TECHNICAL FIELD

The invention relates in general to the field of proximity sensing of objects, and more particularly, to capacitive proximity sensing of objects close to a mobile communication device.

BACKGROUND

Modern mobile communication devices, such as mobile phones, are usually fitted with a proximity sensor for detecting when an object is present in proximity to the device. The most common use of a proximity senor in a mobile phone is for detecting when the user is talking in the mobile phone, by detecting the proximity of the user's head in relation to the mobile phone, so that the background lighting and the touch sensitivity of the display may be turned off during the call.

The typical proximity sensor in a mobile phone is based on the emission of an optical signal (e.g. infrared light) and the detection of the reflected optical signal, and thus provide a binary signal indicative of whether or not an object is present in proximity to the mobile phone or not. However, these proximity sensors suffers from several drawbacks such as that they do not work well on persons having black hair, there are often problem with the production of the sensors due to tolerance problems, different performance is achieved based on the colour of the mobile phone, they are limited to a small area in the front which is an issue when going to larger handsets, and they may require an opening in a housing of the mobile phone in order to allow light to be emitted to the outside of the housing and reflected light to be received within the housing which can both be troublesome to achieve in some designs and is often not aesthetical pleasing to the eye. Thus, finding a way to improve the proximity sensing in a mobile phone and at the same time allow for grater design variation is therefore highly sought after.

SUMMARY OF THE INVENTION With the above description in mind, then, an aspect of the present invention is to provide a proximity sensing solution which seeks to mitigate, alleviate, or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination.

As will be described in more detail by the aspects of the present invention below, one way to provide such a proximity sensing solution in a mobile communication device such as a mobile phone is to provide at least an additional capacitive touch-sensitive area (i.e. additional to the capacitive touch-sensitive area of the display) adapted for proximity sensing, according to the aspects of the present invention below. A first aspect of the present invention relates to a method for proximity sensing in a mobile communication device comprising adapting a first capacitive touch-sensitive area for touch input, adapting at least a second capacitive touch-sensitive area for proximity sensing of an object in proximity to said mobile communication device, configuring a touch integrated circuit, coupled to said first capacitive touch-sensitive area and said at least a second capacitive touch-sensitive area, to acquire measurement signals indicative of an object in proximity to said first capacitive touch-sensitive area and said at least a second capacitive touch-sensitive area, configuring a processor to receive said measurement signals from said touch integrated circuit and to determine, from said measurement signals, if an object is in proximity to said first capacitive touch-sensitive area or to said at least a second capacitive touch-sensitive area or to both, and further configuring said processor to take an action in said mobile communication device depending on if said determined object is in proximity to said first capacitive touch-sensitive area or to said at least a second capacitive touch-sensitive area or to both.

The method wherein said at least a second capacitive touch-sensitive area may be spaced apart from said first capacitive touch-sensitive area.

The method wherein said at least a second capacitive touch-sensitive area may be a part of said first capacitive touch-sensitive area.

The method wherein said first capacitive touch-sensitive area may be a part of a touch-sensitive display in said mobile communication device.

The method wherein said at least a second capacitive touch-sensitive area may be any from the group consisting of a: zero-dimensional sensor, one-dimensional sensor and two-dimensional sensor.

The method wherein the method may further comprise placing said at least a second capacitive touch-sensitive area at a distance from a speaker opening in a casing of the mobile communication device, and adapting said at least a second capacitive touch-sensitive area, said touch integrated circuit and said processor for proximity sensing of a user's head when the user is in proximity to said speaker opening in said casing of said mobile communication device when engaging in a call.

A second aspect of the present invention relates to a system for proximity sensing in a mobile communication device comprising, a first capacitive touch-sensitive area adapted for touch input, at least a second capacitive touch-sensitive area adapted for proximity sensing of an object in proximity to said mobile communication device, a touch integrated circuit, coupled to said first capacitive touch-sensitive area and said at least a second capacitive touch-sensitive area, configured to acquire measurement signals indicative of an object in proximity to said first capacitive touch- sensitive area and said at least a second capacitive touch-sensitive area, a processor configured to receive said measurement signals from said touch integrated circuit and to determine, from said measurement signals, if an object is in proximity to said first capacitive touch-sensitive area or to said at least a second capacitive touch-sensitive area or to both and wherein said processor is further configured to take an action in said mobile communication device depending on if said determined object is in proximity to said first capacitive touch-sensitive area or to said at least a second capacitive touch-sensitive area or to both. The system wherein said at least a second capacitive touch-sensitive area may be spaced apart from said first capacitive touch-sensitive area.

