GB2292507A

GB2292507A - A method of processing information incribed on an electronic display screen

Info

Publication number: GB2292507A
Application number: GB9503670A
Authority: GB
Inventors: Haufai Harvey Wong
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 1994-02-25
Filing date: 1995-02-23
Publication date: 1996-02-21
Anticipated expiration: 2015-02-23
Also published as: KR950033861A; GB2292507B; JPH07248880A; GB9503670D0; CN1157955A

Description

1 2292507 A Method Of Processing Information Inscribed On An Electronic

Display Screen

Field of Invention

This invention relates generally to an electronic device having an electronic display screen, and more particularly to a method of processing information inscribed and detected on the surface of the display screen by a 10 detection panel.

Background of the Invention

Electronic devices with display screens are known in the art. The display screens of such electronic devices show a variety of visual information using a fluorescent screen or a panelized array of light emitting diodes or liquid crystals. The visual information displayed is obtained from various elements of an electronic device, such as a keyboard. A type of display screen that obtains information inputs from its surface has additional features that detect the inputs through the display screen. These additional features, as explained below, distinguish such a display screen from those that only display visual information.

Information inputs through the display screen can be accomplished using a detection panel that is generally coupled to, and disposed on, the screen's surface. Tbus, the display screen and the detection panel appear as one component. (Detection panels are well known in the art and include an electromagnetic field sensing panel or a physical pressure sensing panel.) Detecting such inputs will additionally require an electronic circuit (hereafter known as a detection panel circuit) that drives the detection panel and derives an output therefrom. The detection panel circuit is activated at regular time instances for detection, depending on a predetermined sampling frequency set by a control unit within the electronic device. These regular time instances is related to a time interval that sets the predetermined sampling frequency. For example, a sampling frequency of 120 Hertz provides 120 time instances over a time duration of one second. This is equivalent to 120 regular time intervals of 1/120 th of a second duration or about 8.33 milliseconds (one second divided by 120).

0 1 0 0 2 1 9 w a Upon obtaining the outputs from the detection panel circuit, representing information inputs, the electronic device will then convert such outputs to a data format for storage, typically within a data storage unit of the electronic device. The stored data is then extracted for processing, generally by a processing or control unit of the electronic device. Once processed, the data is then displayed at corresponding positions on the display screen to show the information that was inscribed.

An LCD screen panel comprised of a plurality of liquid crystals is widely used in such an electronic apparatus. Each liquid crystal is a discrete display element and referred to as a pixel. In addition, each pixel represents a point on the display screen in relation to orthogonal coordinates that allow a unique spatial identification of the point.

An example of an electronic device that obtains information inputs through an LCD screen in the method described above is commonly known as a 'pen and pad' device. Such a 'pen and pad' device typically includes a stylus-shaped inscribing apparatus serving as a tool to inscribe the information onto its detection panel. Inscriptions, such as handwritten characters or graphic symbols, are typical inputs for these 'pen and pad' devices. The inscriptions are detected by monitoring the effects of the inscribing apparatus on the surface of the detection panel. In addition, tracking the physical movement of the inscribing apparatus, as it forms the inscriptions on the detection panel, allows the electronic device to detect and display the inscriptions back onto the display screen.

The 'pen and pad' device described above requires the user to physically perform the actions of writing, much like writing on paper with a pen or pencil. Different users, as is well known, write in different ways. Some users write in a plain form (forming one letter or character at a time), while others write in a cursive form Ooining the letters of a word in a continuos manner). Whatever the manner of writing adopted by a user, the inscribing apparatus and the display screen operate very much like writing on a piece of paper, hence, the term 'pen and pad'.

In the above background description of a 'pen and pad' device, the electronic device scans the surface of the sensitve panel at the maximum predetermined sampling frequency. However, scanning at the maximum predetermined sampling frequency is not necessary when a user inscribes slowly such that the control unit will then be processing an inscribed point repeatedly, especially when a user pauses at the inscribed point.

