JPH10307676A - Pen type input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable accurate writing input by the pen type input device. SOLUTION: A coordinate conversion arithmetic part 60 converts the acceleration of a pen axis coordinate system detected on the basis of an angle of rotation during writing by using an acceleration sensor into the acceleration of a gravity coordinate system. A speed arithmetic part 62 calculates a speed by integrating the acceleration after the coordinate conversion. A speed zero detection part 64 detects the stop state of a pen tip part on the basis of the high frequency component of the acceleration signal while the pen tip part is in contact with a writing surface. A speed correction part 65 when detecting the pen tip part being in a stop state sets the speed of the gravitational coordinate system to zero. A movement quantity arithmetic part 66 calculates the moving direction and movement distance of the device on the basis of the speed of the gravitational coordinate system.

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 such as computer devices. With the miniaturization of computer devices, the need for portable terminal devices has increased and the number of users has been increasing year by year. Therefore, a small input device has been required.

[0003] There is a limit in miniaturizing a keyboard in terms of a human interface, and it is not practical as an input device of a portable terminal device. Although a mouse can be downsized as a pointing device, it is not suitable for inputting figures, characters, and the like.

For this reason, a pen-type input device using a tablet and a pen is often used as an input device for a portable terminal device. In order to further reduce the size of the pen-type input device using the tablet, the size of the tablet becomes a problem. Therefore, for example, a data input device described in JP-A-7-84716, a handwriting input device described in JP-A-7-200127, and a pen-type computer input device described in JP-A-6-67799 are disclosed. Tablet-less input devices such as. JP-A-7-847
The data input device disclosed in Japanese Patent Application Publication No. 16 detects the direction and amount of movement of the device based on signals indicating the polarity and amplitude from vibrating gyros arranged at right angles to each other. Furthermore, the handwriting input device disclosed in Japanese Patent Application Laid-Open No. 7-200127 obtains the moving direction and the moving distance of the device based on signals from two acceleration sensors. The pen-type computer input device disclosed in Japanese Patent Application Laid-Open No. 6-67799 has a gyro and two acceleration sensors, calculates the rotation of the pen axis using the gyro, and calculates the calculated rotation and two rotations. The moving direction and the moving distance of the apparatus are obtained based on the signal from the acceleration sensor.

Further, as a device provided with two sets of acceleration sensors for detecting acceleration in two directions perpendicular to a plane perpendicular to the pen axis, for example, a pencil type input device disclosed in Japanese Patent Laid-Open Publication No. After integrating the outputs of the two sets of acceleration sensors, the influence of the mounting position of the acceleration sensor is corrected, and the direction and amount of movement of the pen tip are detected.

[0006] Further, the present invention is not related to a pen-type input device, but is used for, for example, a game machine, and has a moving speed of a human head,
Japanese Patent Application Laid-Open No. 7-29424 detects the position, posture, and the like.
The position sensor disclosed in Japanese Patent Publication No. 0 is provided with an acceleration sensor that detects acceleration in the X-axis direction, the Y-axis direction, and the Z-axis direction, and a gyro that detects angular velocities around the X-axis, Y-axis, and Z-axis. Based on the detected acceleration and angular velocity, a calculation of the strap-down method is performed to detect the moving speed, position, posture, and orientation of the head.

[0007]

However, the data input device described in Japanese Patent Application Laid-Open No. 7-84716 detects the rotational movement of the wrist and inputs the moving direction and the moving distance. Is not suitable.

Further, in the handwriting input device disclosed in Japanese Patent Application Laid-Open No. 7-200127, since there is no means for correcting the inclination of the device, it cannot be corrected when the device has a dynamic inclination. The normal writing operation involves a dynamic tilt of the device, which may result in inaccurate detection results.

Further, in the pen-type computer input device disclosed in Japanese Patent Application Laid-Open No. 6-67799, the rotation of the pen shaft is calculated, but it cannot be corrected when the device involves a dynamic inclination. .

In the pencil type input device disclosed in Japanese Patent Application Laid-Open No. Hei 6-230886, correction is performed after integration of acceleration. However, integration of acceleration before correction allows detection of an error. It becomes difficult and cannot make accurate corrections. Further, it does not consider that the detection component of the acceleration at the pen tip changes due to the inclination of the pen axis.

The position sensor disclosed in Japanese Patent Application Laid-Open No. 7-294240 spatially detects the moving speed, position, posture, and orientation of the head, and thus employs a complicated calculation process. Since the pen-type input device is required to be miniaturized, the moving direction and the moving distance on the writing surface must be accurately detected by simple arithmetic processing.

Further, it is difficult to provide three acceleration sensors in the pen tip portion of the pen-type input device, and if the mounting position of the acceleration sensor is far from the pen tip portion, the acceleration sensor may be tilted by the pen shaft. Components may be picked up. The component due to the tilting movement of the pen shaft was large, and had a great influence on the detection accuracy.

Further, in order to detect a handwriting trajectory based on the acceleration detected by using the acceleration sensor, the integral operation must be performed twice, and errors due to the two integral operations have accumulated. In particular, the longer the measurement time, the larger the accumulated error.

SUMMARY OF THE INVENTION The present invention has been made to solve such a disadvantage, and an object of the present invention is to provide a small pen-type input device for accurately detecting handwriting input with a simple configuration.

[0015]

A pen-type input device according to the present invention has a plurality of acceleration sensors, and detects a moving direction and a distance of the device based on a signal indicating acceleration output from each acceleration sensor. The type input device has a zero speed detection unit and a speed correction unit, and the zero speed detection unit detects a high frequency component of an acceleration signal from each acceleration sensor in a state where the pen tip is in contact with the writing surface. The acceleration correction unit detects whether the pen tip is in a stopped state, and when the acceleration correction unit detects that the pen tip is in a stopped state, the speed calculated based on the acceleration at the time of the detection is set to zero. The speed is corrected, the moving direction and the distance of the apparatus are detected based on the corrected speed, and the occurrence of a cumulative error is prevented.

The pen-type input device has three acceleration sensors, three gyros, and a calculation unit. The three acceleration sensors are respectively in the Xs axis direction of a pen coordinate system (Xs, Ys, Zs). A signal indicating acceleration in the Ys-axis direction and Zs-axis direction is output. The three gyros output signals indicating rotation angular velocities around the Xs axis, around the Ys axis, and around the Zs axis, respectively. Unit, a writing angle rotation unit, a coordinate conversion calculation unit, a speed calculation unit, a speed zero detection unit, a speed correction unit, and a movement amount calculation unit, and the initial rotation angle calculation unit detects using the acceleration sensor in a stationary state. Pen axis coordinate system (X
s, Ys, Zs), the initial rotation angle of the device is calculated based on the acceleration, and during writing, the rotation angle calculation unit calculates the initial rotation angle calculated by the initial rotation angle calculation unit and the rotation angular speed detected using the gyro. The rotation angle during writing is calculated, and the coordinate conversion operation unit detects the pen axis coordinate system (Xs, Ys, Zs) detected using each acceleration sensor based on the rotation angle during writing calculated by the rotation angle operation unit during writing. Acceleration in the gravitational coordinate system (X
g, Yg, Zg), and the velocity calculator calculates the gravitational coordinate system (Xg, Yg,
Zg) is integrated to obtain the gravitational coordinate system (Xg, Y
g, Zg), and the zero speed detecting unit detects the high frequency components of the signals from each acceleration sensor and each gyro when the pen tip is in contact with the writing surface. When the speed correction unit detects that the pen tip is in a stopped state, the speed correction unit detects whether or not the pen tip is stopped, and the speed correction unit calculates the gravity coordinate system (Xg, Yg) calculated by the speed calculation unit at the time of the detection. , Zg), the gravity coordinate system (Xg, Yg, Z) calculated by the speed calculation unit so that the speed becomes zero.
g), the moving amount calculation unit calculates the moving direction and the moving distance of the device based on the speed in each axis direction in the gravitational coordinate system (Xg, Yg, Zg), and the influence of the pen shaft inclination. And prevents the occurrence of a cumulative error in speed.