The system wherein said at least a second capacitive touch-sensitive area may be a part of said first capacitive touch-sensitive area.

The system wherein said first capacitive touch-sensitive area may be a part of a touch-sensitive display in said mobile communication device.

The system wherein said at least a second capacitive touch-sensitive area may be any from the group consisting of a: zero-dimensional sensor, one-dimensional sensor and two-dimensional sensor.

The system may further comprise a speaker opening in a casing of said mobile communication device, wherein said at least a second capacitive touch-sensitive area is at a distance from, and wherein said at least a second capacitive touch-sensitive area, said touch integrated circuit and said processor are further adapted for proximity sensing of a user's head when the user is in proximity to said speaker opening in said casing of said mobile communication device when engaging in a call.

The different variations in each aspect above may be combined in any possible way forming different variants and embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects, features, and advantages of the present invention will appear from the following detailed description of some embodiments of the invention, wherein some embodiments of the invention will be described in more detail with reference to the accompanying drawings, in which: Fig. 1a shows a typical mobile phone having a proximity sensor according to prior art; and

Fig. 1b illustrates the different layers of a touch sensitive screen employed in a mobile phone; and

Fig. 2a shows a mobile phone with two capacitive sensors which may be used for touch input and for proximity sensing, according to an embodiment of the present invention; and

Fig. 2b shows a block diagram according to an embodiment of the present invention; and

Fig. 2c shows a flowchart of an embodiment of the present invention; and

Fig. 3 shows another mobile phone with two capacitive sensors which may be used for touch input and for proximity sensing, according to an embodiment of the present invention; and

Fig. 4a - 4d shows several examples of a mobile phone with several capacitive sensors which may be used for touch input and for proximity sensing, according to embodiments of the present invention; and Fig. 5 shows a mobile phone with a single capacitive sensors which may be used for touch input and for proximity sensing, according to an embodiment of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference signs refer to like elements throughout.

Embodiments of the present invention will be exemplified using a mobile communication device such as a mobile phone. However, it should be appreciated that the invention is as such equally applicable to electronic devices having a capacitive touch display which may, or may not have, wired- and/or wireless radio communication capabilities. Examples of such devices may for instance be any type of mobile phone, laptops (such as standard, ultra portables, netbooks, micro laptops, and pads), handheld computers, PDAs, pads, tablet computers, personal digital assistant, gaming devices, accessories to mobile phones, etc. However, for the sake of clarity and simplicity, the embodiments outlined in this specification are exemplified with and related to mobile phones only. Figure 1a shows a mobile phone 100 comprising a casing 101 , a touch-sensitive display 102, and navigation means 103 for operating the user-interface of the mobile phone. The navigation means 103 may be a set of buttons, a rotating input, a joystick, a touch pad, a multidirectional button, but can also be implemented using a touch-sensitive display, wherein the displayed items directly can be tapped by a user for selection and manipulation. The mobile phone 100 may also comprise other elements normally present in such a device, such as a keypad (not shown in this figure), a speaker 104, a microphone 105, a camera 106, a processor or processing means (not shown), a memory (not shown), an accelerometer (not shown), a vibration device (not shown), a device for global positioning, an infrared (IR) proximity sensor 107 (comprising a IR emitter and a IR sensor), an ambient light sensor 108, and other types of sensors. The IR proximity sensor 107 is used for detecting the proximity of an object, such as the head of the used when the user puts the mobile phone close to his or hers ear engaging in a call.

As previously mentioned above, the IR proximity sensor 107 suffers from a number of drawbacks such as that the performance of the IR proximity sensors 107 may change due to the hair colour of the user, a wide spread in tolerance due to manufacturing problems, the performance of the IR proximity sensor 107 may change due to the colour of the casing of the mobile phone, the IR proximity sensor 107 is limited to a small area in the front which is an issue when going to larger handsets, and the IR proximity sensor 107 may require an opening in the housing of the mobile phone in order to allow light to be emitted to the outside of the housing and reflected light to be received in through the housing which can both be troublesome to achieve in some designs and is often not aesthetical pleasing to the eye.

According to an embodiment of the present invention, a capacitive touch-sensitive display 102 may be used instead of an IR proximity sensor 107 to detect the proximity of an object in relation to the touch display 102.

