JP3505057B2 - Pen-type input device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pen type input device for inputting figures and characters.

[0002]

2. Description of the Related Art Keyboards, mice, digitizers, light pens, tablets and the like are used as input devices for computer devices and the like. With the miniaturization of computer devices, the needs for mobile terminal devices have increased and the number of users has been increasing year by year. Therefore, a small input device has been demanded.

The miniaturization of a keyboard has a limit in terms of a human interface, and is not practical as an input device of a mobile terminal device. Further, although the mouse can be downsized as a pointing device, it is not suitable for inputting figures and characters.

Therefore, for example, a pen type computer input device disclosed in Japanese Patent Laid-Open No. 6-67799, Japanese Patent Laid-Open No. 7-8
Data input device disclosed in Japanese Patent No. 4716, Japanese Patent Laid-Open No. 7-200
Handwriting input device disclosed in Japanese Patent Publication No. 127 and JP-A-6-23
A tabletless input device, such as the pencil type input device disclosed in Japanese Patent No. 0886, has been developed.

A pen-type computer input device disclosed in Japanese Patent Laid-Open No. 6-67799 examines a moving direction and a moving distance by an acceleration sensor, and detects the moving direction and the moving distance by a piezoelectric vibration gyro. It compensates for the effects of computer input device rotation. Further, the data input device disclosed in Japanese Unexamined Patent Publication No. 7-84716 detects the moving direction and the moving distance of the device based on the signals indicating the polarity and the amplitude from the vibrating gyros arranged at right angles to each other. Further, the handwriting input device disclosed in Japanese Patent Laid-Open No. 7-200127 obtains the moving direction and moving distance of the device based on signals from two acceleration sensors. Further, in the pencil type input device disclosed in Japanese Patent Laid-Open No. 6-230886, two sets of acceleration sensors are provided at different positions on the pen shaft, and the acceleration sensors are attached based on the outputs from the two sets of acceleration sensors. The moving direction and moving distance of the pen tip portion, which is corrected for the influence of the position, are obtained.

Further, the position sensor disclosed in Japanese Patent Laid-Open No. 7-294240 is not related to the pen-type input device but is used in, for example, a game machine. It is equipped with an acceleration sensor that detects acceleration in the Z-axis direction and a gyro that detects angular velocities around the X-axis, the Y-axis, and the Z-axis, and performs a strapdown calculation based on the accelerations and angular velocities detected by the gyro. It detects the moving speed, position, posture, and orientation of parts.

[0007]

However, in the pen type computer input device disclosed in Japanese Patent Laid-Open No. 6-67799, the effect of rotation of the device is corrected, and when the device is accompanied by a dynamic tilt. Cannot be corrected. Since the normal writing operation involves a dynamic tilt of the device, the detection result may be inaccurate.

Further, the data input device disclosed in Japanese Patent Laid-Open No. 7-84716 is not suitable for inputting figures and the like because it detects the rotational movement of the wrist and inputs the moving direction and moving distance.

Furthermore, in the handwriting input device disclosed in Japanese Patent Laid-Open No. 7-200127, there is no correction means for the inclination and rotation of the device, so the detection result may be inaccurate.

Further, since the pencil type input device disclosed in Japanese Patent Laid-Open No. 6-230886 does not consider that the acceleration detected by the acceleration sensor includes a component with respect to the rotation angle of the device, it detects the moving distance. The error may increase.

The position sensor disclosed in Japanese Unexamined Patent Publication No. 7-294240 employs a complicated arithmetic process because it spatially detects the moving speed, position, posture and orientation of the head. Since the pen-type input device is required to be downsized, it is necessary to accurately detect the moving direction and the moving distance on the writing surface by a simple arithmetic process.

The present invention has been made in order to eliminate such disadvantages, and an object thereof is to accurately detect a handwriting input with a simple structure.

[0013]

A pen type input device according to the present invention has an acceleration sensor, a gravity sensor, a magnetic field sensor, and a calculation section, and the acceleration sensor has a pen axis coordinate system (Xs , Ys, Zs) in the Xs-axis direction, Ys-axis direction and Zs-axis direction are output, and the gravity sensor outputs a signal indicating the Xs-axis direction and the Ys-axis direction of the pen-axis coordinate system (Xs, Ys, Zs). The magnetic field sensor outputs a signal indicating the gravity component applied in one direction, and the magnetic field sensor uses the pen axis coordinate system (Xs, Ys,
Zs) outputs a signal indicating a vector component of the geomagnetism in a direction orthogonal to the Zs axis, and the calculation unit includes a coordinate conversion matrix calculation unit, a coordinate conversion calculation unit, and a movement amount calculation unit, and the coordinate conversion matrix calculation unit is a gravity sensor. The tilt angle of the pen axis in the Xs axis direction and the Ys axis direction is calculated based on the gravity component applied in the Xs axis direction and the Ys axis direction detected by using the magnetic field sensor. Based on the vector component of the geomagnetism in the direction orthogonal to the Zs axis, the axis extending from the pen axis coordinate system (Xs, Ys, Zs) in the direction of gravity acceleration is the gravity coordinate system (Xg,
Yg, Zg) to calculate the coordinate transformation matrix for coordinate transformation,
The coordinate conversion calculation unit calculates the acceleration of the pen axis coordinate system (Xs, Ys, Zs) detected by the acceleration sensor using the coordinate conversion matrix calculated by the coordinate conversion matrix calculation unit, in the gravity coordinate system (Xg, Y).
g, Zg), and the movement amount calculation unit calculates the movement direction and movement distance of the pen tip based on the acceleration of the gravity coordinate system (Xg, Yg, Zg) obtained by the conversion by the coordinate conversion calculation unit. By calculating and directly obtaining the coordinate conversion matrix based on the inclination angle of the pen axis and the like, the integration calculation process is reduced.

Further, it has three acceleration sensors, two gravity sensors and one magnetic field sensor, and the three acceleration sensors are respectively in the Xs axis direction of the pen axis coordinate system (Xs, Ys, Zs) and Ys. A signal indicating the acceleration in the axial direction and the Zs axis direction is output, and the two gravity sensors are respectively provided in the pen axis coordinate system (Xs,
Ys, Zs) outputs a signal indicating the component of gravity applied in the Xs axis direction and the Ys axis direction, and the magnetic field sensor outputs the pen axis coordinate system (X
(s, Ys, Zs) outputs a signal indicating a vector component of the geomagnetism in one direction orthogonal to the Zs axis.

