JP2015203915A - Information processing apparatus, display device, display control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the discomfort of a user in predicting a position of a pointer.SOLUTION: An information processing apparatus 1 includes: acquisition means 20 for acquiring coordinates of a pointer periodically detected; calculation means 12 for calculating a speed vector and an acceleration vector of the pointer, on the basis of the coordinates detected at three or more times, out of the acquired coordinates; prediction means 13 which predicts coordinates p(n+1) to be detected at a time (n+1), with respect to coordinates p(n) detected at a time n, by use of the calculated speed vector v and acceleration vector (a), in a formula p(n+1)=p(n)+αv+βa; and drawing control means 14 which generates an image including a point corresponding to the predicted coordinates p(n+1).

Description

  The present invention relates to a technique for displaying an image corresponding to a position designated by an indicator, and more particularly to a technique for predicting the position of the indicator.

  In a tablet terminal, a technique is known in which a user indicates a position on a screen with an indicator such as a pen or a finger, and the tablet terminal displays a line corresponding to the indicated locus. In order to improve the followability of a drawn line, a technique for predicting a position indicated by an indicator is known. Patent Document 1 discloses a technique for predicting a next position using a movement amount and acceleration of a touched position in a display device having a touch panel.

JP 2010-97552 A

  In the technique described in Patent Document 1, there is a case where the prediction is wrong and the user feels uncomfortable.

  On the other hand, this invention provides the technique which reduces the discomfort given to a user, when estimating the position of a pointer.

The present invention provides an acquisition means for acquiring the coordinates of the indicator detected periodically, and the speed of the indicator based on coordinates detected at three or more different times among the coordinates acquired by the acquisition means. A coordinate at time (n + 1) with respect to a coordinate p (n) detected at time n using a calculation means for calculating a vector and an acceleration vector, and a velocity vector v and acceleration vector a calculated by the calculation means. prediction means for predicting p (n + 1) by the following equation (1);
p (n + 1) = p (n) + αv + βa (1)
(Where α and β are coefficients)
There is provided an information processing apparatus having a drawing control means for generating an image including a point corresponding to the coordinate p (n + 1) predicted by the prediction means.
According to this information processing apparatus, it is possible to reduce a sense of discomfort given to the user.

The image may be a line corresponding to the locus of the indicator, and the prediction means may change the values of the coefficients α and β according to the thickness of the line.
According to this information processing apparatus, it is possible to reduce a sense of discomfort given to the user as compared with the case where the coefficients α and β are constant regardless of the thickness of the line.

The predicting means may decrease the values of the coefficients α and β when the line thickness is b2 (where b2> b1) than when the line thickness is b1. .
According to this information processing apparatus, it is possible to reduce a sense of discomfort given to the user as compared with the case where the coefficients α and β are constant regardless of the thickness of the line.

The calculation means uses a weighted average using a weighting coefficient according to the time at which the coordinates are detected based on the coordinates detected at four or more different times among the coordinates acquired by the acquisition means. The velocity vector and acceleration vector of the indicator may be calculated.
According to this information processing apparatus, the speed and acceleration can be predicted more accurately.

When the coordinates detected at time n1 among the coordinates acquired by the acquisition means are the latest, the weighting coefficient corresponding to time n1 is higher than the weighting coefficient corresponding to time n2 (where n1> n2). It can be large.
According to this information processing apparatus, it is possible to predict the speed and acceleration more accurately by giving weight to the latest information.

Further, the present invention provides a display means, a detection means for detecting coordinates indicated by a pointer on the surface of the display means, and coordinates detected at three or more different times among the coordinates detected by the detection means. Based on the calculation means for calculating the velocity vector and acceleration vector of the indicator, and the coordinate p (n) detected at time n using the velocity vector v and acceleration vector a calculated by the calculation means. Prediction means for predicting the coordinate p (n + 1) at time (n + 1) by the following equation (1):
p (n + 1) = p (n) + αv + βa (1)
(Where α and β are coefficients)
There is provided a display device having drawing control means for generating an image including a point corresponding to the coordinate p (n + 1) predicted by the prediction means.
According to this display device, the uncomfortable feeling given to the user can be reduced.

