Pointer driving device, electronic watch, pointer driving method, and recording medium

Abstract

The present invention provides a pointer drive device, an electronic timepiece, a pointer drive method, and a recording medium. The pointer drive device includes first to third stepping motors, a drive circuit, a magnetic sensor, and a processor. The first to third stepping motors move the pointer. The drive circuit drives the first to third stepping motors. The processor controls the magnetic sensor based on the movement of the first to third stepping motors. When the magnetic sensor is not performing a measurement, the processor determines whether the drive circuit is rotating the stepping motor. If it is determined that the stepping motor is not rotating, the processor causes the magnetic sensor to start measuring.

Description

[0001] This application is a divisional application of application No. 2020113324964 filed with the State Intellectual Property Office of China on November 24, 2020. Technical Field

[0002] The technical field relates to a pointer driving device, an electronic watch, a pointer driving method, and a recording medium. Background Art

[0003] For example, Japanese Patent Application Publication No. 2019-49436 discloses an electronic watch having: a stepping motor having a rotor, a stator, and a coil having a conductive wire wound around a coil core; and a magnetic-resistant plate covering at least a portion of the stepping motor. Summary of the Invention

[0004] This embodiment is characterized by comprising: a motor for moving a pointer; a drive circuit for driving the motor; a magnetic sensor; and a processor for controlling the magnetic sensor based on the movement of the motor.

[0005] In a state where the magnetic sensor is not performing measurement, the processor determines whether the drive circuit is rotating the motor, and if it is determined that the motor is not rotating, causes the magnetic sensor to start measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 An electronic watch showing an embodiment.

[0007] Figure 2 A stepping motor according to an embodiment is shown.

[0008] Figure 3 This is a block diagram showing the structure of a pointer driving device according to an embodiment.

[0009] Figure 4 1 is a flowchart showing the hand movement control process according to the embodiment.

[0010] Figure 5 This is a flowchart showing the first hand movement process according to the embodiment.

[0011] Figure 6 1 is a flowchart showing the second hand movement process according to the embodiment.

[0012] Figure 7 The hand movement control process according to the embodiment will be described.

[0013] Figure 8 This figure shows an electronic timepiece according to a modified example.

[0014] Figure 9 This figure shows an electronic timepiece according to a modified example. DETAILED DESCRIPTION

[0015] Hereinafter, a hand driving device and an electronic timepiece according to the present embodiment will be described with reference to the drawings.

[0016] like Figure 1 As shown, the electronic watch 1 of this embodiment is a wristwatch including hands 20a to 20c, a dial 30, a case 40, a band 50, and a hand driving device 100. The hand driving device 100 drives the hands 20a to 20c and includes first to third stepping motors (motors) 120a to 120c, a drive circuit 130, a timing circuit 140, a magnetic sensor 150, a power supply unit 160, and a control unit 110. The first to third stepping motors 120a to 120c, the drive circuit 130, the control unit 110, and the timing circuit 140 constitute the motor driving device 200.

[0017] Hand 20a is the second hand, indicating seconds; hand 20b is the minute hand, indicating minutes; and hand 20c is the hour hand, indicating the time. Hands 20a-20c are arranged to rotate freely about the rotation axis of dial 30. Dial 30 is a display panel with hour characters 31 indicating the time. Case 40 includes a glass cover 41 that covers hands 20a-20c and dial 30, and a crown 42 for adjusting the position of hands 20a-20c. It houses hands 20a-20c, dial 30, and hand drive device 100. A strap 50 is attached to case 40 for wearing on the wrist.

[0018] The first stepper motor 120a drives the second hand 20a via one or more gears. The second stepper motor 120b drives the minute hand 20b via one or more gears. The third stepper motor 120c drives the hour hand 20c via one or more gears.

[0019] like Figure 2 As shown, the first to third stepping motors 120a to 120c have the same structure, including a rotor 61, a stator 62, and a coil 63. The rotor 61 is rotatable about an axis (not shown) provided on the stator 62. By applying a drive pulse to the coil 63, the rotor 61 can rotate in either the clockwise or counterclockwise direction at a predetermined step angle. One or more gears, such as those used to move the second hand 20a, are connected to the rotor 61. Rotation of the rotor 61 causes the gears to rotate.

