FR2954981A1 - MULTICONTACT BIDIMENSIONAL TOUCH SENSOR AND SENSOR WITH LONGITUDINAL ELEMENTS INCLINED CONDUCTORS - Google Patents

Abstract

The invention relates to a multicontact two-dimensional tactile sensor (1) comprising an upper layer (2) provided with conductive longitudinal elements (3) organized along an upper axis (X) and a lower layer (4) provided with longitudinal elements conductors (5) arranged along a lower axis (Y) non-parallel to the upper axis (X). In this sensor, at least one of the longitudinal elements (3,5) has on at least a portion of its edge a non-zero inclination with respect to its axis (X, Y). The invention also relates to a display (20) provided with a two-dimensional tactile sensor multiconctacts according to the invention.

Description

MULTICONTACT BIDIMENSIONAL TOUCH SENSOR AND SENSOR WITH LONGITUDINAL ELEMENTS INCLINED CONDUCTORS

The present invention relates to a two-dimensional touch sensor multicontacts, and to a display provided with such a sensor.

This type of sensor is described for example in patent document EP 1 719 047, which teaches a multicontact tactile sensor comprising: an upper layer provided with conductive longitudinal elements organized along an upper axis, and a lower layer provided with conductive longitudinal elements organized along a lower axis not parallel to the upper axis.

The conductive longitudinal elements are conductive tracks made of indium tin oxide (ITO), which is a translucent conductive material. The conductive tracks of the upper layer are organized in rows and those of the lower layer in columns, so that these tracks form in projection on each other a matrix of square cells. The top layer can be positioned under a layer of polyethylene terephthalate (PET) and the bottom layer on a layer of glass. The arrangement of the layers inside the sensor is therefore as follows: a PET layer, a series of conductive lines, a series of conductive columns and a glass layer.

This sensor operates in such a way as to sequentially scan the rows and columns of conductive tracks, which makes it possible to simultaneously detect several contact zones during the same scanning phase.

More specifically, when a user presses on this sensor, the upper layer comes into contact with the lower layer in the parts between spacers. An electrical signal is sequentially injected into the conductive tracks of the upper layer and the detection takes place at the conductive tracks of the lower layer. The detection of a signal at some of these tracks therefore makes it possible to locate the position of the contact points.

Because of the remote setting, in the absence of electrical contact, between the conductive tracks of the upper and lower layers respectively, these tracks are separated by air.

However, the optical refractive index of air is much lower than that of ITO, just as the optical refractive index of PET is much lower than that of ITO. As the sensor has areas where only the PET layer and areas where the ITO conductive tracks are seen, these differences in optical refractive index between the different elements of the sensor cause the appearance of reflections. internal parasites inside it. It is therefore created a phenomenon of spatial optical interference between the two networks of conductive tracks.

When such a two-dimensional multi-touch tactile sensor equips a display, two networks are superimposed: first, the pixel array of the display part and, secondly, the network of conductive tracks of the sensor part. A backlighting device generally illuminates the screen from below, passing through the sensor and its conductive track networks.

Consequently, the spatial optical interferences between the conductive tracks of the sensor lead to the appearance of Moiré effect problems at the level of the pixel array, which is at the origin of a degradation of the optical performance of the display.

In the state of the art, these problems were solved by adding a dielectric material (insulator) in order to plug the areas where there are no ITO tracks, and whose index of optical refraction is the same as that of the ITO. This material makes it possible to avoid differences in reflections between the zones where there are ITO and the areas where there are none. However, it requires the addition of an additional layer, which has the disadvantage of increasing the cost of producing the sensor and is effective only for capacitive slab sensors. It is indeed not very effective for the resistive slab sensors, for which the air zones always induce problems of high deviations of optical refractive indices. The state of the art also knows tactile sensors whose lines and columns are arranged in diamond patterns to break the parallelism of the conductive tracks with the pixels of the display. This pattern nevertheless enhances the electrical resistance of the lines and columns of the sensor, which disturbs the electrical measurements on the sensor.

An object of the invention is therefore to improve the optical performance of the sensors and displays of the state of the art, by eliminating Moiré effects inside the sensor, without requiring the addition of additional layers likely to make the more expensive and complex sensor to manufacture.

