Position detection device and imaging device

Abstract

This position detection device comprises: a motor that causes a driven body to rotate; a period sensor that detects a plurality of periods included in periodic changes produced by the rotation of the motor; an origin sensor that detects an origin in the direction of rotation of the motor; and a control unit that controls the rotation of the motor on the basis of signals output from the period sensor and the origin sensor. A repeated detection error, when the origin is detected by the origin sensor, is smaller than a range of rotation of the motor corresponding to each of a plurality of periods detected by the period sensor.

Description

[Technical Field]

[0001] The present disclosure relates to a position detection device and an imaging device including the position detection device. [Background technology]

[0002] Conventionally, position detection devices that detect the tilt and pan direction positions of a camera have been known. As an example of this type of position detection device, Patent Document 1 discloses a technique in which the detection level of a tilt direction detection sensor is measured while the camera is rotated in the pan direction, and the origin of the tilt direction is detected at the pan direction rotation position where the sensor is least affected by external light. This technique makes it possible to detect the origin in a state where the influence of external light on the tilt direction detection sensor is reduced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-219880 Summary of the Invention

[0004] In a position detection device, the origin must be determined again each time the power is turned on, but if there is a detection variation when detecting the origin, the position of the origin cannot be reproduced with high accuracy. In that case, the position of the origin will be different each time the power is turned on, and the camera position cannot be reproduced with high accuracy.

[0005] Therefore, an object of the present disclosure is to provide a position detection device or the like that can accurately reproduce the position of the origin.

[0006] A position detection device according to one aspect of the present disclosure includes a motor that rotates a driven object, a period sensor that detects a plurality of periods included in a periodic change generated by the rotation of the motor, an origin sensor that detects an origin in the rotation direction of the motor, and a control unit that controls the rotation of the motor based on signals output from the period sensor and the origin sensor, wherein a repeated detection error when detecting the origin by the origin sensor is smaller than a rotation range of the motor corresponding to each of the plurality of periods detected by the period sensor, The period sensor outputs a waveform signal having the plurality of periods to the control unit, and the origin sensor outputs an origin detection signal to the control unit indicating that the origin has been detected. The control unit 1) calculates, based on the waveform signal output from the period sensor, a first count value which is an integrated value of the plurality of periods when the origin detection signal is acquired, and a first intra-period rotation amount which is the amount of rotation of the motor within a period of the period corresponding to the first count value, when initially setting the origin of the motor; and 2) calculates, based on the waveform signal output from the period sensor, a second count value which is an integrated value of the plurality of periods when the origin detection signal is acquired, and a second intra-period rotation amount which is the amount of rotation of the motor within a period of the period corresponding to the second count value, and sets the origin using the first intra-period rotation amount, the second intra-period rotation amount, the first count value, and the second count value.

[0007] An imaging device according to an aspect of the present disclosure includes the position detection device described above and the driven object including a camera.

[0008] According to a position detection device and the like according to one aspect of the present disclosure, the position of the origin can be reproduced with high accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a front view of an imaging device including a position detection device according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram of a motor included in the position detection device according to the embodiment. [Figure 3] 10 is a diagram showing a repeated detection error when detecting the origin by the origin sensor, and a rotation range of the motor corresponding to each of a plurality of periods detected by the period sensor. FIG. [Figure 4] 1 is a block diagram of a position detection device according to an embodiment; [Figure 5] 4A to 4C are diagrams showing waveform signals input to a control unit of a position detection device according to an embodiment, count values ​​calculated by the control unit, the amount of rotation of a motor within a period, and the accumulated amount of rotation of the motor. [Figure 6] 10 is a flowchart showing the operation of the position detection device when the origin of the motor is initially set. [Figure 7] FIG. 10 is a diagram illustrating a process executed by the position detection device when the origin of the motor is initially set. [Figure 8] FIG. 10 is a diagram showing an origin set in the initial setting. [Figure 9] 10 is a flowchart showing the operation of the position detection device when resetting the origin of the motor. [Figure 10] FIG. 10 is a diagram illustrating a process executed by the position detection device when resetting the origin of the motor. [Figure 11] FIG. 10 is a diagram showing an origin that is set by resetting. [Figure 12] FIG. 10 is a diagram showing another example of the origin set in the initial setting. [Figure 13] FIG. 10 is a diagram showing another example of the origin that is set by resetting. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not described in independent claims will be described as optional components.

[0011] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Furthermore, in each figure, substantially the same configuration is assigned the same reference numeral, and duplicate explanations may be omitted or simplified. Furthermore, even when the same object is illustrated in each figure, the scale may be changed for convenience.

[0012] Furthermore, in this specification, terms indicating the relationship between elements, such as coincidence, equality, and parallelism, terms indicating the shape of elements, such as plate-like and rectangular, as well as numerical values ​​and numerical ranges, are not expressions that only express the strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of about a few percent.

[0013] (Embodiment) [Configuration of position detection device and imaging device] The configurations of a position detection device and an imaging device according to an embodiment will be described with reference to FIGS.

[0014] FIG. 1 is a front view of an imaging device 5 including a position detection device 1 according to an embodiment.