Further, the calculation unit includes an angular acceleration calculation unit and an acceleration correction unit. The angular acceleration calculation unit obtains a rotation angular acceleration from the rotation angular velocity detected using three gyros, and the acceleration correction unit includes three acceleration correction units. Inclined motion of the acceleration detected using three acceleration sensors based on the rotational angular velocity detected using the gyro, the rotational angular acceleration calculated by the angular acceleration calculation unit, and the mounting position of each acceleration sensor around the pen tip And the acceleration of the pen axis coordinate system (Xs, Ys, Zs) at the mounting position of the acceleration sensor is corrected based on the calculated acceleration component due to the tilting motion, and the pen axis coordinate system (Xs , Ys, Zs).
The coordinate transformation calculation unit corrects the pen tip coordinate of the pen tip in the pen axis coordinate system (Xs, Ys,
Zs) is converted into an acceleration based on a gravitational coordinate system (Xg, Yg, Zg), and the influence of the tilt motion of the pen shaft caused by the mounting position of the acceleration sensor being away from the pen tip is removed.

When the zero speed detector detects that the acceleration in the gravitational coordinate system (Xg, Yg, Zg) is equal to or lower than a predetermined threshold for a predetermined period of time, the pen tip stops. The stop state is detected with a simple configuration by judging the state.

Further, the zero speed detector detects the acceleration in the gravity coordinate system (Xg, Yg, Zg) and the gravity coordinate system (Xg, Yg).
g, Zg), when it is detected that the value obtained by differentiating the acceleration with respect to time is equal to or less than a predetermined threshold value, it is determined that the pen tip is in a stopped state, and the stopped state is accurately detected with a simple configuration. I do.

Further, the zero speed detector detects that the difference between the magnitude of the acceleration detected by using the acceleration sensor and the magnitude of the gravitational acceleration is equal to or less than a predetermined threshold for a predetermined time or more. It is determined that the pen tip is in the stopped state.

The zero speed detector may be configured such that the difference between the magnitude of the acceleration detected by using the acceleration sensor and the magnitude of the gravitational acceleration is equal to or less than a predetermined threshold value, and the pen axis coordinate detected by using the acceleration sensor. When it is detected that the value obtained by differentiating the acceleration by the system (Xs, Ys, Zs) with respect to time is equal to or less than a predetermined threshold value, it is determined that the pen tip is in a stopped state, and the stopped state is accurately and quickly detected. I do.

The zero speed detector determines whether the pen tip is in a stopped state when the pen tip is in contact with the writing surface, and determines whether the pen tip is moving in the air or not. This prevents erroneous detection of the case.

The zero speed detector compares the time during which no high-frequency component is detected from the acceleration signal of each acceleration sensor with a predetermined time interval, and determines whether the time is shorter than the predetermined time interval. Determines that the pen tip is in a stopped state, and if the duration is longer than a predetermined time interval, determines that the pen tip is in a state of stopping for a long time or in a state of moving in the air. In addition, it is possible to quickly detect that the pen tip is in a stopped state, and to detect whether the pen tip is in contact with the writing surface without providing a separate sensor or the like.

When the zero speed detector detects the stop state of the pen tip, the speed corrector integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) at the time of detecting the stop state. The obtained speed is reset to zero to prevent the occurrence of an accumulated speed error.

When the zero speed detector detects the stop state of the pen tip, the speed corrector integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when the stop state is detected. The speed of the gravitational coordinate system (Xg, Yg, Zg) from the detection of the previous stop state to the detection of the current stop state is corrected so that the obtained speed becomes zero, and the occurrence of a speed error is more accurately performed. To prevent.

When the zero speed detector detects the stop state of the pen tip, the speed corrector integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when the stop state is detected. The obtained speed is set to zero, and the correction by spline interpolation is performed so that the acceleration change and the speed change of the gravitational coordinate system (Xg, Yg, Zg) are continuous, so that the trajectory of the pen tip can be accurately detected. I do.

When the zero speed detecting unit detects the stop state of the pen tip, the speed correction unit integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when the stop state is detected. A correction amount for making the obtained speed zero is calculated, and the speed of the gravitational coordinate system (Xg, Yg, Zg) until the next stop state is detected is corrected based on the calculated correction amount.

When the zero speed detector detects the stop state of the pen tip, the speed correction unit integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when the stop state is detected. The initial rotation angle is corrected so that the obtained speed becomes zero, thereby eliminating the accumulated error of the speed detection and eliminating the rotation angle detection error of the pen-type input device.

When the zero speed detector detects the stop state of the pen tip, the speed corrector integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when the stop state is detected. The correction amount is calculated so that the obtained speed becomes zero, and the rotation angle during writing until the next stop state is detected is corrected based on the calculated correction amount.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pen-type input device according to the present invention is for inputting characters, symbols, figures, and the like to a computer device or the like. The pen-type input device is a pen axis coordinate system (Xs, Ys, Zs) detected using an acceleration sensor in a stationary state.
Calculates the initial rotation angle of the device based on the acceleration in, calculates the rotation angle during writing based on the calculated initial rotation angle and the rotation angular speed detected using the gyro, and based on the calculated rotation angle during writing. The acceleration in the pen axis coordinate system (Xs, Ys, Zs) detected using each acceleration sensor is defined as a gravity coordinate system (Xg, Y
g, Zg), and calculates the moving direction and the moving distance of the pen tip based on the converted acceleration to accurately detect the handwriting.

Here, the above processing includes an integration processing.
An error may occur. Further, there may be a case where a detection error of the rotation angle of the pen shaft occurs, and the component of the gravitational acceleration cannot be accurately removed. Therefore, these effects are eliminated, and the accurate movement amount and movement distance are calculated.

The pen-type input device has, for example, three acceleration sensors, three gyros, a pressure-sensitive sensor, and a calculation unit.
Each of the three acceleration sensors has a pen axis coordinate system (Xs, Y
(s, Zs) are output in the Xs-axis direction, the Ys-axis direction, and the Zs-axis direction. Each of the three gyros outputs a signal indicating a rotational angular velocity around the Xs axis, around the Ys axis, and around the Zs axis in the pen axis coordinate system (Xs, Ys, Zs). The pressure-sensitive sensor detects, for example, pressure from a writing surface applied to the pen tip.

The calculation unit includes, for example, an AD converter, a high-pass filter (hereinafter, referred to as “HPF”), a low-pass filter (hereinafter, referred to as “LPF”), a stillness determination unit, an initial rotation angle calculation unit, and a rotation angle change calculation unit. It includes a rotation angle calculation unit during writing, an angular acceleration calculation unit, an acceleration correction unit, a coordinate conversion calculation unit, a gravitational acceleration removal unit, a speed calculation unit, a high frequency discrimination unit, a zero speed detection unit, a speed correction unit, and a movement amount calculation unit. The AD converter converts an analog signal from the acceleration sensor, the gyro, and the pressure-sensitive sensor into a digital signal. The HPF extracts high frequency components generated by friction between the pen tip and the writing surface from signals from the acceleration sensor and the gyro. The LPF extracts low frequency components generated by movement of the pen tip from signals from the acceleration sensor and the gyro. The stationary state determination unit determines whether or not the vehicle is in the stationary state based on signals from the acceleration sensors and the gyros, for example.

The initial rotation angle calculation unit detects a pen axis coordinate system (Xs, Ys,
The initial rotation angle of the device is calculated based on the acceleration in Zs). The rotation angle change calculation unit calculates a change in the rotation angle during writing based on the rotation angular velocities around the Xs axis, around the Ys axis, and around the Zs axis detected using a gyro. The writing rotation angle calculation unit calculates the rotation angle during writing based on the change in the rotation angle calculated by the rotation angle change calculation unit and the initial rotation angle calculated by the initial tilt rotation angle calculation unit. The angular acceleration calculation unit calculates the rotational angular acceleration from the rotational angular velocities detected using the three gyros. The acceleration correction unit is a pen tip of the acceleration detected by using the three acceleration sensors based on the rotation angular velocity detected by using the three gyros, the rotation angular acceleration calculated by the angular acceleration calculation unit, and the mounting position of each acceleration sensor. An acceleration component due to the tilting motion centered on the part is calculated, and the acceleration in the pen axis coordinate system (Xs, Ys, Zs) at the mounting position of the acceleration sensor is corrected based on the calculated acceleration component due to the tilting motion, and the pen tip portion is corrected. Is calculated in the pen axis coordinate system (Xs, Ys, Zs). The coordinate conversion operation unit calculates the acceleration of the pen tip in the pen axis coordinate system (Xs, Ys, Zs) obtained by correcting the acceleration based on the rotation angle during writing in the gravity coordinate system (X
g, Yg, Zg). The gravitational acceleration removing unit converts the gravitational coordinate system (X
g, Yg, Zg), the gravitational acceleration component is removed from the acceleration. The speed calculation unit integrates the acceleration obtained by removing the gravitational acceleration component by the gravitational acceleration removing unit, and calculates the gravitational coordinate system (X
g, Yg, Zg).