This problem is solved according to the invention by a two-dimensional contact sensor multicontacts as described above, at least one of the longitudinal elements has on at least a portion of its edge a non-zero inclination relative to its axis.

Thanks to the invention, the longitudinal conducting elements constituting the sensor matrix are not perfectly linear elements along the axis with which they are associated. On the contrary, they have an inclination with respect to the situation of a perfectly linear longitudinal conducting element.

Under these conditions, when the sensor equips a display provided with a network of pixels in a plane parallel to that of the longitudinal elements of the sensor, these elements are parallel to the pixels of the display, but the angle of inclination of the edge of the these elements cancel the Moiré effect with respect to the pixels.

Preferably, the non-zero inclination on the edge of the longitudinal element is achieved by means of a beveling of this element.

In the latter case, the bevelling can be advantageously performed according to at least one pattern.

Here, a pattern will be understood to mean a portion of the edge of the conductive longitudinal element, that is to say a longitudinal portion of this edge. This pattern therefore forms a part of the edge of the element and has an inclination with respect to the axis of the element, in the plane formed by the two networks of elements.

The pattern can be of any shape. More particularly, according to alternative embodiments, at least one pattern is a polygon or a triangle. In addition, to facilitate the manufacture of the conductive longitudinal element, at least one pattern is periodic.

Preferably, it is provided that: - all the longitudinal elements have on at least part of their edge a non-zero inclination with respect to their axis, and / or at least one of the longitudinal elements present on the whole from its edge a non-zero inclination with respect to its axis.

According to a first embodiment of the conductive longitudinal elements, at least one of them is in the form of a conductive track made of a transparent conductive oxide-based material, for example based on oxide indium tin (ITO).

According to a second embodiment of the conductive longitudinal elements, at least one of them is in the form of a conductive wire.

Preferably, the upper layer is located beneath a layer of polyethylene terephthalate (PET) and the lower layer is located above a layer of glass.

Preferably, the upper and lower layers are transparent, which allows for a transparent multicontact tactile sensor.

The invention also relates to a display with a multicontact two-dimensional tactile sensor according to any one of the embodiments described above.

In order to optimally eliminate Moiré effects, the inclination of at least one pattern with respect to the axis of the corresponding longitudinal element, in the plane defined by the upper and lower axes, is greater than the threshold of appearance of Moiré effects within the display / sensor pair.

In order also to optimally eliminate Moiré effects, the amplitude of the edge of at least one longitudinal element, induced by the inclination thereof, is preferably substantially equal to that of the cells formed by the intersection of two longitudinal elements respectively of the upper layer and the lower layer.

Preferably, the display is in the form of a matrix of pixels. The display comprises backlighting means in the form of a matrix of pixels. Finally, in the case where the non-zero inclination on the edge of the longitudinal element is achieved by means of a beveling of this element made according to at least one pattern, the dimensions of at least one of the patterns are substantially equal to those of the pixels of the display. The dimensions of at least one pattern are substantially equal to those of the pixels of the backlighting means. Other advantageous features of the invention are described hereinafter with reference to the appended figures in which: FIG. 1 represents a view of a display provided with a two-dimensional tactile touch sensor, and FIG. section of a multicontact tactile sensor in the absence of contact according to the prior art, - Figure 3 shows a sectional view of a multicontact tactile sensor in a contact according to the prior art, - the FIG. 4 represents a view from above of the arrangement of the conductive tracks of a prior art multicontact tactile sensor; FIG. 4b shows a prior art diamond arranged multicontact track sensor; FIG. lines and columns of conductive tracks according to a first embodiment of the invention, FIG. 6 represents a view comparing the arrangement of rows and columns according to this first embodiment and according to FIG. 7 shows a view of the rows and columns of conductive tracks according to a second embodiment of the invention; FIG. 8 represents a view of the arrangement of rows and columns according to this second embodiment of FIG. realization, and - Figure 9 illustrates the use of a multicontact touch sensor coupled to a display. For better legibility, in these figures, identical reference numerals refer to similar technical elements.

With reference to FIG. 1, a display 20 according to the invention comprises a matrix multicontact tactile sensor 1, a display screen 22, a capture interface 23, a main processor 24 and a graphic processor 25.