[0015] The imaging device 5 is a device that captures images by moving, for example, a camera 45 in a pan direction and a tilt direction. When the imaging device 5 is installed on a ceiling, for example, it is installed upside down as shown in FIG.

[0016] The imaging device 5 includes a driven object 40 and a position detection device 1.

[0017] The driven object 40 includes a camera 45, a first base 41 serving as a base, and a second base 42 provided on the first base 41. The camera 45 is, for example, a visible light camera, a near-infrared light camera, or a camera capable of detecting visible light and near-infrared light. The first base 41 is fixed to a building material such as a ceiling. The second base 42 includes a flat plate and two side plates erected perpendicularly from the flat plate.

[0018] The position detection device 1 can rotate the driven object 40 including the camera 45 in the pan direction and the tilt direction. The position detection device 1 can also detect the position of the camera 45 in the pan direction and the tilt direction.

[0019] The position detection device 1 includes a plurality of motors 30a and 30b, a plurality of period sensors 10a and 10b, a plurality of origin sensors 20a and 20b, and a control unit 50.

[0020] The multiple motors 30a, 30b are, for example, stepping motors, and their rotation angles are changed by control commands output from the control unit 50. Motor 30a is fixed to a flat plate of second base 42, and the rotation shaft of motor 30a is connected to first base 41 via a shaft member extending vertically. Motor 30b is fixed to one side plate of second base 42, and the rotation shaft of motor 30b is connected to camera 45 via a shaft member extending horizontally. This position detection device 1 employs a direct drive structure in which the driven object 40 or camera 45 is directly rotated by motors 30a, 30b.

[0021] For example, by rotating motor 30a, second base 42 and camera 45 can be rotated in the pan direction using first base 41 as a base, and by rotating motor 30b, camera 45 can be rotated in the tilt direction using second base 42 as a base. For example, the movable range of motor 30a is 360°, and the movable range of motor 30b is 90°.

[0022] Hereinafter, either or both of the motors 30a and 30b may be referred to as motor 30. Either or both of the period sensors 10a and 10b may be referred to as period sensor 10, and either or both of the origin sensors 20a and 20b may be referred to as origin sensor 20.

[0023] FIG. 2 is a schematic diagram of the motor 30 and the period sensor 10 included in the position detection device 1. As shown in FIG.

[0024] The motor 30 has a motor body 31 and a sensor magnet 33 connected to the rotation shaft of the motor 30 .

[0025] The sensor magnet 33 has a plurality of magnetic poles 34 aligned in the direction of rotation of the motor 30. The magnetic poles 34 are magnetized so that south poles and north poles are aligned alternately in the direction of rotation. The number of magnetic poles 34 of the sensor magnet 33 is, for example, 432. The magnetic poles 34 rotate as the motor 30 rotates. The rotation of the magnetic poles 34 generates changes in the magnetic field in and around the motor main body 31.

[0026] The period sensor 10 is disposed near the sensor magnet 33 and detects the multiple periods contained in the periodic change caused by the rotation of the motor 30. The period sensor 10 is, for example, an MR (Magneto Resistance) sensor, and detects the multiple periods by detecting changes in the magnetic field caused by the rotational movement of the multiple magnetic poles 34. The periods contained in the periodic change correspond one-to-one to the magnetization periods of the multiple magnetic poles 34 aligned in the rotational direction of the motor 30.

[0027] For example, period sensor 10a, which detects the pan rotation of motor 30a, is fixed to the flat plate of second base 42, and period sensor 10b, which detects the tilt rotation of motor 30b, is fixed to the side plate of second base 42. Each period sensor 10a, 10b detects multiple periods within the movable range of each motor 30a, 30b. For example, period sensor 10a detects 432 periods while motor 30a rotates 360°. For example, period sensor 10b detects 108 periods while motor 30b rotates 90°. Each period sensor 10a, 10b outputs a waveform signal s1 including multiple periods to control unit 50.

[0028] Origin sensor 20 detects the origin in the rotation direction of motor 30. Origin sensor 20 is, for example, a transmission-type photoelectric sensor, and is composed of a photointerrupter and a shielding member that blocks light emitted and received by the photointerrupter. For example, the photointerrupter of origin sensor 20a that detects the origin in the pan direction of motor 30a is fixed to a flat plate of second base 42, and the shielding member is fixed to first base 41. In addition, the photointerrupter of origin sensor 20b that detects the origin in the tilt direction of motor 30b is fixed to a side plate of second base 42, and the shielding member is fixed to camera 45.

[0029] Each of the origin sensors 20a and 20b detects the origin once within the movable range of each of the motors 30a and 30b. For example, the origin sensor 20a detects the origin once while the driven object 40 including the camera 45 rotates 360°. For example, the origin sensor 20b detects the origin once while the camera 45 rotates 90°. Each of the origin sensors 20a and 20b outputs an origin detection signal s2 indicating that the origin has been detected to the control unit 50.