Further, it has three acceleration sensors, one gravity sensor and two magnetic field sensors, and the three acceleration sensors are respectively in the Xs axis direction of the pen axis coordinate system (Xs, Ys, Zs).
Outputs a signal indicating the acceleration in the Ys axis direction and the Zs axis direction,
Gravity sensor is pen axis coordinate system (Xs, Ys, Zs)
Outputs a signal indicating the component of gravity applied in the Xs-axis direction or the Ys-axis direction, and the magnetic field sensor uses the pen-axis coordinate system (Xs, Ys, Z
s) outputs a signal indicating the vector component of the geomagnetism in two directions orthogonal to the Zs axis, and the coordinate conversion matrix calculation unit is based on the gravity component applied in the Xs axis direction or the Ys axis direction detected using the gravity sensor. The tilt angle of the pen axis in the Xs axis direction or the Ys axis direction is obtained, and the pen axis coordinate system is based on the obtained tilt angle of the pen axis and the vector component of the geomagnetism in two directions orthogonal to the Zs axis detected using the magnetic field sensor. Gravity coordinate system (Xg, Yg, Z) with the axis extending from (Xs, Ys, Zs) in the direction of gravity acceleration as the Zg axis.
The size of the device is reduced by calculating the coordinate conversion matrix for g) and reducing the number of gravity sensors and increasing the number of small magnetic sensors instead.

Further, it has three acceleration sensors, two gravity sensors and two magnetic field sensors, and each of the three acceleration sensors is in the Xs axis direction of the pen axis coordinate system (Xs, Ys, Zs).
Outputs a signal indicating the acceleration in the Ys axis direction and the Zs axis direction,
Each of the two gravity sensors has a pen axis coordinate system (Xs, Ys,
Zs) outputs a signal indicating the component of gravity applied in the Xs axis direction and the Ys axis direction, and the magnetic field sensor outputs the pen axis coordinate system (Xs, Y
s, Zs) outputs a signal indicating the vector component of the geomagnetism in two directions orthogonal to the Zs axis, and the coordinate conversion matrix operation unit detects the gravity component applied in the Xs axis direction or the Ys axis direction detected using the gravity sensor. Based on the tilt angle of the pen axis in the Xs axis direction or the Ys axis direction, the pen axis is determined based on the calculated tilt angle of the pen axis and the vector component of the geomagnetism in two directions orthogonal to the Zs axis detected using the magnetic field sensor. Gravity coordinate system (Xg, Y) with the axis extending from the coordinate system (Xs, Ys, Zs) in the direction of gravity acceleration as the Zg axis.
g, Zg) to calculate a coordinate conversion matrix for performing coordinate conversion.

Further, a high-pass filter that transmits high-frequency components of signals from the acceleration sensor, the gravity sensor, and the magnetic field sensor with a frequency near 10 Hz as a boundary is provided, and one of the signals passed through the high-pass filter is the first high-frequency component. The writing start is determined based on the signal including the signal, and the writing end is determined based on the signal including the high-frequency component up to the end of the signals that have passed through the high-pass filter.

Further, the coordinate conversion calculation unit uses the pen-position coordinate system (Xs, Xs, detected by using the acceleration sensor) by using the mounting position of each acceleration sensor, the coordinate conversion matrix, and the coordinate conversion matrix calculated by the coordinate conversion matrix calculation unit. Ys, Zs) acceleration is converted to the acceleration of the pen tip in the gravity coordinate system (Xg, Yg, Zg), and the component of the acceleration detected by the acceleration sensor due to the tilting motion centered on the pen tip is removed. To do.

Further, the calculation unit includes a stationary state detecting unit and a velocity correcting unit, and the stationary state detecting unit is a gravity coordinate system (Xg,
(Yg, Zg) Acceleration is integrated once, and the stationary state is detected based on the change in the velocity of the gravity coordinate system (Xg, Yg, Zg). The velocity correction unit detects the stationary state by the stationary state detection unit. Each time, the velocity of the gravity coordinate system (Xg, Yg, Zg) obtained by integrating once the acceleration of the gravity coordinate system (Xg, Yg, Zg) is reset to zero to reduce the accumulated velocity error.

Further, the arithmetic unit includes a stationary state detecting unit and a speed correcting unit, and the stationary state detecting unit is a gravity coordinate system (Xg, Y).
Gravity coordinate system (X
g, Yg, Zg) detects the stationary state based on the change of speed,
The velocity correction unit uses the gravity coordinate system (Xg, Yg,
Gravity coordinate system (Xg,
The velocity waveforms (Yg, Zg) are corrected so that the velocity becomes zero in each stationary state to further reduce the accumulated error of velocity.

Further, the stationary state detecting section detects a pen axis coordinate system (Xs, Ys, Zs) using an acceleration sensor.
Based on the acceleration in each axis direction of the pen axis coordinate system (Xs, Ys,
Zs) calculates a composite vector of accelerations, compares the size of the calculated composite vector and the magnitude of gravitational acceleration, and judges that the difference is within a predetermined value as a stationary state, and corrects with a simple configuration. To determine the still state.

Further, the stationary state detecting unit determines that the stationary state is when the Xg-axis direction and Yg-axis direction accelerations obtained by conversion by the coordinate conversion calculating unit is below a predetermined threshold value, and has a simpler configuration. Determine the still state.

In addition, the stationary state detecting section uses the pen axis coordinate system (Xs, Ys, Zs) based on the acceleration in each axis direction of the pen axis coordinate system (Xs, Ys, Zs) detected using the acceleration sensor.
s) calculates a composite vector of accelerations, compares the size of the calculated composite vector and the magnitude of gravitational acceleration, and when the difference is within a predetermined value, and
When the accelerations in the Xg axis direction and the Yg axis direction obtained by conversion by the coordinate conversion calculation unit are equal to or less than a predetermined threshold value, the stationary state is determined, and the stationary state is determined more accurately.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The pen type input device of the present invention is a pen axis coordinate system (Xs, Ys, Zs) in which the gravity component and the pen axis coordinate applied in the Xs axis direction and / or the Ys axis direction. Based on the vector component of the geomagnetism in the direction orthogonal to the Zs axis of the system (Xs, Ys, Zs), the pen axis coordinate system (Xs, Ys,
Zs) is a coordinate transformation matrix that performs coordinate transformation to the gravity coordinate system (Xg, Yg, Zg) with the axis extending from the direction of gravity acceleration as Zg axis, and the calculated coordinate transformation matrix is used to calculate the pen axis coordinate system (Xs , Ys, Zs) is the acceleration in the gravity coordinate system (Xg, Y
g, Zg), and based on the acceleration of the gravity coordinate system (Xg, Yg, Zg) obtained by the conversion, the moving direction and the moving distance of the pen tip portion are calculated, and characters and symbols are displayed on the computer device. And a figure etc. are input.