The first fundamental element of this tactile device is the multicontact tactile sensor 1, necessary for the acquisition - the multicontact manipulation - by means of a capture interface 23. This capture interface 23 contains the acquisition and acquisition circuits. analysis. The touch sensor 1 is of the matrix type. This sensor can be optionally divided into several parts to accelerate the capture, each part being scanned simultaneously.

The data from the capture interface 23 is transmitted after filtering to the main processor 24. The latter executes the local program for associating the data of the slab with graphical objects which are displayed on the screen 22 so that to be manipulated. The main processor 24 also transmits to the graphical interface 25 the data to be displayed on the display screen 22. This graphic interface can also be driven by a graphics processor.

The touch sensor is controlled as follows: one feeds successively, during a first scanning phase, the conductive tracks of one of the networks and the response is detected on each of the conductive tracks of the other network. These contact areas are determined as a function of these responses, which correspond to the nodes whose state is modified with respect to the idle state. One or more sets of adjacent nodes whose state is changed is determined. A set of such adjacent nodes defines a contact area. From this set of nodes is computed a position information qualified in the sense of the present cursor patent. In the case of several sets of nodes separated by non-active zones, several independent cursors will be determined during the same scanning phase.

This information is refreshed periodically during new scan phases. Cursors are created, tracked or destroyed based on information obtained during successive scans. The cursor is for example calculated by a barycentre function of the contact zone. The general principle is to create as many sliders as there are zones detected on the touch sensor and to follow their evolution over time. When the user removes his fingers from the sensor, the associated sliders are destroyed. In this way, it is possible to capture the position and the evolution of several fingers on the touch sensor simultaneously.

The matrix sensor 1 is for example a resistive type sensor or projected capacitive type. It is composed of two transparent layers on which rows or columns corresponding to conductive tracks are arranged. These tracks consist of conductive wires. These two layers of conductive tracks thus form a matrix network of conducting wires.

When one wants to know if a line has been put in contact with a column, determining a contact point on the sensor 1, the electrical characteristics - voltage, capacitance or inductance - are measured at the terminals of each node of the matrix. The device makes it possible to acquire the data on the whole of the sensor 1 with a sampling frequency of the order of 100 Hz, by implementing the sensor 1 and the control circuit integrated in the main processor 24.

The main processor 24 executes the program for associating the sensor data with graphic objects that are displayed on the display screen 22 for manipulation. The second element making it possible to produce the display is the display screen 22. This screen comprises an array of display pixels, as represented for example in FIG. 9. These pixels are provided with three zones respectively red, green and blue, to make a display that is multicolored. A backlighting device furthermore makes it possible to illuminate the screen from below, by passing through the sensor and its networks of conductive tracks, in order to allow the display.

FIGS. 2 to 4 show a multicontact two-dimensional tactile sensor in accordance with the prior art.

In FIG. 2, the sensor 1 comprises an upper layer 2 provided with conductive tracks 3 organized in lines, as well as a lower layer 4 provided with conductive tracks organized in columns. The arrangement of these tracks in rows and columns makes it possible to have a matrix of cells, each cell being formed by the intersection of a conductive track 3 of the upper layer 2 and of a conductive track 5 of the lower layer. 4. These conductive tracks consist of ITO (indium tin oxide), which is a translucent conductive material.

In FIG. 3, when a finger 9 (or any other pointing means) presses on the sensor 1, when the columns 5 are fed, the contact zone 10 generated by the finger modifies the electrical properties of the lines 3 disposed just below. When the columns 5 are electrically powered and an electrical characteristic (voltage, capacitance or inductance) is measured at the level of the lines 3, a value for this characteristic is detected at the row / column intersection of the matrix. which is greater than a threshold value of contact.

The operation of such a sensor is more specifically described in patent document EP 1 719 047.

The sensor 1 also comprises, in its upper part, a layer of PET (polyethylene terephthalate) 6. Under this layer of PET 6, is the top layer 2. The layer 2 of ITO thus forms a structuring of the PET layer 6 and corresponds to lines of the sensor 1.

The sensor 1 further comprises, in its lower part, a glass layer 7. Above this layer, is the lower layer 4. The ITO layer 4 thus forms a structuring of the glass layer and corresponds to columns of the sensor 1.