The high frequency discriminating unit determines whether any of the acceleration signal and the rotational angular velocity signal input via the HPF contains a high frequency component due to friction between the pen tip and the writing surface. The zero speed detector detects whether or not the pen tip has stopped moving, based on the pressure from the writing surface on the pen tip using the pressure-sensitive sensor and the result of the discrimination by the high frequency discriminator. For example, when the high frequency determination unit determines that neither the acceleration signal nor the rotation angular velocity signal input via the HPF includes a high frequency component due to friction between the pen tip and the writing surface, the pen tip may be used for writing. There are a case where the movement is stopped on the surface and a case where the pen tip is in the air. If these two cannot be distinguished, it is not possible to accurately detect whether the pen tip has stopped moving on the writing surface. Therefore, the zero-speed detector detects that the high-frequency determination unit determines that neither the acceleration signal nor the rotation angular velocity signal input via the HPF contains a high-frequency component due to friction between the pen tip and the writing surface. And, when detecting the pressure from the writing surface against the pen tip using the signal from the pressure-sensitive sensor, the pen tip stops moving on the writing surface at the `` turning angle '' of the writing trajectory, etc. Is determined to be in a stopped state (stop state).

When the speed zero detecting unit detects that the pen tip is stopped on the writing surface, the speed correcting unit sets the speed calculating unit so that the speed calculated by the speed calculating unit at that time becomes zero. Calculated by the gravity coordinate system (Xg, Yg, Z
Correct the speed in g). Here, as a method of correcting the speed in the gravity coordinate system (Xg, Yg, Zg) calculated by the speed calculation unit to be zero, for example, the speed in the direction in which the stationary state is detected is reset to zero, and the speed is reset to zero. The error caused by the reset is calculated using the gravity coordinate system (X
g, Yg, Zg), or subtract the velocity in the gravitational coordinate system from the previous detection of the stationary state to the current detection of the stationary state so that the velocity when the stationary state is detected becomes zero. Or Further, the speed correction unit may correct the initial rotation angle so that the speed in the direction in which the stationary state is detected becomes zero.

The moving amount calculation unit is provided with a gravity coordinate system (Xg, Yg, Z).
The moving direction and the moving distance of the apparatus are calculated based on the velocity in each axial direction in g), and the handwriting of the apparatus is accurately detected.

[0038]

FIG. 1 is a block diagram of a pen-type input device 1 according to an embodiment of the present invention. In the following description, a coordinate system in which the pen tip 8 is the origin and the pen axis 9 is the Zs axis as shown in FIG. 2 is referred to as a pen axis coordinate system (Xs, Ys, Zs). The axes are described as an Xs axis and a Ys axis. A coordinate system in which an axis extending in the direction of gravitational acceleration is the Zg axis is called a gravity coordinate system (Xg, Yg, Zg), and two axes orthogonal to the Zg axis are called an Xg axis and a Yg axis. Furthermore, the writing surface, the Xg axis and the Yg
It is assumed that the axis is coincident with the plane formed by the axis.

As shown in the figure, the pen-type input device 1 includes acceleration sensors 2a, 2b, 2c, gyros 3a, 3b, 3
c, a pressure sensor 4, a processing unit 5, a storage unit 6, and a power supply unit 7. The acceleration sensors 2a, 2b, and 2c each have X
A signal provided in the Xsa-axis direction parallel to the s-axis, the Ysa-axis direction parallel to the Ys-axis direction, and the Zs-axis direction, and indicates acceleration (Axs, Ays, Azs) in the Xsa-axis direction, the Ysa-axis direction, and the Zsa-axis direction. Is output. The acceleration sensors 2a, 2b, and 2c may be small, high-sensitivity, and have good linearity with respect to acceleration detection, and may be any of a piezoresistive sensor, a piezoelectric sensor, and a capacitance sensor. Gyro 3
a, 3b and 3c are Xs parallel to the Xs axis and the Xsa axis, respectively.
around the b axis, around the Ysb axis parallel to the Ys axis and the Ysa axis, and Zs
A signal indicating the rotational angular velocity around the axis (ωxs, ωys, ωzs) is output. The gyros 3a, 3b, and 3c may be small as long as they have good scale factors (accuracy of rotational motion detection) and drift rates (stability of output offset).
Any of a rotary gyro, a vibration gyro, an optical gyro, and the like may be used. The pressure-sensitive sensor 4 is attached to, for example, the pen tip 8 and outputs a detection signal of a pressure applied to the pen tip 8 from a writing surface.

The processing section 5 has an input section 5a as shown in FIG.
And an operation unit 5b. The input unit 5a includes an AD converter 51
a to 51g, HPFs 52a to 52f, and LPFs 53a to 5
3f. The AD converters 51a to 51g are respectively composed of acceleration sensors 2a, 2b, 2c, gyros 3a, 3b,
3c and an analog signal from the pressure sensor 4 are converted into a digital signal. The HPFs 52a to 52f are, for example, approximately 10
High frequency components of signals from the acceleration sensors 2a, 2b, 2c and the gyros 3a, 3b, 3c generated by the frictional force between the pen tip 8 and the writing surface at a cut negative / unfrequency of about Hz are extracted. The LPFs 53a to 53f block high-frequency components of signals from the acceleration sensors 2a, 2b, 2c and the gyros 3a, 3b, 3c generated by the frictional force between the pen tip 8 and the writing surface. This is because the acceleration sensors 2a, 2b, 2c and the gyros 3a, 3b,
This is because a high frequency component is generated in the signal from 3c.

The operation unit 5b includes a stationary determination unit 54, an initial rotation angle operation unit 55, a rotation angle change operation unit 56, a writing rotation angle operation unit 57, an angular acceleration operation unit 58, and an acceleration correction unit 5.
9, a coordinate transformation calculating unit 60, a gravitational acceleration removing unit 61, a speed calculating unit 62, a high frequency discriminating unit 63, a zero speed detecting unit 64, a speed correcting unit 65, and a moving amount calculating unit 66. The stillness determination unit 54 includes the acceleration sensors 2a, 2b, 2c and the gyro 3
It is determined based on the signals from a, 3b and 3c whether or not the vehicle is stationary. The initial rotation angle calculator 55 calculates the initial rotation angle based on the accelerations Axso, Ayso, Azso of the pen axis coordinate system (Xs, Ys, Zs) detected using the acceleration sensors 2a, 2b, 2c at the start of writing. (Φo, θo, Ψo) is calculated. The rotation angle change calculator 56 calculates the change in the rotation angle (dφ / dt, dθ / dt, dΨ / dt) based on the rotation angular speeds (ωxs, ωys, ωzs) detected by the gyros 3a, 3b, 3c. The writing rotation angle calculation unit 57 includes an initial rotation angle calculation unit 5.
5 and the change in the rotation angle (dφ / d) calculated by the rotation angle change calculator 56 and the initial rotation angle (φo, θo, Ψo).
The rotation angle (φ, θ, Ψ) during writing is calculated based on (t, dθ / dt, dΨ / dt).

The angular acceleration calculator 58 includes three gyro 3
a, 3b, 3c, the rotational angular velocity (ωxs, ω
ys, ωzs) to the rotational angular acceleration (dωxs / dt, dωys /
dt, dωzs / dt). The acceleration correction unit 59 includes the rotational angular velocities (ωxs, ωys, ωzs) detected using the three gyros 3a, 3b, 3c, and the rotational angular accelerations (dωxs / dt, dωys / dt, d) calculated by the angular acceleration calculation unit 58.
ωzs / dt) and the pen tip 8 of the acceleration (Axs, Ays, Azs) detected using the three acceleration sensors 2a, 2b, 2c based on the mounting position of each acceleration sensor 2a, 2b, 2c. The acceleration component due to the tilting motion is calculated.
The acceleration correction unit 59 detects the acceleration (Ax in the pen axis coordinate system (Xs, Ys, Zs) detected using the three acceleration sensors 2a, 2b, and 2c based on the calculated acceleration component due to the tilting motion.
s, Ays, Azs), and the acceleration (Axos, Ayos, Ayos, Ax) of the pen axis coordinate system (Xs, Ys, Zs) at the pen tip 8 is corrected.
Azos) is calculated.

