JP2015087692A - Attitude detection device and control method of the same, and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately calculate an attitude angle in a specific installation state, while reducing the number of calibrations.SOLUTION: An attitude detection device according to the present invention is an attitude detection device that is attached to an apparatus and detects an attitude of the apparatus, and the attitude detection device includes: an acceleration sensor that detects accelerations in mutually orthogonal three axis directions; and a calculation unit that preliminarily stores a correction value of a detection result by the acceleration sensor obtained by calibration in a case where the apparatus takes a prescribed attitude, corrects the acceleration detected by the acceleration sensor by the stored correction value, and calculates an attitude angle indicative of a tilt of the apparatus with respect to a reference surface by using any of a plurality of calculation expressions on the basis of the corrected acceleration. When calculating the attitude of the apparatus, the calculation unit determines whether the attitude of the apparatus is close to the prescribed attitude on the basis of the acceleration detected by the acceleration sensor, and selects the calculation expression for use in calculation of the attitude angle of the apparatus in accordance with the determination result.

Description

  The present invention relates to an attitude detection device, a control method therefor, and a projector.

  Some projectors that project an image according to an image signal include an acceleration sensor that detects acceleration in three axial directions orthogonal to each other, and has a function of detecting the installation state of the projector based on the detection result of the acceleration sensor (For example, refer to Patent Document 1 (Japanese Patent Laid-Open No. 2011-35536)).

  As an installation state of the projector, for example, a floor installation state in which the projection lens 11 provided in front of the projector 10 faces the screen surface 20 and the legs 12 supporting the projector 10 are in contact with the floor surface. (FIG. 5A), the projector 10 is suspended from the ceiling so that the projector 10 is upside down with respect to the floor-installed state (FIG. 5B), and the projection lens 11 faces vertically upward. Centered on the projection optical axis of the projector 10 with respect to the upward installation state (FIG. 5C), the downward installation state (FIG. 5D) where the projection lens 11 is oriented vertically downward, and the floor installation state. In the portrait installation state (FIG. 5E) in which the projector 10 is vertically installed so as to be rotated 90 degrees in the horizontal direction, the projector 10 is And the like installed oblique installation state (Fig. 5F) obliquely oriented against. In general, the projector 10 is often used in a floor-mounted state or a ceiling-mounted state.

  Among projectors, there are projectors that change the cooling mode of a lamp that is a light source and projectors that change the direction of a projected image in accordance with the installation state. According to the projector including the acceleration sensor, the installation state can be detected based on the detection result of the acceleration sensor, and the cooling mode of the lamp and the direction of the projection image can be changed according to the detected installation state.

  When projecting a rectangular image by a projector, if the projection optical axis is not perpendicular to the screen surface, the projection image is not rectangular and is distorted into a trapezoid. Although the trapezoidal distortion of the projected image can be suppressed by the distortion correction process, the image quality of the projected image deteriorates when the distortion correction process is performed. For this reason, it is desirable to install the projector so that the projection optical axis is perpendicular to the screen surface.

  In general, the screen surface on which an image is projected is often installed parallel to the vertical direction as shown in FIGS. 5A and 5B.

  Therefore, in a projector having an acceleration sensor, it is considered to calculate an inclination angle (hereinafter referred to as an attitude angle) of the projector with respect to a reference plane based on a detection result of the acceleration sensor. By notifying the user of the calculated attitude angle, it is possible to assist the user in installing the projector so that the projection optical axis is perpendicular to the screen surface.

JP 2011-35536 A

  In general, the detection result of the acceleration sensor includes an error.

  When detecting the installation state of the projector, even if an error is included in the detection result of the acceleration sensor, it does not matter much. On the other hand, when calculating the attitude angle of the projector, if an error is included in the detection result of the acceleration sensor, the error is also included in the calculated attitude angle, and the projection optical axis is based on the calculated attitude angle. It becomes difficult to install the projector so that is perpendicular to the screen surface. Therefore, when calculating the attitude angle of the projector, a highly accurate acceleration detection result is required.

  Hereinafter, calculation of the attitude angle of the projector will be described in detail.

  In the following, as shown in FIG. 5A, the direction in which the projection lens 11 of the projector 10 faces, that is, the direction of the projection optical axis of the projector 10 is the Y axis, is orthogonal to the Y axis, and the Y axis is perpendicular to the vertical direction. An axis that is perpendicular to each other and that faces in the vertical direction is a Z axis, and an axis that is orthogonal to the Y axis and the Z axis is an X axis. The acceleration sensor detects an X-axis direction acceleration Xoutput, a Y-axis direction acceleration Output, and a Z-axis direction acceleration Zoutput.

