GB2381499A

GB2381499A - :Detecting a degree of manual interaction with a manually operable key

Info

Publication number: GB2381499A
Application number: GB0125983A
Authority: GB
Inventors: David Lee Sandbach; Christopher Chapman
Original assignee: Electrotextiles Co Ltd
Current assignee: Electrotextiles Co Ltd
Priority date: 2001-10-30
Filing date: 2001-10-30
Publication date: 2003-05-07
Also published as: GB0125983D0

Abstract

A degree of manual interaction with a manually operable key is detected. An input signal (801,802 Fig 8) is produced in relation to a degree of manual interaction. A processing procedure is initiated if the input signal exceeds a first threshold level (T1). The value of the input signal is examined after a time interval (t2-t1). The examined value is compared against the threshold value (T2) to identify a first or second degree of interaction. The strength of the input signal is controlled by the pressure applied to the key. A soft push that is greater than the first threshold level generates one output signal whereas a harder push that is grater than the second threshold level generates a different output signal. The various output signals result in different character displays on the keyboard even though only one key has been depressed.

Description

Detecting a Degree of Manual Interaction with a Manually Operable Key Field of the Invention The present invention relates to detecting the degree of manual interaction with a manually operable key. In particular, the present invention relates to processing an input signal that has been produced in relation to a degree of manual interaction.

Background to the Invention A manually operable key may be considered as any device that is responsive to a manually operation in order to convey information to a data processing environment. In particular, this includes keys of the type that are combined into an array so as to form a keyboard, either a full keyboard, such as that used for a personal computer, or a keyboard of reduced size such as that used for a mobile telephone.

The present invention is concerned with manually operable keys that produce an input signal in relation to a degree of manual interaction. Thus, some keys are entirely digital in construction and may represent a first condition, to the effect that the key has not been pressed or may represent a second condition to the effect that the key has been pressed. Such keys are not within the scope of the present invention. However, it must be appreciated that some keys, although producing a digital output, are more analogue in nature and initially produce a varying signal which must be applied to some sort of comparator in order to determine whether a threshold has been exceeded representing the condition to the effect that the key has been pressed. Such keys do fall within the scope of the present invention.

The present invention is concerned with the detection of a degree of manual interaction in order to derive additional data from this degree of mechanical interaction. In particular, the invention is directed towards an environment in which a hard key press may be distinguished from a soft key press. In alternative embodiments, several threshold levels could be exploited, thereby identifying a very soft, a soft, a moderate, a hard or a very hard key press for example. However, it is appreciated that the number of threshold levels is restricted by a user's ability to effect these levels, therefore a preferred embodiment is directed towards the detection of three conditions, namely, that the key has not been pressed, that the key has been pressed softly or that the key has received a hard press.

Depending upon the nature of the key mechanics, the actual cause of an input signal may vary. Thus, for example, the extent of an input signal may be responsive to force, pressure, area or speed of application for example.

Each of these may vary in degree, along with other mechanical conditions and all are to be considered as being examples of the manual interaction varying in degree. Thus, a manual interaction could be measured by effectively being responsive to pressure or the extent of the manual interaction may be derived by an actual evaluation of key press velocity. The essential point is that under a first condition the interaction falls below a threshold and under a second harder interaction the input signal level lies above the threshold.

A known approach to identifying the degree of a manual interaction is to wait until the first threshold level has been exceeded and then continue to sample the input signal so as to determine whether it exceeds a second threshold level. A problem with this approach is that the sampling rate may be insufficiently low and therefore it is possible for a high level peak to be

missed. Altematively, if the sampling rate is increased, a greater burden is placed on available processing capabilities and eventually an upper constraint will exist, possibly enforced by electrical or mechanical limitations, such as capacitive effects or inertia related effects.

Brief Summary of the Invention According to an aspect of the present invention, there is provided a method of detecting a degree of manual interaction with a manually operable key, wherein an input signal is produced in relation to the degree of manual interaction; and a processing procedure is initiated if said input signal exceeds a first threshold level ; said processing procedure comprising the steps of examining the value of said input signal after an interval; and comparing said examined value against a second threshold level to identify a first degree of interaction or to identify a second degree of interaction.