The pen-type input device has, for example, three acceleration sensors, two gravity sensors, one magnetic field sensor, and an arithmetic unit. Each of the three acceleration sensors outputs a signal indicating the acceleration in the Xs axis direction, the Ys axis direction, and the Zs axis direction of the pen axis coordinate system (Xs, Ys, Zs). Each of the two gravity sensors outputs a signal indicating a gravity component applied in the Xs axis direction and the Ys axis direction of the pen axis coordinate system (Xs, Ys, Zs).
The magnetic field sensor outputs a signal indicating a vector component of geomagnetism in one direction orthogonal to the Zs axis of the pen axis coordinate system (Xs, Ys, Zs).

The calculation unit includes, for example, a coordinate conversion matrix calculation unit, a coordinate conversion calculation unit, and a movement amount calculation unit. The coordinate transformation matrix calculation unit obtains the inclination angle of the pen axis in the Xs axis direction and the Ys axis direction based on the gravity component applied in the Xs axis direction and the Ys axis direction detected by the gravity sensor, and the obtained inclination of the pen axis. Based on the vector component of the geomagnetism in the direction orthogonal to the Zs axis detected using the angle and magnetic field sensors, the axis extending from the pen axis coordinate system (Xs, Ys, Zs) in the direction of gravity acceleration is defined as the Zg axis. Xg, Yg, Zg) to calculate a coordinate conversion matrix for performing coordinate conversion. The coordinate conversion calculation unit calculates the acceleration of the pen axis coordinate system (Xs, Ys, Zs) detected by the acceleration sensor using the coordinate conversion matrix calculated by the coordinate conversion matrix calculation unit, in the gravity coordinate system (Xg, Yg, Zg). Convert to acceleration. The movement amount calculation unit includes, for example, a speed calculation unit, a stationary state detection unit, a speed correction unit, and a speed integration unit. The velocity calculation unit integrates the acceleration in each axis direction of the gravity coordinate system (Xg, Yg, Zg) obtained by conversion by the coordinate conversion calculation unit, and then the gravity coordinate system (Xg, Yg, Zg).
The velocity in each axial direction of is calculated. The stationary state detection unit detects the stationary state based on the change in the velocity of the gravity coordinate system (Xg, Yg, Zg) obtained by the velocity calculation unit. The velocity correction unit calculates the acceleration of the gravity coordinate system (Xg, Yg, Zg) from when the stationary state detection unit detects the stationary state to when the stationary state is detected next time by integrating once. , Yg, Zg) velocity waveforms are corrected so that the velocity becomes zero in each stationary state. The velocity integration unit is the gravity coordinate system (Xg, Y
g, Zg) are integrated to calculate the moving direction and moving distance of the pen tip. In this way, by directly obtaining the coordinate conversion matrix, it is possible to reduce the time and effort required to synchronize the respective sensors, and the number of integration processes and the like are reduced as compared with the case where the tilt angle is obtained, and the occurrence of errors is reduced. it can.

[0027]

1 is a block diagram of a pen type input device 1 according to an embodiment of the present invention. As shown in the figure, the pen type input device 1
a is an acceleration sensor 2a, 2b, 2c, a gravity sensor 3a,
3b, magnetic field sensor 4, calculation unit 5, storage unit 6, and power supply unit 7
Have. The acceleration sensors 2a, 2b, 2c are provided in the Xs axis direction, the Ys axis direction, and the Zs axis direction that are orthogonal to the Zs axis when the pen axis 9 is the Zs axis. A signal indicating the acceleration in the Zs axis direction is output. The acceleration sensors 2a, 2b, 2c may be of a piezoelectric type or a capacitance type other than the piezoresistive type. The gravity sensors 3a and 3b detect components of gravitational acceleration in the Xs-axis direction and the Ys-axis direction. For example, a tilt angle sensor adopting a fluid phase capacitance method that detects gravitational acceleration by using the motion of fluid. To use. The magnetic field sensor 4 detects a vector component of geomagnetism (about 0.3 gauss in the vicinity of Japan). As the magnetic field sensor 4, for example, a small one of fluxgate sensors, which has a high manufacturing accuracy of the winding and the core material and is capable of detecting the hourly density due to the geomagnetism with high resolution, is used. Here, the gravity sensors 3a, 3
b and the detection axis of the magnetic field sensor 4 do not need to match if the angle between the detection axes is known. In the following description, a coordinate system with the pen axis 9 as the Zs axis is referred to as a pen axis coordinate system (Xs, Ys, Zs) unless otherwise specified. In addition, a coordinate system whose axis extending in the direction of gravity acceleration is the Zg axis is a gravity coordinate system (Xg, Yg,
Zg). Further, in the following description, it is assumed that the writing surface and the surface formed by the Xg axis and the Yg axis of the gravity coordinate system (Xg, Yg, Zg) coincide with each other. Further, the angles formed by the Xs axis, Ys axis, and Zs axis and the Xg axis, Yg axis, and Zg axis are taken as oiler angles φ, θ, and ψ, respectively. Further, in the following description, “during inputting” refers to a series of inputting operations of characters and figures, and there are cases where the pen tip portion 8 moves while making contact with the writing surface and cases where the pen tip portion 8 does not make contact. In addition, “during writing” refers only to the case where the pen tip portion 8 comes into contact with the writing surface and moves.