  In addition, as described above, since the projector is often used in a floor-mounted installation state or a ceiling-mounted installation state, that is, in a state where the XY plane is horizontal, in the following, as shown in FIG. The tilt angle (angle θyz) that is the tilt angle of the Y axis with respect to the plane orthogonal to the direction, and the Roll angle (angle) that is the tilt angle of the X axis with respect to the horizontal plane as shown in FIG. 6B. θxz) is calculated as the attitude angle of the projector 10.

  First, the characteristics of the acceleration sensor will be described.

  The acceleration sensor detects Xoutput, Output, and Zoutput using the gravitational acceleration (1 g). The acceleration in each axial direction is 1 when the direction of each axis and the direction of gravity coincide with each other, and is 0 when the direction of each axis and the direction of gravity is 90 degrees.

  As shown in FIG. 6A, when the Y axis is inclined by an angle θyz with respect to the horizontal plane, the relationship between the angle θyz and each of Output and Zoutput is expressed by the following expressions (1) and (2).

... Formula (1)
... Formula (2)
As shown in FIG. 6B, when the X axis is inclined by an angle θxz with respect to the horizontal plane, the relationship between the angle θxz and each of Xoutput and Zoutput is expressed by the following expressions (3) and (4).

... Formula (3)
... Formula (4)
FIG. 7 is a diagram showing the relationship between the angle θyz and each of Output and Zoutput shown in Expressions (1) and (2). In FIG. 7, the vertical axis represents Output and Zoutput, and the horizontal axis represents the angle θyz.

  As shown in FIG. 7, in the state where the Y-axis is substantially horizontal (the state where the angle θyz is near 0 degrees), the change in Output with respect to the change in the angle θyz becomes large, and the detection accuracy of the Output increases. Further, in a state where the Z-axis is directed substantially in the horizontal direction (a state where the angle θyz is −90 degrees or in the vicinity of 90 degrees), the change in Zoutput with respect to the change in the angle θyz becomes large, and the detection accuracy of Zoutput increases.

  Further, in a state where the Y axis is substantially in the vertical direction (a state where the angle θyz is −90 degrees or in the vicinity of 90 degrees), the change in Output with respect to the change in the angle θyz becomes small, and the detection accuracy of the output decreases. Further, in a state where the Z-axis is in a substantially vertical direction (a state where the angle θyz is around 0 degrees), the change in Zoutput with respect to the change in the angle θyz is small, and the detection accuracy of Zoutput is lowered.

  As described above, in a state in which a specific axis is oriented substantially in the horizontal direction, the acceleration sensor has a higher accuracy in detecting the acceleration in the specific axis direction, and is perpendicular to the specific axis and in the axial direction facing the substantially vertical direction. There is a characteristic that the detection accuracy of acceleration is lowered.

  The detection result of the acceleration sensor usually includes an error. The errors included in the detection result of the acceleration sensor mainly include a sensitivity error and a offset error (Zero-g offset error).

  The sensitivity error is a detection error per unit gravity acceleration of the acceleration sensor. The offset error is an error detected in a state where the acceleration of each axis is 0 g (a state where each axis faces the horizontal direction).

  Because of the sensitivity error and offset error, the waveform indicating the relationship between the angle θyz and Output is not usually an ideal waveform as shown in FIG. FIG. 8 is a diagram showing a change in the waveform shown in FIG. 7 due to a sensitivity error. FIG. 9 is a diagram showing a change in the waveform shown in FIG. 7 due to an offset error. FIG. 10 is a diagram showing changes in the waveform shown in FIG. 7 due to sensitivity errors and offsets. 8 to 10, the vertical axis indicates Output, and the horizontal axis indicates the angle θyz.

  As shown in FIGS. 8 to 10, the detection result of the acceleration sensor includes a sensitivity error and an offset error, thereby causing a deviation from an ideal waveform.

  Therefore, calibration is usually performed to remove sensitivity errors and offset errors included in the detection results of the acceleration sensor and improve detection accuracy. The correction value for correcting the detection result so as to remove the sensitivity error and the offset error is acquired by the calibration, and the detection result of the acceleration sensor is corrected using the correction value.