The coordinate transformation calculating section 60 calculates the rotation angle (φ, θ,
Ψ), the acceleration (Axos, Ayos, Azos) in the pen axis coordinate system (Xs, Ys, Zs) detected using the acceleration sensors 2a, 2b, 2c is converted into the gravity coordinate system (Xg, Yg,
Zg) is converted to an acceleration (Axog, Ayog, Azog). The gravitational acceleration removing unit 61 uses a gravitational coordinate system (Xg, Yg,
Zg), the component of the gravitational acceleration g is removed from the acceleration (Axog, Ayog, Azog), and the influence of the gravitational acceleration g is removed. The velocity calculator 62 calculates the gravitational coordinate system (Xg, Y) after the gravitational acceleration remover 61 removes the component of the gravitational acceleration g.
g, Zg) in each axial direction (Axog, Ayog, A
zog) is integrated to calculate the velocity (Vxog, Vyog, Vzog) in each axis direction in the gravity coordinate system (Xg, Yg, Zg).

Here, the moving direction and the moving amount of the pen point portion 8 in the pen-type input device 1 having the above configuration will be described.

First, the acceleration (Axs) detected by the initial rotation angle calculation unit 55 using the acceleration sensors 2a, 2b, 2c.
o, Ayso, Azso) based on the initial rotation angle (φo, θo, Ψ
The case where o) is calculated will be described. In the stationary state, the accelerations (Axso, Ayso, Azso) detected using the acceleration sensors 2a, 2b, 2c and the initial rotation angles (φo, θ
o, Ψo), the following relationship holds.

[0046]

(Equation 1)

From the above equation, the absolute values of the initial rotation angles φo and θo in the stationary state are obtained. Here, whether or not the vehicle is in the stationary state is determined by monitoring the temporal change of the output signals of the acceleration sensors 2a, 2b, 2c and the gyros 3a, 3b, 3c. Also, the initial rotation angle Ψo resets the initial value to zero.

Here, for two unknowns φo, θo, 3
Since this equation is established, the gravitational acceleration g can be treated as an unknown value, and the absolute values of φo and θo can be calculated without defining the value of the gravitational acceleration g. Further, the value of the gravitational acceleration g may be calculated, and the calculated value of the gravitational acceleration g may be monitored, and a warning or the like may be issued if the calculated value greatly fluctuates.

Next, the rotation angle change calculator 56 changes the rotation angle during writing (dφ / dt, dθ / dt, dｄ / d).
The case of calculating t) will be described.

The change of the rotation angle (d) is based on the rotation angular speeds (ωxs, ωys, ωzs) detected by the gyros 3a, 3b, 3c.
The differential equation for calculating (φ / dt, dθ / dt, dΨ / dt) can be expressed by the following equation.

[0051]

(Equation 2)

Next, the writing rotation angle calculating section 57 calculates the initial rotation angles (φo, θo, Ψo) calculated by the initial rotation angle calculating section 56 and the rotation angle change calculating section 56 as described above.
Calculated during rotation (dφ / dt, dθ /
dt, dΨ / dt), the rotation angle (φ, θ, Ψ) during writing is calculated using the following equation.

[0053]

(Equation 3)

Next, based on the rotation angles (φ, θ, Ψ) during writing obtained as described above, each of the acceleration sensors 2a, 2
b, 2c, the pen axis coordinate system (Xs,
The case where the acceleration (Axs, Ays, Azs) of Ys, Zs) is converted into the acceleration (Axg, Ayg, Azg) of the gravity coordinate system (Xg, Yg, Zg) will be described.

Based on the rotation angle (φ, θ, Ψ) during writing, the pen axis coordinate system (Xs, Ys, Zs) is changed to the gravity coordinate system (Xg, Y
g, Zg), a coordinate conversion matrix used for conversion to invE
(Φ, θ, Ψ) can be expressed by the following equation. Where in
vE (φ, θ, Ψ) represents an inverse matrix of the matrix E (φ, θ, Ψ).

[0056]

(Equation 4)

Each of the acceleration sensors 2a in the Xs-axis direction, the Ys-axis direction, and the Zs-axis direction in the pen tip coordinate system (Xs, Ys, Zs).
The mounting coordinates of 2b and 2c are respectively (Xas, Yas, Za
s), (Xbs, Ybs, Zbs), (Xcs, Ycs, Zcs), and taking the gravitational acceleration g into account, the coordinate transformation matrix invE
When (φ, θ, Ψ) is used, each acceleration sensor 2a, 2
b, 2c, the acceleration (Axs, Ays, Azs) of the pen tip 8 in the gravity coordinate system (Xg, Yg, Zg)
xog, Ayog, Azog) are obtained as follows.

[0058]

(Equation 5)

The second and third terms in parentheses in the above equation are the rotational angular velocities (ω) detected using the gyros 3a, 3b, 3c.
xs, ωys, ωzs) and rotational angular velocities (dωxs / dt, dωys / dt, d) obtained from the rotational angular velocities (ωxs, ωys, ωzs).
ωzs / dt), the acceleration correction unit 58 calculates the second and third terms in parentheses in the above equation, and calculates the acceleration (based on the signals from the acceleration sensors 2a, 2b, 2c). Axs, Ays, Azs) are corrected to obtain the acceleration in the pen axis coordinate system (Xs, Ys, Zs) at the pen tip 8 shown in parentheses. The gravitational acceleration removing unit 62 further removes the gravitational acceleration component from the above equation.

The high-frequency discriminating section 63 includes HPFs 52a to 52f.
It is determined whether any of the accelerations (Axh, Ayh, Azh) and the rotational angular velocities (ωxs, ωys, ωzs) input via the pen contains a high frequency component due to friction between the pen tip 8 and the writing surface. I do. Here, acceleration (Axh, Ayh, Azh)
Are the high frequency components of the accelerations (Axos, Ayos, Azos) detected using the acceleration sensors 2a, 2b, 2c, respectively. For example, the high-frequency determination unit 63
acceleration (Axh, Ayh, Az)
h) is compared with a threshold value previously determined based on the noise level, and a state in which none of the signals contains a high frequency component is a stop state or a state in which the pen tip portion 8 is in the air.
Here, the high frequency discriminating unit 63 sets the acceleration (Axh, Ayh, Azh) input through the HPFs 52a to 52f as a vector orthogonal to the vector and the magnitude of the vector √ (Axh ² + Ayh ² +
Azh ² ) may be calculated with an envelope and compared with a threshold.

The zero speed detector 64 determines whether or not the pen tip 8 has stopped moving based on the pressure from the writing surface on the pen tip 8 using the pressure-sensitive sensor 4 and the result of the discrimination by the high frequency discriminator 63. To detect. For example, the zero-speed detector 64 outputs the accelerations (Axh, Ayh, Azh) and the rotational angular velocities (ωxs, ωy) input by the high frequency discriminator 63 via the HPFs 52a to 52f.
s, ωzs) when it is determined that high frequency components due to friction between the pen tip 8 and the writing surface are not included, and the writing to the pen tip 8 is performed using the pressure-sensitive sensor 4. When the pressure from the surface is detected, it is determined that the pen point 8 is in the stopped state in which the pen tip 8 stops moving on the writing surface. For example, when the character “ru” is actually drawn as shown in FIG.
At the locations A1, A2, A3, and A4 where the pen tip 8 stops, the high frequency discriminating unit 63 selects one of the acceleration (Axos, Ayos, Azos) and the rotational angular velocity (ωxs, ωys, ωzs) input through the HPFs 52a to 52f. Also, it is determined that high frequency components due to friction between the pen tip 8 and the writing surface are not included. FIG. 5 shows an example of the signal B input to the high frequency discriminator 63. In the figure, B1 indicates a signal when the pen tip 8 is moving in the air, and B2 and B3 indicate signals when the pen tip 8 is stationary on the writing surface. By detecting whether the pen tip 8 is in contact with the writing surface as described above, the zero speed detection unit 64 detects whether the writing surface is stationary on the writing surface.