As shown in FIG. 2, the arithmetic unit 5 includes A / D converters 51a to 51f, a low-pass filter (hereinafter referred to as "LPF").
Say. ) 52a to 52f, high-pass filters (hereinafter referred to as "HPF") 53a to 53f, handwriting detection section 5
4, a coordinate conversion matrix calculation unit 55, a coordinate conversion calculation unit 56, and a movement amount calculation unit 57. A / D converters 51a to 51
f converts the analog signals from the acceleration sensors 2a, 2b and 2c, the gravity sensors 3a and 3b and the magnetic field sensor 4 into digital signals, respectively. The LPFs 52a to 52f block high-frequency components of signals from the acceleration sensors 2a, 2b, 2c, the gravity sensors 3a, 3b, and the magnetic field sensor 4, which are generated by the frictional force between the pen tip portion 8 and the writing surface. HPF53a
53f extract high frequency components due to friction of signals from the acceleration sensors 2a, 2b, 2c, the gravity sensors 3a, 3b and the magnetic field sensor 4. The writing detection unit 54 is the HPF 53a.
Of the signals from the acceleration sensors 2a, 2b, 2c, the gravity sensors 3a, 3b, and the magnetic field sensor 4 via ~ 53f, the writing start is determined based on the signal containing the high-frequency component first, and the HPFs 53a to 53f are determined. The end of writing is determined based on the signal including the high-frequency component until the end of any of the above-mentioned signals that have passed. This is because the writing acceleration component appears in a portion having a relatively low frequency, and the component due to the friction between the pen tip portion 8 and the writing surface appears in a portion having a relatively high frequency. It is a judgment.

The coordinate conversion matrix calculation unit 55 is the gravity sensor 3
The tilt angle of the pen shaft 9 is calculated based on the gravity component applied in the Xs axis direction and the Ys axis direction detected using a and 3b, and the Zs axis detected using the calculated tilt angle of the pen shaft 9 and the magnetic field sensor 4. Based on the vector component of the geomagnetism in the direction orthogonal to the pen axis coordinate system (Xs, Ys, Zs) to the gravity coordinate system (Xg, Yg, Z
Compute the coordinate transformation matrix for g).

Here, by the coordinate conversion matrix calculation unit 55,
The process of calculating the coordinate conversion matrix will be described.

As shown in FIG. 3, unit vectors in the Xg-axis, Yg-axis, and Zg-axis directions are set to ig, jg, and kg, respectively, and the Xs-axis and Ys are set.
Let z, js, ks be the unit vectors in the Z and Zs axis directions, and Z
The angles formed by the g-axis, the Xs-axis, and the Ys-axis are tilt angles α and β.
In addition, the acceleration of the pen axis coordinate system (Xs, Ys, Zs) is Ax
s, Ays, Azs, and the acceleration of the gravity coordinate system (Xg, Yg, Zg) is Axg, Ayg, Azg, the gravity coordinate system (Xg, Yg,
The accelerations Axg, Ayg, Azg of Zg) can be expressed by the following equations.

[0032]

[Equation 1]

Here, the vectors (is) g, (js) g,
(Ks) g represents the unit vector is, js, ks of the pen axis coordinate system (Xs, Ys, Zs) in the gravity coordinate system (Xg, Yg, Zg).

First, the inclination angles α and β are obtained using the gravity acceleration components in the Xg-axis direction and the Yg-axis direction detected by the two gravity sensors 3a and 3b. As the inner product of the unit vectors in each of the inclination angles α and β, there is a relationship represented by the following formula.

[0035]

[Equation 2]

From the above equation, the following equation can be derived.

[0037]

[Equation 3]

Since the vectors (is) g and (js) g are unit vectors, they are expressed by the following equation.

[0039]

[Equation 4]

Further, the following equation holds from the orthogonal condition of the vectors (is) g and (js) g.

[0041]

[Equation 5]

Next, assuming that the output signal of the magnetic field sensor 4 is V and the absolute value of the geomagnetic vector is N, the following expression is established from the detection output of the magnetic field sensor.

[0043]

[Equation 6]

By solving the above equations as simultaneous equations, the vectors (is) g and (js) g can be obtained. If the vector (is) g, (js) g, that is, the plane formed by the Xs axis and the Ys axis is obtained, (ks) g can be uniquely obtained, and the coordinate conversion matrix can be obtained.

The coordinate conversion calculation unit 56 uses the coordinate conversion matrix calculated by the coordinate conversion matrix calculation unit 55 to calculate the acceleration sensor 2
a, 2b, 2c detected pen axis coordinate system (Xs,
Accelerations Axs, Ays, Azs of Ys, Zs) are expressed in the gravity coordinate system (X
g, Yg, Zg) are converted into accelerations Axg, Ayg, Azg.

The movement amount calculation unit 57 is, for example, the speed calculation unit 5.
71, a stationary state detection unit 572, a speed correction unit 573, and a speed integration unit 574. The velocity calculation unit 571 converts the gravity coordinate system (Xg, Yg, Z obtained by the conversion by the coordinate conversion calculation unit 56).
g) The accelerations Axg, Ayg, Azg in the respective axis directions are integrated to calculate the velocities in the respective axis directions of the gravity coordinate system (Xg, Yg, Zg). The stationary state detection unit 572 is, for example, the gravity coordinate system (Xg, Y) calculated by the velocity calculation unit 573 as illustrated in FIG.
The stationary state is detected based on the change in speed of g, Zg). The velocity correction unit 573 detects the stationary state by the stationary state detection unit 572 and detects the stationary state next time.
g, Yg, Zg) based on the velocity waveform, a straight line a as shown in FIG. 4 (b) is obtained, corrected so that the slope of this straight line becomes zero, and as shown in FIG. 4 (c). Make sure that the speed is zero in each stationary state. The speed integration unit 574 integrates the speed corrected by the speed correction unit 572 as described above, calculates the moving direction and the moving distance of the pen tip portion 8, and stores the moving direction and moving distance in the storage unit 6.

Here, the speed correction unit 573 is shown in FIG.
The velocity waveform as shown in FIG. 4 may be corrected to be zero in the stationary state as shown in FIG.

The operation of the pen type input device 1a having the above structure will be described with reference to the flowchart of FIG.

The writing detection unit 54 of the pen type input device 1a is set to H
When a high frequency component is detected from the signal output from any of the PFs 53a to 53f (step S1), the coordinate transformation matrix calculation unit 55 causes the LPFs 52d to 5f as described above.
A coordinate conversion matrix is calculated based on the signal indicating the gravity component and the signal indicating the geomagnetic component input from the gravity sensors 3a and 3b and the magnetic field sensor 4 via 2f (step S2).
Since the coordinate conversion matrix is directly calculated in this way, the number of integrations can be reduced as compared with the case where the tilt angle is calculated by performing the integration processing a plurality of times, and the error generated by the integration can be reduced, and the device The configuration can be simplified.