  Specifically, as shown in FIG. 11A, the X-axis and Y-axis face the horizontal direction, and the Z-axis faces the vertical direction (posture 1). As shown in FIG. 11B, the Y-axis and Z-axis are horizontal. State in which the X-axis is oriented in the vertical direction (posture 2), and as shown in FIG. 11C, the X-axis and Z-axis are in the horizontal plane direction, and the Y-axis is in the vertical direction (posture 3). Thus, the acceleration in the three-axis direction is detected by the acceleration sensor.

  A correction value for each axis is obtained from the detection results for each of posture 1 to posture 3. By correcting the detection result of the acceleration sensor with the correction value obtained by calibration, the sensitivity error and the offset error can be removed.

  In addition, as a method of calculating the posture angle, using the equations (1) to (4), the method of calculating the posture angle based on the detection result of the acceleration in the uniaxial direction is different from the method of calculating the acceleration in the biaxial direction. There is a method of calculating a posture angle based on a detection result. In this method, the angle θyz is calculated using the following equation (5), and the angle θxz is calculated using the equation (6).

... Formula (5)
... Formula (6)
FIG. 12 is a diagram illustrating the relationship between the angle θyz and the Output / Zoutput shown in Expression (5). In FIG. 12, the vertical axis represents Output / Zoutput, and the horizontal axis represents the angle θyz. Note that the relationship between the angle θxz and Xoutput / Zoutput is the same as the relationship between the angle θyz and Output / Zoutput shown in FIG.

  When the angle θyz is around 0 degrees (Youtput / Zoutput is small), as shown in FIG. 7, the output has a large change with respect to the change in the angle θyz, and the Zoutput has a small change with respect to the change in the angle θyz. Therefore, even if some errors occur in Zoutput, Output takes a value near 0, so Output / Zoutput also takes a value near 0. Therefore, even if an error is included in Zoutput, the error of the angle θyz calculated using Expression (5) is relatively small.

  On the other hand, when the angle θyz is around 90 degrees (Youtput / Zoutput is large), as shown in FIG. 7, Zoutput has a large change with respect to the change in angle θyz, and Output has a small change with respect to the change in angle θyz. . Therefore, even if some errors occur in Output, Zoutput takes a value near 0, so Output / Zoutput is a value close to infinity. Therefore, even if an error is included in Output, the error of the angle θyz calculated using Expression (5) is small.

  Similarly, in equation (6), even if one of Xoutput and Zoutput includes some error, the error of the angle θxz calculated using equation (6) is relatively small.

  The calibration described above is performed in the manufacturing process of the projector.

  Here, it takes time and effort to prepare an adjustment stand for installing the projector for calibration, or to perform calibration by installing the projector in the three postures shown in FIGS. 11A to 11C. There is a problem that increases. Therefore, it is difficult to perform calibration with a plurality of different postures as shown in FIGS. 11A to 11C. This problem is particularly noticeable in a commercial projector having a large apparatus size.

  As described above, the posture angle error can be reduced by using the equation (5) or the equation (6). However, this is limited to the case where calibration is performed in a plurality of postures and an acceleration detection result with a certain degree of accuracy is obtained. As described above, in the state where a specific axis is oriented substantially in the horizontal direction, the acceleration sensor has a higher accuracy in detecting the acceleration in the axial direction, and the acceleration in the axial direction perpendicular to the specific axis and oriented in the substantially vertical direction. There is a characteristic that the detection accuracy of is reduced.

  Therefore, when calibration is not performed, the method of calculating the attitude angle based on the detection result of the biaxial acceleration using the equations (5) and (6), the detection result of the biaxial acceleration Among them, at least one of the detection accuracy is poor, and the accuracy of the posture angle calculated based on such a detection result may be worse than the accuracy of the posture angle calculated based on the detection result of the uniaxial acceleration. . As described above, since projectors are often used in a floor-mounted state or a ceiling-mounted state, it is often sufficient to calculate the attitude angle with high accuracy in these installed states.

  An object of the present invention is to provide an attitude detection apparatus, a control method therefor, and a projector that can calculate an attitude angle with high accuracy in a specific installation state even if the number of calibrations is reduced.

In order to achieve the above object, the projector of the present invention provides:
An acceleration sensor that detects acceleration in three axial directions orthogonal to each other;
A correction value of the detection result of the acceleration sensor obtained by calibration when the projector is in a predetermined posture is stored in advance, and the acceleration detected by the acceleration sensor is corrected by the stored correction value, A calculation unit that calculates an attitude angle indicating an inclination of the projector with respect to a reference plane using any one of a plurality of calculation formulas based on the corrected acceleration;
When calculating the attitude angle of the projector, the calculation unit determines whether the attitude of the projector is close to the predetermined attitude based on the acceleration detected by the acceleration sensor. According to the result, a calculation formula used to calculate the attitude angle of the projector is selected.