The display device includes storage means, generation means for generating line segment image data based on coordinates detected at three or more different times by the detection means, and image data generated by the generation means. When the coordinates are detected at three or more different times by the detection means since the display on the display means was updated last time, an update command for updating the display on the display means is output. Output means, and output means for outputting a signal for causing the display means to display an image corresponding to the image data stored in the storage unit in response to the update command, and the prediction means, Of the coordinates detected at the three or more times, a coordinate next to the coordinates detected at the latest time may be predicted.
According to this information processing apparatus, it is possible to reduce discomfort given to the user while suppressing display delay.

Furthermore, the present invention provides a step of obtaining the coordinates of the indicator detected periodically, and the velocity vector of the indicator based on the coordinates detected at three or more different times among the obtained coordinates. The step of calculating the acceleration vector, and using the calculated velocity vector v and acceleration vector a, the coordinate p (n + 1) at time (n + 1) is next to the coordinate p (n) detected at time n. Predicting by equation (1);
p (n + 1) = p (n) + αv + βa (1)
(Where α and β are coefficients)
And a step of generating an image including a point corresponding to the predicted coordinate p (n + 1).
According to this display control method, the uncomfortable feeling given to the user can be reduced.

Furthermore, the present invention provides the computer with the step of acquiring the coordinates of the indicator detected periodically, and the coordinates of the indicator based on the coordinates detected at three or more different times among the acquired coordinates. A step of calculating a velocity vector and an acceleration vector, and a coordinate p (n + 1) at time (n + 1) with respect to a coordinate p (n) detected at time n using the calculated velocity vector v and acceleration vector a. ) By the following equation (1):
p (n + 1) = p (n) + αv + βa (1)
(Where α and β are coefficients)
A program for executing a step of generating an image including a point corresponding to the predicted coordinate p (n + 1) is provided.
According to this program, the uncomfortable feeling given to the user can be reduced.

The figure which shows the function structure of the information processing apparatus 1 which concerns on one Embodiment. 2 is a diagram illustrating a hardware configuration of the information processing apparatus 1. FIG. 2 is a diagram showing a software configuration of the information processing apparatus 1. FIG. The flowchart which shows the drawing process of a handwritten line. The flowchart which shows the detail of the prediction process of a coordinate. The figure which illustrates the predicted coordinates. 4 is a diagram illustrating transition of an image displayed by the information processing apparatus 1. FIG. 4 is a diagram illustrating transition of an image displayed by the information processing apparatus 1. FIG.

1. Configuration FIG. 1 is a diagram illustrating a functional configuration of an information processing apparatus 1 according to an embodiment. The information processing device 1 is a display device having a display unit that displays an image of a line indicating a locus of a position designated by an indicator, and is a so-called tablet terminal. The position of the indicator is periodically (periodically) detected, and a line is drawn using information on the detected position. Since the line is drawn using the detected position information, a time lag occurs between the actual position of the indicator and the drawn line. In order to compensate for this time lag, the information processing apparatus 1 predicts the position of the indicator. As the indicator, for example, a stylus (pen) or a finger of the user of the display device is used.

The information processing apparatus 1 includes a display unit 10, a detection unit 11, a calculation unit 12, a prediction unit 13, a drawing control unit 14, a storage unit 15, a generation unit 16, a storage control unit 17, and an output unit. 18, an output unit 19, and an acquisition unit 20. The display means 10 displays an image. The detection means 11 detects the coordinates indicated by the indicator on the surface of the display means 10. The acquisition unit 20 acquires the coordinates detected by the detection unit 11. The calculation means 12 calculates the velocity vector v and acceleration vector a of the pointer movement. At least the acceleration vector a is calculated based on coordinates detected at three or more different times among the coordinates detected by the detection means 11. The prediction means 13 uses the velocity vector v and the acceleration vector a calculated by the calculation means 12 with respect to the coordinate p (n) detected at the time n, and then calculates the coordinate p (n + 1) at the time (n + 1). Prediction is based on equation (1)
p (n + 1) = p (n) + αv + βa (1)
Note that α and β are coefficients indicating weights of velocity and acceleration, respectively. The drawing control unit 14 causes the display unit 10 to display an image including a point corresponding to the coordinate p (n + 1) predicted by the prediction unit 13.

  The storage unit 15 stores image data to be drawn. The generation unit 16 generates line segment image data based on the coordinates detected by the detection unit 11 at three or more different times. The storage control unit 17 stores the image data generated by the generation unit 16 in the storage unit 15. The output unit 18 outputs an update command for updating the display of the display unit 10 when coordinates are detected at three or more different times by the detection unit 11 since the display of the display unit 10 was updated last time. The output means 19 outputs a signal for causing the display means 10 to display an image corresponding to the image data stored in the storage means 15 in response to the update command. Moreover, the prediction means 13 predicts the coordinate next to the coordinate detected at the latest time among the coordinates detected at three or more times.