What is needed, then, is a method to allow the control unit to effectively 3 adjust the processing of inscribed information in a way that corresponds to the manner of inscribing. This is an important consideration in the design of such 'pen and pad' devices where reducing power consumption is an important consideration.

Summary of the Invention lle invention embodies a method for processing information inscribed on a detection panel that is disposed upon a display screen of an electronic device. It should be noted that such a display screen includes the detection panel for sensing insriptions on the display screen. lhe information may be inscribed using an inscribing apparatus, such as a stylus shaped pen.

Besides the display screen, the electronic device also includes a data storage unit and a control unit. lle control unit sets a predetermined sampling frequency that the electronic device uses to scan the surface of the display screen for information inputs. Detection of the movement of the inscribing apparatus, when inscribing the information, provides at least one inscribed physical location as an information input. The one inscribed physical location is then converted to a two number co-ordinate that corresponds to the physical location of a pixel of the display screen. After the conversion, the one inscribed physical location is displayed.

Following the above, the processing of the one inscribed physical location determines whether to change, or maintain, the predetermined sampling frequency for scanning the surface of the display screen. The determination to change or maintain the predetermined sampling frequency is based on a criterion that compares a space interval between two inscribed physical locations to one pixel width. The space interval is determined using the two number co-ordinates that uniquely identifies the two inscribed physical locations. For a first inscribed physical location, there is no space interval, but the embodiment takes into account this condition as well.

The embodiment of the invention then continues to process each additional inscribed physical location after the electronic device detects, displays, and stores each additional inscribed physical location. The processing of each additional inscribed physical location follows the steps of the embodiment according to the criterion. Again, the control unit determines whether to change, or maintain, the predetermined sampling frequency depending on the results of the processing. The method ends 4 when the electronic device does not detect any additional inscribed physical location.

Brief Description of the Drawings

FIG. 1 is a block diagram of an electronic device with a display screen in accordance with the present invention.

FIG. 2 is a flow diagram of the procedure for displaying inscribed information on a display screen in accordance with the present invention.

Description of a Preferred Embodiment

In accordance with the present invention, a block diagram of such an electronic device (11) is shown in FIG. 1. The electronic device (11) includes a display screen (12), a control unit (13), and a data storage unit (14). These elements of the electronic device operate to provide a visual representation of information to the display screen (12). Also illustrated in FIG. 1 is an inscribing apparatus (15) that inscribes information on the surface of the display screen (12). However, it is recognized by a person skilled in the art that, typically, any stylusshaped apparatus andlor method can be used in accordance with the invention. For instance, a user may inscribe the information using his finger. Together, the electronic device (11) and the inscribing apparatus (15) represent a "pen and pad" device (10).

FIG. 2 is a flow diagram detailing a preferred embodiment of this disclosure. (As this embodiment discloses a method to process the inscribed information for displaying, the method of detecting the inscribed information will not be discussed.) In this embodiment, a point is first displayed on an otherwise blank display screen and stored (202) in the data storage unit (14). This point corresponds to one inscribed physical location (or a pixel of the LCD screen) on the display screen (12) where the inscribing apparatus (15) is first detected. In addition to displaying the point (202), the relative position of the one inscribed physical location to two planarly, perpendicular axes is stored as a two number X and Y co-ordinate and represented as {X 1, Y 11. Here, (X 1, Y 1} corresponds to the position of a pixel in an LCD panel. In this embodiment, it does not matter which is the X axis or the Y axis. The standard adopted here, and well known in the art, is that the first number is an X axis co-ordinate and the second, a Y axis co-ordinate.