In order to achieve the above object, the posture detection apparatus of the present invention is:
A posture detection device that is attached to a device and detects the posture of the device,
An acceleration sensor that detects acceleration in three axial directions orthogonal to each other;
A correction value of a detection result of the acceleration sensor obtained by calibration when the device is in a predetermined posture is stored in advance, and an acceleration detected by the acceleration sensor is corrected by the stored correction value, A calculation unit that calculates an attitude angle indicating an inclination of the device with respect to a reference plane using any one of a plurality of calculation formulas based on the corrected acceleration;
When calculating the posture of the device, the calculation unit determines whether the posture of the device is close to the predetermined posture based on the acceleration detected by the acceleration sensor, and the result of the determination The calculation formula used for calculating the attitude angle of the device is selected according to the above.

In order to achieve the above object, the control method of the attitude control device of the present invention includes:
A method of controlling an attitude detection device that is attached to an apparatus and detects the attitude of the apparatus,
A detection step of detecting acceleration in three axial directions orthogonal to each other by an acceleration sensor;
A correction value of a detection result of the acceleration sensor obtained by calibration when the device is in a predetermined posture is stored in advance, and an acceleration detected by the acceleration sensor is corrected by the stored correction value, A calculation step of calculating an attitude angle indicating an inclination of the device with respect to a reference plane using any one of a plurality of calculation formulas based on the corrected acceleration;
In the calculating step, when calculating the posture of the device, it is determined whether or not the posture of the device is close to the predetermined posture based on the acceleration detected by the acceleration sensor, and the result of the determination The calculation formula used for calculating the attitude angle of the device is selected according to the above.

  According to the present invention, even if the number of calibrations is reduced, the posture angle can be calculated with high accuracy in a specific installation state.

It is a block diagram which shows the structure of the projector of one Embodiment of this invention. It is a figure which shows the external appearance of the projector shown in FIG. It is a figure which shows the processing flow in a related projector. It is a figure which shows the processing flow in the projector shown in FIG. It is a figure which shows an example of the installation state of a projector. It is a figure which shows an example of the installation state of a projector. It is a figure which shows an example of the installation state of a projector. It is a figure which shows an example of the installation state of a projector. It is a figure which shows an example of the installation state of a projector. It is a figure which shows an example of the installation state of a projector. It is a figure which shows an example of the attitude | position angle of a projector. It is a figure which shows an example of the attitude | position angle of a projector. It is a figure which shows an example of the relationship between the acceleration detected by an acceleration sensor, and a posture angle. It is a figure which shows the change of the waveform shown in FIG. 7 by a sensitivity error. It is a figure which shows the change of the waveform shown in FIG. 7 by offset error. It is a figure which shows the change of the waveform shown in FIG. 7 by a sensitivity error and an offset error. It is a figure which shows an example of the attitude | position at the time of the calibration of a projector. It is a figure which shows an example of the attitude | position at the time of the calibration of a projector. It is a figure which shows an example of the attitude | position at the time of the calibration of a projector. It is a figure which shows an example of the relationship between the acceleration detected by an acceleration sensor, and a posture angle.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated with reference to drawings.

  FIG. 1 is a block diagram showing a configuration of a projector 100 according to an embodiment of the present invention.

  A projector 100 illustrated in FIG. 1 includes a control unit 101, a light source 102, a modulation unit 103, a projection lens 104, and an attitude detection device 105. In FIG. 1, a white arrow indicates a light beam.

  The control unit 101 receives an image signal from the outside and outputs the image signal to the modulation unit 103. Further, the control unit 101 requests the posture detection device 105 to detect the posture angle of the projector 100 when projecting an image according to the image signal. When the control unit 101 receives the attitude angle of the projector 100 from the attitude detection device 105, the control unit 101 performs control according to the attitude angle. Examples of the control according to the posture angle include setting of the cooling mode, setting of the orientation of the projection image, and display of the posture angle on the projection image.

  The light source 102 outputs light that illuminates the modulation unit 103.

  The modulation unit 103 modulates the light output from the light source 102 according to the image signal output from the control unit 101, and outputs the modulated light to the projection lens 104. Specific examples of the modulation unit 103 include a liquid crystal panel and a DMD (Digital Micromirror Device).