[0020] The stator 62 has a generally rectangular core around which coils 63 are wound. The stator 62 has a circular hole 64 formed therein, and the rotor 61 is disposed within this hole 64. When current flows through the coils 63, magnetic poles appear near regions 65 and 66 in the stator 62. The polarity of the magnetic poles in regions 65 and 66 is determined by the direction of the current flowing through the coils 63. The coils 63 are connected to the drive circuit 130 via a terminal block 67.

[0021] When a voltage is applied to coil 63 so that magnetic poles that repel south pole 61S and north pole 61N appear in regions 65 and 66, rotor 61 rotates. Furthermore, two recesses 64a are formed on the inner circumference of hole 64 in stator 62, which accommodates rotor 61. These two recesses 64a help maintain rotor 61 in a stationary state.

[0022] When the S pole 61S and the N pole 61N are opposite to the regions 65 and 66, the indexing torque (holding torque) of the first to third stepping motors 120a to 120c becomes maximum. Figure 2 The magnetically stable stop is achieved in the indicated stop position or in a stop position rotated 180 degrees from the stop position.

[0023] The drive circuit 130 includes a bridge circuit that drives the first to third stepping motors 120a to 120c. Based on commands from the control unit 110, it applies voltage to the coils 63 of the first to third stepping motors 120a to 120c. Specifically, the drive circuit 130 applies drive pulses, correction pulses, and current difference detection pulses to the coils 63. The drive circuit 130 includes switching elements composed of MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) and an H-bridge circuit composed of resistors. Furthermore, the switching elements and resistors form a discharge circuit that discharges energy stored in the coils 63. The terminal voltage of the coil 63 is referred to as the coil voltage V1, and the current flowing through the coil 63 is referred to as the coil current I1.

[0024] Timer circuit 140 is a counter circuit that counts the current time and includes an oscillator circuit and a frequency divider circuit. The oscillator circuit uses a circuit that oscillates in combination with a resonator such as a quartz crystal. This circuit generates a unique frequency signal and outputs it to the frequency divider circuit. The frequency divider circuit divides the signal input from the oscillator circuit into a frequency signal and outputs it. Timer circuit 140 counts the number of times the predetermined frequency signal output from the frequency divider circuit occurs and adds this to an initial time to calculate the current time.

[0025] The magnetic sensor 150 measures data for deriving the magnetic field strength, derives and obtains data representing the magnetic field strength. The obtained data is output to the control unit 110. In addition, the control unit 110 can also derive and obtain data representing the magnetic field strength based on data including current values, resistance values, impedance, etc. used to derive the magnetic field strength measured by the magnetic sensor 150. In the initial state, the magnetic sensor 150 is set to be disconnected (OFF), and no power is provided for measuring the magnetic field strength. Here, disconnection includes a mode in which the magnetic field strength is not measured, such as when a power saving mode such as sleep mode is set. The magnetic sensor 150 can use a Hall element that uses the Hall effect to detect the magnetic field strength, or a magnetoresistive effect element that uses the magnetoresistive effect in which the resistance of a solid changes due to a magnetic field to measure the magnitude of the magnetic field. In addition, a pulse can be output to a wire such as an amorphous wire, and the change in the magnetic field can be detected by a coil, thereby detecting the strength of the magnetic field.

[0026] The power supply unit 160 includes a battery and a DC-DC converter, and has a structure capable of maintaining a constant output voltage during operation, thereby allowing the hand driving device 100 to operate continuously and stably for a long period of time.

[0027] The control unit 110 includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. The control unit 110 reads programs stored in the ROM into the RAM and executes them, thereby functioning as a pointer control unit 111, a rotation determination unit 112, a magnetic sensor control unit 113, a magnetism determination unit 114, and a timer unit 115.