Following the display and storage of the point as one inscribed physical location (202), the control unit (13) then determines whether the one inscribed physical location is a first inscribed physical location (203) detected on the display screen (12). When determined as such, the control unit (13) then initializes three control factors (204) that will deternline how this first inscribed physical location is subsequently processed. Otherwise, when the one inscribed physical location is not the first inscribed physical location, the initialization does not occur, and what happens under this condition will be discussed later.

lle three control factors initialized (204) by the control unit (13) are as follows. First, the control unit (13) sets a factor that selects a predetermined sampling frequency for the electronic device (11) to scan the surface of the display screen (12). In this embodiment, the factor determining the selection of the predetermined sampling frequency is given the term DELAYINDEX". 7he DELAYINDEX is a numerical integer accorded to a setting for a time interval that corresponds to a specific predetermined sampling frequency. The range of integer values in the DELAYINDEX, from minimum to maximum, depends on the total possible number of different sampling frequencies that the control unit (13) is designed to scan at. Setting the DELAYINDEX to a maximum value will correspond to a minimum time interval between the time instances of scanning the surface of the display screen (12), and therefore, to a maximum predetermined sampling frequency. Second, the control unit (13) initializes an internal status setting to indicate this inscribed physical location as a new point.

Initializing a new point allows the control unit (13) to process the new point in a different manner compared to a point that is part of the subsequent physical movement of the inscribing apparatus (15) and detected after the new point. (The difference in processing a subsequent point is explained later.) 'llie third initialization involves storing the detected physical location (X 1, Y 1) as {X2, Y2}. This storing step is done in preparation for the subsequent processing of the first inscribed physical location.

With the three control factors initialized (204), the first inscribed physical location (X 1, Y 1) can now be processed further. In the next step of processing, the co-ordinates of the physical location {X 1, Y 1} is 6 compared to the initialized value I X2, Y2) (205). Since this is the first inscribed physical location detected, f X I, Y I) has the same value as I X2 Y2), and therefore in the next step (208), the control unit (13) checks whether the setting of the DELAYINDEX is minimized. As earlier initialized in step (204), the DELAYINDEX was maximized and not minimized, and therefore the control unit (13) will decrease the DELAYINDEX by a factor of I in step (209). With this decrement of the DELAYINDEX, the control unit (13) then sets the predetermined sampling frequency for the detection of any additional inscribed physical location according to the DELAYINDEX just determined (211).

Following the decrement of the DELAYINDEX, the control unit (13) has now determined a new time interval that specifies a new predetermined sampling frequency for scanning the surface of the display screen (12). In addition to the new predetermined sampling frequency, the control unit (13 also stores (XI, Y1 I as M, Y2) (212). in preparation for any subsequent processing. Finally, for the first inscribed physical location, the control unit (13) determines whether to end (214) or continue the processing of any additional inscribed physical location (202) at step (213) which determines whether an additional inscribed physical location is detected or not.

In the embodiment as described above, the electronic device (11) processes only the first inscribed physical location. However, in the use of the electronic device (11), a plurality of additional inscribed physical locations, detected after the first inscribed physical locations, is possible. In accordance with the present invention, this possibility will now be discussed.

For a next inscribed physical location detected, the electronic device (11) will repeat the step (202) and again display and store the next inscribed physical location as I X I, Y fl. After determining that this next inscribed physical location is not the first inscribed physical location, the control unit (13) will skip the initialization step (204) and proceed to compare (205) the next inscribed physical location to the first inscribed physical location that was previously stored as I X2, Y2) in step (212). Under this condition, whether (XI, YJ I equals (X2, Y2) depends on the speed of inscribing the information.

When I X I, Y I) equals I X2, Y2), then the subsequent processing continues to the step (208). This occurs when the inscribing apparatus (15) has not moved to a different physical location (a different pixel location compared to the first inscribed physical location) when the control unit (13) 7 next scans the display screen (12) after the lapse of the time interval determined by the predetermined sampling frequency. The control unit (13) then determines the setting of the DELAYMEX (208), and decrements or maintains the DELAYINDEX depending on the current value of the DELAYINDEX. After decrernenting or maintaining the DELAYINDEX, the processing goes to the subsequent processing steps as for the first inscribed physical location.

