Secondary rear surface touch sensor for handheld devices

Abstract

A second touch area (314) is provided on the rear side of the mobile phone (300) in a position such that the index finger of one hand can provide input when the mobile phone (300) is being held in one hand. Various types of input provided using the second touch area (314) do not require use of the other hand. This allows the mobile phone (300) to be used in a single-handed operation in many situations.

Description

Technical Field

[0001] The present invention relates to an input method for a handheld device. Background Art

[0002] Mobile phones have experienced tremendous growth over the past few years. Many feature large touchscreens on their fronts. These large touchscreens allow for very complex and sophisticated input methods, such as virtual keyboards and multi-touch. However, another general trend among mobile phones is for them to become increasingly larger. This makes them more difficult to hold, and attempting to operate a phone one-handed becomes extremely challenging. Consequently, to operate a mobile phone, users need to use both hands: one to hold the phone and one to provide input. This can be cumbersome in many situations. Summary of the Invention

[0003] A second touch area is provided on the back side of the mobile phone in a position where the index finger of one hand can provide input when the mobile phone is being held in one hand. Various types of input can be provided using this second touch area without using the other hand. This allows the mobile phone to be used with one hand in many situations. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 is a block diagram of an example mobile phone.

[0005] Figure 2 is a block diagram of a capacitive touch system.

[0006] Figure 3 is a rear view of a mobile phone illustrating example locations of example capacitive touch sensors.

[0007] Figure 4 yes Figure 3 Top view of a capacitive touch sensor.

[0008] Figure 5 It is a display Figure 3 A view of an inner view of a back cover of a mobile phone.

[0009] Figure 6A yes Figure 3 Cross-sectional view of the back cover of a mobile phone.

[0010] Figure 6B yes Figure 6A A cross-sectional view of a mobile phone with a first exemplary case attached to the mobile phone.

[0011] Figure 6C yes Figure 6A A cross-sectional view of a mobile phone with a second exemplary case attached to the mobile phone.

[0012] Figure 6D yes Figure 6C A rear view of a mobile phone and a second exemplary case.

[0013] Figure 6E yes Figure 6A A cross-sectional view of a mobile phone with a third example case attached to the mobile phone.

[0014] Figure 7 is a rear view of a mobile phone illustrating an example location of a second example capacitive touch sensor that allows right- and left-hand operation.

[0015] Figure 8 is a rear view of a mobile phone illustrating an example location of a third example capacitive touch sensor.

[0016] Figure 9 is a rear view of a mobile phone illustrating an example location of a fourth example capacitive touch sensor that enables right-hand and left-hand operation.

[0017] Figure 10 This is a flowchart of the operation to calibrate the rear touch sensor. DETAILED DESCRIPTION

[0018] Figure 1A block diagram of an exemplary mobile phone 100 is illustrated. Mobile phone 100 may include a phone system-on-a-chip (SOC) 102. Phone SOC 102 includes multiple processors 104, a large amount of RAM 106, and a Long Term Evolution (LTE) modem 108. This is a very simplified illustration of an exemplary phone SOC, and many other variations with some of the components described (e.g., an off-board modem) may be used. A power subsystem 110 provides power to phone SOC 102. A battery 112 provides power to power subsystem 110. A USB port 114 is provided for external wired communication with phone SOC 102. A large amount of dynamic RAM (DRAM) 116 is provided as primary storage, with internal RAM 106 serving more as operating memory for the various processors 104. A display 118 is connected to phone SOC 102 to provide a primary front view of mobile phone 100. A front touch sensor system 120 is connected to phone SOC 102 and overlaid on display 118, with a separate processor operating the touch sensor. Speaker 122 provides audio output for mobile phone 100, while microphone 124 provides audio input to phone SOC 102. A subscriber identity module (SIM) 126 is connected to phone SOC 102 to provide personalization information. A radio frequency (RF) section 128 is connected to phone SOC 102 to perform the actual wireless transmissions used in the mobile phone. Flash memory or non-volatile memory is connected to phone SOC 102 to store programs executed by processor 104. Optionally, a series of buttons 130 are connected to phone SOC 102, such as a power button, volume buttons, etc. A rear touch sensor system 132 is connected to phone SOC 102 to provide a rear touch system on mobile phone 100.

[0019] Figure 2FIG2 is a block diagram of the rear touch sensor system 132. A touch sensor controller 200 is the computational portion of the rear touch sensor system 132. A processor or CPU 202 is provided within the touch sensor controller 200 to perform the necessary computations. A nonvolatile memory 204, which stores programs executed by the CPU 202, is connected to the CPU 202. A RAM 206 is also connected to the CPU 202 for use as working memory. An analog-to-digital converter (ADC) section 208 is provided to allow the rear touch sensor system 132 to perform analog operations. Input / output (I / O) ports 210 are provided and connected to the CPU 202 to allow the CPU 202 to interface with the phone SOC 102. Most relevant to this discussion, a capacitive touch interface 212 is connected to the CPU 202 to perform analog operations for capacitive touch sensing. A rear touch sensor area 214 is connected to the capacitive touch interface 212. In normal operation, the touch sensor controller 200 provides the position of the user's index finger on or relative to the back touch sensor area 214 to the phone SoC 102 to allow control of the mobile phone 100. The MSP430FR2633 capacitive touch sensing mixed signal microcontroller from Texas Instruments is an example of a back touch sensor controller 200.