When the speed correcting section 65 detects that the zero speed detecting section 64 is in the stopped state, the speed calculated by the speed calculating section 62 and the writing angle calculated by the in-writing rotation angle calculating section 57 when the zero speed detecting section 64 is detected are detected. Gravity coordinate system (Xg, Yg, Gg) calculated by the speed calculation unit 63 based on the rotation angles (φ, θ, Ψ) of
The speed at Zg) is corrected to zero. Moving amount calculator 6
Reference numeral 6 denotes the speed (Vxog, Vxog, V) of the pen tip 8 in the gravitational coordinate system (Xg, Yg, Zg) after the speed correction unit 65 corrects as necessary.
Vyog, Vzog), and the locus (Xog,
Yog, Zog).

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

The acceleration sensors 2a, 2b, and 2c and the gyros 3a, 3b, and 3c are accelerations Axs, Ays, Aza, and Xsb, Xsb, and Zs, respectively, in the Xsa, Ysa, and Zs directions. Rotational angular velocity (ωxs, ωy
s, ωzs). AD converter 51a-
51f is an acceleration (Axs, Ax) detected using each of the acceleration sensors 2a, 2b, 2c and the gyros 3a, 3b, 3c.
ys, Azs) and the rotational angular velocities (ωxs, ωys, ωzs). The HPFs 52a to 51f convert acceleration (Axs, Ays, Az) obtained by digitally converting signals from the acceleration sensors 2a, 2b, 2c and the gyros 3a, 3b, 3c.
s) and high-frequency components are extracted from the rotational angular velocities (ωxs, ωys, ωzs).

At a predetermined fixed period of sampling timing, the stillness determining unit 54 sets the AD converters 51a to 51a to
Acceleration (Axs, Ays, Az) after digital conversion from 51f
s) and the rotational angular velocities (ωxs, ωys, ωzs) are read (step S1), for example, the read accelerations (Axs, Axs)
ys, Azs) and the rotational angular velocities (ωxs, ωys, ωzs) are observed over time, and when there is no change, it is determined to be in a stationary state, and when the change occurs, it is determined to be in writing.

When the stationary state determining section 54 determines that the apparatus is in the stationary state (step S2), the initial rotation angle calculating section 55 determines the accelerations (Axso, Ayso, Azso) detected by using the acceleration sensors 2a, 2b, 2c as described above. ) To calculate the initial rotation angles (φo, θo, Ψo) (Step S)
3).

After that, the acceleration signal and the rotational angular velocity signal are read from the acceleration sensors 2a, 2b, 2c and the gyros 3a, 3b, 3c (step S4), and the rotational angle change calculator 56 uses the gyros 3a, 3b, 3c. Changes in the rotation angle (dφ / dt, dθ / dt, dΨ / dt) are obtained based on the detected rotation angular velocities (ωxs, ωys, ωzs) (step S5). As described above, the rotation angle calculation unit 57 writes φ = φo + Σ (dφ) based on the initial rotation angle (φo, θo, Ψo) and the change in the rotation angle (dφ / dt, dθ / dt, dΨ / dt). / Dt), θ = θo + Σ (dθ
/ Dt) and Ψ = Ψo + Σ (dΨ / dt) to calculate the rotation angle (φ, θ, Ψ) during writing (step S).
6).

The angular acceleration calculator 58 is provided with the gyro 3a, 3
b, 3c, the rotational angular velocity (ωxs, ωys, ω
zs), the rotational angular acceleration (dωxs / dt, dωys / d
t, dωzs / dt) is calculated (step S7). The acceleration correction unit 60 calculates the rotational angular velocities (ωxs, ωys, ωzs) and the rotational angular accelerations (dωxs / dt, dωys / dt, dωzs / d).
t), the acceleration sensors 2a, 2
acceleration detected using b, 2c (Axs, Ays, Azs)
Is corrected and the pen axis coordinate system (Xs,
The acceleration (Axos, Ayos, Azos) at Ys, Zs) is calculated (step S8). Thus, the acceleration sensors 2a,
Acceleration (Axs, Ays, Az) detected using 2b and 2c
s) based on the pen axis coordinate system (Xs, Y
Since the acceleration (Axos, Ayos, Azos) at (s, Zs) is calculated, the influence of the tilt motion of the pen shaft 9 due to the mounting position of the acceleration sensors 2a, 2b, 2c being away from the pen tip 8 is eliminated. be able to.

The coordinate transformation calculation unit 60 calculates the rotation angle (φ, φ) of the pen shaft 9 during writing calculated by the rotation angle calculation unit 57 during writing.
θ, Ψ), the acceleration (Axos, Ayos, Azos) in the pen axis coordinate system (Xs, Ys, Zs) of the pen tip 8 calculated by the acceleration correction unit 59 is converted into the gravity coordinate system (Xg, Yg,
Zg), the acceleration of the pen tip 8 (Axog, Ayog, Az)
og) (step S9). Thus, the accelerations (Axos, Ayos, and Axos) in the pen axis coordinate system (Xs, Ys, Zs)
Azos) is converted into acceleration (Axog, Ayog, Azog) in the gravitational coordinate system (Xg, Yg, Zg), so that the influence of the inclination of the pen shaft 9 can be removed. The gravitational acceleration removing unit 61 removes the component of the gravitational acceleration g from the acceleration (Axog, Ayog, Azog) of the pen tip 8 in the gravitational coordinate system (Xg, Yg, Zg), and removes the influence of the gravitational acceleration g ( Step S10). The speed calculation unit 62 calculates the gravitational coordinate system (X) after the gravitational acceleration removing unit 61 removes the gravitational acceleration.
g, Yg, Zg), the acceleration (Axog, A) of the pen tip 8
yog, Azog) and integrate the speed (Vxog, Vy) of the pen tip 8
og, Vzog) (step S11).

When the zero speed detector 64 detects the stop state of the pen tip 8 (step S12) as described above, the speed corrector 65 calculates the speed so that the speed of the pen tip 8 becomes zero. The gravity coordinate system (Xg,
The speed (Vxog, Vyog, Vzog) at Yg, Zg) is corrected (step S13). Thus, it is possible to prevent a writing error from occurring due to the accumulated error. A more specific method of the correction by the speed correction unit 65 will be described later. The movement amount calculation unit 66 calculates the speeds (Vxog, Vyo) of the gravity coordinate system (Xg, Yg, Zg) obtained as described above.
g, Vzog) based on the moving direction and moving amount (Xog, Yog, Z)
og) (step S14), the trajectory of the pen tip 8 is obtained, and the above operation is repeated until the input processing is completed (step S15).

Next, a more specific method of the correction by the speed correcting section 65 will be described.

The speed correcting section 65 includes a speed zero detecting section 6
When the pen 4 detects the stop state of the pen tip part 8, the speed calculating part 6
2 is a pen axis coordinate system (Xs, Ys, Z
s) The speed in each axis direction is reset to zero, and the speed in the stop state is set to zero. This is, for example, shown in FIG.
When the correction is not performed on the ideal speed change C1 as shown in (1), drift occurs due to the accumulated error due to integration, and the waveform of the speed change C2 falls to the right. On the other hand, by correcting the speed in the stop state indicated by E1 to E4 in the drawing to zero, it is possible to obtain an ideal speed change C1 and a speed change C3 with a small error as shown in FIG. 7B. it can. In this way, drift can be reduced only by resetting the speed at the time of detecting the stop state to zero, and an ideal speed waveform of the pen tip 8 can be obtained. By performing such a simple correction, the processing speed can be increased. Therefore, this is an effective correction when the stop state of the pen tip 8 can be accurately detected, and the acceleration is detected using an acceleration sensor having a good S / N ratio and offset.

When the zero speed detector 64 detects that the pen tip 8 has stopped, the speed corrector 65 calculates the pen axis coordinate system (Xs, Y
(s, Zs) to correct the speed in the gravitational coordinate system (Xg, Yg, Zg) from the previous stop state detection to the current stop state detection so that the velocity in each axis direction of the axis becomes zero. Is also good. For example, the correction is performed by subtracting the speed difference F surrounded by a dotted line from the calculation result of the speed calculation unit 62.
In this case, it is necessary to store the speed in the gravity coordinate system (Xg, Yg, Zg) from the detection of the previous stop state to the detection of the current stop state in the storage unit 7, as shown in FIG. In this way, a more accurate velocity waveform C4 of the pen tip portion 8 can be obtained without any steps in the corrected portion. In addition, since the calculation is simple, quick correction can be performed. here,
Weighting may be performed based on the time difference from the stop time of the pen tip portion 8.