When {X 1, Y 1} does not equal 1 X2, Y2L then the subsequent processing continues to a step of determining a space interval, in co- ordinate terms, between X 1 and X 2 (206). Here, the control unit (13) calculates the magnitude of a co-ordinate difference between X I and X 2, and compares the result to a factor of '1' (206). Ilie factor of '1' equates to one pixel and the co-ordinate difference is based on the X- axis co-ordinates of 1 X 1, Y 1} and 1 X 2, Y2}. Mathematically, the coordinate difference is represented as IXI - X21. Such a comparison relates directly to the coordinates of the pixel locations on the LCD screen. Hence, this step (206) determines whether the space interval between X I and X 2 is greater than one pixel width. When IX 1 - X21 is greater than one pixel width, the control unit (13) sets the DELAYINDEX to a maximum value corresponding to the maximum predetermined sampling frequency. The assumption here is that X I and X 2 are far apart from each other because the user is inscribing at a speed that requires the electronic device (11) to detect the inscribing at the maximum predetermined sampling frequency. Otherwise, for a slow predetern-fined sampling frequency, a subsequent inscribed physical location may not be detected at one or more pixels when the speed of the inscribing exceeds more than one pixel width in one time interval of the slow predetern-fined sampling frequency. When IXI - X21 is less than or equal to one pixel width, the control unit (13) continues to a next step where a space interval between Yl and Y2 is now determined in order to compare with one pixel width (207).

For this next step (207), the processing is similar to that for the Xaxis co-ordinates. Here, the control unit (13) will also set the DELAYINDEX to the maximum value (210) when the magnitude IY I - Y21 is greater than one pixel width (210), with the same assumption as above for the X-axis co- ordinates. However, when the magnitude IY 1 - Y21 is less than or equal to one, the control unit (13) maintains the current value of the DELAYINDEX.

At this stage in the processing, the control unit (13) has completed 8 processing the next inscribed physical location following the first inscribed physical location. The control unit (13) then stores this next inscribed physical location {X 1, Y 1} as 1 X2, Y2} to prepare for the subsequent processing of each additional inscribed physical location that is detected. When no other additional inscribed physical location is detected, the processing ends (214). Otherwise, the control unit (13) starts processing each additional inscribed physical location at the step of displaying and storing one inscribed physical location (202).

In accordance with the present invention, the method disclosed above applies to any number of inscribed physical locations beginning with, and continuing from, the detection of the first inscribed physical location. When the inscribing apparatus (15) is not detected at any physical location on the display screen (12) (for example, when the inscribing apparatus (15) leaves the surface of the display screen), the method ends. However, as in writing on any other type of surfaces, inscriptions (such as words or graphic symbols) are not always written continuosly without pausing or without physical gaps at which the inscriptions do not appear on the display screen. Ilie method in this disclosure accounts for such pauses (for example, a stationary point) by lowering the current value of the predetermined sampling frequency. For such a stationary point, {Xl, Y1) equals (X2, Y2}, and the stationary point is sampled with a lower predetermined sampling frequency at each subsequent time instance of the predetermined sampling frequency. The predetermined sampling frequency is continuously lowered for the stationary point until the inscribing apparatus (15) is physically moved on (or physically removed from) the surface of the display screen (12). When the stationary point is detected at a lowest predetermined sampling frequency, the electronic apparatus (12) is then continuously detecting the stationary point at a lowest possible power consumption. As for physical gaps, the method accounts for such physical gaps by checking at step (213) for any additional inscribed physical location. In other words, each time the inscribing apparatus (15) is physically removed from the surface of the display screen (12), an additional inscribed physical location will not be detected at the next time instance of the predetermined sampling frequency and processing will end at step (214). An inscribed physical location following a physical gap is then detected and processed from the beginning at step (202). Such an inscribed physical location is then further processed as a first inscribed physical location following step (203). Hence, the electronic apparatus (12) 9 0.6 distinguishes a pause or a new point and processes these accordingly. Tberefore, though the method disclosed applies to inscribing information continuosly, the different circumstances encountered when inscribing information (such as the physical gaps between words and the pausing at a 5 point) are also considered.