[0028] The pointer control unit 111 controls the drive circuit 130 based on the current time counted by the timing circuit 140 to drive the first to third stepping motors 120a to 120c. Once per second, the drive circuit 130, controlled by the pointer control unit 111, outputs a drive pulse to the first to third stepping motors 120a to 120c, rotating the rotor 61. As the rotor 61 rotates, the pointers 20a to 20c rotate via one or more gears. However, for example, when a magnetic field is applied to the electronic watch 1, the drive pulse may fail to rotate the rotor 61. In such cases, the pointer control unit 111 can output a correction pulse with at least one of the applied voltage and pulse width greater than the drive pulse. For example, if the rotor 61 fails to rotate, the magnetic field strength obtained by the magnetic sensor control unit 113 is determined by the magnetic determination unit 114 to be less than a first reference value. A correction pulse stronger than the drive pulse is output. The first reference value and the control when it is determined to be greater than the first reference value will be described later. Furthermore, when the magnetic field intensity obtained by the magnetic sensor control unit 113 is determined by the magnetism determination unit 114 to be less than the second reference value, the pointer control unit 111 controls the drive circuit 130 to drive the first to third stepping motors 120a to 120c based on the period of time during which the rotor 61 stops rotating, as measured by the timing unit 115. This causes the positions of the pointers 20a to 20c to return to the positions indicating the current time. The second reference value will be described later.

[0029] The rotation determination unit 112 causes the drive circuit 130 to output a current difference detection pulse. This current difference detection pulse is used to detect the difference in magnetic flux density caused by the stall angle of the magnet when the rotor 61 is rotating and when it is not, based on the current difference flowing through the coil 63. The unit detects the coil current I1 when the current difference detection pulse is supplied, and determines whether the rotor 61 is rotating based on the current difference flowing through the coil 63. When the rotor 61 is rotating, the magnetic field generated by the current difference detection pulse weakens the magnetic field generated by the magnet. Therefore, the magnetic field H obtained by adding the two together falls within a region where the influence of magnetic saturation is relatively small, resulting in a relatively large slope dB / dH of the tangent line of the BH characteristic. The slope dB / dH of the tangent line corresponds to the differential magnetic permeability μ. Since the inductance of the coil 63 is proportional to the differential magnetic permeability μ, the inductance is relatively large. Therefore, the coil current I1 when the current difference detection pulse is supplied is relatively low. Furthermore, if the peak value of the coil current I1 is below a threshold, the rotation determination unit 112 determines that the rotor 61 is rotating.

[0030] The width of the current difference detection pulse is preferably set in the range of 0.01 milliseconds to 1 millisecond, and more preferably in the range of 0.05 milliseconds to 0.1 milliseconds. In addition, in relative relationship with the width of the drive pulse, the width of the current difference detection pulse is preferably set in the range of 1 / 3 to 1 / 300 of the width of the drive pulse, and more preferably in the range of 1 / 30 to 1 / 60. The significance of these values ​​is that if the current difference detection pulse is too short, the accuracy of the rotation detection deteriorates, and if it is too long, the rotor 61 moves. In addition, the details of the rotation detection method for detecting whether the rotor 61 is rotating are disclosed in Japanese Patent Application Laid-Open No. 2017-173037.

[0031] When the rotation determination unit 112 determines that the rotor 61 is not rotating, the magnetic sensor control unit 113 turns on the magnetic sensor 150 to obtain the strength of the magnetic field using the magnetic sensor 150. When the magnetism determination unit 114 determines that the strength of the magnetic field is less than the second reference value, the magnetic sensor control unit 113 turns off the magnetic sensor 150.

[0032] The magnetism determination unit 114 determines whether the magnetic field strength obtained by the magnetic sensor control unit 113 is greater than a first reference value. Furthermore, the magnetism determination unit 114 determines whether the magnetic field strength obtained by the magnetic sensor control unit 113 is less than a second reference value, which is smaller than the first reference value. If a correction pulse stronger than the drive pulse is output to the first to third stepping motors 120a to 120c, the first reference value is the upper limit of the magnetic field strength at which the rotor 61 can rotate. If a drive pulse is output to the first to third stepping motors 120a to 120c, the second reference value is a value smaller than the upper limit of the magnetic field strength at which the rotor 61 can rotate.

[0033] The timing unit 115 measures the period during which the rotor 61 is stopped. The timing unit 115 measures the period during which the rotor 61 is stopped, as determined by the magnetism determination unit 114 to be equal to or greater than the first reference value. The timing unit 115 adds up the period of time during which the rotor 61 is stopped, and stores the added period in RAM. Furthermore, when a calibration pulse is applied from the drive circuit 130 and the rotation determination unit 112 determines that the rotor 61 is not rotating, the timing unit 115 measures the period during which the rotor 61 is not rotating, and adds up the period of time during which the rotor 61 is stopped, and stores the added period in RAM.

[0034] Next, the hand movement control process executed by the hand driving device 100 having the above configuration will be described.