[0020] Figure 3 The diagram illustrates a rear view of an exemplary mobile phone 300. The mobile phone 300 has a top 304, a bottom 306, a right side 308 (when viewed from the front), and a left side 310. An opening 302 is provided in the back cover or plate 301 to allow for access to a camera and associated optical components. Other openings may be provided, such as for a power button or fingerprint sensor. Shown in dashed lines is a rear touch sensor 314 of the mobile phone 300. The rear touch sensor 314 is shown in phantom and is located behind the back cover 301 of the mobile phone 300. Observe again Figure 3 If the mobile phone 300 is held in an individual's right hand with the top 304 of the mobile phone 300 in an upward direction, the back touch sensor 314 is positioned so that the user's index finger can easily swipe over the back touch sensor 314. The arcuate shape of the back touch sensor 314 conforms to the path of the user's fingertip. This allows the user to use the secondary input when holding the phone in one hand without using the other hand.

[0021] Figure 4The backside touch sensor 314 is illustrated in greater detail. A printed circuit board 402 has a series of electrodes or traces 404, 406, 408, 410, 412, 414, 416, 418, and 420 on the surface of the printed circuit board 402. Traces 406-420 are configured in a mutual-capacitive touch sensing configuration in the illustrated example. A self-capacitive sensing configuration may also be utilized. A flexible cable 422 having a series of contacts 424 is connected to the printed circuit board 402 to allow for electrical connection between the touch-sensor controller 200 and the printed circuit board 402.

[0022] Figure 5 3 is a view of the back cover 301 of the mobile phone 300 , the view being from the inside of the mobile phone 300 so that the capacitive sensor PCB 402 and cable 422 can be easily viewed when mounted to the back cover 301 .

[0023] Figure 6A Illustrated is a cross-sectional view of a back cover 301 with a printed circuit board 402, with various traces 406 to 420 attached to the back cover 301 as illustrated. In this arrangement, the traces 406 to 420 are very close to the outside or back of the mobile phone 300 and therefore operate at a smaller gain level due to the higher sensitivity of the configuration. Figure 6B In FIG. 4 , a case 600 has been added to the mobile phone 300, where the case 600 covers the back cover 301 to extensively protect the mobile phone 300. As shown, this increases the distance between the user's finger and the traces 406 to 420. Depending on the thickness and electrical properties of the protective material of the case 600, the sensitivity of the back touch sensor system 132 may vary. Figure 6A The changes may occur, for example, by increasing the conversion gain or count compared to the uncased example. Figure 6C An alternative sleeve 602 is shown. The sleeve 602 includes an external raised portion or curved finger guide 604, such as Figure 6D As shown in FIG. 6 , the outer raised portion or curved finger guide 604 generally indicates or outlines the rear touch sensor 314 to allow a user to easily align their index finger with the rear touch sensor 314 . Figure 6E 6. In case 606, instead of the external ridges 604 used with case 602, case 606 has an opening or cutout area 608 that generally indicates or conforms to the back touch sensor 314. This allows for both registration of a user's index finger and increased sensitivity or decreased gain because the cover thickness and material now do not block the capacitive sensor.

[0024] Figure 7The illustration shows a mobile phone 700 having a capacitive touch sensor area 702 formed generally as a 180° arc rather than a 90° arc of the rear touch sensor 314. This allows the touch sensor area to be used with either left or right hand operation, thus reducing the number of phones that need to be developed, produced, and stocked.

[0025] Figure 8 The diagram illustrates an example phone 800 in which the arcuate rear touch sensor 314 is replaced by an areal or area sensor 802. By using the area sensor 802, two-dimensional movement of a user's index finger can be easily detected compared to the curved one-dimensional operation of the rear touch sensor 314. This allows for improved user control, although not as precise as using a front touch system. Figure 9 Illustrated is a mobile phone 900 having an area sensor 902 suitable for left-handed and right-handed operation.

[0026] Figure 10 Flowchart 1000 is a flowchart of operations for calibrating the rear touch sensor system 132. As discussed above, in some examples, the mobile phone may have a case installed to protect the mobile phone. The protective material of the case and the proximity (or lack thereof) of the case back cover may alter the capacitive properties of the rear touch sensor system 132, necessitating recalibration. In step 1002, a user interface (UI) is displayed to provide user instructions for the calibration process. In step 1004, the user is instructed to place their finger over the rear touch sensor. In step 1006, the user is instructed to begin moving their finger along the rear touch sensor. In step 1008, initial adjustments are made to touch sensitivity parameters. These parameters include conversion gain and conversion count. In step 1010, a determination is made as to whether satisfactory movement of the user's finger is detected. If not, in step 1012, a determination is made as to whether the parameter adjustments have achieved maximum sensitivity. If maximum sensitivity has been achieved, in step 1014, an error message is displayed to the user indicating that calibration has failed. If the maximum sensitivity has not been reached, the operation returns to step 1008 for the next adjustment of the sensitivity parameters.