Further, when the zero speed detector 64 detects the stop state of the pen tip portion 8, the speed corrector 65 detects the gravitational coordinate system (Xg, Yg,
The speed obtained by integrating the acceleration of Zg) may be set to zero, and the correction by spline interpolation may be performed so that the acceleration change and the speed change of the gravity coordinate system (Xg, Yg, Zg) are continuous. .

When the zero speed detector 64 detects the stop state of the pen tip portion 8, the speed corrector 65 detects the gravitational coordinate system (Xg, Yg, Z) when the stop state is detected.
g) calculates a correction amount that makes the speed obtained by integrating the acceleration calculated to zero to zero, and based on the calculated correction amount, the gravity coordinate system (Xg, Yg, Z) until the next stop state is detected.
The speed of g) may be corrected. For example, as described above, the speed at the time when the stop of the pen tip 8 is detected is set to zero, and at the same time, the speed error and time integration are used to divide the subsequent correction amount by dividing the speed error by the integration time. The value obtained by dividing the speed error by the integration time corresponds to the speed error F already described.

Further, as shown in FIG. 8, the calculation unit 5b includes a stationary determination unit 54, an initial rotation angle calculation unit 55, a rotation angle change calculation unit 56, a writing rotation angle calculation unit 57, an angular acceleration calculation unit 58, and an acceleration correction. Unit 59, coordinate conversion operation unit 60, gravitational acceleration removal unit 61, speed operation unit 62, high frequency discrimination unit 6
3, a zero speed detection unit 64, a correction determination unit 67, a speed correction unit 65, and a movement amount calculation unit 66 may be provided.
When the zero speed detecting unit 64 detects the stop state of the pen tip unit 8, the correction determining unit 67 integrates and calculates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) at the time of detecting the stop state. Is checked to determine whether or not the speed is equal to or less than a predetermined threshold value, and whether or not the speed needs to be corrected is checked. When the correction determining unit 67 determines that the speed needs to be corrected, the speed correcting unit 65 integrates and calculates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when the stop state is detected. The initial rotation angle (φo,
θo, Ψo). Thereby, the inclination of the pen shaft 9 can be corrected, and the gravity coordinate system (Xg,
Yg, Zg) can be calculated.

The speed correction unit 65 may correct the rotation angle (φ, θ, Ψ) during writing instead of correcting the initial rotation angle (φo, θo, Ψo). By correcting the rotation angle during writing, the inclination of the pen shaft 9 during writing can be corrected more accurately, and the acceleration in the gravity coordinate system (Xg, Yg, Zg) can be calculated more accurately. .

In each of the above embodiments, the zero speed detector 64 detects the high frequency components of the signals from the acceleration sensors 2a, 2b, 2c and the gyros 3a, 3b, 3c and the signal from the pressure sensitive sensor 4. Although the stop state of the pen tip portion 8 was detected, the acceleration (Ax) of the gravity coordinate system (Xg, Yg, Zg) was detected.
(og, Ayog, Azog) may be determined to be in a stopped state when it is detected that a state of not more than a predetermined threshold has continued for a predetermined time or more. The input unit 5a includes AD converters 51a to 51f and LPFs 53a to 5f as shown in FIG.
3f. The calculation unit 5b includes a stationary determination unit 54, an initial rotation angle calculation unit 55, a rotation angle change calculation unit 56, a writing rotation angle calculation unit 57, an angular acceleration calculation unit 58, an acceleration correction unit 59, a coordinate conversion calculation unit 60, and gravity. It includes an acceleration removing unit 61, a speed calculating unit 62, a speed zero detecting unit 64, a speed correcting unit 65, and a moving amount calculating unit 66. The zero speed detection unit 64
Acceleration (Axog, Ayo) of gravity coordinate system (Xg, Yg, Zg)
g, Azog) are determined to be in a stopped state when it is detected that the state where each of them is equal to or less than a predetermined threshold has continued for, for example, 0.05 seconds or more. Here, the value of 0.05 second depends on the cutoff frequency of the LPF. The threshold value is determined from the noise level. In this case, although the detection of the stop state is delayed, it is not necessary to use the pressure sensor 4 or the like, and the apparatus can be downsized.

The pen-type input device 1 is, for example, as shown in FIG.
As shown in the figure, the stillness determination unit 54, the initial rotation angle calculation unit 55, the rotation angle change calculation unit 56, the writing rotation angle calculation unit 57, the angular acceleration calculation unit 58, and the acceleration correction unit 5 are added to the calculation unit 5b.
9, a coordinate transformation calculating unit 60, a gravitational acceleration removing unit 61, a speed calculating unit 62, a differential calculating unit 68, a zero speed detecting unit 64, a speed correcting unit 65a, and a moving amount calculating unit 66 may be provided. The differential operation unit 68 differentiates the acceleration (Axog, Ayog, Azog) in the gravitational coordinate system (Xg, Yg, Zg) obtained by the coordinate conversion by the coordinate conversion operation unit 60. The zero-speed detector 64c calculates accelerations (Axog, Ayo) in the gravitational coordinate system (Xg, Yg, Zg) obtained by the coordinate conversion by the coordinate conversion calculator 60.
g, Azog) and the differential operation unit 68 are based on the gravity coordinate system (Xg, Yg,
When it is detected that both the value obtained by differentiating the acceleration by Zg) with respect to time is equal to or less than a predetermined threshold value, it is determined that the pen tip 8 is in the stopped state. In this case, there is no need to wait for a certain time to elapse, and the stop state can be detected quickly.

The pen-type input device 1 is, for example, as shown in FIG.
As shown in the figure, the AD converters 51a to 51f are
LPFs 53a to 53f, a stillness determination unit 54, an initial rotation angle calculation unit 55, a rotation angle change calculation unit 56, a writing rotation angle calculation unit 57, an angular acceleration calculation unit 58, an acceleration correction unit 59,
A coordinate transformation calculating unit 60, a gravitational acceleration removing unit 61, a speed calculating unit 62, a zero speed detecting unit 64, a speed correcting unit 65, and a moving amount calculating unit 66 may be provided. The zero speed detection unit 64 calculates the acceleration (Axos, Ayos, Azos) in the pen axis coordinate system (Xs, Ys, Zs) after the acceleration correction unit 59 corrects the acceleration.
Size of (Axos ² + Ayos ² + Azos ² ) and gravitational acceleration g
When it is detected that the state where the difference of the magnitudes is equal to or smaller than the predetermined threshold has continued for a predetermined period of time or more, it is determined that the pen tip portion 8 is in the stopped state. In this case, since it is determined whether or not the camera is in the stationary state before the coordinate conversion, the coordinate conversion processing and the like can be omitted in the stationary state, and the processing can be performed quickly.

Further, the zero speed detector 64 detects the pen axis coordinate system (Xs, Ys, Zs) corrected by the acceleration corrector 59.
The magnitude of the acceleration (Axos, Ayos, Azos) √ (Axos ²
+ Ayos ² + Azos ² ) and the magnitude of the gravitational acceleration g are equal to or smaller than a predetermined threshold value, and the acceleration (Ax) of the pen axis coordinate system (Xs, Ys, Zs) after being corrected by the acceleration correction unit 59.
(os, Ayos, Azos) may be determined to be in a stopped state when it detects that the value obtained by differentiating with respect to time is equal to or less than a predetermined threshold value.

Further, the speed zero detecting section 64 determines whether or not the pen point 8 is stopped when the pen point 8 is in contact with the writing surface by using the pressure-sensitive sensor 4 or the like. In short, the case where the pen point portion 8 is in the air may be excluded.

Further, the zero speed detecting section 64 compares a time interval in which the high frequency component of the acceleration signal from each of the acceleration sensors 2a, 2b, 2c is not detected with a predetermined time interval, and compares the time interval with the predetermined time interval. Is shorter than the predetermined time interval, it is determined that the pen tip is in the stopped state. Thus, it is possible to quickly detect a state where the speed is zero and the acceleration is not zero. When the time interval is equal to or longer than the predetermined time interval, the speed zero detecting unit 64 determines that the pen tip 8 has been stopped for a long time or is moving in the air, and the speed and acceleration are determined. Are both zero (a long-term stop state). Thus, the stopped state of the pen tip 8 can be quickly detected, and the state in which the pen tip 8 is in the air can be detected without using the pressure sensor 4 or the like.