Relating further to the pauses and physical gaps mentioned above, users also do not inscribe at a constant speed. In accordance with the present invention, the method disclosed above also accounts for users who inscribe at a plurality of different speeds. Users who inscribe slowly do not require the maximum predetermined sampling frequency to scan their information inputs. Hence, the predetermined sampling frequency is reduced to a level that will still allow the detection of such slowly inscribed information.

In existing methods of processing inscribed information on the display screen (12) of the electronic device (11), the predetermined sampling frequency is typically set at a maximum predetermined level. Scanning the display screen (12) at the maximum predetermined sampling frequency causes the control unit (13) to process the detected information without accounting for the speed of the inscribing. As in any display screen (12) or electronic device (11), scanning for information inputs consumes power.

Ibus, within a fixed time period, scanning more times (higher sampling frequency) consumes more power than scanning lesser times (lower sampling frequency). Hence, in accordance with the present invention, the above embodiment discloses a novel method of processing inscribed information according to the speed at which the information is inscribed. In addition, the above embodiment conserves power compared to an existing display screen (12), especially when the maximum predetermined sampling frequency is unnecessary. Such a condition applies when, for example, a user places the inscribing apparatus (15) on the display screen (12) and hesitates before inscribing any additional information. Under this condition, setting a lower predetermined sampling frequency effectively lowers the power consumed.

Claims

We claim:

Claims 1. In an electronic device that includes a display screen, a data storage unit, and a control unit, wherein information inscribed on the display screen is detected at a predetermined sampling frequency for one inscribed physical location, displayed on the display screen, and stored in the data storage unit for processing by the control unit, a method of processing the information inscribed on the display screen comprising the steps of:

a) comparing, by the control unit, the one inscribed physical location to a next inscribed physical location, wherein the next inscribed physical location is detected and displayed after a time interval determined by the predetermined sampling frequency; b) determining, by the control unit, a space interval between the one inscribed physical location and the next inscribed physical location; c) changing, by the control unit, the predetermined sampling frequency, based on the space interval, when the control unit has determined that the predetermined sampling frequency needs to be changed; and d) repeating, by the control unit, the steps (a), (b), and (c) above for each additional inscribed physical location that is detected, displayed, and stored when the information continues to be inscribed on the display screen following the next inscribed physical location.
2. The method of claim 1 wherein the information comprises information inscribed in a continuos movement by an inscribing apparatus.
3. The method of claim 1 wherein step (a) comprises comparing the one inscribed physical location and the next inscribed physical location after the step of converting, by the control unit, the one inscribed physical location to a first co-ordinate and the next inscribed physical location to a second co- ordinate.
4. The method of claim 3 wherein the first co-ordinate and the second coordinate are relative to two planarly, perpendicular axes on the display screen.
5. The method of claim 1 wherein step (b) further includes the step of comparing the space interval between the one inscribed physical location and the next inscribed physical location to a predetermined criterion.
6. The method of claim 1 wherein step (c) further includes the step of keeping the predetermined sampling frequency unchanged when it is determined not to change the predetermined sampling frequency.
7. The method of claim 1 wherein step (d) further includes the step of storing the next inscribed physical location as the one inscribed physical location and each additional inscribed physical location as the next inscribed physical location before repeating the steps (a), (b), and (c).
8. An electronic device for displaying inscribed information comprising: a) a display screen; b) an inscribing apparatus for defining inscriptions on the display screen; 20 c) means for the inscriptions on the display screen to be detected at a predetermined sampling frequency; and d) means for varying the predetermined sampling frequency.