  FIG. 2 is a diagram illustrating a hardware configuration of the information processing apparatus 1. The information processing apparatus 1 includes a display unit 101, a CPU 102, a RAM 103, a storage device 104, a frame buffer 105, a drive unit 106, a display controller 107, and a digitizer 108.

  The display unit 101 includes an electro-optical panel for displaying an image. In this example, the electro-optical panel is a dot matrix type panel, and has a plurality of pixels arranged in a matrix in the row direction and the column direction. Each pixel has an electro-optic element. As the electro-optic element, a memory-type display element that can maintain display without supplying power is used. For example, the display unit 101 is a microcapsule type EPD (Electrophoretic Display).

  The CPU 102 is a device that controls another hardware configuration of the information processing apparatus 1. The RAM 103 is a storage device that functions as a work area when the CPU 102 executes a program. The storage device 104 is a nonvolatile storage device that stores data and programs. The frame buffer 105 is a storage device that stores image data to be displayed on the display unit 101.

  The driving unit 106 is a device that drives the display unit 101, and includes a scanning line driving circuit and a data line driving circuit (both not shown). The scan line driver circuit selects a pixel group to which data is written from the plurality of pixels. The data line driving circuit writes data to the selected pixel group. The display controller 107 controls the drive unit 106 so as to write the data read from the frame buffer 105 to the pixels.

  The digitizer 108 detects the position indicated by the indicator. In this example, the information processing apparatus 1 is an apparatus having a so-called touch screen, and the digitizer 108 has a planar sensor provided on the surface of the display unit 101. As this sensor, for example, an electromagnetic induction type or a capacitance type is used.

  The information processing apparatus 1 includes a sensor (an inclination sensor, an acceleration sensor, a temperature sensor, a brightness sensor, etc.), an input device (eg, a button, a keypad, etc.), and a communication device (eg, a wireless communication device) (all of them). (Not shown).

  FIG. 3 is a diagram illustrating a software configuration of the information processing apparatus 1. In FIG. 3, related hardware configurations are also shown. The information processing apparatus 1 includes an OS (Operating System) 200, a graphic system 210, and an application 220.

  The OS 200 is a program for performing basic processing such as file processing and hardware control. The OS 200 includes a digitizer driver 201 and a display driver 202. The digitizer driver 201 is a program for driving the digitizer 108. The display driver 202 is a program for controlling reading / writing of data to / from the frame buffer 105. The graphic system 210 is a program for controlling image drawing. The application 220 is a program for causing a user to execute a process of drawing an image corresponding to a locus traced on the surface of the display unit 101 using an indicator.

  The display unit 101 and the drive unit 106 are an example of the display unit 10. The digitizer 108 is an example of the detection unit 11. The CPU 102 executing the application 220 is an example of the calculation unit 12, the prediction unit 13, the generation unit 16, the storage control unit 17, and the output unit 18. The display controller 107 is an example of the drawing control unit 14 and the output unit 19. The frame buffer 105 is an example of the storage unit 15.

2. Operation 2-1. Update of Display on Display Unit 101 First, update of display on the display unit 101 will be described. In the following, a program such as the digitizer driver 201 may be described as the subject of processing, but this is because the CPU 102 executing the program performs processing in cooperation with other hardware. Means.

  Data of an image to be displayed next on the display unit 101 (hereinafter referred to as “next image”) is written into the frame buffer 105 by the application 220 or the display driver 202. The frame buffer 105 also stores data of an image currently displayed on the display unit 101 (hereinafter referred to as “current image”). In this example, the display controller 107 and the drive unit 106 themselves do not necessarily update the display of the display unit 101 periodically or regularly. When receiving an update command from the application 220 or the like, the display unit 107 Processing to update the display of 101 is performed.

  In this example, since the application 220 is an application for drawing a handwritten line, an update command is periodically output to the display controller 107. Hereinafter, the cycle in which the application 220 outputs the update command is referred to as “command cycle”, and the reciprocal of the command cycle is referred to as “command frequency”.