In the above embodiment, the pen-type input device 1 adopting the Euler-type coordinate transformation has been described. However, a pen-type input device employing the strap-down method may be used. The pen-type input device adopting the strap-down method has the acceleration sensors 2a and 2a in a stationary state.
b, 2c, the pen axis coordinate system (Xs, Ys, Z
s), an initial rotation angle of the device is calculated based on the acceleration, and the calculated initial rotation angle and the gyros 3a, 3b, 3c are calculated.
The rotation angle during writing is calculated on the basis of the rotation angular velocity detected by using the acceleration sensor 2a, 2b, 2c based on the calculated rotation angle during writing.
s, Ys, Zs) is calculated by using the gravitational coordinate system (Xg, Y
g, Zg).

[0085]

As described above, the present invention detects a high frequency component of an acceleration signal from each acceleration sensor in a state where the pen tip is in contact with the writing surface, and stops the pen tip. When the pen tip is stopped, the speed is corrected so that the speed obtained based on the acceleration at the time of detection is zero, and the corrected speed is used as the basis. Since the moving direction and the distance of the apparatus are detected at the same time, it is possible to prevent the occurrence of a cumulative error.

Further, an initial rotation angle of the apparatus is calculated based on the acceleration in the pen axis coordinate system (Xs, Ys, Zs) detected using the acceleration sensor in the stationary state, and the calculated initial rotation angle and the gyro are used. The rotation angle during writing is calculated based on the detected rotation angular velocity, and the acceleration in the pen axis coordinate system (Xs, Ys, Zs) detected using each acceleration sensor based on the calculated rotation angle during writing is calculated as gravity coordinates. System (Xg,
Yg, Zg), the acceleration in the gravitational coordinate system (Xg, Yg, Zg) obtained by the conversion is integrated,
Calculate the velocity in the gravity coordinate system (Xg, Yg, Zg)
Detects high-frequency components of signals from each acceleration sensor and each gyro when the pen tip is in contact with the writing surface, detects whether the pen tip is stopped, and stops the pen tip When the state is detected, the velocity in the gravity coordinate system (Xg, Yg, Zg) is corrected so that the velocity in the gravity coordinate system (Xg, Yg, Zg) at the time of the detection is zero, and the gravity coordinate system is corrected. Since the moving direction and the moving distance of the apparatus are calculated based on the speeds in the respective axial directions at (Xg, Yg, Zg), it is possible to eliminate the influence of the tilt of the pen shaft and prevent the occurrence of the cumulative error of the speed.

Further, the rotational angular acceleration is calculated from the rotational angular velocities detected using the three gyros, and the rotational angular velocity detected using the three gyros, the calculated rotational angular acceleration, and the mounting position of each acceleration sensor are calculated. Calculates the acceleration component of the acceleration detected by using the three acceleration sensors due to the tilting motion around the pen tip, and based on the calculated acceleration component by the tilting motion, the pen axis coordinate system at the mounting position of the acceleration sensor ( Xs, Ys, Zs) are corrected to determine the acceleration in the pen axis coordinate system (Xs, Ys, Zs) at the pen tip, and the pen tip is corrected based on the rotation angle during writing. Since the acceleration in the pen axis coordinate system (Xs, Ys, Zs) is converted into the acceleration in the gravity coordinate system (Xg, Yg, Zg), the pen axis caused by the mounting position of the acceleration sensor being separated from the pen tip portion. of Can a number of removing the effects of oblique movement.

When it is detected that the acceleration in the gravitational coordinate system (Xg, Yg, Zg) is equal to or less than a predetermined threshold for a predetermined time or more, it is determined that the pen tip is in a stopped state. Therefore, the stop state can be detected with a simple configuration.

When it is detected that both the acceleration in the gravitational coordinate system (Xg, Yg, Zg) and the value obtained by differentiating the acceleration in the gravitational coordinate system (Xg, Yg, Zg) with respect to time are below a predetermined threshold value. Since it is determined that the pen tip is in the stop state, the stop state can be accurately detected with a simple configuration, and the stop state can be detected quickly without having to wait for a certain time when detecting the stop state. Become like

When it is detected that the state in which the difference between the magnitude of the acceleration detected by using the acceleration sensor and the magnitude of the gravitational acceleration is equal to or smaller than a predetermined threshold has continued for a predetermined period of time, the pen tip is stopped. By judging the state, the stop state can be detected with a simpler configuration.

The difference between the magnitude of the acceleration detected using the acceleration sensor and the magnitude of the gravitational acceleration is equal to or less than a predetermined threshold value, and the pen axis coordinate system (Xs, Ys, When it is detected that the value obtained by differentiating the acceleration by Zs) with respect to time is equal to or less than a predetermined threshold value,
Since it is determined that the pen tip is in the stopped state, the stopped state can be detected accurately and quickly with a simple configuration.

Since it is determined whether or not the pen tip is stopped when the pen tip is in contact with the writing surface,
It is possible to prevent erroneous detection between the case of moving in the air and the case of a stop state.

The time during which no high-frequency component is detected from the acceleration signal of each acceleration sensor is compared with a predetermined time interval. If the duration is shorter than the predetermined time interval, the pen tip stops. If the duration is longer than the predetermined time interval, it is determined that the pen tip has been stopped for a long time or it is moving in the air, so the pen tip is quickly Is stopped, and it can be detected whether or not the pen tip is in contact with the writing surface without separately providing a sensor or the like.

When the stop state of the pen tip is detected,
The gravity coordinate system (Xg,
Since the speed obtained by integrating the acceleration of (Yg, Zg) is reset to zero, it is possible to prevent the occurrence of a cumulative error in the speed.

When the stop state of the pen tip is detected,
The gravity coordinate system (Xg,
The speed of the gravitational coordinate system (Xg, Yg, Zg) from the detection of the previous stop state to the detection of the current stop state is corrected so that the speed obtained by integrating the acceleration of Yg, Zg) becomes zero. Therefore, occurrence of a speed error can be more accurately prevented.

When the stop state of the pen tip is detected,
The gravity coordinate system (Xg,
Yg, Zg) is calculated by integrating the acceleration, the speed obtained is made zero, and the correction by spline interpolation is performed so that the acceleration change and the speed change in the gravity coordinate system (Xg, Yg, Zg) are continuous. The trajectory at the tip can be accurately detected.

When the stop state of the pen tip is detected,
The gravity coordinate system (Xg,
Yg, Zg) to calculate a correction amount that makes the speed obtained by integrating the accelerations zero, and based on the calculated correction amount, a gravity coordinate system (Xg, Yg) until the next stop state is detected.
g, Zg), the processing can be accelerated by calculating the correction amount in advance.

When the stop state of the pen tip is detected,
The gravity coordinate system (Xg,
Since the initial rotation angle is corrected so that the speed obtained by integrating the accelerations of Yg and Zg) becomes zero, the accumulated error in speed detection and the rotation angle detection error of the pen-type input device are eliminated. Can be.

When the stop state of the pen tip is detected,
The gravity coordinate system (Xg,
Yg, Zg) The amount of correction is calculated so that the speed obtained by the integral calculation of the acceleration becomes zero, and the rotation angle during writing until the next stop is detected based on the calculated amount of correction. Is corrected, the accumulated error in speed detection can be eliminated, and the detection error of the rotation angle of the pen-type input device during writing can be eliminated.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of a coordinate system.

FIG. 3 is a configuration diagram of a calculation unit.

FIG. 4 is an explanatory diagram showing a stop point of a pen tip.

FIG. 5 is a waveform diagram of a high-frequency component of acceleration.

FIG. 6 is a flowchart illustrating a handwriting input operation.

FIG. 7 is a waveform diagram of a speed deviation and a corrected speed signal.

FIG. 8 is a configuration diagram of a calculation unit that corrects a rotation angle.

FIG. 9 is a configuration diagram of a calculation unit that determines a stop state based on acceleration.

FIG. 10 is a configuration diagram of a calculation unit that determines a stop state from a speed and a differential value thereof.

FIG. 11 is a configuration diagram of a calculation unit that determines a stop state based on detected acceleration and gravitational acceleration.