The coordinate conversion calculation unit 56 is composed of LPFs 52d to 52d.
Acceleration Axs, Ays, of the pen axis coordinate system (Xs, Ys, Zs) input from the acceleration sensors 2a, 2b, 2c via f.
Acceleration Axg of the gravity coordinate system (Xg, Yg, Zg) is calculated by using the coordinate conversion matrix calculated by Azs by the coordinate conversion matrix calculation unit 55.
Convert to Ayg and Azg (step S3).

As described above, the movement amount calculating unit 57 has a gravity coordinate system (Xg, Yg, Z) from when the stationary state detecting unit 572 detects the stationary state to when the stationary state is detected next.
The velocity waveform of g) is corrected so that the velocity becomes zero in each stationary state, and the corrected velocity is integrated to calculate the moving direction and moving distance of the pen tip portion 8 (step S4). In this way, the velocity waveform of the gravity coordinate system (Xg, Yg, Zg) is corrected so that the velocity becomes zero in each stationary state, the corrected velocity is integrated, and the moving direction and movement of the pen tip portion 8 are moved. Since the distance is calculated, it is possible to prevent the accumulated error due to integration from accumulating and causing an error in the trajectory detection in the pen tip portion 8.

The calculation unit 5 stores the movement direction and the movement amount of the pen tip portion 8 calculated as described above in the storage unit 6 (step S5), and the above processing (until the writing detection unit 54 detects the end of writing). Steps S2 to S5) are repeated (step S6). As a result, the pen tip portion 8 for each sampling
The moving direction and moving distance of the pen tip 8 can be stored, and the trajectory of the pen tip portion 8 can be detected.

In the above embodiment, the pen type input device 1a is used.
Are acceleration sensors 2a, 2b, 2c and gravity sensors 3a, 3
b, the magnetic field sensor 4, the operation unit 5, the storage unit 6, and the power supply unit 7 are provided. However, as shown in the configuration diagram of FIG. 6, the pen-type input device 1b includes the acceleration sensors 2a, 2b, 2c, and the gravity sensor 3. The magnetic field sensors 4a and 4b, the calculation unit 5, the storage unit 6, and the power supply unit 7 may be provided. The gravity sensor 3 detects a gravity acceleration component in either the Xs axis direction or the Ys axis direction. The magnetic field sensors 4a and 4b detect geomagnetic components in the Xs axis direction and the Ys axis direction. Here, assuming that the direction in which the gravity sensor 3 detects the gravitational acceleration component is the Xs axis direction, the following equation holds as already explained.

[0054]

[Equation 7]

Here, Vx and Vy represent outputs of vector components in the direction perpendicular to the earth's magnetism. As described above, by solving these equations as simultaneous equations, (is) g,
Since (js) g can be obtained and (ks) g is also uniquely determined, the coordinate conversion matrix can be obtained. Since the magnetic field sensor 4b has smaller elements than the gravity sensor 3b, the device can be downsized.

Further, as shown in FIG. 7, the pen type input device 1
c is the acceleration sensor 2a, 2b, 2c, the gravity sensor 3a,
3b, magnetic field sensors 4a and 4b, a calculation unit 5, a storage unit 6, and a power supply unit 7 may be provided. In this case, the following equation holds.

[0057]

[Equation 8]

In this way, the geomagnetic value N can be set to an unknown value, and even if processing is performed at points with different geomagnetic values, the handwriting can be accurately input without being affected by the geomagnetic difference. be able to.

Further, the detection values of the gravity sensors 3a and 3b and the magnetic field sensor 4 are not affected by the distances of these sensors from the pen tips, and it is sufficient that the detection axes are orthogonal to each other. Acceleration sensor 2 provided at a remote position
When acceleration is detected using a, 2b, and 2c, it is affected by the inertial force and centrifugal force due to the writing operation. Therefore, the coordinate conversion calculation unit 56 uses the acceleration sensors 2a, 2b,
Acceleration sensors 2a, 2b, 2c using the mounting position of 2c and the coordinate conversion matrix calculated by the coordinate conversion matrix calculation unit 55.
The acceleration of the pen axis coordinate system (Xs, Ys, Zs) at the mounting position of the acceleration sensor 2a, 2b, 2c detected by using is converted into the acceleration of the pen tip 8 in the gravity coordinate system (Xg, Yg, Zg). The acceleration component due to the tilting motion such as inertial force may be removed. The operation will be described below.

Gravity coordinate system at a certain time (Xg, Yg, Zg)
Let (Xga, Yga, Zga) be the coordinates of point A in
The point coordinates are the coordinates (Xga, Yga, Zga) of the pen tip portion 8 and the coordinates (Lx, Ly, Zs) of the pen axis coordinate system (Xs, Ys, Zs) of the point A.
Lz) can be obtained by the following equation from the coordinate-transformed value by the coordinate transformation matrix.

[0061]

[Equation 9]

The expression obtained by differentiating the above expression twice with respect to time is the acceleration (Axga, Ayg) in the gravity coordinate system (Xg, Yg, Zg) at point A.
a, Azga). Since the coordinate transformation matrix is also a function of time, the following equation can be obtained.

[0063]

[Equation 10]

Gravity acts in the Zg axis direction of the gravity coordinate system (Xg, Yg, Zg) regardless of the movement of the pen tip 8.
Therefore, the acceleration (Axga, Ayga, Azga) in the gravitational coordinate system (Xg, Yg, Zg) at point A is given by the following equation.

[0065]

[Equation 11]

Gravity coordinate system of point A (Xg, Yg, Zg)
Acceleration (Axga, Ayga, Azga) in the pen axis coordinate system (Xs, Ys, Zs) based on the formula already explained (Ax
When converted into sa, Aysa, Azsa), the following equation is obtained.

[0067]

[Equation 12]

Here, the conversion matrix is set as in the following equation.

[0069]

[Equation 13]

Pen axis coordinate system (Xs, Ys, Xs, Ys, Zs) of acceleration sensors 2a, 2b, 2c.
Zs) are coordinates A (Lxx, Lxy, Lxz), B respectively
(Lyx, Lyy, Lyz) and C (Lzx, Lzy, Lzz), the acceleration (Ax in the pen axis coordinate system (Xs, Ys, Zs)
s, Ays, Azs) can be expressed by the following equation.