  When receiving the update command, the display controller 107 reads the data of the current image and the next image from the frame buffer 105 and controls the drive unit 106 so as to apply a voltage corresponding to these data. Application of a voltage for updating the image of the display unit 101 is performed in units of a predetermined time (for example, 16.7 msec corresponding to 60 Hz). Hereinafter, this unit period is referred to as “frame”, and the reciprocal of the frame is referred to as “update frequency” of the display unit 101. The update frequency is determined by the characteristics of the EPD and the design of the drive unit 106 and the display controller 107. Due to the characteristics of EPD, updating from the current image to the next image requires a plurality of frames.

2-2. Transfer of Coordinate Data Next, transfer of coordinate data from the digitizer 108 to another software configuration will be described. The digitizer 108 outputs coordinate data. The coordinate data includes data indicating the presence or absence of contact of the indicator (hereinafter referred to as “first data”) and data indicating the coordinates of the detected position (hereinafter referred to as “second data”). In this example, the digitizer 108 periodically detects the position where the indicator is in contact with the display unit 101. The cycle in which the digitizer 108 detects the position of the indicator is called a sampling cycle, and the reciprocal of the sampling cycle is called a sampling frequency. The sampling period is, for example, 10 msec corresponding to 100 Hz. That is, the digitizer 108 detects a position every 10 msec and outputs coordinate data. When the indicator is not in contact with the display unit 101, the value of the second data indicates a null value.

  In the following description, coordinates detected at time n are represented as coordinates p (n), and coordinate data including the coordinates p (n) are represented as coordinate data D (n). As described above, since the coordinate detection is performed periodically, the time n takes a discrete value. Therefore, a coordinate detected immediately before the coordinate p (n) is expressed as a coordinate p (n−1), and a coordinate detected immediately after the coordinate p (n−1) is expressed as a coordinate p (n + 1).

  The digitizer driver 201 acquires coordinate data D (n) from the digitizer 108. The digitizer driver 201 outputs the acquired coordinate data D (n) to the graphic system 210.

  When the coordinate data D (n) is acquired from the digitizer driver 201, the graphic system 210 generates a pen event according to the coordinate data. More specifically, the graphic system 210 confirms the first data included in the coordinate data D (n) and the first data included in the coordinate data D (n−1), and at least one of these two first data. If indicates that there is a touch, a pen event is generated. If both of these two first data indicate no contact, the graphics system 210 does not generate a pen event.

  The generated pen events include a pen touch event, a pen release event, and a pen movement event. The pen touch event is data indicating that the indicator has newly touched the display unit 101. The pen release event is data indicating that the pen that has been in contact so far has been released from the display unit 101. The pen movement event is data indicating that the position of the pen in contact has moved.

  Which of the three pen events is to be generated is determined as follows. If the first data included in the coordinate data D (n−1) indicates no contact, and the first data included in D (n) indicates that there is contact, the graphic system 210 generates a pen touch event. When both of the first data included in the coordinate data D (n−1) and D (n) indicate that there is a touch, the graphic system 210 generates a pen movement event. If the first data included in the coordinate data D (n−1) indicates that there is contact and the first data included in D (n) indicates that there is no contact, the graphic system 210 generates a pen release event.

  The generated pen event includes an identifier indicating which of the pen event, the pen release event, and the pen movement event, and the coordinate p corresponding to the pen event. When the pen touch event and the pen movement event are generated from the coordinate data D (n−1) and D (n), the event includes the coordinate p (n), and when the pen release event is generated, the event includes Coordinate p (n-1) is included. In the following, a pen event generated from the coordinate data D (n−1) and D (n) is represented as a pen event E (n).

  The graphic system 210 outputs the generated pen event E (n) to the application 220. The application 220 performs handwritten line drawing processing using the acquired pen event.

2-3. Drawing of Handwritten Line FIG. 4 is a flowchart showing a drawing process of a handwritten line. The flow in FIG. 4 is started when the application 220 is started, for example.

  In step S100, the application 220 initializes a counter t. Here, t = 0 is initialized. The counter t indicates the number of times a pen event has been acquired.

  In step S101, the application 220 determines whether a new pen event has been acquired. If it is determined that a new pen event has been acquired (S101: YES), the application 220 proceeds to step S102. In the following, the pen event E (n) is the latest pen event. When it is determined that a new pen event has not been acquired (S101: NO), the application 220 waits until a new pen event is acquired.

