIGS. 1 and 2 in that an active layer 36 is provided between the two electrodes 3 and 7 an organic material is arranged, which is made both in the areas of the first partial electrodes 4 and in the areas of the second partial electrodes 5 of the same organic material. In the case of the present embodiment, the organic layer 36 consists of poly-phenylene-vinylenes.

Depending on the control device 10 used, the touch screen 30 shown in FIG. 3 can be activated according to the touch screen 1 shown in FIG. 1 or controlled as follows:

During an image cycle, the control device 10 controls both the thin-film transistors connected to the first sub-electrodes 4 of the first electrode 3 and the second sub-electrodes 5 of the first electrode 3 to be connected to the second electrode 7 and the second sub-electrodes 5 organic active layer 36 display an image on the display surface 8 of the touch screen 30. Thus, substantially all of the organic layer 36 is used to display the image during one image cycle.

Between two consecutive image cycles a time window is provided. During the time window, the thin-film transistors of the second partial electrodes 5 associated with the second partial electrodes 5 of the first electrode 3 and the corresponding regions of the second electrode 7 and the corresponding regions of the organic active layer 36 interposed therebetween are connected as photodiodes. The corresponding thin-film transistors read out the electrical signals at the second sub-electrodes 5, which in turn are evaluated by the control device 10. On the basis of the evaluation, the control device 10 determines the coordinates of a possible contact location on the display surface 8, which an operator touches.

In the case of the present embodiment, the organic layer 36 is unstructured. However, the organic layer 36 may also be similar to the organic layer 6 of the 1 illustrated touch screen 1 to be structured.

FIG. 4 shows a further exemplary embodiment of a touchscreen 40 in a partial representation. The touch screen 40 comprises a substrate 42 on which a planar structured, a plurality of partial electrodes comprising the first electrode 43 is arranged. Each of the sub-electrodes is associated with a pixel of an image to be displayed with the touch screen 40. The structured first electrode 43 is provided with an active layer 46, which in turn is provided with an at least semitransparent second electrode 47. The second electrode 47 is provided with an at least semitransparent insulating layer 48.

On the insulation layer 48, in turn, a structured planar third electrode 49 comprising a plurality of partial electrodes is arranged. The structured third electrode 49 is at least semitransparent and provided with a further active layer 50, which in the case of the present exemplary embodiment is a polythiophene mixed with fuller-derivative-containing organic semiconductor layer. The active layer 50 is in turn provided with a planar structured, at least semitransparent fourth electrode 51 comprising a plurality of partial electrodes, which in turn is coated with a transparent protective layer, which is the display surface 52 of the touch screen 40. In the case of the present exemplary embodiment, the third electrode 49 and the fourth electrode 51 are structured in a strip-like manner perpendicular to one another.

In the case of the present embodiment, a control device, not shown in FIG. 4, controls thin-film transistors, not shown in FIG. 4, arranged in the substrate 42 such that it consists of the first electrode 43, the second electrode 47 and the active layer 46 first layer system generates an image displayed on the display surface 52. The active one Layer 46 comprises an organic semiconductor material in the case of the present embodiment. The first layer system is thus operated in the active-matrix drive.

The second layer system comprising the third and fourth electrodes 49 and 51, as well as the active layer 50, is essentially a photodetector having a plurality of organic photodiodes arranged in matrix form, which are connected to the control device and serve as touch-sensitive elements. The second layer system is operated in the case of the present embodiment in the passive matrix drive.

The second layer system in conjunction with the control device is designed in such a way that the charge distribution between the partial electrodes of the third electrode 49 and the partial electrodes of the fourth electrode 51 resulting from the incidence of light on the touch screen 40 is measured. If an operating person, not shown in the figures, for example touches the display surface 52 with a finger, the corresponding photodiodes are covered, whereby the electric current flow in the corresponding photodiodes changes. The electrical signals applied between the third electrode 49 and the fourth electrode 51 are read out with the control device. Based on these electrical signals, the controller then determines the coordinates of the touch location on the display surface 52 that the operator touches.

FIG. 5 shows a further embodiment of a touch screen 53 in partial representation. The touch screen 53 comprises a substrate 54, on one side of which a planar structured first electrode 55 comprising a plurality of partial electrodes is arranged. The structured first electrode 55 is provided with an active layer 56, which in turn is provided with a second electrode 57. The structured second electrode 57 is coated with a protective layer 58. The second side of the substrate 54 is coated with a planar structured, comprising a plurality of partial electrodes third electrode 59, which in turn is provided with an active layer 60. Arranged on the active layer 60 is a planar fourth electrode 61, which in turn is coated with an at least semitransparent layer representing the display surface 62 of the touch screen 53.