Thus, the present invention does not continue to monitor the input signal to determine whether it exceeds a second threshold level. As an altemative, after exceeding a first threshold level the processing procedure waits for a period of time such that the value of the input signal is examined again after this interval. The exact duration of this interval is not critical, provided that its duration remains substantially constant throughout the use of the device. Thus, the procedure is not waiting for the input signal to pass some predetermined level. In accordance with the present invention, the processing procedure determines to what extent the level has increased after a predetermined interval of time. Thus, this effectively involves a determination of rate of change of the input signal as an alternative to observing many individual signal samples in an attempt to identify an appropriate instant at which the signal exceeds a predetermined level.

In a preferred embodiment, a plurality of manually operable keys are arranged as a manually operable keyboard. Preferably, a key is defined as a portion of a fabric position detector having conducting fabric layers separated by an insulating layer. In such a detector, the degree of manual interaction may be determined by measuring current.

According to a second aspect of the present invention, there is provided apparatus for detecting a degree of manual interaction with a manually operable key, wherein an input signal is produced in relation to a degree of manual interaction, comprising processing means configured to initiate a processing procedure if said input signal exceeds the first threshold, wherein the value of said input signal is examined after an interval and the examined value is compared against the second threshold level to identify a first degree of interaction or to identify a second degree of interaction.

Brief Description of the Several Views of the Drawings Figure 1 shows a fabric keyboard interfaced to a hand held computer.

Figure 2 shows two examples of an input signal being produced.

Figure 3a shows an example of a result of a soft key press and Figure 3b shows an example of the result of a hard key press; Figure 4 shows a schematic representation of the assembly shown in Figure 1.

Figure 5 shows an example of operations performed by a micro controller.

Figure 6 shows an example of a keyboard driver.

Figure 7 shows an alternative keyboard driver; and Figure 8 shows examples of Input signals generated by a hard key press by a soft key press.

Best Mode for Carrying Out the Invention Figure 1 A fabric keyboard 101 is interfaced to a hand held computer 102.

When not in use, the fabric keyboard 101 may be wrapped around the hand held computer 102 so as not to distract from the portability of the hand held computer 102. Thereafter, when a user wishes to enter data into the hand held computer 102, the keyboard is unwrapped and placed upon a flat surface. The hand held computer 102 may be supported by a stand or held by the user as shown in Figure 1. Thus, after supporting the hand held computer by right hand 103 it is possible for data to be entered by manual operation of the keyboard 101 by the left hand 104. Either hand could be used for either application or if the hand held computer 102 is supported by a stand, both hands may be used for data entry.

The keyboard 101 includes an array of manually operable keys, such as key 105. Application of the key causes fabric layers to be brought into contact thereby allowing electrical conductivity to occur between a first outer layer and a second outer layer through an appropriate inner separating layer. From a subsequent measurement of voltage gradients, it is possible to identify the x y location of a manual interaction and thereby identify the key that has been pressed. Furthermore, by measuring the degree of current flow, it is possible to identify the extent of the press. Thus, if a user hits a key softly, the degree of current flow is relatively low whereas if a user effects a hard key press the degree of current flow is relatively high.

A multiple fabric layer detector is described in the present applicants' co-pending European Patent Publication No 1 099 190.

The present invention uses a fabric construction to provide an array of keys in a keyboard. However, it should be appreciated that other fabrications of keyboards or individual keys may be employed provided that an input signal is produced that relates to the degree of the manual interaction. The user will consider the key press to be either hard or soft. The mechanics in turn will either respond to the force of the key press or the velocity of the key press etc. and one of these attributes, or a combination of these attributes, is then be used to produce the input signal.

The present embodiment shows a keyboard communicating with a hand held computer such as that manufactured under the trademark "Palm". However, in alternative configurations, other processing devices may be used, such as a personal computer, a mobile telephone or other dedicated processing apparatus.

Figure 2 Two examples of an input signal being produced in response to respective manual interactions are illustrated in Figure 2. Figure 2 plots input signal extent against time. An input signal produced in response to a relatively soft key press is illustrated at 201. Similarly, an input signal produced in response to a relatively hard key press is illustrated at 202. The system has been configured to have a first T1 threshold 203 and a second T2 threshold 204. The system monitors input signals to identify key press interactions that exceed threshold T1. Any input signal having a level below threshold T1 is considered merely to be background noise and is treated as representing the un-pressed state.