  In step S102, the application 220 determines which of the pen touch event, the pen release event, and the pen movement event the pen event E (n) is. When the pen event E (n) is a pen touch event (S102: T), the application 220 proceeds to step S103. If the pen event E (n) is a pen movement event (S102: M), the application 220 proceeds to step S104. If the pen event E (n) is a pen release event (S102: R), the application 220 proceeds to step S109.

  In step S103, the application 220 draws a point at the coordinate p (n). Specifically, the application 220 writes data for drawing a point at the coordinate p (n) in the frame buffer 105. At this time, the application 220 writes data directly to the frame buffer 105 without going through the graphic system 210. Note that when data is written to the frame buffer 105 in the following processing, the application 220 writes data directly to the frame buffer 105 without using the graphic system 210. When the data is written, the application 220 proceeds to step S105.

  In step S104, the application 220 draws a line segment connecting the coordinates p (n) and the coordinates p (n-1). Specifically, the application 220 writes data for drawing the line segment in the frame buffer 105. When the data is written, the application 220 proceeds to step S105.

  In step S104, when the counter t is t = 1, that is, when the coordinate of the first point is detected after the counter t is initialized, the application 220 is first stored in the frame buffer 105. The data of the line connecting the coordinates p (n) and the coordinates p (n-1) is deleted. The case where t = 1 in step S104 is a case where a pen movement event has been continuously detected since the last display update on the display unit 101, and is stored in the frame buffer 105 at this time. A line segment connecting the coordinate p (n) and the coordinate p (n−1) is a line segment drawn using the predicted coordinate p (n). Since the coordinate p (n) is actually measured, the line segment based on the prediction is deleted. After deleting the line segment data based on the prediction, the application 220 writes the line segment data connecting the actually measured coordinates p (n) and the coordinates p (n−1) to the frame buffer 105.

  In step S105, the application 220 increments the counter t.

In step S106, the application 220 determines whether the value of the counter t has reached the threshold value th. The threshold th is determined according to the update frequency of the display unit 101 and the command frequency of the application 220, for example. More specifically, the threshold value th is determined so that the difference between the update frequency and the instruction frequency is minimized. In this example, the update frequency is a fixed value determined by the hardware configuration. On the other hand, the command frequency is a value determined by the application 220. More specifically, the command frequency ωc is determined by the threshold th and the sampling period Ts of the digitizer 108,
ωc = 1 / (Ts · th) (2)
It is. For example, when the sampling frequency ωs of the digitizer 108 is 133 Hz, that is, when Ts = 7.5 msec, the command frequency is as follows.
ωc = 133 Hz (when th = 1)
ωc = 66.5 Hz (when th = 2)
ωc = 44.3Hz (when th = 3)
ωc = 33.3 Hz (when th = 4)
Therefore, in order to minimize the difference between the update frequency and the command frequency, th = 2 when the update frequency of the display unit 101 is 60 Hz, and th = 3 when the update frequency is 50 Hz.

  Thus, by determining the threshold value th so that the difference between the update frequency and the command frequency is minimized, the position is indicated by the indicator until the line is actually displayed on the display unit 101. Can be reduced. The reason is as follows. When an update command is issued each time an event related to the operation of the indicator occurs, a new update command is issued when the drive unit 106 controls the display unit 101 by the previously issued update command. End up. If the drive unit 106 that controls the display unit 101 cannot receive a new update command, the display controller 107 waits for the transfer of the update command. If the cycle of detecting the coordinates of the indicator is short, update commands are issued frequently and waiting for transfer of update commands increases, so that handwritten line drawing becomes slow. On the other hand, in this embodiment, control is performed so that the difference between the update frequency and the command frequency is minimized. For this reason, it is less likely that the display controller 107 waits for the transfer of the update command, and the handwritten line is drawn faster than when the update command is issued each time an event related to the operation of the indicator occurs.

  If it is determined that the value of the counter t has reached the threshold value (S106: YES), the application 220 proceeds to step S107. When it is determined that the value of the counter t has not reached the threshold value (S106: NO), the application 220 proceeds to step S101. If it is determined that the value of the counter t has reached the threshold value (S106: YES), the application 220 proceeds to step S107.

  In step S107, the application 220 predicts the coordinate p (n + 1). At this time, the latest coordinate is p (n), and the coordinate p (n + 1) has not been acquired yet.