  The projection lens 104 is provided in front of the projector 100 and projects the light output from the modulation unit 103 onto the screen surface 20.

  The attitude detection device 105 is attached to the projector 100 and detects the attitude of the projector 100. The posture detection device 105 includes an acceleration sensor 106 and a calculation unit 107.

  The acceleration sensor 106 detects acceleration and outputs the detection result to the calculation unit 107.

  FIG. 2 is a diagram illustrating an appearance of the projector 100. In general, the control unit 101, the light source 102, the modulation unit 103, the acceleration sensor 106, and the calculation unit 107 are disposed in the housing of the projector 100, and thus are not shown in FIG.

  In the following, the direction in which the projection lens 104 faces, that is, the direction of the projection optical axis of the projector 100 is defined as the Y axis, the axis that is perpendicular to the Y axis, and the Y axis is perpendicular to the vertical direction. The Z axis is defined as the X axis, and the Y axis and the axis orthogonal to the Z axis are defined as the X axis.

  The acceleration sensor 106 detects acceleration in the X-axis direction, the Y-axis direction, and the Z-axis direction.

  Referring again to FIG. 1, when the control unit 101 requests the detection unit 107 to detect the attitude angle of the projector 100, the calculation unit 107 calculates the attitude angle of the projector 100 based on the detection result of the acceleration sensor 106, and calculates the calculation result. Output to the control unit 101.

  Next, the operation of the projector 100 of this embodiment will be described.

  In the following, the angle θyz (Tilt angle) shown in FIG. 6A and the angle θxz (Roll angle) shown in FIG. The case of obtaining will be described as an example.

  First, for comparison, a processing flow from a manufacturing process in a general projector provided with an acceleration sensor that detects acceleration in three axial directions will be described with reference to FIG.

  Calibration is performed in the manufacturing process. Here, when the acceleration sensor detects accelerations in the three-axis directions, calibration is usually performed in a state where each axis faces the horizontal direction and a direction which faces the vertical direction.

  Specifically, for example, as shown in FIG. 11A, acceleration in the three-axis direction is detected by the acceleration sensor in a state where the X-axis and the Y-axis are in the horizontal direction and the Z-axis is in the vertical direction (posture 1). (Step S201).

  Next, as shown in FIG. 11B, acceleration in the three-axis direction is detected by the acceleration sensor in a state where the Y-axis and the Z-axis are in the horizontal direction and the X-axis is in the vertical direction (posture 2) (step S202). ).

  Next, as shown in FIG. 11C, the acceleration in the three-axis direction is detected by the acceleration sensor in a state where the X-axis and the Z-axis are in the horizontal direction and the Y-axis is in the vertical direction (posture 3) (step S203). ).

  Based on the detection result of the acceleration sensor in steps S201 to S203, correction values for the respective axes are calculated.

  The processes from step S201 to step S203 described above are performed in the manufacturing process.

  When the image signal is input to the projector and the image is projected, the acceleration sensor detects the acceleration in the triaxial direction (step S204).

  Next, the detection result (Xoutput, Output, Zoutput) of the acceleration sensor is corrected by the correction value obtained by the calibration. The angle θyz (Tilt angle) and the angle θxz (Roll angle) are calculated using the above-described equations (1) to (4) based on the corrected Xoutput, Yououtput, and Zoutput (step S205). .

  As described above, the sensitivity error and the offset error are removed by correcting the detection results (Xoutput, Output, Zoutput) of the acceleration sensor by the correction value obtained by the calibration. By calculating the angle θyz and the angle θxz based on the corrected Xoutput, Yououtput, and Zoutput, the posture angle error can be reduced. However, as described above, it is difficult to perform calibration in a plurality of postures.

  Next, a processing flow from the manufacturing process in the projector 100 of the present embodiment will be described with reference to FIG.

  Calibration is performed in the manufacturing process. Here, in the projector 100, as shown in FIG. 11A, calibration is performed only in a state where the X axis and the Y axis are in the horizontal direction and the Z axis is in the vertical direction (attitude 1) (step S301). .

  In the posture 1, since the X axis and the Y axis are oriented in the horizontal direction and the Z axis is oriented in the vertical direction, Xoutput and Output are ideally 0 g and Zoutput is 1 g. However, in reality, the detection result of the acceleration sensor 106 includes a sensitivity error and an offset error.