Figure 1b shows a crude illustration of how a capacitive touch- sensitive display 120 may be implemented. The top layer 122, which in figure 1b is closest to the user ^' s finger 121 or any other kind of conductive stylus or other conductive material made to be used on a capacitive touch panel, may comprise a protective cover which may be made of glass, plastic or any other material that is see-through and which may protect the underlying layers from wear and tear. The top layer 122 may also comprise other type of bonding layers, anti-reflection layers, polarization layers, etc. The middle layer 123 comprises the capacitive sensor which may comprise the driving lines (Tx lines) and sensing lines (Rx lines) and a substrate (e.g. a glass or one or/several plastic substrate(s)) which the driving and sensing lines are fixed onto. The bottom layer 124 comprises the display module onto which the capacitive sensor 123 and the protective layer 122 are placed. Thus, the three layers, the top layer 122, the middle layer 123 and the bottom layer 124, makes out the capacitive touch-sensitive display 120. The middle layer 123 with the TX lines and the Rx lines do not have to be the same size as the top layer 122 or the bottom layer 124. In a variant the middle layer extend only under a portion of the top layer 122 and/or the bottom layer, and in another variant the middle layer may extend beyond the top layer 122 and/or the bottom layer 124.

To be able to detect the proximity of a body part of the user, such as a finger 121 , an ear or a head, the capacitive touch-sensitive display 120 must be connected to some kind of processing means 125,126 that is able to decode the signals coming from the capacitive touch-sensitive display 120, and capable of determine the position of the detected object in relation to the capacitive touch-sensitive display 120. Usually the signal processing means is comprised of an integrated circuit (IC) 125, hereinafter referred to as the touch IC 125, specially designed for handling the capacitive touch- sensitive display 120. The touch IC 125 may in its turn be connected to a processor 126, and/or some other signal processing means 126, in the mobile phone for signal processing of the data, relating to the detection of an object 121 in proximity to the capacitive touch-sensitive display 120, coming from the touch IC 125. Figure 2a illustrates a capacitive proximity sensing solution 200 according to an embodiment of the present invention. In figure 2a the mobile phone 201 has a large capacitive touch-sensitive display 202 acting as a regular touch-sensitive display. In addition to the large capacitive touch- sensing display 202 the mobile phone 201 has been fitted with an addition capacitive touch-sensitive area 203, in this case just below the mobile phone speaker 204. The capacitive touch-sensitive area 203 is separated from the capacitive touch-sensing display 202 area. In this way the capacitive touch- sensitive area 203 may be used as a proximity sensor capable of detecting the proximity of an object such as the user ^' s head. When the user puts the mobile phone, and thus the capacitive touch-sensitive area 203, close to the head when engaging in a call, the proximity of the user ^' s head is detected and actions like for example turning the screen off for saving power may be taken. Most touch IC ^' s have, in addition to the usual inputs for the touch- sensitive display, also support for connecting so called zero-dimensional buttons (hereinafter called 0D buttons). A 0D button detects the presence of an object in proximity and generates either a Ό', meaning no presence of an object is detected, or a , meaning presence of an object detected. Since only proximity of an object need to be detected the capacitive touch-sensitive area 203 may preferably by connected to a 0D button input on the touch IC, and in this way eliminate the need for additional touch IC for determining the proximity of an object to the capacitive touch-sensitive area 203. Further, by physically separating the capacitive touch-sensitive area 203 from the capacitive touch-sensing display area 202 it is possible to tune the capacitive touch-sensitive area 203 so that the correct sensitivity for proximity detection may be achieved. The tuning of the capacitive touch-sensitive area 203 may for instance involve adjusting the sensitivity gain (wherein adjusting the sensitivity gain is often equal to raising the sensitivity gain) so that an object a distance from the capacitive touch-sensitive area 203 may be detected and not only objects touching the capacitive touch-sensitive area 203. This is due to the fact that it is likely that the user ^' s head not always will touch the capacitive touch-sensitive area 203 when he or she is talking in the mobile phone, but it will instead be situated at a distance from (but in close proximity to) the capacitive touch-sensitive area 203. In a variant the capacitive touch-sensitive area 203 is not treated as a 0D button but is instead treated as an ordinary touch-sensitive area tuned for capacitive proximity sensing. In this way not only the states "object in close proximity" and "object not in close proximity" may be detected, but also the shape and size of the object in proximity may be determined giving vital clues in the determination of what kind of object it is. In this way the mobile phone may differentiate between objects such as fingers and the head, and thus accordingly take appropriate actions.

The benefits with using a capacitive proximity sensing solution as described above are many, for instance that the capacitive touch-sensitive area 203 may be scaled to any size, it may be designed into any shape or form, it will be more or less invisible and does not demand an opening in the in the casing to work and thus allowing for more design options, the performance is not sensitive to the colour of the mobile phone or the hair of the user, etc.