FIG. 5 is a flowchart showing details of the coordinate prediction process in step S107. In step S201, the application 220 calculates a velocity vector v (n). The velocity vector v (n) is calculated by the following equation (3).
v (n) = p (n) -p (n-1) (3)
In general, v (n) = dp (n) / dt. However, since p (n) is sampled at a constant period, the term “/ dt” is omitted for convenience. The velocity vector is calculated by equation (3).

In step S202, the application 220 calculates an acceleration vector a (n). The acceleration vector a (n) is calculated by the following equation (4).
a (n) = v (n) −v (n−1) (4)
In addition,
v (n-1) = p (n-1) -p (n-2)
It is.

In step S203, the application 220 predicts the coordinate p (n + 1). For the prediction, the already described formula (1) is used.
p (n + 1) = p (n) + αv (n) + βa (n) (1)
Here, α and β are coefficients indicating weights of velocity and acceleration, respectively. The coefficients α and β are
α <1, β <1 (5)
It is preferable that
α> β (6)
It is more preferable that

  The application 220 stores at least th coordinates p and (th−1) speed vectors v from the latest in order to perform the calculations in steps S201 to S203.

  FIG. 6 is a diagram illustrating predicted coordinates. In this example, coordinates p (n-2), p (n-1), and p (n) are actually measured coordinates, and coordinates p (n + 1) are predicted coordinates. For the prediction of p (n + 1), v (n) and a (n) are used.

  Refer to FIG. 4 again. In step S108, the application 220 draws a line segment connecting the coordinates p (n + 1) and the coordinates p (n). Specifically, the application 220 writes data for drawing the line segment in the frame buffer 105. After writing the data, the application 220 moves the process to step S109.

  In step S109, the application 220 specifies an area for updating the display. The area for updating the display is an area including a line segment drawn using the position p (n) sampled last when the display was updated last time.

  If the pen event E (n) acquired in step S101 is a pen movement event, the area whose display is updated in step S109 is at least (th + 2) coordinates p (n−th) to p (n + 1). It is an area including For example, when th = 3, the region whose display is updated is a region including five coordinates of coordinates p (n−3) to p (n + 1). When a pen touch event has occurred between times (n-3) to (n-1), the area whose display is updated is an area including coordinates after the pen touch event.

  When the pen event E (n) acquired in step S101 is a pen release event, the area whose display is updated in step S109 includes t coordinates from coordinates p (nt) to p (n-1). It is an area to include. For example, when t = 2, the region whose display is updated is a region including two coordinates of coordinates p (n−2) to p (n−1).

  In step S <b> 110, the application 220 outputs an update command to the display controller 107. When the update instruction is output, the application 220 proceeds to step S100.

  7A and 7B are diagrams illustrating transition of images displayed by the information processing apparatus 1. In these drawings, the time is described with the sampling period of the digitizer 108 as a unit. Moreover, the value of the counter t at each time is also described. Of the images in FIGS. 7A and 7B, the left column image indicates the position detected by the digitizer 108, the central column image indicates the image stored in the frame buffer 105, and the right column image indicates the display unit 101. The images displayed in are respectively shown. In this example, the threshold value th = 3.

  At time n = 1 to 3, data of line segments connecting two continuous coordinates in time series are written in the frame buffer 105 according to the detected positions (FIG. 7A). At time n = 3, the coordinate p ′ (4) is further predicted. Here, in order to distinguish the actually measured coordinate from the predicted coordinate, the predicted coordinate is represented as p ′. Here, for the sake of explanation, the predicted coordinates are indicated by white dots. In the frame buffer 105, data of a line segment group connecting four points p (1) to p (3) and p ′ (4) is written. A rectangular area including the four points p (1) to p (3) and p ′ (4) is specified as an area for updating the display (broken line portion in the figure). And the display of this area | region is updated in the display part 101. FIG.

  At time n = 4, p (4) is detected. First, the data of the line connecting p ′ (4) and P (3) stored in the frame buffer 105 is erased, and then the data of the line connecting p (4) and P (3) is framed. It is written in the buffer 105 (FIG. 7B). At times n = 5 and 6, data of line segments connecting two coordinates that are continuous in time series are written into the frame buffer 105 according to the detected positions. At time n = 6, the coordinate p ′ (7) is further predicted. In the frame buffer 105, data of a line segment group connecting seven points p (1) to p (6) and p '(7) is written. A region including five points p (3) to p (6) and p '(7) is specified as a region for updating the display (the broken line portion in the figure). And the display of this area | region is updated in the display part 101. FIG. That is, to delete the line segment drawn using the predicted position last time, and to add the line segment drawn using the actually measured position and the predicted position this time, an area including these line segments The display of is updated.