[0030] The position detection device 1 needs to perform origin return to determine the origin every time the power is turned on, but when detecting the origin, a repetitive detection error occurs. The repetitive detection error is a detection variation when the origin is repeatedly detected. In this embodiment, the repetitive detection error when the origin is detected by the origin sensor 20 has the following configuration.

[0031] 3 is a diagram showing the repetitive detection error α when detecting the origin by origin sensor 20, and the rotation range β of motor 30 corresponding to each of the multiple periods detected by period sensor 10. FIG. 3(a) is a diagram schematically showing the frequency distribution of the detection values ​​when the origin is detected by origin sensor 20. FIG. 3(b) is a diagram schematically showing multiple periods detected by period sensor 10. The repetitive detection error α and the rotation range β of motor 30 are each a value expressed in degrees.

[0032] 3, in this embodiment, the repeat detection error α when detecting the origin by origin sensor 20 is smaller than the rotation range β of motor 30 corresponding to each of the multiple periods detected by period sensor 10. In other words, the rotation range β of motor 30 corresponding to each period is designed to be larger than the repeat detection error α when detecting the origin. This makes it possible to accurately reproduce the position of the origin.

[0033] 4 is a block diagram of the position detection device 1. In the figure, the driven object 40 and the magnetic pole 34 of the sensor magnet 33 are shown in a simplified form. Here, the motor 30 that rotates in the pan direction will be described as an example, but the same applies to the motor 30 that rotates in the tilt direction.

[0034] 4, the position detection device 1 includes a motor 30, a period sensor 10, an origin sensor 20, and a control unit 50. The motor 30, the period sensor 10, and the origin sensor 20 are as described above.

[0035] The control unit 50 includes AD conversion units 51 and 52, a rotation amount calculation unit 53, an origin acquisition unit 54, an origin setting unit 55, a rotation amount setting unit 56, a drive control unit 59, and a storage unit 60. The control unit 50 is configured by a processor such as a CPU (Central Processing Unit), the storage unit 60 having a volatile memory and a non-volatile memory, and a program stored in the storage unit 60. The functional block configuration of the control unit 50 is realized by executing the program.

[0036] AD conversion unit 51 acquires waveform signal s1 output from period sensor 10, performs AD conversion on the signal, and outputs the result to rotation amount calculation unit 53. Based on the signal output from AD conversion unit 51, rotation amount calculation unit 53 calculates count value c, the amount of rotation of the motor within a period r, and the accumulated amount of rotation of the motor rc.

[0037] 5 is a diagram showing the waveform signal s1 input to the control unit 50 of the position detection device 1, the count value c calculated by the control unit 50, the in-cycle rotation amount r of the motor 30, and the cumulative rotation amount rc of the motor 30. Note that in FIG. 5, for ease of understanding, the waveform signal s1, the count value c, the in-cycle rotation amount r, and the cumulative rotation amount rc are expressed as analog data.

[0038] The horizontal axis in FIG. 5 represents the rotation angle of the motor 30 when the motor 30 is rotated from one end to the other end within the movable range of the motor 30.

[0039] 5(a), two-phase waveform signals s1 that are 90° out of phase with each other are input to the control unit 50. Each of the two-phase waveform signals s1 is a sinusoidal signal, and the amplitude on the vertical axis corresponds to the output voltage of the period sensor 10.

[0040] 5(b) shows the count value c obtained by accumulating the periods included in one phase of the two-phase waveform signal s1. For example, if the waveform signal s1 has 432 periods when the motor 30 rotates 360°, one period is approximately 0.83°, and therefore the count value c is incremented every time the motor 30 rotates approximately 0.83°.

[0041] 5(c) shows sawtooth waveform signal s1a generated by calculation based on two-phase waveform signal s1. This waveform signal s1a has the same period as one-phase waveform signal s1 of the two-phase waveform signal s1, and its amplitude changes in proportion to the rotation angle of motor 30.

[0042] The rotation amount calculation unit 53 shown in FIG. 4 reads the sawtooth waveform signal s1a to obtain the rotation angle of the motor 30 within a period, i.e., the in-period rotation amount r. The rotation amount calculation unit 53 also obtains the accumulated rotation amount rc of the motor 30 by accumulating the in-period rotation amount r for each period (see FIG. 5(c)). The rotation amount calculation unit 53 outputs rotation angle information including the count value c, the in-period rotation amount r of the motor 30, and the accumulated rotation amount rc to the origin acquisition unit 54, origin setting unit 55, rotation amount setting unit 56, and storage unit 60. This rotation angle information is used when setting the origin of the motor 30 and when setting the rotation amount of the motor 30.

[0043] 4 acquires the origin detection signal s2 output from the origin sensor 20 and performs AD conversion on it. The AD conversion unit 52 outputs the AD-converted origin detection signal s2 to the origin acquisition unit .

[0044] The origin acquisition unit 54 acquires the position of the origin based on the origin detection signal s2 and the rotation angle information output from the rotation amount calculation unit 53. Specifically, the origin acquisition unit 54 acquires the count value c when the origin sensor 20 detects the origin and the in-cycle rotation amount r of the motor 30 from the rotation amount calculation unit 53, and specifies the position of the origin. Origin information including the position of the origin specified by the origin acquisition unit 54 is output to the origin setting unit 55 and the memory unit 60.