Figure 2b shows a block diagram of a system 210 for proximity sensing in a mobile communication 214 device according to an embodiment of the present invention. In the figure a first capacitive touch-sensitive area 212 is adapted for touch input, at least a second capacitive touch-sensitive area 213 is adapted for proximity sensing of an object 211 such as a finger or a user's head in proximity to the mobile communication device214. A touch integrated circuit (touch IC) 215 is coupled to the first capacitive touch- sensitive area 212 and the at least a second capacitive touch-sensitive area213 and configured to acquire measurement signals indicative of an object 211 in proximity to the first capacitive touch-sensitive area and the at least a second capacitive touch-sensitive area. A processor 216 is configured to receive the measurement signals from the touch integrated circuit 215 and to determine, from the measurement signals, if an object 21 is in proximity to the first capacitive touch-sensitive area 212 or to the at least a second capacitive touch-sensitive area 213 or to both 212, 213 and wherein the processor 216 is further configured to take an action in the mobile communication device 214 depending on if the determined object 211 is in proximity to the first capacitive touch-sensitive area 212 or to the at least a second capacitive touch-sensitive area 213 or to both 212,213. Figure 2c shows a flowchart 220 describing the main steps of an embodiment of the present invention. In the first step 221 a first capacitive touch-sensitive area is adapted for touch input followed by a second step 222 of adapting at least a second capacitive touch-sensitive area for proximity sensing of an object in proximity to the mobile communication device. The third step 223 entails configuring a touch integrated circuit, coupled to the first capacitive touch-sensitive area and the at least a second capacitive touch-sensitive area, to acquire measurement signals indicative of an object in proximity to the first capacitive touch-sensitive area and the at least a second capacitive touch-sensitive area, and in the fourth step 224 the processor is configured to receive the measurement signals from the touch integrated circuit and to determine, from the measurement signals, if an object is in proximity to the first capacitive touch-sensitive area or to the at least a second capacitive touch-sensitive area or to both. The final step in the method the the processor is configured to take an action in the mobile communication device depending on if the determined object is in proximity to the first capacitive touch-sensitive area or to the at least a second capacitive touch-sensitive area or to both.

Figure 3 show a variant of the capacitive proximity sensing solution 300 according to the present invention. In figure 3 the mobile phone 301 has a large capacitive touch-sensing display 302 acting as a regular touch-sensitive display, and capacitive touch-sensitive area 303 acting as the proximity sensor. This variant shows the flexibility (especially the design flexibility) of using a capacitive touch-sensitive area as a proximity sensor in that the mobile phone speaker 304 may be placed right in the middle of the touch-sensitive area 303. In this way the proximity sensor is optimally placed for detecting the user ^' s head and in particular the user ^' s ear since the user tend to place the ear on or very close to the speaker when engaging in a call.

Figure 4a to 4d will describe different variations on how capacitive touch-sensitive areas may be used and implemented in a mobile phone. Figure 4a show a capacitive proximity sensing solution 400 according to the present invention. In figure 4a the mobile phone 401 has a large capacitive touch-sensing display 402 acting as a regular touch-sensitive display, and two capacitive touch-sensitive areas 403,404, one on each side of the speaker 405, acting as two (or one, but divided in two) proximity sensors. By adding an additional capacitive touch-sensitive area acting as a 0D button it is, for example, possible to eliminate false readings, for instance like when a user ^' s finger accidently touches the capacitive touch-sensitive area 303 in figure 3 and thus turning off the display by mistake. By having two capacitive touch-sensitive areas 403,404 the processing means may be configured by software to only turn off the display when both areas are detecting the proximity of an object. Another variant is if both capacitive touch-sensitive areas 403,404 are treated as regular touch-sensitive areas and not 0D buttons, then the signal processing means may also be able to determine the type and shape of the object in proximity by performing signal processing on the signals coming from the two capacitive touch-sensitive areas 403,404.

Figure 4b shows a variant, according to the present invention, of the capacitive proximity sensing solution 400 shown and discussed in figure 4a. In figure 4b the mobile phone 401 has a large capacitive touch-sensing display 402 acting as a regular touch-sensitive display, and two capacitive touch-sensitive areas 404,406 on top of each other acting as two (or one, but divided in two) proximity sensors. In this variant the speaker 405 may be placed in the capacitive touch-sensitive area 406 as shown in the figure, allowing for more flexible designs. One example of how the implementation in figure 4b could work is for example if a finger is dragged from the top of the mobile phone casing 401 downwards over the top proximity sensor 406, the touch IC will first determine that an object is close to the proximity sensors and switch off the touch-sensitive display 402. If the finger continues downward over and past the second proximity sensor 403 and onto the top of the touch-sensitive display 402, the touch IC may then turn on the touch-sensitive display 402 again since the user might want to use it. Thus the proximity senor solution may anticipate the actions a user want to take. The same analysis by the touch IC may be performed in the variation shown in figure 4a, but with the difference that the finger only may move over one of the two sensors and down onto the touch-sensitive display 402.