  In the case of posture 1, Xoutput and Youput include an offset error. Therefore, a correction value is calculated so that Xoutput and Output are 0 g. By correcting using this correction value, an offset error can be removed from Xoutput and Output.

  Zoutput includes a sensitivity error and an offset error. Therefore, a correction value is calculated such that Zoutput is 1 g. However, as shown in FIG. 8, since the sensitivity error varies depending on the posture angle, the accuracy of the detection result of the acceleration sensor 106 in the Z-axis direction is sufficient even if the correction is performed using this correction value depending on the posture angle. It cannot be improved.

  Therefore, even if the correction value obtained by calibration in posture 1 is used, the posture angle may not be calculated with high accuracy depending on the installation state. However, as described above, the projector is usually used in a floor-mounted state or a ceiling-mounted state (the X axis and the Y axis are directed in the horizontal direction and the Z axis is directed in the vertical direction). In these installation states, it is almost sufficient to calculate the angle θyz shown in FIG. 6A and the angle θxz shown in FIG. 6B with high accuracy.

  The calculation unit 107 stores the correction value obtained by the calibration in step S301.

  Thus, in the projector 100, calibration is performed only in one posture in the manufacturing process.

  When an image signal is input to the projector 100 and an image is projected, the control unit 101 requests the posture detection device 105 to detect the posture angle of the projector 100. In response to a request from the control unit 101, the calculation unit 107 causes the acceleration sensor 106 to detect acceleration (step S302).

  Next, the calculation unit 107 corrects Xoutput and Output detected by the acceleration sensor 106 with the correction value obtained by the calibration in step S301. By doing so, an offset error included in Xoutput and Output can be removed.

  Next, the calculation unit 107 determines whether or not Zoutput is within a predetermined range (step S303). The predetermined range is a direction in which the Z axis is inclined by a predetermined angle (for example, 45 degrees) with respect to the vertical direction from the acceleration (1 g) generated in the Z axis direction when the Z axis is oriented in the vertical direction. This is the range up to the value of the acceleration that occurs in the Z-axis direction when facing.

  If Zoutput is within the predetermined range (step S303: Yes), the calculation unit 107 corrects Zoutput using the correction value obtained by the calibration in step S301 (step S304). As described above, this correction value can remove the offset error and the sensitivity error when the Z-axis direction is the vertical direction. Therefore, when Zoutput detected by the acceleration sensor 106 is within a predetermined range, accuracy can be improved by correcting Zoutput based on this correction value.

  On the other hand, if Zoutput is not within the predetermined range, that is, if the Z-axis is in a direction inclined more than a predetermined angle from the vertical direction (step S303: No), Zoutput is calibrated in step S301. Even if correction is performed using the correction value obtained in step 1, the accuracy cannot be sufficiently improved. Therefore, the calculation unit 107 does not correct Zoutput.

  Next, the calculation unit 107 determines whether the installation state of the projector 100 is a floor-standing installation state or a ceiling-mounted installation state based on the detection result of the acceleration sensor 106 (step S305). That is, the calculation unit 107 determines whether or not the attitude of the projector 100 is close to the calibrated attitude 1. Even when the detection result of the acceleration sensor 106 includes an error, the installation state of the projector 100 can be detected.

  When it is determined that the installation state of the projector 100 is the floor installation state or the ceiling installation state (step S305: Yes), the calculation unit 107 uses the above-described equation (1) as a calculation equation used for calculating the angle θyz. ) Is selected, and the angle θyz is calculated using the selected equation (1). Further, the calculation unit 107 selects the above-described formula (3) as a calculation formula used for calculating the angle θxz, and calculates the angle θxz using the selected formula (3).

  As described above, in general, in an acceleration sensor, in a state where a specific axis is oriented substantially in the horizontal direction, the detection accuracy of the acceleration in the axial direction is improved, and the axial direction orthogonal to the specific axis and oriented in the substantially vertical direction. The acceleration detection accuracy is reduced.

  In a floor-mounted installation state or a ceiling-mounted installation state, the X axis and the Y axis face the horizontal direction, and the Z axis faces the vertical direction. Therefore, the detection accuracy of Xoutput and Output is high, but the detection accuracy of Zoutput is low. That is, a large error is included in Zoutput.

  Since Zoutput includes a large error, the accuracy of the angle θyz calculated using Youput and Zoutput and the accuracy of the angle θyz calculated using Xoutput and Zoutput based on the above-described equation (5) are not so great. not high.