5, not shown, are arranged in the substrate 54, of which in each case a thin-film transistor is connected to a respective partial electrode of the structured first electrode 55 and to a partial electrode of the structured third electrode 59. The thin-film transistors of the substrate 54 are in turn connected to an electrical line 63 with a control device 64.

In the case of the present embodiment, the active layer 56 composed of the substrate 54, the first electrode 55, the second electrode 57 and the intermediate therebetween constitutes a display device which is controlled by the control device 64 such that a displayable surface 62 is displayed Image is displayed.

The planar third electrode 59, the planar fourth electrode 61 and the intermediate active layer 60, which in the case of the present exemplary embodiment is an organic semiconductor layer composed of a mixture of a polythiophene and fullerene derivatives, are controlled by the control device 64 in such a way that that this layer system represents a touch-sensitive element. The laminar third electrode 59, the planar fourth electrode 61 and the layered active layer 60 having an intermediate layer system, and the substrate 55 are made of at least one semitransparent material. so that the image to be displayed can be seen through this layer system.

Although the present invention has been described in terms of preferred embodiments, the invention is not limited to these, but modifiable in many ways. In particular, the touch screen according to the invention can also be executed with a passive matrix drive.

Claims

claims

A touch screen comprising a display surface (8, 52, 62), a structured areal first electrode (3, 43, 55) comprising a plurality of first constituent electrodes (4), a planar second electrode (7, 47, 57), and at least one between the first electrode (3, 43, 55) and the second electrode (7, 47, 57) arranged first active layer (6, 36, 46, 56), wherein the first part electrodes (4) of the first electrode (3, 43, 55) are driven so as to cooperate with the second electrode (7, 47, 57) and the first active layer (6, 36, 56) disposed therebetween, thereby displaying an image on the display surface (8, 52, 62) and organic photodetectors integrated in the touch screen (1, 30, 40, 53) having at least one second active layer (6, 36, 50, 60) of an organic material, wherein on the organic photodetectors upon touching the display surface (8, 52, 62) at the touch location of the display surface (8, 52, 62) assigned signal.

2. Touch screen according to claim 1, wherein the planar first electrode (3) additionally comprises second partial electrodes (5), the first active layer (6, 36) arranged between the first electrode (3) and the second electrode (7) has an active Layer of an organic material and the organic photodetectors comprise the second sub-electrodes (5) of the first electrode (3) and the second electrode (7), so that upon touching the display surface (8) to the touch location of the display surface (8) associated signal the second part electrodes (5) is applied.

3. A touch screen according to claim 2, wherein the first active layer (6, 36) and the second active layer (6, 36) form an active layer of organic material structured according to the structured first electrode (3).

A touch screen according to claim 3, wherein the first active layer (6) and the second active layer (6) comprise different organic materials.

A touch screen according to claim 2 or 3, wherein the first active layer (36) and the second active layer (36) are made of the same organic material.

The touch screen of claim 2, wherein the first active layer and the second active layer is an unstructured active layer of the same organic material.

7. A touch screen according to claim 2 or 3, wherein the second sub-electrodes (5) during a first time period with the second electrode (7) and the second active layer

(36) cooperate such that when touching the display surface (8) the touch location of the display area associated signal to the second sub-electrodes (5) is applied, and during a second period of time, the first sub-electrodes (4) and the second sub-electrodes (5) so driven to cooperate with the second electrode (7) and the first active layer (36) and the second active layer (36), respectively, so that the image is displayed on the display surface (8).

8. Touch screen according to one of claims 1 to 5, wherein the first electrode (3), the second electrode (7), the first active layer (6,36), the second active layer (6, 36) and the display surface ( 8) are made of a flexible and / or flexible material.

The touch screen according to claim 1, comprising a substrate (42, 54) having a planar first side and a planar second side, on the first side of which the first electrode (43, 55) is applied, the organic photodetector a plurality of third sub-electrodes comprehensive textured third electrode (49, 59) and a planar fourth electrode (51, 61), between which the second active layer (50, 60) is arranged, wherein the third electrode (49, 59) on the second side of the substrate (54) or on the second electrode (47) is applied.

A touch screen according to claim 7, wherein the first active layer (46, 56) is an active layer of an organic material or an active layer of an inorganic material.

11. A touch screen according to claim 7 or 8, wherein the substrate (43, 55), the first electrode (42, 55), the second electrodes (47, 57), the third electrode (49, 59), the fourth electrode ( 51, 61), the first active layer (46, 56), the second active layer (50, 60) and the display surface (52, 62) are made of a flexible and / or flexible material.