It is understood that the notions of lines and columns are relative notions and can be interchanged according to the orientation of the sensor. By convention only, it will be considered that the top layer of ITO 2 forms the lines of a matrix sensor, but it is clear to those skilled in the art that it could also form the columns. In this case, the lower layer of ITO 4 would form the lines of this matrix sensor. In both cases, the direction of the ITO tracks 3 forming the upper layer 2 is perpendicular to the direction of the ITO tracks 5 forming the lower layer 4.

Spacer spacers 8 are disposed between the upper 2 and lower 4 layers so as to isolate these layers from one another. More specifically, the spacers 8 are arranged to be connected to the lower layer 4. They are positioned at the level of the areas where the tracks of the upper layer 2 and those of the lower layer 4 are not likely to form intersections defining detection cells.

Those skilled in the art will understand that it is possible, however, to connect the spacer spacers 8 to the upper layer 2, or some spacers to the lower layer 4 and others to the upper layer 2, without departing from the scope of the present invention.

Those skilled in the art will understand that in the case of a projected capacitive sensor, the spacers may be replaced by a uniform intermediate layer.

In FIG. 4, in accordance with the prior art in this field, the lines 3 of conductive tracks (on the upper layer 2) and the columns 5 of conductive tracks 30 (on the lower layer 4) are perfectly linear, ie their edges. are linear, each along its axis respectively upper X and lower Y.

As mentioned above, in the absence of electrical contact, the conductive tracks are separated by air. However, the index variations within the sensor induce a phenomenon of spatial optical interference between the two networks of conductive tracks. These interferences between the conductive tracks of the sensor 1 thus cause the appearance of a Moiré effect at the pixel array of the screen 22.

FIG. 4b shows a multicontact sensor with tracks arranged in diamond. The rows and columns of this sensor are arranged in diamond patterns to break the parallelism of the conductive tracks with the pixels of the display. This pattern nevertheless enhances the electrical resistance of the lines and columns of the sensor, which disturbs the electrical measurements on the sensor.

Figures 5 and 6 illustrate a first embodiment of the invention for solving the Moiré effect problem.

For this, the edge of each of the conductive tracks (the columns 5 in Figure 5A, lines 3 in Figure 5B) is inclined over its entire length, by means of a suitable beveling. The angle of inclination is greater than the limiting angle of appearance of the Moiré effect on the pixel array of the screen 22, which the skilled person can calculate according to the pixel parameters of the screen.

In this embodiment, to be certain that the angle will be greater than the limited angle along the entire length of the track 3 or 5, the inclination of the edge is repeated periodically, in a pattern 15. This pattern 15 can be of polygonal shape, with an inclination of each edge greater than the limit angle. Those skilled in the art will note that an elliptical shape of this pattern is not satisfactory in order to solve the invention, since such a shape gives rise to a variation of the inclination up to a zero angle, hence less than limit angle.

In this embodiment, the pattern 15 is triangular in shape, so as to generate a conductive track whose edges are sawtooth.

When the arrays 2 (of lines 3) and 4 (of columns 5) are superimposed, as shown in FIG. 6A, potential contact zones 11 are formed, by superposition of lines and columns. The edges of each zone 11 are sawtoothed. This arrangement is then to be compared with the conventional arrangement of FIG. 6B (or FIG. 4), in which the edges of the tracks are linear.

Figures 7 and 8 illustrate a second embodiment of the invention to solve the Moiré effect problem.

For this, the edge of each of the conductive tracks (the columns 5 in Figure 7A, the lines 3 in Figure 7B) is inclined over its entire length, by means of a suitable beveling. As in the first embodiment, the angle of inclination is greater than the limiting angle of appearance of the Moiré effect on the pixel array of the screen 22.

In this embodiment, to be certain that the angle will be greater than the limited angle along the entire length of the track 3 or 5, the inclination of the edge is repeated periodically, in a pattern 16. This pattern 16 is of polygonal shape (see more precisely in Figure 7C), so as to generate a conductive track whose edges are crenellated.