  On the other hand, in the equation (1), the angle θyz is calculated using only Output. In Expression (3), the angle θxz is calculated using only Xoutput. As described above, the detection accuracy of Xoutput and Output is high in the floor-mounted installation state and the ceiling-mounted installation state. Further, since the correction is performed using the correction value obtained by the calibration, the offset error is also removed. Therefore, the angle θyz calculated using the equation (1) is more accurate than the angle θyz calculated using the equation (5), and the angle θxz calculated using the equation (3). Is more accurate than the angle θyz calculated using the above-described equation (6).

  Therefore, the calculation unit 107 calculates the angle θyz based on the equation (1) when the installation state of the projector 100 is a floor-standing installation state or a ceiling-mounted state, and calculates the angle θxz based on the equation (3). Is calculated. By doing so, when the installation state of the projector 100 is a floor installation state or a ceiling installation state, the attitude angle can be detected with high accuracy.

  When it is determined that the installation state of the projector 100 is not the floor installation state or the ceiling installation state (step S305: No), the calculation unit 107 uses the above equation (5) as a calculation equation used for calculating the angle θyz. And the angle θyz is calculated using the selected equation (5). Further, the calculation unit 107 selects the above-described formula (6) as a calculation formula used to calculate the angle θxz, and calculates the angle θxz using the selected formula (6).

  When the installation state of the projector 100 is not a floor-standing installation state or a ceiling-mounted installation state, there is a possibility that a large error is included in Xoutput and Output. However, as described above, when calculating the attitude angle based on the detection result of the biaxial acceleration, even if an error is included in the acceleration detection result of one of the axes, the attitude angle is calculated with a certain degree of accuracy. Can be calculated.

  That is, even if a large error is included in one of Output and Zoutput, a certain degree of accuracy can be ensured by calculating the angle θyz using Equation (5). Even if a large error is included in one of Xoutput and Zoutput, a certain degree of accuracy can be ensured by calculating the angle θxz using equation (6). In addition, when the Zoutput is corrected in step S304, the accuracy of the calculated posture angle is improved.

  Note that the attitude angle calculated in step S307 (the attitude angle calculated when the projector 100 is not installed on the floor or the ceiling is not installed) is the attitude angle calculated in step S306 (installation of the projector 100). The accuracy is lower than the attitude angle calculated when the state is a floor-mounted installation state or a ceiling-mounted installation state.

  There are projectors that change the cooling mode and those that change the orientation of the projected image, for example, depending on the installation state. The cooling mode is changed, for example, by changing the amount of air to be cooled or the place to be cooled. For changing the direction of the projected image, for example, the image is turned upside down according to the ceiling-mounted state or the floor-mounted state, or the image is rotated by 90 degrees according to the portrait installation state. Since such control can be performed if a rough posture angle can be detected, it can be handled with a relatively low accuracy of the acceleration sensor.

  Further, the projector causes a trapezoidal distortion in the projected image due to the angle between the optical axis of the projection lens that projects the image and the projection surface that projects the image, for example, the screen surface. When trapezoidal distortion occurs, the projected image is corrected to a rectangular shape by correcting the trapezoidal distortion. However, if the projected image is corrected using trapezoidal distortion correction, the image quality deteriorates. Therefore, in order to project an image into a rectangular shape without degrading the image quality, it is desirable to install the projector so that trapezoidal distortion does not occur. In this case, since it is necessary to accurately adjust the angle with the screen surface, it is necessary to install it accurately. In general, as an installation state in which image quality is emphasized, a state in which the screen surface is installed in parallel with the vertical direction and the projector is set so that the projection optical axis is perpendicular to the screen surface is used. That is, the installation surface of the projector is installed so as to be parallel to the horizontal plane. In this case, the attitude angle of the projector with respect to the horizontal plane can be detected using an acceleration sensor, but it is desired that the acceleration sensor has high accuracy.

  In other words, as described above, since projectors are often used in a floor-mounted state or a ceiling-mounted state, even if the attitude angle detection accuracy in an installed state other than these installed states is low, there is a problem. It is rare to become.

  Thus, according to the present embodiment, the projector 100 is calibrated only in a predetermined posture, and whether or not the posture of the projector 100 is close to the predetermined posture based on the acceleration detected by the acceleration sensor 106. And a calculation formula to be used for calculating the attitude angle of the projector 100 is selected according to the result of the determination.

  Therefore, the posture angle can be detected with high accuracy in a specific installation state, and the posture angle can be detected with a certain degree of accuracy even in installation states other than the specific installation state.