Figure 4c shows another variant, according to the present invention, of the capacitive proximity sensing solutions 400 shown and discussed in figure 4a and figure 4b. In figure 4c the mobile phone 401 has a large capacitive touch-sensing display 402 acting as a regular touch-sensitive display, and several capacitive touch-sensitive areas 403,404,405,406 acting as one (spread over several capacitive touch-sensitive areas) or as several proximity sensors. In the figure, several capacitive touch-sensitive areas are placed both side by side 403,404, on top of each other 404,406 and in several columns 407, as to form a matrix with capacitive touch-sensitive areas acting as one or several proximity sensors. Also, in this variant the speaker 405 may be placed in the capacitive touch-sensitive area as shown in the figure. By having multiple proximity sensors it is, for instance, possible to detect and even track the movement of the object in proximity over (or on) the mobile phone surface of where the proximity sensor is located. By tracking the movement of the object in proximity it will be, to some extent, possible to anticipate the movement and take appropriate actions.

The capacitive touch-sensitive areas does not have to be placed in a matrix formation as shown in figure 4c, but could be placed in any type of pattern and also the capacitive touch-sensitive areas may be made in any shape wanted.

Figure 4d shows yet another variant, according to the present invention, of the capacitive proximity sensing solutions 400 shown and discussed in figure 4a to 4c. In figure 4d the mobile phone 401 has a large capacitive touch-sensing display 402 acting as a regular touch-sensitive display, and several capacitive touch-sensitive areas 403,404,406,407,408, 409,410 placed around the touch-sensing display 402 acting as one or several proximity sensors. Also, in this variant the speaker 405 may be placed in the capacitive touch-sensitive area as well as the microphone 11 may be placed in a capacitive touch-sensitive area as shown in the figure. In this way it will be possible to detect and track objects, such as the user's hand and fingers, over a larger casing area when the user touches and handles the mobile phone. The variants shown in figure 4a to 4dmay, but not necessarily, be implemented using more than one touch IC in the mobile phone or with some kind of multiplexing unit if only one touch IC is used. If two or more touch ICs are used, the touch ICs may communicate with each other to

Figure 5 shows an additional variant of the capacitive proximity sensing solution 500 according to the present invention. In figure 5 the mobile phone 501 has a large capacitive touch-sensing display 502 acting as a regular touch-sensitive display. However, a portion of the capacitive touch- sensing display 502 is configured to be a capacitive touch-sensitive area 503 acting as a proximity sensor. In this variant only one touch-sensor 502,503 is used but with a portion or part, in this case surrounding the speaker 504, is configured to be used as a capacitive proximity sensor. The border between the two types of sensors 502,503 is indicated with a dotted line 505 in figure 5. In this case there is no physical difference between the two areas 502,503, and the different functionalities between the areas may instead be defined in the software analyzing the touch sensitivity. This variant allows for a very 71375

15 flexible solution where the user via the software (or rather via an application in the mobile phone) may define the sensitivity, size and shape of the touch- sensitive area himself. The capacitive touch-sensitive areas are set in the firmware of the touch IC. This enables the touch IC to be able to do its calculations without enabling the host (in this case the mobile phone) itself. In the embodiment and the variations thereof presented above the capacitive touch-sensitive areas has been placed close to the speaker on the mobile phone. However, in other variants the capacitive touch-sensitive areas may instead be placed close to the microphone in the lower part of the mobile phone casing detecting the proximity of the cheek and chin instead of the head, hair, and ear of the user. In yet other variant one or more capacitive touch-sensitive areas may be placed in the vicinity of the speaker and one or more capacitive touch-sensitive areas may be placed in the vicinity of the microphone, and thus allowing for a more advanced proximity sensing solution.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" "comprising," "includes" and/or "including" when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The foregoing has described the principles, preferred embodiments and modes of operation of the present invention. However, the invention should be regarded as illustrative rather than restrictive, and not as being limited to the particular embodiments discussed above. The different features of the various embodiments of the invention can be combined in other combinations than those explicitly described. It should therefore be appreciated that variations may be made in those embodiments by those skilled in the art without departing from the scope of the present invention as defined by the following claims.