[0045] The storage unit 60 stores the origin information and the like output from the origin acquisition unit 54. The origin information includes the rotation angle information described above.

[0046] When initially setting the origin of the motor 30, the origin setting unit 55 sets the origin based on the origin information output from the origin acquisition unit 54. When resetting the origin of the motor 30, the origin setting unit 55 resets the origin based on the origin information output from the origin acquisition unit 54 and the origin information read from the storage unit 60. The origin setting information set by the origin setting unit 55 is output to the rotation amount setting unit 56. Specific examples of these will be described later.

[0047] The rotation amount setting unit 56 sets the cumulative rotation amount rc of the motor 30 based on the origin, based on the origin setting information output from the origin setting unit 55 and the rotation angle information output from the rotation amount calculation unit 53, and outputs it to the drive control unit 59. The drive control unit 59 controls the rotation of the motor 30 based on the signal output from the rotation amount setting unit 56.

[0048] In this way, the control unit 50 determines the amount of rotation r of the motor 30 within each of the multiple periods based on the waveform signal s1 and the count value c, which is an integrated value of the multiple periods, and also determines the origin of the motor 30 based on the origin detection signal s2. In this way, the control unit 50 obtains the cumulative amount of rotation rc, which is the cumulative value of the amount of rotation r within a period of the motor 30 relative to the origin, and can control the rotation of the motor 30.

[0049] [How to set the origin of a position detection device] A method for setting the origin of the position detection device 1 will be described with reference to Figs. 6 to 11. In this example, the explanation will be divided into a scene for initially setting the origin of the motor 30 and a scene for resetting it. Note that, although the explanation will be given here using the motor 30 that rotates in the pan direction as an example, the same applies to the motor 30 that rotates in the tilt direction.

[0050] Fig. 6 is a flowchart showing the operation of the position detection device 1 when initially setting the origin of the motor 30. Fig. 7 is a diagram showing the processing executed by the position detection device 1 when initially setting the origin of the motor 30.

[0051] First, when the position detection device 1 is powered on, information relating to the origin of the motor 30 is initialized (step S11).

[0052] Next, control unit 50 rotates motor 30 until the origin of motor 30 is detected. This rotation of motor 30 causes origin sensor 20 to detect the origin of motor 30 (step S12). Origin sensor 20 outputs origin detection signal s2 to origin acquisition unit 54. In addition, period sensor 10 outputs waveform signal s1 to rotation amount calculation unit 53.

[0053] The origin acquisition unit 54 acquires the first count value c1 and the first in-period rotation amount r1 when the origin sensor 20 detects the origin from the rotation amount calculation unit 53. Specifically, the origin acquisition unit 54 acquires the first count value c1, which is an integrated value of multiple periods when the origin detection signal s2 is acquired, and the first in-period rotation amount r1, which is the in-period rotation amount of the motor 30 for the period corresponding to the first count value c1, from the rotation amount calculation unit 53. The origin acquisition unit 54 identifies the position of the origin based on the acquired first count value c1 and first in-period rotation amount r1 (step S13).

[0054] FIG. 8 is a diagram showing the origin set in the initial setting.

[0055] The upper part of FIG. 8 shows a count value c indicating an integrated value over multiple periods, and a first count value c1(n) which is an integrated value over multiple periods when the origin detection signal s2 is acquired. Note that the actual count value is shown in parentheses around the count value c1. The waveform signal s1a in the middle part of FIG. 8 shows a first in-period rotation amount r1, which is the in-period rotation amount of the motor 30 for the period corresponding to the first count value c1(n), as a white circle. The position of the white circle coincides with the rising trigger of the origin detection signal s2 shown in the lower part of FIG. 8.

[0056] The control unit 50 stores the first count value c1(n) and the first in-cycle rotation amount r1 acquired by the origin acquisition unit 54 in the storage unit 60 (step S14). These steps S11 to S13 complete the initial setting of the origin of the motor 30. The control unit 50 of the position detection device 1 controls the rotation of the motor 30 based on the initially set origin.

[0057] Next, we will explain the operation of the position detection device 1 when resetting the origin of the motor 30. When resetting the origin of the motor 30, the origin is set again using the first count value c1(n) and the first in-cycle rotation amount r1 saved in step S14.

[0058] Fig. 9 is a flowchart showing the operation of the position detection device 1 when resetting the origin of the motor 30. Fig. 10 is a diagram showing the processing executed by the position detection device 1 when resetting the origin of the motor.

[0059] First, the position detection device 1 is powered on, thereby initializing the temporarily stored data (step S21). Note that the first count value c1(n) and the first in-period rotation amount r1 in the storage unit 60 are not erased but continue to be stored.

[0060] Next, control unit 50 rotates motor 30 until the origin of motor 30 is detected. This rotation of motor 30 causes origin sensor 20 to detect the origin of motor 30 (step S22). Origin sensor 20 outputs origin detection signal s2 to origin acquisition unit 54. In addition, period sensor 10 outputs waveform signal s1 to rotation amount calculation unit 53.