  As described above, according to the present embodiment, it is possible to reduce a sense of discomfort given to the user when predicting the position of the indicator.

3. Modifications The present invention is not limited to the above-described embodiments, and various modifications can be made. Hereinafter, some modifications will be described. Two or more of the following modifications may be used in combination.

3-1. Modification 1
The prediction of coordinates may be performed for each pen movement event. That is, the application 220 may predict the coordinate p (n + 1) every time for the coordinate p (n). In this case, the optimization of the instruction frequency ωc using the counter t may not be performed.

ここで、ｃ_iは重み付け係数である。ｃ_iはｉによらず等しくてもよいが、より時間的に直近の情報を重視する観点から、ｃ_i＞ｃ_i-1であることが好ましい。加速度ベクトルａについても同様に、３つ以上の速度ベクトルｖ（すなわち４つ以上の座標ｐ）を用いて算出されてもよい。 3-2. Modification 2
The method of calculating the velocity vector and the acceleration vector is not limited to the method using the equations (3) and (4) described in the embodiment. For example, the velocity vector v may be calculated by the following equation (7) using three or more coordinates p.

Here, c _i is a weighting coefficient. Although c _i may be equal regardless of i, it is preferable that c _i > c _i-1 from the viewpoint of emphasizing the latest information in terms of time. Similarly, the acceleration vector a may be calculated using three or more velocity vectors v (that is, four or more coordinates p).

3-3. Modification 3
At least one of the values of the coefficients α and β in the equation (1) may be dynamically changed instead of a fixed value. For example, the values of the coefficients α and β may change according to the thickness of the drawn line. More specifically, the coefficients α and β may be made smaller when the line is thicker. Even if the amount of deviation in prediction is the same, the area where the thicker line is rewritten is wider, and rewriting may become conspicuous. For this reason, the thicker the line, the smaller the coefficients α and β are made so that the area to be rewritten becomes smaller when the prediction is lost.

3-4. Modification 4
The hardware configuration of the information processing apparatus 1 is not limited to that described in the embodiment. For example, the information processing apparatus 1 may be a stylus type device (pen type device) separate from the display device. That is, in the embodiment, an example has been described in which a tablet terminal detects a position touched by a stylus in a system having a tablet terminal and a stylus. However, in this system, the stylus may have a function of detecting a position touched by the stylus. In this case, the stylus type information processing apparatus 1 includes, for example, an optical sensor as the detection unit 11 and detects its own position by reading a pattern formed on the surface of the display unit. In such a configuration, the stylus type information processing apparatus 1 predicts the next coordinate and causes the display device to display an image including a point corresponding to the predicted coordinate.

  Further, the information processing apparatus 1 may be an electronic book reader, an electronic notebook, a calculator, a POS terminal, a digital still camera, a mobile phone, or the like other than the tablet terminal and the stylus type apparatus described above.

3-5. Modification 5
The image corresponding to the coordinates p (n) and p (n-1) is not limited to the line segment connecting these two points. For example, a curve may be generated using spline interpolation or the like for a plurality of points including these two points, and the curve may be drawn.

3-6. Other Modifications The display device is not limited to a microcapsule type EPD. Other memory display elements such as a partition type (microcup) electrophoresis system, an electronic powder, a cholesteric liquid crystal, and an electrochromic may be used. Alternatively, a non-memory display element such as a liquid crystal display or an organic EL (Electro Luminescence) display may be used.

  The software configuration of the information processing apparatus 1 is not limited to that described with reference to FIG. The information processing apparatus 1 may have any software configuration as long as the required function can be realized.

  In the above-described embodiment, the program executed by the CPU 102 or the like is a magnetic recording medium (magnetic tape, magnetic disk (HDD, FD (Flexible Disk)), etc.), optical recording medium (optical disk (CD (Compact Disk)), DVD (Digital Versatile Disk))), a magneto-optical recording medium, and a computer-readable recording medium such as a semiconductor memory (flash ROM or the like). The program may be downloaded via a network such as the Internet.