  In addition, in a state where a specific axis is oriented substantially in the horizontal direction, the acceleration detection accuracy of the axial direction is increased, and the detection accuracy of the acceleration in the axial direction perpendicular to the specific axis and directed to the substantially vertical direction is decreased. By using this characteristic, the posture angle can be detected with high accuracy in a specific installation state without performing calibration in a plurality of postures. In addition, since it is not necessary to perform calibration in a plurality of postures, the manufacturing cost can be reduced.

  As described above, the projector is often used in a floor-mounted installation state or a ceiling-mounted installation state. Therefore, if the posture angle can be detected with high accuracy in a state where the usage frequency is high (the projector 100 is installed on the floor or the ceiling), the posture in a state where the usage frequency is low. Even if the corner detection accuracy is low, there is little problem.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Projector 101 Control part 102 Light source 103 Modulation part 104 Projection lens 105 Posture detection apparatus 106 Acceleration sensor 107 Calculation part

Claims (6)

A projector,
An acceleration sensor that detects acceleration in three axial directions orthogonal to each other;
A correction value of the detection result of the acceleration sensor obtained by calibration when the projector is in a predetermined posture is stored in advance, and the acceleration detected by the acceleration sensor is corrected by the stored correction value, A calculation unit that calculates an attitude angle indicating an inclination of the projector with respect to a reference plane using any one of a plurality of calculation formulas based on the corrected acceleration;
When calculating the attitude angle of the projector, the calculation unit determines whether the attitude of the projector is close to the predetermined attitude based on the acceleration detected by the acceleration sensor. A projector that selects a calculation formula used to calculate the attitude angle of the projector according to a result. The projector according to claim 1, wherein
The acceleration sensor is perpendicular to the acceleration Output in a first direction that is the direction of the projection optical axis of the projector and perpendicular to the first direction, and the first direction is perpendicular to the vertical direction. Detecting the acceleration Zoutput in the second direction facing the direction and the acceleration Xoutput in the third direction orthogonal to the first direction and the second direction,
The projector according to claim 1, wherein the predetermined posture is a posture in which the first direction and the third direction are directed in a horizontal direction. The projector according to claim 2, wherein
The calculation unit calculates an inclination angle θ1 from the horizontal direction of the first direction as the posture angle,
When it is determined that the attitude of the projector is close to the predetermined attitude, Expression (1)

... Formula (1)
The tilt angle θ1 is calculated using
When it is determined that the installation state of the projector is not close to the predetermined posture, the expression (2)

... Formula (2)
And calculating the tilt angle θ1. The projector according to claim 2 or 3,
The calculation unit calculates an inclination angle θ2 from the horizontal direction of the third direction as the posture angle,
To determine that the attitude of the projector is close to the predetermined attitude, formula (3)

... Formula (3)
The tilt angle θ2 is calculated using
When it is determined that the attitude of the projector is not close to the predetermined attitude, Expression (4)

... Formula (4)
And calculating the tilt angle θ2. A posture detection device that is attached to a device and detects the posture of the device,
An acceleration sensor that detects acceleration in three axial directions orthogonal to each other;
A correction value of a detection result of the acceleration sensor obtained by calibration when the device is in a predetermined posture is stored in advance, and an acceleration detected by the acceleration sensor is corrected by the stored correction value, A calculation unit that calculates an attitude angle indicating an inclination of the device with respect to a reference plane using any one of a plurality of calculation formulas based on the corrected acceleration;
When calculating the posture of the device, the calculation unit determines whether the posture of the device is close to the predetermined posture based on the acceleration detected by the acceleration sensor, and the result of the determination A posture detection apparatus that selects a calculation formula used to calculate the posture angle of the device according to the above. A method of controlling an attitude detection device that is attached to an apparatus and detects the attitude of the apparatus,
A detection step of detecting acceleration in three axial directions orthogonal to each other by an acceleration sensor;
A correction value of a detection result of the acceleration sensor obtained by calibration when the device is in a predetermined posture is stored in advance, and an acceleration detected by the acceleration sensor is corrected by the stored correction value, A calculation step of calculating an attitude angle indicating an inclination of the device with respect to a reference plane using any one of a plurality of calculation formulas based on the corrected acceleration;
In the calculating step, when calculating the posture of the device, it is determined whether or not the posture of the device is close to the predetermined posture based on the acceleration detected by the acceleration sensor, and the result of the determination A calculation method used for calculating a posture angle of the device is selected according to the control method.

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