[0061] The origin acquisition unit 54 acquires from the rotation amount calculation unit 53 the second count value c2 and the second in-period rotation amount r2 when the origin sensor 20 detects the origin. Specifically, the origin acquisition unit 54 acquires from the rotation amount calculation unit 53 the second count value c2, which is an integrated value of multiple periods when the origin detection signal s2 is acquired, and the second in-period rotation amount r2, which is the in-period rotation amount of the motor 30 for the period corresponding to the second count value c2. The origin acquisition unit 54 identifies the position of the origin based on the acquired second count value c2 and second in-period rotation amount r2 (step S23). The origin information related to the origin acquired by the origin acquisition unit 54, i.e., the second count value c2 and the second in-period rotation amount r2, is output to the origin setting unit 55.

[0062] The origin setting unit 55 resets the origin using the first count value c1(n) and the first in-period rotation amount r1 stored in the memory unit 60, and the second count value c2 and the second in-period rotation amount r2 calculated in step S23 (step S24).

[0063] FIG. 11 is a diagram showing the origin that is reset.

[0064] The upper part of FIG. 11(a) shows a count value c2 indicating an integrated value over multiple periods, and a second count value c2(n-1), which is an integrated value over multiple periods when the origin detection signal s2 is acquired. Note that the actual count value is shown in parentheses around the count value c2. The waveform signal s1a in the middle part of FIG. 11(a) shows a second in-period rotation amount r2, which is the in-period rotation amount of the motor 30 for the period corresponding to the second count value c2(n-1), as a black circle. The position of the black circle coincides with the rising trigger of the origin detection signal s2 shown in the lower part of FIG. 11(a).

[0065] 11(a), the second in-period rotation amount r2 corresponding to the origin detection signal s2 is within ±0.5 periods of the first in-period rotation amount r1 within the period corresponding to the first count value c1(n). This configuration is achieved by designing the period sensor 10 so that the repeated detection error α when detecting the origin is smaller than the rotation range β of the motor 30 corresponding to each of the multiple periods detected by the period sensor 10. This design makes it possible to accurately reproduce the position of the origin.

[0066] A specific example of a method for setting the origin will be described with reference to FIGS.

[0067] As shown in FIG. 11(a), when the second in-period rotation amount r2 is located in a period different from the period corresponding to the first count value c1(n), the control unit 50 corrects the origin by matching the first count value c1(n) to the second count value c2(n-1). In this example, since the second in-period rotation amount r2 is located at a count value c2(n-1) different from the first count value c1(n), the control unit 50 decrements the count value by one, changing the first count value c1(n) to the count value c2(n-1). The position of the origin is represented by the count value c2(n-1) and the second in-period rotation amount r2.

[0068] Furthermore, as shown in FIG. 11(b), when the second in-period rotation amount r2 is located in the same period as the period corresponding to the first count value c1(n), the control unit 50 sets the origin using the first count value c1(n) as is. That is, in this example, since the second in-period rotation amount r2 is located at the same count value c2(n) as the first count value c1(n), the value of the first count value c1(n) is maintained. The position of the origin is a value represented by the count value c1(n) and the second in-period rotation amount r2. The origin reset in this manner becomes the origin when the power is turned off and on again.

[0069] The reset origin setting information is output to rotation amount setting unit 56. Rotation amount setting unit 56 sets the cumulative rotation amount rc of motor 30 based on the origin, based on the origin setting information output from origin setting unit 55 and the rotation angle information output from rotation amount calculation unit 53, and outputs the cumulative rotation amount rc to drive control unit 59.

[0070] [Another example of setting the origin] Next, another example of setting the origin will be described.

[0071] FIG. 12 shows another example of an origin set in the initial setting. The upper part of FIG. 12 shows a count value c indicating an integrated value over multiple periods, and a first count value c1(n) which is an integrated value over multiple periods when the origin detection signal s2 is acquired. The waveform signal s1a in the middle part of FIG. 12 shows a first intra-period rotation amount r1, which is the intra-period rotation amount of the motor 30 in the period corresponding to the first count value (n), as a white circle. The position of the white circle coincides with the rising trigger of the origin detection signal s2 shown in the lower part of FIG. 12.

[0072] The control unit 50 stores the first count value (n) and the first in-cycle rotation amount r1 acquired by the origin acquisition unit 54 in the storage unit 60.

[0073] FIG. 13 is a diagram showing another example of the origin that is set by resetting.

[0074] The upper part of Fig. 13(a) shows a count value c2 indicating an integrated value over multiple periods, and a second count value c2(n+1) which is an integrated value over multiple periods when the origin detection signal s2 is acquired. The waveform signal s1a in the middle part of Fig. 13(a) shows a second in-period rotation amount r2, which is the in-period rotation amount of the motor 30 for the period corresponding to the second count value (n+1), as a black circle. The position of the black circle coincides with the rising trigger of the origin detection signal s2 shown in the lower part of Fig. 13(a).