[0071]

[Equation 14]

The above equation can be summarized as the following equation.

[0073]

[Equation 15]

From the above equation, it is possible to eliminate the influence of the tilting movement of the pen tip portion 8.

Further, in the above embodiment, the stationary state detecting section 57 is used.
2 is the gravity coordinate system (Xg, Y determined by the velocity calculation unit 573.
The stationary state is detected based on the change in speed of g, Zg), but based on the acceleration in each axis direction of the pen axis coordinate system (Xs, Ys, Zs) detected using the acceleration sensors 2a, 2b, 2c. A composite vector of accelerations in the pen axis coordinate system (Xs, Ys, Zs) is calculated, the size of the calculated composite vector and the size of the gravitational acceleration g are compared, and when the difference is within a predetermined value, the stationary state is set. May be determined. For example, the stationary state detection unit 572 uses the following formula to calculate the acceleration in the pen axis coordinate system (Xs, Ys, Zs) based on the change in the velocity of the gravity coordinate system (Xg, Yg, Zg) obtained by the velocity calculation unit 573. Compute the combined vector of

[0076]

[Equation 16]

Here, if the obtained composite vector is in a stationary state, it is equal to the absolute value of the square of the gravitational acceleration.
Therefore, the stationary state detecting unit 572 can determine whether or not the stationary state is obtained by checking whether or not the difference between the obtained combined vector and the absolute value of the square of the gravitational acceleration is within a certain range.

Further, the stationary state detecting section 572 may judge the stationary state when the accelerations in the Xg axis direction and the Yg axis direction obtained by conversion by the coordinate conversion calculating section 56 are equal to or less than a predetermined threshold value. . As a result, the load of arithmetic processing can be reduced, and the processing can be speeded up.

The stationary state detecting section 572 detects the pen axis coordinate system (X) detected by using the acceleration sensors 2a, 2b and 2c.
s, Ys, Zs), the combined vector of accelerations in the pen axis coordinate system (Xs, Ys, Zs) is calculated based on the acceleration in each axis direction, and the magnitude of the calculated combined vector and the magnitude of gravity acceleration are compared. , When the difference is within a predetermined value, and Xg obtained by conversion by the coordinate conversion calculation unit.
The stationary state may be determined when the axial acceleration and the Yg axial direction acceleration are equal to or less than a predetermined threshold value. As a result, the stationary state detection accuracy can be improved.

Further, the entire housing of the pen-type input device 1 or the portion covering the magnetic field sensor 4 may be formed of a member through which a magnetic field easily passes, thereby improving the magnetic field detection accuracy.

Further, for example, when writing with the pen type input device 1 on the writing surface 21 provided on the desk 20 as shown in FIG. 8, the magnetic field detected by the magnetic field sensor 4 incorporated in the pen type input device 1 A magnetic field generation source 30 may be provided as a generation source of the. Here, consider a writing surface using normal vision or the like. Further, the magnetic flux density of the magnetic field generated by the magnetic field generation source 30 is made larger than that due to the earth magnetism, and the influence due to the earth magnetism is reduced. Further, a plurality of magnetic field generation sources 30 are arranged so as to generate a parallel magnetic field around the writing surface. By doing so, the detection accuracy of the magnetic field can be improved.

Furthermore, for example, as shown in FIG. 9, the magnetic field generation source 30 may be built in the portable information terminal device 40 to obtain the inclination of the pen type input device 1. Here, examples of the portable information terminal device 40 include a notebook personal computer, an electronic notebook, and the like. By doing so, the inclination of the pen shaft 8 can be accurately detected by the portable information terminal device 40, and accurate writing input can be performed.

[0083]

As described above, according to the present invention, the inclination angles of the pen axis in the Xs axis direction and the Ys axis direction are obtained from the components of gravity applied in the Xs axis direction and the Ys axis direction of the pen axis coordinate system. A coordinate transformation matrix that performs coordinate transformation from the pen axis coordinate system to the gravity coordinate system based on the inclination angle of the pen axis and the vector component of the geomagnetism in the direction orthogonal to the Zs axis of the pen axis coordinate system, and the calculated coordinate transformation matrix The acceleration of the pen axis coordinate system detected by using the acceleration sensor is converted to the acceleration of the gravity coordinate system, and the moving direction and movement distance of the pen tip are calculated based on the acceleration of the gravity coordinate system obtained by the conversion. Therefore, it is possible to accurately detect the writing trajectory without the influence of the inclination of the pen axis.

Further, the accelerations in the Xs axis direction, the Ys axis direction and the Zs axis direction of the pen axis coordinate system, the gravity component applied in the Xs axis direction and the Ys axis direction, and the geomagnetic vector component in one direction orthogonal to the Zs axis are calculated. The tilt angle of the pen axis in the Xs-axis direction and the Ys-axis direction is detected from the detected gravity component applied in the Xs-axis direction and the Ys-axis direction of the pen-axis coordinate system. Based on the vector component of the geomagnetism in the direction orthogonal to the Zs axis, a coordinate transformation matrix for performing coordinate transformation from the pen axis coordinate system to the gravity coordinate system is calculated, and the pen detected using the acceleration sensor is calculated using the calculated coordinate transformation matrix. Since the acceleration in the axis coordinate system is converted into the acceleration in the gravity coordinate system, the angle sensor can be adjusted easily and the number of integrations can be reduced compared to the case where the tilt angle is obtained by integration and then the coordinates are converted. , By integration The occurrence of the difference can be reduced.

The three acceleration sensors output signals indicating the acceleration in the Xs-axis direction, the Ys-axis direction and the Zs-axis direction of the pen axis coordinate system, and the gravity sensors respectively output the signals in the Xs-axis direction of the pen axis coordinate system. It outputs a signal indicating the gravity component applied in the Ys axis direction, and the magnetic field sensor outputs a signal indicating the vector component of the geomagnetism in two directions orthogonal to the Zs axis of the pen axis coordinate system. A magnetic field sensor with a small size can be used instead, and the device can be downsized.