[Explanation of symbols]

 Reference Signs List 1 pen-type input device 2 acceleration sensor 3 gyro 4 pressure-sensitive sensor 5 processing unit 5a input unit 5b calculation unit 54 stillness determination unit 55 initial rotation angle calculation unit 56 rotation angle change calculation unit 57 rotation angle calculation unit during writing 58 angular acceleration calculation Unit 59 Acceleration correction unit 60 Coordinate conversion calculation unit 61 Gravitational acceleration removal unit 62 Speed calculation unit 63 High frequency discrimination unit 64 Speed zero detection unit 65 Speed correction unit 66 Movement amount calculation unit 67 Correction determination unit 68 Differential calculation unit 8 Pen tip unit 9 Pen axis

Claims (15)

[Claims] 1. A pen-type input device having a plurality of acceleration sensors and detecting a moving direction and a distance of the device based on a signal indicating an acceleration output from each of the acceleration sensors. The zero speed detecting unit detects whether or not the pen tip is stopped by detecting a high frequency component of an acceleration signal from each acceleration sensor in a state where the pen tip is in contact with the writing surface. A pen-type input device, wherein the acceleration correction unit detects that the pen tip is in a stopped state, and corrects the speed so that the speed obtained based on the acceleration at the time of the detection is zero. . 2. An acceleration sensor comprising three acceleration sensors, three gyros, and a calculation unit, wherein each of the three acceleration sensors is in the Xs-axis direction of a pen coordinate system (Xs, Ys, Zs) with the pen axis being the Zs axis. , Ys-axis direction and Zs-axis direction acceleration, and the three gyros output signals indicating the Xs axis rotation, the Ys axis rotation, and the rotation angular velocity around the Zs axis, respectively. It has a calculation unit, a writing rotation angle calculation unit, a coordinate conversion calculation unit, a speed calculation unit, a speed zero detection unit, a speed correction unit, and a movement amount calculation unit. The initial rotation angle calculation unit detects using an acceleration sensor in a stationary state. Pen axis coordinate system (X
s, Ys, Zs), the initial rotation angle of the device is calculated based on the acceleration, and during writing, the rotation angle calculation unit calculates the initial rotation angle calculated by the initial rotation angle calculation unit and the rotation angular speed detected using the gyro. The rotation angle during writing is calculated, and the coordinate conversion operation unit detects the pen axis coordinate system (Xs, Ys, Zs) detected using each acceleration sensor based on the rotation angle during writing calculated by the rotation angle operation unit during writing. Coordinate system (Xg, Yg, Zg) with the axis extending in the direction of gravitational acceleration as the Zg axis
, And the velocity calculator integrates the acceleration in the gravitational coordinate system (Xg, Yg, Zg) obtained by the coordinate conversion by the coordinate conversion calculator to obtain the gravitational coordinate system (Xg, Yg, Zg).
, The zero speed detector detects high frequency components of signals from each acceleration sensor and each gyro when the pen tip is in contact with the writing surface, and determines whether the pen tip is stopped. When the speed correction unit detects that the pen tip is in a stopped state, the speed correction unit detects whether or not the pen tip is in a stopped state, and based on the speed calculated by the speed calculation unit at the time of the detection, detects the gravity coordinate system (Xg, Yg). , Zg), the gravity coordinate system (Xg, Yg, Z) calculated by the speed calculation unit so that the speed becomes zero.
g), the moving amount calculation unit calculates the moving direction and the moving distance of the device based on the speed in each axis direction in the gravity coordinate system (Xg, Yg, Zg). apparatus. 3. The calculation unit includes an angular acceleration calculation unit and an acceleration correction unit. The angular acceleration calculation unit obtains a rotation angular acceleration from rotation angular velocities detected by using three gyros. Inclined motion of the acceleration detected using three acceleration sensors based on the rotational angular velocity detected using the gyro, the rotational angular acceleration calculated by the angular acceleration calculation unit, and the mounting position of each acceleration sensor around the pen tip Is calculated based on the calculated acceleration component due to the tilting motion, and the pen axis coordinate system (X
s, Ys, Zs) is corrected to determine the acceleration in the pen axis coordinate system (Xs, Ys, Zs) at the pen tip, and the coordinate conversion calculation unit corrects the acceleration based on the rotation angle during writing. Axis coordinate system (Xs, Ys, Zs) of the pen tip obtained by
3. The pen-type input device according to claim 1, wherein the acceleration is converted into an acceleration based on a gravity coordinate system (Xg, Yg, Zg). 4. The speed zero detecting unit according to claim 1, wherein said speed zero detecting unit is a gravity coordinate system (X).
g, Yg, Zg) when it is detected that the state of being equal to or less than a predetermined threshold has continued for a predetermined time or more,
4. The pen-type input device according to claim 1, wherein the pen tip portion is determined to be in a stopped state. 5. The apparatus according to claim 1, wherein the speed zero detecting unit is a gravitational coordinate system (X).
g, Yg, Zg) and the gravitational coordinate system (Xg, Yg,
4. The pen-type input device according to claim 1, wherein when it is detected that the value obtained by differentiating the acceleration by Zg with respect to time is equal to or less than a predetermined threshold value, it is determined that the pen tip is in a stopped state. 6. The speed zero detection unit detects that a state in which a difference between the magnitude of the acceleration detected by using the acceleration sensor and the magnitude of the gravitational acceleration is equal to or less than a predetermined threshold has continued for a predetermined time or more. 4. The pen-type input device according to claim 1, wherein the pen tip portion is determined to be in a stopped state. 7. The pen speed coordinate detecting unit according to claim 1, wherein a difference between the magnitude of the acceleration detected by using the acceleration sensor and the magnitude of the gravitational acceleration is equal to or less than a predetermined threshold value, and the pen axis coordinate detected by using the acceleration sensor. 4. The pen according to claim 1, wherein the pen tip is determined to be in a stopped state when a value obtained by differentiating the acceleration by the system (Xs, Ys, Zs) with respect to time is equal to or less than a predetermined threshold value. Type input device. 8. The pen according to claim 4, wherein the zero speed detecting unit determines whether or not the pen tip is stopped when the pen tip is in contact with the writing surface. Type input device. 9. The speed zero detecting section compares a continuous time interval in which no high frequency component is detected from the acceleration signal of each acceleration sensor with a predetermined time interval, and determines that the continuous time interval is longer than the predetermined time interval. If it is shorter, it is determined that the pen tip is in a stopped state, and if the continuous time interval is equal to or longer than a predetermined time interval, it is determined that the pen tip is in a state of stopping for a long time or in a state of moving in the air. 7. The pen-type input device according to claim 4, wherein the pen-type input device detects whether to judge. 10. The speed correction unit, when the zero speed detection unit detects the stop state of the pen tip, integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when detecting the stop state. 2. The method according to claim 1, wherein the determined speed is reset to zero.
10. The pen-type input device according to any one of claims 9 to 9. 11. The speed correction unit integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when the zero speed detection unit detects the stop state of the pen tip, when the stop state is detected. 10. The speed in the gravitational coordinate system (Xg, Yg, Zg) from the previous stop state detection to the current stop state detection so that the obtained speed becomes zero is corrected. Pen type input device. 12. The speed correction unit, when the speed zero detection unit detects the stop state of the pen tip, integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when the stop state is detected. 2. The method according to claim 1, wherein the determined speed is set to zero, and a correction by spline interpolation is performed so that a change in acceleration and a change in speed in the gravitational coordinate system (Xg, Yg, Zg) are continuous.
10. The pen-type input device according to any one of claims 9 to 9. 13. The speed correction unit, when the zero speed detection unit detects the stop state of the pen tip, integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when detecting the stop state. Calculate the correction amount that makes the obtained speed zero,
10. The pen-type input device according to claim 1, wherein the speed of the gravity coordinate system (Xg, Yg, Zg) until the next stop state is detected is corrected based on the calculated correction amount. 14. The speed correction unit integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when the zero speed detection unit detects the stop state of the pen tip unit when the stop state is detected. 10. The pen-type input device according to claim 1, wherein the initial rotation angle is corrected so that the determined speed becomes zero. 15. The speed correction unit integrates the acceleration of the gravitational coordinate system (Xg, Yg, Zg) when the zero speed detection unit detects the stop state of the pen tip, when the stop state is detected. A correction amount is calculated so that the obtained speed becomes zero, and the rotation angle during writing until the next stop state is detected is corrected based on the calculated correction amount.
10. The pen-type input device according to any one of claims 9 to 9.