[0075] 13(a), the second in-period rotation amount r2 corresponding to the origin detection signal s2 is within ±0.5 periods of the first in-period rotation amount r1 within the period corresponding to the first count value c1(n). This configuration is achieved by designing the period sensor 10 so that the repeated detection error α when detecting the origin is smaller than the rotation range β of the motor 30 corresponding to each of the multiple periods detected by the period sensor 10. This design makes it possible to accurately reproduce the position of the origin.

[0076] A specific example of a method for setting the origin will be described with reference to FIGS.

[0077] As shown in FIG. 13(a), when the second in-period rotation amount r2 is located in a period different from the period corresponding to the first count value (n), the control unit 50 corrects the origin by matching the first count value c1(n) to the second count value c2(n+1). In this example, since the second in-period rotation amount r2 is located at a count value c2(n+1) different from the first count value c1(n), the control unit 50 increments the count value by one, changing the first count value c1(n) to the count value c2(n+1). The position of the origin is represented by the count value c2(n+1) and the second in-period rotation amount r2.

[0078] Furthermore, as shown in FIG. 13(b), when the second in-period rotation amount r2 is located in the same period as the period corresponding to the first count value (n), the control unit 50 sets the origin using the second count value c2(n) as is. That is, in this example, since the second in-period rotation amount r2 is located at the same count value c2(n) as the first count value c1(n), the value of the first count value c1(n) is maintained. The position of the origin is a value represented by the count value c1(n) and the second in-period rotation amount r2. The origin reset in this manner becomes the origin when the power is turned off and on again.

[0079] (summary) As described above, the position detection device 1 according to this embodiment includes the motor 30 that rotates the driven object 40, the period sensor 10 that detects multiple periods included in the periodic changes generated by the rotation of the motor 30, the origin sensor 20 that detects the origin in the rotation direction of the motor 30, and the control unit 50 that controls the rotation of the motor 30 based on the signals output from the period sensor 10 and the origin sensor 20. The repeated detection error α when detecting the origin by the origin sensor 20 is smaller than the rotation range β of the motor 30 that corresponds to each of the multiple periods detected by the period sensor 10.

[0080] In this way, by making the repeated detection error α when detecting the origin smaller than the rotation range β of the motor 30 corresponding to each period, it becomes possible, for example, to correct the position of the origin detected when resetting the origin to match the position of the origin detected when the origin was initially set. This allows the position detection device 1 to reproduce the position of the origin with high accuracy.

[0081] In addition, the motor 30 may have multiple magnetic poles 34 aligned in the direction of rotation, and the multiple magnetic poles 34 may rotate and move as the motor 30 rotates, and the period sensor 10 may detect multiple periods by detecting changes in the magnetic field generated by the rotation and movement of the multiple magnetic poles 34.

[0082] In this way, the period sensor 10 detects multiple periods due to changes in the magnetic field, thereby accurately obtaining the rotation range β of the motor 30 corresponding to the multiple periods. This allows the position of the origin to be obtained accurately, and the position of the origin can be reproduced accurately in the position detection device 1.

[0083] The period may also correspond one-to-one to the magnetization period of the plurality of magnetic poles 34 aligned along the rotation direction.

[0084] In this way, the periods detected by the period sensor 10 correspond one-to-one to the magnetization periods of the multiple magnetic poles 34, so that the rotation range β of the motor 30 corresponding to the multiple periods can be obtained with high accuracy. This allows the position of the origin to be obtained with high accuracy, and the position of the origin can be reproduced with high accuracy in the position detection device 1.

[0085] Furthermore, each of the repeated detection error α and the rotation range β of the motor 30 may be a value expressed as an angle in the rotation direction.

[0086] This makes it possible to correct the angular position of the origin detected when resetting the origin to match the angular position of the origin detected when the origin was initially set, thereby enabling the position detection device 1 to accurately reproduce the angular position of the origin.

[0087] Alternatively, the period sensor 10 may detect the period multiple times within the movable range of the motor 30, and the origin sensor 20 may detect the origin once within the movable range of the motor 30.

[0088] In this way, by having the period sensor 10 detect more periods than the origin sensor 20, the position of the origin can be obtained with high accuracy using the period sensor 10 and the origin sensor 20, and the position of the origin can be reproduced with high accuracy in the position detection device 1.

[0089] Furthermore, the period sensor 10 outputs a waveform signal s1 having multiple periods to the control unit 50, and the origin sensor 20 outputs an origin detection signal s2 indicating that the origin has been detected to the control unit 50. The control unit 50 determines the amount of rotation r of the motor 30 within a period for each of the multiple periods based on the waveform signal s1 and a count value c which is an integrated value of the multiple periods, and determines the origin of the motor 30 based on the origin detection signal s2, thereby obtaining a cumulative rotation amount rc which is an accumulated value of the amount of rotation r of the motor 30 within a period based on the origin, and controlling the rotation of the motor 30.

[0090] This makes it possible to accurately determine the origin of the motor 30 based on the waveform signal s1 and the origin detection signal s2. Also, by acquiring the cumulative rotation amount rc of the motor 30 relative to the origin, it becomes possible to improve the accuracy of position control of the rotation of the motor 30.