When the networks 2 (lines 3) and 4 (of columns 5) are superimposed, as shown in FIG. 8, potential contact zones 11 are formed by superimposing the rows and columns. The edges of each zone 11 are crenellated.

The two embodiments above are given as examples. It is clear that those skilled in the art will adapt these examples to make tracks whose edges are inclined in order to solve the aforementioned technical problem. In particular, it can make non-periodic or non-polygonal patterns.

Finally, FIG. 9 illustrates the use of a multicontact tactile sensor according to the first embodiment of the invention in order to produce a display.

The pixel array of the display part (the screen 22) is superimposed thereon with the network of conductive tracks of the capture part (the sensor 1). Each pixel 17 of dimension d u of the screen comprises a plurality of red 12, green 13 and blue 14 filters.

As illustrated in this figure, a conductive track is superimposed on the pixels 17, in a triangular pattern. The inclination formed by this pattern 15, with respect to the dimensions of the pixel array 17, is such that Moiré effects are not observed at the screen 22.

The previously described embodiments of the present invention are given by way of examples and are in no way limiting. It is understood that the skilled person is able to realize different variants of the invention without departing from the scope of the patent.

Claims (1)

CLAIMS1 multicontact two-dimensional tactile sensor (1) comprising an upper layer (2) provided with conductive longitudinal elements (3) organized along an upper axis (X) and a lower layer (4) provided with conductive longitudinal elements (5) organized according to a lower axis (Y) not parallel to the upper axis (X), characterized in that at least one of said longitudinal elements (3,5) has on at least part of its edge a non-zero inclination relative to its axis (X, Y), the angle of said inclination being calculated so that the minimum width of the non-zero inclined conductive longitudinal elements is comparable to the minimum width of the zero-tilt conductive longitudinal elements. 2 multicontact two-dimensional tactile sensor (1) according to claim 1, wherein the non-zero inclination on the edge of the longitudinal element (3,5) is achieved by means of a beveling of said element (3,5). The multicontact two-dimensional tactile sensor (1) according to claim 2, wherein the bevel is made in a pattern (15; 16). The multicontact two-dimensional tactile sensor (1) according to claim 3, wherein at least one pattern (15; 16) is a polygon. The multicontact two-dimensional tactile sensor (1) according to claim 3 or 4, wherein the pattern (15; 16) is a triangle. The multicontact two-dimensional tactile sensor (1) according to one of claims 3 to 5, wherein at least one pattern (15; 16) is periodic. 7 multicontact two-dimensional tactile sensor (1) according to one of the preceding claims, in which all the longitudinal elements (3,5) have on at least part of their edge a non-zero inclination with respect to their axis (X, Y). 8 multicontact two-dimensional tactile sensor (1) according to one of the preceding claims, wherein at least one of the longitudinal elements (3,5) has on the whole of its edge a non-zero inclination with respect to its axis (X, Y) .259. A multicontact two-dimensional tactile sensor (1) according to one of the preceding claims, wherein at least one of the longitudinal elements (3,5) is in the form of a conductive track made of a conductive oxide material transparent. 10. multicontact two-dimensional tactile sensor (1) according to one of the preceding claims, wherein at least one of the longitudinal elements (3,5) is in the form of a conductive wire. 11. multicontact two-dimensional touch sensor (1) according to one of the preceding claims, wherein the upper layer (2) and lower (4) are transparent. 12. A display (20) with a multicontact two-dimensional tactile sensor (1) according to one of the preceding claims. The display (20) according to claim 12, wherein the inclination of at least one pattern (15; 16) with respect to the axis (X, Y) of the corresponding longitudinal element (3,5), 20 in the (XY) plane defined by the upper (X) and lower (Y) axes, is greater than the Moiré effect threshold within said display. The display (20) according to claim 12 or 13, wherein the edge amplitude of at least one longitudinal member (3,5), induced by the inclination thereof, is preferably substantially equal to that of the cells formed by the intersection of two longitudinal elements (3,5) respectively of the upper layer (2) and the lower layer (4). 15. Display (20) according to one of claims 12 to 14, comprising means 30 for backlighting in the form of pixel matrix (11). The display (20) of claim 15, wherein the dimensions of at least one pattern (15; 16) are substantially equal to those of the pixels (11) of the backlighting means.