The three acceleration sensors output signals indicating the accelerations in the Xs-axis direction, the Ys-axis direction and the Zs-axis direction of the pen axis coordinate system, and the two gravity sensors respectively output Xs of the pen axis coordinate system. The magnetic field sensor outputs a signal indicating the gravity component applied in the axial direction and the Ys axis direction, and the magnetic field sensor is Zs in the pen axis coordinate system.
Since a signal indicating the vector component of the geomagnetism in two directions orthogonal to the axis is output, it is possible to calculate using the geomagnetism as a variable,
It is possible to eliminate the difference in the detection result due to the difference in the geomagnetism of the use place.

Further, the high frequency component of the signal from the acceleration sensor, the gravity sensor and the magnetic field sensor is transmitted with the frequency near 10 Hz as a boundary, and the writing start is judged based on the signal containing the high frequency component first, It is possible to determine whether or not the writing is being performed with a simple configuration in the field where the end of the writing is determined based on the signal including the high frequency component until the end.

Further, since the acceleration of the pen axis coordinate system detected by the acceleration sensor using the mounting position of each acceleration sensor and the coordinate conversion matrix is converted into the acceleration of the pen tip in the gravity coordinate system, the acceleration sensor is used. It is possible to remove the component of the acceleration detected by the tilting motion centered on the pen tip.

Further, since the stationary state is detected based on the change in the velocity of the gravity coordinate system and the velocity of the gravity coordinate system is reset to zero every time the stationary state is detected, a cumulative error of the velocity due to integration may occur. Can be prevented.

Further, the stationary state is detected based on the change in the velocity of the gravity coordinate system, and the velocity waveform of the gravity coordinate system from the detection of the stationary state to the next detection of the stationary state is the velocity in each stationary state. Since the correction is made so that it becomes zero, it is possible to more accurately eliminate the error caused by the integration.

Further, a combined vector of accelerations in the pen axis coordinate system is calculated based on the acceleration in each axis direction of the pen axis coordinate system detected using the acceleration sensor, and the size of the calculated combined vector and the magnitude of gravitational acceleration are calculated. Are compared, and when the difference is within a predetermined value, it is determined to be the stationary state, and thus it is possible to accurately determine whether or not the stationary state.

Further, when the acceleration in the Xg-axis direction and the acceleration in the Yg-axis direction is equal to or less than the predetermined threshold value, it is determined that the vehicle is in the stationary state.

Further, a combined vector of accelerations in the pen axis coordinate system is calculated based on the acceleration in each axis direction of the pen axis coordinate system, and the size of the calculated combined vector and the magnitude of gravitational acceleration are compared. When it is within a predetermined value and when the acceleration in the Xg-axis direction and the acceleration in the Yg-axis direction is equal to or less than the predetermined threshold value, the stationary state is determined, so that it can be more accurately determined whether or not the stationary state.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a calculation unit.

FIG. 3 is an explanatory diagram of a coordinate system.

FIG. 4 is a waveform diagram of a speed signal.

FIG. 5 is a flowchart showing the operation of the pen-type input device.

FIG. 6 is a configuration diagram of a pen-type input device including two magnetic field sensors.

FIG. 7 is a configuration diagram of a pen-type input device including two gravity sensors and two magnetic field sensors.

FIG. 8 is a perspective view of a writing surface.

FIG. 9 is a perspective view of a portable information terminal device.

[Explanation of symbols]

1 Pen type input device 2 Accelerometer 3 Gravity sensor 4 magnetic field sensor 5 computing section 54 Writing detector 55 Coordinate conversion matrix operation unit 56 Coordinate conversion calculation unit 57 Movement amount calculation unit 572 Stationary state detection unit 573 Speed correction unit 8 Pen tip

Continuation of the front page (56) Reference JP-A-6-44005 (JP, A) JP-A-6-289986 (JP, A) JP-A-7-200127 (JP, A) JP-A-7-49745 (JP , A) JP 6-67799 (JP, A) JP 7-84716 (JP, A) JP 6-230886 (JP, A) JP 4-256009 (JP, A) JP 7-295736 (JP, A) JP-A-8-95697 (JP, A) JP-A-7-159165 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G06F 3/03 -3/037

Claims (11)