[0091] Furthermore, period sensor 10 outputs waveform signal s1 having a plurality of periods to control unit 50, and origin sensor 20 outputs origin detection signal s2 indicating that the origin has been detected to control unit 50. Control unit 50 then: 1) calculates, based on waveform signal s1 output from period sensor 10, a first count value c1 which is an integrated value of a plurality of periods when origin detection signal s2 is acquired when the origin of motor 30 is initially set, and a first intra-period rotation amount c2 which is an intra-period rotation amount of motor 30 for a period corresponding to first count value c1. 2) when resetting the origin of motor 30, a second count value c2, which is an integrated value of multiple periods when origin detection signal s2 is acquired, and a second in-period rotation amount r2, which is the in-period rotation amount of motor 30 for the period corresponding to second count value c2, may be calculated based on waveform signal s1 output from period sensor 10, and the origin may be set using first in-period rotation amount r1, second in-period rotation amount r2, first count value c1, and second count value c2.

[0092] In this way, by setting the origin using the first in-cycle rotation amount r1, the second in-cycle rotation amount r2, the first count value c1, and the second count value c2, it is possible to correct the position of the origin detected when resetting the origin to match the position of the origin detected when the origin was initially set. This allows the position detection device 1 to reproduce the position of the origin with high accuracy.

[0093] The second in-period rotation amount r2 may be within ±0.5 periods with the first in-period rotation amount r1 of the period corresponding to the first count value c1 as a reference.

[0094] In this way, since the second in-period rotation amount r2 is within ±0.5 periods of the first in-period rotation amount r1 as a reference, it is possible to correct the position of the origin detected when resetting the origin to match the position of the origin detected when the origin was initially set. This allows the position detection device 1 to reproduce the position of the origin with high accuracy.

[0095] In addition, when the second intra-period rotation amount r2 is located in a period different from the period corresponding to the first count value c1, the control unit 50 may set the origin by matching the first count value c1 to the second count value c2.

[0096] This makes it possible to correct the position of the origin detected when resetting the origin to match the position of the origin detected when the origin was initially set, thereby enabling the position detection device 1 to reproduce the position of the origin with high accuracy.

[0097] In addition, the position detection device 1 may further include a memory unit 60 in which the first count value c1 and the first in-period rotation amount r1 are stored, and the control unit 50 may set the origin using the first count value c1 and the first in-period rotation amount r1 stored in the memory unit 60, and the second count value c2 and the second in-period rotation amount r2.

[0098] In this way, by storing the first count value c1 and the first in-period rotation amount r1 in the storage unit 60, it becomes possible to correct the position of the origin detected when resetting the origin to match the position of the origin stored in the storage unit 60. This allows the position detection device 1 to reproduce the position of the origin with high accuracy.

[0099] Moreover, the imaging device 5 according to this embodiment includes the position detection device 1 described above and a driven object 40 including a camera 45.

[0100] This makes it possible to provide an imaging device 5 equipped with a position detection device 1 that can accurately reproduce the position of the origin.

[0101] (Other embodiments) Although the embodiments have been described above, the present disclosure is not limited to such embodiments.

[0102] The period sensor 10 in the above embodiment is not limited to a magnetic sensor. For example, the period sensor may be an optical sensor as long as it detects periodic changes. The origin sensor 20 in the above embodiment is not limited to a transmissive photoelectric sensor. For example, the origin sensor may be a reflective photoelectric sensor, a magnetic sensor, or a mechanical switch sensor as long as it can detect the origin of the motor 30.

[0103] The position detection device 1 of the above embodiment may also execute the following origin setting method. That is, the origin setting method for the position detection device 1 includes a motor 30 that rotates a driven object 40, a period sensor 10 that detects multiple periods included in periodic changes caused by the rotation of the motor 30, an origin sensor 20 that detects an origin in the rotation direction of the motor 30, and a control unit 50 that controls the rotation of the motor 30 based on signals output from the period sensor 10 and the origin sensor 20, and includes the steps of: 1) the period sensor 10 outputting a waveform signal s1 having multiple periods to the control unit 50; 2) the origin sensor 20 outputting an origin detection signal s2 indicating that the origin has been detected to the control unit 50; and 3) when initially setting the origin of the motor 30, detecting the waveform signal s1 outputted from the period sensor 10. 3) calculating, based on the waveform signal s1 output from period sensor 10, a first count value c1 which is an integrated value of multiple periods when the origin detection signal s2 is acquired, and a first in-period rotation amount r1 which is the in-period rotation amount of motor 30 for the period corresponding to first count value c1; and 4) when resetting the origin of motor 30, calculating, based on the waveform signal output from period sensor 10, a second count value c2 which is an integrated value of multiple periods when the origin detection signal is acquired, and a second in-period rotation amount r2 which is the in-period rotation amount of motor 30 for the period corresponding to second count value c2, and setting the origin using the first in-period rotation amount r1, the second in-period rotation amount r2, the first count value c1, and the second count value c2.

[0104] The general or specific aspects of the present disclosure may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0105] The order of the processes described in the flowcharts of the above embodiments is merely an example. The order of multiple processes may be changed, or multiple processes may be executed in parallel.