[0027] If satisfactory movement is detected in step 1010, the sensitivity parameters are stored for continued use in step 1016. In step 1018, the user is informed that they can stop finger movement and calibration is complete.

[0028] The illustrated capacitive touch sensor configuration is an example, and other specific designs may use variations. For example, self-capacitive or mutual-capacitive configurations may be used. Different configurations and numbers of PCB traces may be used. Alternative sensor areas and shapes may be used. For example, instead of using the illustrated 90° arc, a larger or smaller arc may be used, where the arc starts or stops at different locations.

[0029] This description uses the movement of a user's finger as an example touch action. Other touch actions may also be recognized, such as double-clicks or multi-finger gestures. For example, a double-click of a user's finger on the rear touch sensor may be used to answer a phone call or as a response to a request provided on the front screen. This description also uses the index finger as an example finger for interacting with the touch sensor. Other fingers or the thumb (considered as the finger for this application) may also be used, especially in instances where the only action allowed is a click rather than a full motion.

[0030] This description is based on information from Texas Instruments and CapTIvate TM A more complete description will be provided with a microcontroller using touch sensing technology, but other touch sensing microcontrollers and technologies may be used. Additionally, a touch sensor with an embedded processor may be used, but one of the processors in the handheld device provides processing functionality instead of the embedded processor.

[0031] Although a mobile phone is used as an example handheld device, the backside touch sensor can be used on other handheld devices.

[0032] Modifications may be made to the described embodiments and other embodiments are possible within the scope of the claims.

Claims

1. A handheld device that is connected to the back side of a mobile phone, the handheld device comprising: a back cover having a top, a bottom, left and right sides, and outer and inner sides; a touch sensor attached to the inside of the back cover, the touch sensor being located on the back cover in a location that is operated by a user's finger when the handheld device is held, wherein the touch sensor has an arcuate shape to allow for one-dimensional finger placement; and A touch sensor controller is coupled to the touch sensor and configured to determine a position of a user's finger relative to the touch sensor and provide the position of the user's finger relative to the touch sensor to a system-on-a-chip SoC of the mobile phone. 2 . The handheld device of claim 1 , wherein the touch sensor is a capacitive touch sensor and the touch sensor controller is a capacitive touch sensor controller.

3. The handheld device of claim 1, wherein the arcuate shape is configured for left-handed operation or right-handed operation. 4 . The handheld device according to claim 1 , further comprising a case covering the back cover of the handheld device and overlying the touch sensor.

5. The handheld device of claim 4, wherein the casing includes an external ridge that generally conforms to the arcuate shape of the touch sensor.

6. The handheld device of claim 4, wherein the casing includes an opening that generally conforms to the arcuate shape of the touch sensor.

7. The handheld device of claim 4, wherein the sensitivity of the touch sensor controller changes when operated with the case.

8. The handheld device of claim 1, wherein the touch sensor has an area shape configured for left-hand operation or right-hand operation.

9. A case for use with a handheld device, the handheld device being connected to the back side of a mobile phone and comprising: a back cover having a top, a bottom, left and right sides, and outside and inside sides; and a touch sensor attached to the inside side of the back cover, the touch sensor being located on the back cover in a location operable by a user's index finger when holding the handheld device, wherein the touch sensor has an arcuate shape, and the position of the user's finger relative to the touch sensor is provided to a system-on-a-chip (SoC) of the mobile phone, the case comprising: A protective material covers the back cover of the handheld device and overlies the touch sensor, the protective material including an indication of the arcuate shape of the touch sensor, the indication generally conforming to the arcuate shape of the touch sensor.

10. The case of claim 9, wherein the indicator is an external protrusion.

11. The case of claim 9, wherein the indication is an opening.

12. A mobile phone comprising: a display forming the front face of the mobile phone; a front touch sensor that overlies the display and provides an indication of the position of a user's finger; a mobile phone system-on-a-chip (SoC) comprising at least one processor and coupled to the display and the front touch sensor; a back cover having a top, a bottom, left and right sides, and outer and inner sides; a rear touch sensor attached to the inner side of the rear cover, the rear touch sensor being located on the rear cover in a location operated by a user's finger, the rear touch sensor having an arcuate shape to allow for one-dimensional finger placement; and A backside touch sensor controller is coupled to the backside touch sensor and the SoC and is configured to determine a position of a user's finger relative to the backside touch sensor and provide the position of the user's finger relative to the backside touch sensor to the SoC.

13. The mobile phone of claim 12, wherein the rear touch sensor is a capacitive touch sensor and the rear touch sensor controller is a capacitive touch sensor controller.

14. The mobile phone of claim 12, wherein the arcuate shape is configured for left-hand operation or right-hand operation.

15. The mobile phone of claim 12, wherein the sensitivity of the rear touch sensor controller is configured to change when operated with a case covering the rear cover and overlying the rear touch sensor. 16 . The mobile phone of claim 12 , wherein the rear touch sensor has an area shape configured for left-hand operation or right-hand operation.

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