(57) [Claims] 1. An acceleration sensor, a gravity sensor, a magnetic field sensor, and an arithmetic unit, wherein the acceleration sensor has an Xs axis direction, a Ys axis direction, and a pen axis coordinate system (Xs, Ys, Zs) with the pen axis as the Zs axis. The gravity sensor outputs a signal indicating acceleration in the Zs axis direction, and the gravity sensor measures the Xs axis direction of the pen axis coordinate system (Xs, Ys, Zs) and the Y axis.
The magnetic field sensor outputs a signal indicating a gravity component applied in the s-axis direction, and the magnetic field sensor outputs a signal indicating a geomagnetic vector component in a direction orthogonal to the Zs axis of the pen axis coordinate system (Xs, Ys, Zs),
The calculation unit includes a coordinate conversion matrix calculation unit, a coordinate conversion calculation unit, and a movement amount calculation unit. The coordinate conversion matrix calculation unit calculates Xs based on the gravity component applied in the Xs axis direction and the Ys axis direction detected using the gravity sensor. The tilt angle of the pen axis in the axial direction and the Ys axis direction is obtained, and the obtained tilt angle of the pen axis and Zs detected using the magnetic field sensor
Based on the vector component of the geomagnetism in the direction orthogonal to the axis, coordinate conversion from the pen axis coordinate system (Xs, Ys, Zs) to the gravity coordinate system (Xg, Yg, Zg) with the axis extending in the gravitational acceleration direction as the Zg axis. The coordinate conversion matrix to be performed is calculated, and the coordinate conversion calculation unit uses the coordinate conversion matrix calculated by the coordinate conversion matrix calculation unit to detect the pen axis coordinate system (Xs, Ys, Z
s) is converted into the acceleration of the gravity coordinate system (Xg, Yg, Zg), and the movement amount calculation unit is based on the acceleration of the gravity coordinate system (Xg, Yg, Zg) calculated by the coordinate conversion calculation unit. A pen-type input device, characterized in that the moving direction and the moving distance of the pen tip portion are calculated. 2. An acceleration sensor having three acceleration sensors, two gravity sensors and one magnetic field sensor, each of the three acceleration sensors being in the Xs axis direction of the pen axis coordinate system (Xs, Ys, Zs) and Ys.
Output the signal showing the acceleration in the axial direction and Zs axis direction, and
Each of the gravity sensors has a pen axis coordinate system (Xs, Ys, Z
s) outputs a signal indicating the component of gravity applied in the Xs axis direction and the Ys axis direction, and the magnetic field sensor uses the pen axis coordinate system (Xs, Ys,
The pen type input device according to claim 1, which outputs a signal indicating a vector component of geomagnetism in one direction orthogonal to the Zs axis of (Zs). 3. An acceleration sensor having three acceleration sensors, one gravity sensor and two magnetic field sensors, each of the three acceleration sensors being in the Xs axis direction of the pen axis coordinate system (Xs, Ys, Zs) and Ys.
A signal indicating the acceleration in the axial direction and the Zs axis direction is output, and the gravity sensor outputs a signal indicating the gravity component applied in the Xs axis direction or the Ys axis direction of the pen axis coordinate system (Xs, Ys, Zs), respectively. The magnetic field sensor is a pen axis coordinate system (Xs, Ys, Z
s) outputs a signal indicating the vector component of the geomagnetism in two directions orthogonal to the Zs axis, and the coordinate conversion matrix calculation unit is based on the gravity component applied in the Xs axis direction or the Ys axis direction detected using the gravity sensor. Then, the tilt angle of the pen axis in the Xs axis direction or the Ys axis direction is calculated, and the pen axis coordinate is calculated based on the calculated tilt angle of the pen axis and the vector component of the geomagnetism in two directions orthogonal to the Zs axis detected using the magnetic field sensor. Gravity coordinate system (Xg, Y) with the axis extending from the system (Xs, Ys, Zs) in the direction of gravity acceleration as the Zg axis.
The pen type input device according to claim 1, wherein a coordinate conversion matrix for performing coordinate conversion to g, Zg) is calculated. 4. An acceleration sensor having three acceleration sensors, two gravity sensors and two magnetic field sensors, each of the three acceleration sensors being in the Xs axis direction of the pen axis coordinate system (Xs, Ys, Zs) and Ys.
Output the signal showing the acceleration in the axial direction and Zs axis direction, and
Each of the gravity sensors has a pen axis coordinate system (Xs, Ys, Z
s) outputs a signal indicating the component of gravity applied in the Xs axis direction and the Ys axis direction, and the magnetic field sensor uses the pen axis coordinate system (Xs, Ys,
Zs) outputs a signal indicating a vector component of the geomagnetism in two directions orthogonal to the Zs axis, and the coordinate transformation matrix calculation unit is based on the gravity component applied in the Xs axis direction and the Ys axis direction detected using the gravity sensor. The tilt angle of the pen axis in the Xs axis direction and the Ys axis direction is calculated, and the pen axis coordinate is calculated based on the calculated tilt angle of the pen axis and the vector component of the geomagnetism in two directions orthogonal to the Zs axis detected by the magnetic field sensor. Gravity coordinate system (Xg, Yg, Zs) with the axis extending from the system (Xs, Ys, Zs) in the direction of gravity acceleration as the Zg axis.
The pen-type input device according to claim 1, wherein a coordinate conversion matrix for performing coordinate conversion to Zg) is calculated. 5. A high-pass filter that transmits a high-frequency component of a signal from an acceleration sensor, a gravity sensor, and a magnetic field sensor with a frequency near 10 Hz as a boundary, and the high-frequency component is the first one of the signals passed through the high-pass filter. 5. The writing start is determined based on a signal including a signal, and the writing end is determined based on a signal including a high-frequency component up to any one of the signals that have passed through the high-pass filter. Pen type input device. 6. The pen-axis coordinate system (Xs, which is detected by the acceleration sensor by using the coordinate conversion matrix calculated by the coordinate conversion matrix and the coordinate conversion matrix and the mounting position of each acceleration sensor by the coordinate conversion calculation unit. 5. The pen type input device according to claim 1, wherein the acceleration of (Ys, Zs) is converted into the acceleration of the pen tip in the gravity coordinate system (Xg, Yg, Zg). 7. The calculation unit includes a stationary state detection unit and a speed correction unit, and the stationary state detection unit includes a gravity coordinate system (Xg, Yg, Z).
Gravity coordinate system (Xg, Y)
g, Zg) detects the stationary state based on the change in speed, and the speed correction unit integrates the acceleration of the gravity coordinate system (Xg, Yg, Zg) once each time the stationary state detection unit detects the stationary state. The pen type input device according to any one of claims 1 to 4, wherein the velocity of the gravity coordinate system (Xg, Yg, Zg) obtained by the above is reset to zero. 8. The calculation unit includes a stationary state detection unit and a velocity correction unit, and the stationary state detection unit includes a gravity coordinate system (Xg, Yg, Z).
Gravity coordinate system (Xg, Y)
g, Zg) detects the stationary state based on the change in speed, and the speed correction unit detects the stationary state from the stationary state detecting unit until the next stationary state is detected (Xg, Yg, Zg)
Gravity coordinate system (Xg, Yg,
The pen type input device according to claim 1, wherein the velocity waveform of Zg) is corrected so that the velocity becomes zero in each stationary state. 9. The pen state coordinate system (Xs, Ys, Zs) is based on the acceleration in each axis direction of the pen axis coordinate system (Xs, Ys, Zs) detected by using an acceleration sensor.
9. The pen mold according to claim 7 or 8, wherein a combined vector of accelerations is calculated, the magnitude of the calculated combined vector is compared with the magnitude of gravitational acceleration, and when the difference is within a predetermined value, the stationary state is determined. Input device. 10. The stationary state detecting section determines that the stationary state is when the Xg axis direction and Yg axis direction accelerations obtained by conversion by the coordinate conversion calculating section are equal to or less than a predetermined threshold value. Pen type input device. 11. The stationary state detection unit is based on the acceleration in each axial direction of the pen axis coordinate system (Xs, Ys, Zs) detected using an acceleration sensor, and the pen axis coordinate system (Xs, Ys, Z).
s) calculates a composite vector of accelerations, compares the size of the calculated composite vector and the magnitude of gravitational acceleration, and when the difference is within a predetermined value, and
9. The pen-type input device according to claim 7, wherein when the Xg-axis direction and Yg-axis direction accelerations obtained by conversion by the coordinate conversion calculation unit are equal to or less than a predetermined threshold value, it is determined as a stationary state.