It is considered desirable to distinguish hard key presses, such as that represented by input signal 202 against soft key presses, such as that

represented by input signal 201. To do this, threshold T2 has been established. Thus, as shown in the example, input signal 201 does not exceed threshold T2 and therefore would be considered as a soft key press. Similarly, input signal 202 does exceed threshold level T2 and would therefore be considered a hard key press.

Figure 3a/Figure 3b Given the ability to distinguish between a soft key press and a hard key press, the different types of key press may be used to supply different types of data to an application running on the hand held computer. In the example shown in Figure 3a and Figure 3b, the hand held computer is running an application, such as a note pad, and is thereby recording alphanumeric characters in response to manual operation of the keys. In Figure 3a the word"elektex"has been written by pressing the E L E K T E X keys relatively softly. However, in Figure 3b the same keys have been pressed but this time they have been struck with more force. The system has identified these hard key presses, resulting in different information being supplied to the application; in particular, instead of the word being written in lower case letters, the same word has been written at 302 in upper case letters. Thus, a soft key press or a hard key press is being used to select lower case characters or upper case characters respectively. However, it should be appreciated that many other attributes could be controlled in response to detecting a soft key press or a hard key press.

Figure 4 The combination of a fabric keyboard with a hand held computer is shown schematically in Figure 4. Keyboard 101 includes fabric detector

planes 401 and an interface circuit 402, as described in the aforesaid European Patent Application. The hand held computer 102 executes programs read from its program memory. Users are interested in application programs such as application 403. Thus, an application program could take the form of a notepad, an address book, a diary or that of many other application programs written for the device.

Conventionally, hand held computers and similar devices

communicatie. : with input devices via their operating system. To effect ,,/" communication with alternative peripherals, the operating system is enhanced by means of appropriate drivers, such as keyboard driver 404.

The interface circuit 402 in combination with the keyboard driver 404 provide a means of communication from the planes 401 to the users' application program 403. The circuit 402 and the driver 404 each do a degree of the work and the actual share of the interface work may vary. The interface circuit 402 may be made more simple if the keyboard driver 404 is given more work to do, although this then places an additional overhead on the internal processor of the hand held computer.

In a preferred embodiment, the interface circuit 402 applies electrical signals to the conducting planes 401 and from this determines numerical values for the x y location of a mechanical interaction and a z value representing the extent of the interaction. This x, y, z data is then supplied to the keyboard driver 404 and the keyboard driver is responsible for converting this information into an identification of a particular key press along with an indication of the nature of the press; that is to say, did the device encounter a hard key press or a soft key press. This information is then encoded into a form appropriate for supplying to the application program 403. Thus, the application program 403 is unaware of the soft key

press/hard key press sensitivity of the device and is merely responsive to character information being supplied as if this information had been supplied via conventional means.

Figure 5 As described in the aforementioned European Patent Publication, interface circuit 402 preferably includes a micro-controller with appropriate program instructions. Program instructions required to implement the preferred embodiment of the present invention are illustrated in Figure 5.

Preferably, mechanisms are included for identifying a condition to the effect that the hand held device is in use. When not in use, being a portable device, it is preferable for all non-essential energy consuming components to be powered down, thereby conserving battery life. Thus, a mechanism may be included for powering up the device or, altematively, the device may respond to manual operation of a power button.

After start up, a first z value is fetched at step 501. At step 502 a question is asked as to whether the z value received at step 501 is greater than a threshold value T1. If the sample value is lower than the threshold value, the question asked at step 502 is answered in the negative.

Thereafter, after a short wait at step 503, control is returned to step 501. In the preferred embodiment, the interface circuit produces z values ranging from zero to two hundred and fifty-five and T1 is set equal to a value of twenty-five. Furthermore, in the preferred embodiment, the wait period at step 503 is set so as to produce a sampling rate of approximately one thousand samples per second.

If the question asked at step 502 is answered in the affirmative, to the effect that the z value is higher than the first threshold value, the

interface circuit 402 is instructed to perform a full measurement operation. This consists of getting an x value at step 504 followed by getting a y value at step 505. Thereafter, a second z value is obtained at step 506 and at step 507 a question is asked as to whether the second value is again higher than the first threshold value.