[0106] The division of functional blocks in the block diagram is an example, and multiple functional blocks may be realized as a single functional block, one functional block may be divided into multiple blocks, or some functions may be moved to another functional block.Furthermore, the functions of multiple functional blocks having similar functions may be processed in parallel or in time-sharing by a single piece of hardware or software.

[0107] Furthermore, in the above-described embodiments, each component (for example, a processing unit such as a control unit) may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU (Central Processing Unit) or a processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory. Also, for example, each component may be a circuit (or integrated circuit). These circuits may form a single circuit as a whole, or each may be a separate circuit. Also, each of these circuits may be a general-purpose circuit or a dedicated circuit.

[0108] In addition, this disclosure also includes forms obtained by applying various modifications to the above embodiments, etc. that a person skilled in the art would conceive, or forms realized by arbitrarily combining the components and functions of each embodiment within the scope that does not deviate from the intent of this disclosure. [Industrial Applicability]

[0109] The position detection device and the like of the present disclosure can be used in a surveillance camera device and the like. [Explanation of symbols]

[0110] 1 Position detection device 5. Imaging device 10, 10a, 10b Periodic Sensor 20, 20a, 20b Origin sensor 30, 30a, 30b motors 31 Motor body 33 Sensor Magnet 34 magnetic pole 40 Driven object 41 First Foundation 42 Second Foundation 45 Camera 50 control section 51 AD conversion section 52 AD conversion section 53 Rotation amount calculation unit 54 Origin acquisition section 55 Origin setting section 56 Rotation amount setting section 59 Drive control unit 60 Storage section c, c1, c2 count values s1, s1a waveform signal s2 Origin detection signal r, r1, r2 Intra-cycle rotation amount rc cumulative rotation amount α Repeated detection error when detecting the origin β Motor rotation range corresponding to each period

Claims

1. a motor that rotates the driven object; a period sensor that detects a plurality of periods included in a periodic change that occurs due to rotation of the motor; an origin sensor for detecting an origin in the rotation direction of the motor; a control unit that controls the rotation of the motor based on signals output from the period sensor and the origin sensor; Equipped with a repeat detection error when detecting the origin by the origin sensor is smaller than a rotation range of the motor corresponding to each of the plurality of periods detected by the period sensor; the period sensor outputs a waveform signal having the plurality of periods to the control unit; the origin sensor outputs an origin detection signal indicating that the origin has been detected to the control unit; The control unit 1) When initially setting the origin of the motor, a first count value is calculated based on the waveform signal output from the period sensor, the first count value being an integrated value of the plurality of periods when the origin detection signal is acquired, and a first intra-period rotation amount is an intra-period rotation amount of the motor for the period corresponding to the first count value; 2) When resetting the origin of the motor, a second count value, which is an integrated value of the plurality of periods when the origin detection signal is acquired, and a second in-period rotation amount, which is an in-period rotation amount of the motor for the period corresponding to the second count value, are calculated based on the waveform signal output from the period sensor, and the origin is set using the first in-period rotation amount, the second in-period rotation amount, the first count value, and the second count value. Position detection device.

2. the motor has a plurality of magnetic poles aligned along the rotation direction, the plurality of magnetic poles rotate and move in accordance with the rotation of the motor; The period sensor detects the plurality of periods by detecting a change in a magnetic field generated by the rotational movement of the plurality of magnetic poles. The position detection device according to claim 1 .

3. The period corresponds one-to-one to the magnetization period of the plurality of magnetic poles aligned along the rotation direction. The position detection device according to claim 2 .

4. The repeat detection error and the rotation range of the motor are each a value expressed as an angle in the rotation direction. The position detection device according to claim 1 .

5. the period sensor detects the period a plurality of times within a movable range of the motor; The origin sensor detects the origin once within the movable range of the motor. The position detection device according to claim 1 .

6. the period sensor outputs a waveform signal having the plurality of periods to the control unit; the origin sensor outputs an origin detection signal indicating that the origin has been detected to the control unit; The control unit obtains the amount of rotation of the motor within a period in each of the plurality of periods based on the waveform signal and a count value that is an integrated value of the plurality of periods, and obtains the origin of the motor based on the origin detection signal, thereby obtaining an accumulated amount of rotation that is an accumulated value of the amount of rotation of the motor within a period based on the origin, and controls the rotation of the motor. The position detection device according to claim 1 .

7. The second intra-period rotation amount is within ±0.5 periods with the first intra-period rotation amount of the period corresponding to the first count value as a reference. The position detection device according to claim 1 .

8. When the second intra-period rotation amount is located in a period different from the period corresponding to the first count value, the control unit sets the origin by making the first count value equal to the second count value. The position detection device according to claim 1 .

9. further comprising a storage unit for storing the first count value and the first in-period rotation amount, The control unit sets the origin using the first count value, the first in-period rotation amount, and the second count value, and the second in-period rotation amount stored in the storage unit. The position detection device according to claim 1 .

10. The position detection device according to claim 1 ; the driven object including a camera; An imaging device comprising:

Images