DESCRIPTION OF SYMBOLS 1 ... Information processing apparatus, 10 ... Display means, 11 ... Detection means, 12 ... Calculation means, 13 ... Prediction means, 14 ... Drawing control means, 15 ... Storage means, 16 ... Generation means, 17 ... Storage control means, 18 ... Output means, 19 ... output means, 101 ... display section, 102 ... CPU, 103 ... RAM, 104 ... storage device, 105 ... frame buffer, 106 ... drive section, 107 ... display controller, 108 ... digitizer, 200 ... OS, 201 ... Digitizer driver, 202 ... Display driver, 210 ... Graphic system, 220 ... Application

Claims (9)

Acquisition means for acquiring the coordinates of the indicator detected periodically;
Calculation means for calculating a velocity vector and an acceleration vector of the indicator based on coordinates detected at three or more different times among the coordinates acquired by the acquisition means;
Using the velocity vector v and acceleration vector a calculated by the calculation means, the coordinate p (n + 1) at time (n + 1) is expressed by the following equation (1) with respect to the coordinate p (n) detected at time n. Prediction means to predict;
p (n + 1) = p (n) + αv + βa (1)
(Where α and β are coefficients)
An image processing apparatus comprising: a drawing control unit that generates an image including a point corresponding to the coordinate p (n + 1) predicted by the prediction unit. The image is a line corresponding to the locus of the indicator,
The information processing apparatus according to claim 1, wherein the prediction unit changes at least one of the coefficients α and β according to a thickness of the line. The predicting means reduces the values of the coefficients α and β when the line thickness is b2 (where b2> b1) than when the line thickness is b1. The information processing apparatus according to claim 2. The calculation means uses a weighted average using a weighting coefficient according to the time at which the coordinates are detected based on the coordinates detected at four or more different times among the coordinates acquired by the acquisition means. The information processing apparatus according to claim 1, wherein a velocity vector and an acceleration vector of the indicator are calculated. When the coordinates detected at time n1 among the coordinates acquired by the acquisition means are the latest, the weighting coefficient corresponding to time n1 is higher than the weighting coefficient corresponding to time n2 (where n1> n2). The information processing apparatus according to claim 4, wherein the information processing apparatus is large. Display means for displaying an image;
Detecting means for detecting coordinates indicated by the indicator on the surface of the display means;
Calculation means for calculating a velocity vector and an acceleration vector of the indicator based on coordinates detected at three or more different times among the coordinates detected by the detection means;
Using the velocity vector v and acceleration vector a calculated by the calculation means, the coordinate p (n + 1) at time (n + 1) is expressed by the following equation (1) with respect to the coordinate p (n) detected at time n. Prediction means to predict;
p (n + 1) = p (n) + αv + βa (1)
(Where α and β are coefficients)
A display device comprising: a drawing control unit that causes the display unit to display an image including a point corresponding to the coordinate p (n + 1) predicted by the prediction unit. Storage means;
Generating means for generating image data of line segments based on coordinates detected at three or more different times by the detecting means;
Storage control means for storing the image data generated by the generating means in the storage means;
An output means for outputting an update command for updating the display of the display means when coordinates are detected at three or more different times by the detection means since the display of the display means was updated last time;
Output means for outputting a signal for causing the display means to display an image corresponding to the image data stored in the storage unit in response to the update command;
The display device according to claim 6, wherein the prediction unit predicts a coordinate next to a coordinate detected at the latest time among the coordinates detected at the three or more times. Obtaining the coordinates of the indicator detected periodically;
Calculating a velocity vector and an acceleration vector of the indicator based on coordinates detected at three or more different times among the acquired coordinates;
A step of predicting a coordinate p (n + 1) at time (n + 1) by the following equation (1) with respect to the coordinate p (n) detected at time n using the calculated velocity vector v and acceleration vector a. When,
p (n + 1) = p (n) + αv + βa (1)
(Where α and β are coefficients)
Generating an image including a point corresponding to the predicted coordinate p (n + 1). On the computer,
Obtaining the coordinates of the indicator detected periodically;
Calculating a velocity vector and an acceleration vector of the indicator based on coordinates detected at three or more different times among the acquired coordinates;
A step of predicting a coordinate p (n + 1) at time (n + 1) by the following equation (1) with respect to the coordinate p (n) detected at time n using the calculated velocity vector v and acceleration vector a. When,
p (n + 1) = p (n) + αv + βa (1)
(Where α and β are coefficients)
Generating an image including a point corresponding to the predicted coordinate p (n + 1).

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