The generation of x and y values takes a finite period of time given that the detector surface itself exhibits capacitive effects. Consequently, there is a settling time before it is possible to obtain valid readings for the x and y locations. Consequently, this results in an interval of time elapsing between the question asked at step 502 being answered in the affirmative and the second z value being obtained at step 506. This interval is set in terms of a predetermined number of clock cycles considered appropriate in order to allow an appropriate duration for the settling to occur. Thus, the interval value is determined emperically and will vary with detector construction.

A question asked at step 507 checks that the level has been maintained above the first threshold. If the question asked at step 507 is answered in the negative, the procedure is effectively terminated and control is returned to step 501. However, if the question asked at step 507 is answered in the affirmative, to the effect that the second z reading was again higher than the first threshold value T1, this represents a valid key press. The program executed by the interface circuit, in the preferred embodiment, does not perform any additional processing such that the interface circuit does not itself determine which key has been pressed and it does not determine the extent to which the key has been pressed. However, it should be emphasised that in alternative embodiments more of the processing could be performed by the interface circuit. However in the

present preferred embodiment, this additional processing is performed by the keyboard driver 404.

Figure 6 The keyboard driver 404 is executed within the more sophisticated processing environment of the hand held computer when compared to the relatively modest capabilities of the interface circuit 402. Consequently, the keyboard driver must compete for resources with other user applications and system programs. At step 508, as illustrated in Figure 5, the interface circuit 402 sends data to the keyboard driver 404 by initially issuing an interrupt signal via the"HotSync"terminal of the hand held computer. Thus, the hand held computer is interrupted using the mechanism provided for establishing a HotSync with its host desktop computer. This results in the program counter of the hand held computer jumping to a specified interrupt location where, instead of executing its standard HotSync procedures, a question is first asked as to whether the interrupt represents a HotSync or, alternatively, represents the provision of data via the keyboard. If the latter is identified, this results in the program counter jumping to identify the location of the keyboard driver 404.

Thus, as shown in Figure 6, the keyboard driver 404 initially responds to an interrupt at step 601. Thereafter, at step 602, the x position data and the y position data are processed to determine which actual key has been pressed. This may be done, for example, by using a look up table.

At step 603 the character identified at step 602 is sent to the application 403. Thereafter, at step 604, a question is asked as to whether the z value received from the interface circuit 402 is greater than a second

threshold T2. In the preferred embodiment, this second threshold may be set to a value of one hundred.

If the question asked at step 604 is answered in the negative, to the effect that a soft key press had been made, control is returned to the application at step 606. However, if the question asked at step 604 is answered in the affirmative, to the effect that a hard key press was made, additional characters are supplied to the application at step 605.

I n order to implement the functionality described with respect Figures 3a and 3b, after striking the E key with a hard key press, the lower case"e" character would be supplied to the application at step 603. The question asked at step 604 would then be answered in the affirmative resulting in additional characters being supplied to the application at step 605. In this particular environment, this would consist of a back space character being sent, so as to erase the lower case"E"previously supplied, followed by an upper case"E"character. Thus, in this mode of operation, the hard key press action results in the soft key press event being supplied to the application, followed by characters that delete the previous operation followed by the new operation.

Figure 7 An alternative keyboard driver utility is shown in Figure 7.

At step 701, the driver responds to an interrupt whereafter at step 702 the x and y data are processed to identify the pressed key.

At step 703 a question is asked as to whether the supplied z value was greater than the second threshold value T2 and if answered in the affirmative, one or more characters are supplied to the application as controlled by process 704. These characters, such as upper case"E", are

appropriate to a hard key press.

If the question asked at step 703 is answered in the negative, to the effect that the interaction consisted of a soft key press, control is directed to step 705. At step 705 characters are sent that are appropriate to a soft key press. After the completion of step 704 or the completion of step 705, control is returned to step 706.

Under the keyboard driver illustrated in Figure 7, operation of the E key as a result of a hard key press would subsequently result in an upper case"E"character being supplied to the application under the control of step 704. Similarly a soft E key press would result in a lower case"e"being supplied to the application under the control of step 705.

Figure 8 Input signals generated by a hard key press and by a soft key press are illustrated in Figure 8. A first input signal 801 generated by a soft key press has been placed over a similar input signal 802 generated in response to a hard key press.

Over period 803, sampled values for input signals are below the first threshold T1 (twenty-five units in this example) therefore this is interpreted as the key not being pressed.

In both examples, the input signal goes above the first threshold T1 at 804. This is detected by the interface circuit 402 which, as previously described with respect to Figure 5, results in an x value being obtained at step 504, a y value being obtained at step 505 and then a further z value being obtained at step 506. For both key presses, the first z value was obtained at time T1. For both key presses, a finite interval elapses such that a further z measurement, for value z2 is made at time T2. For the soft key

press, the input signal has reached the value of fifty units and this is then recorded as the z2 value. For the hard key press after the interval, at time T2, the input signal has reached a value of one hundred and twenty units.

Thus, the first (soft) key press has resulted in a relatively slowly increasing curve over the interval T2-T1 and it is then considered to be a soft key press because the z2 value is below the T2 second threshold. Similarly, the second key press is interpreted as a hard key press, the gradient over interval T2-T1 is much steeper, because a value at T2 of one hundred and twenty is recorded which, being above the second threshold value T2 is considered as a hard key press.

In the embodiment, the interval T2 minus T1 is required in order for sufficient settling time to be provided for the x value and the y value to be calculated. In alternative embodiments, it is possible that this interval would not be required for other purposes. The interval period should remain relatively constant between measurements although its absolute value is not critical. Its absolute value should be chosen emperically in order to optimise operational characteristics.

Claims

1. A method of detecting a degree of manual interaction with a manually operable key, wherein an input signal is produced in relation to a degree of manual interaction; and a processing procedure is initiated if said input signal exceeds a first threshold level ; said processing procedure comprising the steps of examining the value of said input signal after an interval ; and comparing said examined value against a second threshold level to identify a first degree of interaction or to identify a second degree of interaction.

2. A method according to claim 1, wherein a plurality of manually operable keys are arranged as a manually operable keyboard.

3. A method according to claim 2, wherein key is defined as a portion of a fabric position detector having conducting fabric layers separated by an insulating layer.

4. A method according to claim 3, wherein said degree of manual interaction is determined by measuring current.

5. A method according to claim 3, wherein the duration of said interval is such as to allow electrical properties to settle.

6. A method according to claim 1, wherein said key is interfaced

to a processing device.

7. A method according to claim 6, wherein said processing device determines appropriate action for a detected degree of interaction.

8. A method according to claim 7, wherein said processing device is a hand held computer.

9. A method according to claim 8, wherein said key is interfaced to said hand held computer via a hot sync connection.

10. A method according to claim 9, wherein said hand held computer is arranged to determine the difference between a true hot sync operation and the reception of characters from a key.

11. Apparatus for detecting a degree of manual interaction with a manually operable key, wherein an input signal is produced in relation to a degree of manual interaction, comprising processing means configured to initiate a processing procedure if said input signal exceeds the first threshold, wherein the value of said input signal is examined after an interval and the examined value is compared against the second threshold level to identify a first degree of interaction or to identify a second degree of interaction.

12. Apparatus for detecting a degree of manual interaction according to claim 11, wherein a plurality of manually operable keys are arranged as a manually operable keyboard.

13. Apparatus according to claim 12, wherein a key is defined as a portion of a fabric position detector having conductive fabric layers separated by an insulating layer.

14. Apparatus according to claim 13, including current measuring means wherein said degree of manual interaction is determined by said current measuring means.

15. Apparatus according to claim 13, wherein the duration of said interval is such to allow electrical properties to settle.

16. Apparatus according to claim 11, wherein said key is interfaced to a processing device.

17. Apparatus according to claim 16, wherein said processing device determines appropriate action for a detector degree of interaction.

18. Apparatus according to claim 17, wherein said processing device is a hand-held computer.

19. Apparatus according to claim 18, wherein said key is interfaced to said hand-held computer via a HotSync connection.

20. Apparatus according to claim 19, wherein said hand-held computer is arranged to determine the difference between a true HotSynch operation and the reception of characters from a key.