[0035] In response to the user's instruction to start processing, the pointer driving device 100 starts Figure 4The following flowchart describes the hand movement control process performed by the hand drive device 100. Note that in the initial state, the magnetic sensor 150 is set to OFF and does not measure the strength of the magnetic field. Furthermore, the positions of the hands 20a-20c are adjusted to the current time by the user via the crown 42.

[0036] When the hand movement control process is started, the first hand movement process is executed (step S101). Figure 5 During the first hand movement process shown, the pointer control unit 111 controls the drive circuit 130 to output a drive pulse to the coil 63 of the first to third stepping motors 120a to 120c once per second (step S201). Next, the rotation determination unit 112 controls the drive circuit 130 and outputs a current difference detection pulse to the coil 63 (step S202). Next, the rotation determination unit 112 detects the coil current I1 when the current difference detection pulse is supplied (step S203). After that, the system returns to Figure 4 The needle movement control process shown.

[0037] Next, the rotation determination unit 112 determines whether the rotor 61 is rotating based on the coil current I1 detected when the current difference detection pulse is supplied (step S102). If the rotation determination unit 112 determines that the rotor 61 is rotating (step S102: Yes), the process returns to step S101 and steps S101 and S102 are repeated.

[0038] If the rotation determination unit 112 determines that the rotor 61 is not rotating (step S102: No), the magnetic sensor control unit 113 turns on the magnetic sensor 150 to obtain the intensity of the magnetic field (step S103). Next, the timing unit 115 starts timing the period during which the rotor 61 stops rotating (step S104).

[0039] Next, the magnetism determination unit 114 determines whether the magnetic field strength obtained by the magnetic sensor control unit 113 is greater than or equal to a first reference value (step S105). If a correction pulse stronger than the drive pulse is output to the first to third stepping motors 120a to 120c, the first reference value is the upper limit of the magnetic field strength within which the rotor 61 can rotate. If the magnetism determination unit 114 determines that the magnetic field strength obtained by the magnetic sensor control unit 113 is not greater than the first reference value (step S105: No), the second hand movement process is executed (step S106).

[0040] When executing Figure 6During the second hand movement process shown, the pointer control unit 111 controls the drive circuit 130 to output a correction pulse that is stronger than the drive pulse to the coil 63 of the first to third stepping motors 120a to 120c (step S301). The correction pulse is a pulse in which at least one of the applied voltage and pulse width is larger than the drive pulse. Next, the rotation determination unit 112 controls the drive circuit 130 and outputs a current difference detection pulse to the coil 63 (step S302). Next, the rotation determination unit 112 detects the coil current I1 when the current difference detection pulse is supplied (step S303). Next, the rotation determination unit 112 determines whether the rotor 61 is rotating based on the detected coil current I1 when the current difference detection pulse is supplied (step S304).

[0041] When the rotation determination unit 112 determines that the rotor 61 is rotating (step S304: Yes), the process returns to step S304. Figure 4 If the rotation determination unit 112 determines that the rotor 61 is not rotating (step S304: No), the timer unit 115 adds the period during which the rotation of the rotor 61 stops and stores it in the RAM (step S305), and returns to the movement control process.

[0042] When the magnetism determination unit 114 determines that the magnetic field intensity acquired by the magnetic sensor control unit 113 is equal to or greater than the first reference value (step S105 : Yes), the timer unit 115 adds the period during which the rotation of the rotor 61 is stopped and stores the added period in the RAM (step S107 ).

[0043] Next, the magnetism determination unit 114 determines whether the magnetic field strength obtained by the magnetic sensor control unit 113 is less than a second reference value that is smaller than the first reference value (step S108). If the magnetic field strength is determined to be not less than the second reference value (step S108: No), the process returns to step S105, and steps S105 through S108 are repeated.

[0044] If it is determined that the magnetic field strength is less than the second reference value (step S108: Yes), the pointer control unit 111 controls the drive circuit 130 to drive the first to third stepping motors 120a to 120c based on the period of rotation stop of the rotor 61 measured by the timing unit 115 (step S109). As a result, the positions of the pointers 20a to 20c return to the positions indicating the current time. For example, Figure 7As shown, if the rotation of pointer 20a stops for 20 seconds due to the magnetic field, the timing unit 115 counts the period during which the rotation of rotor 61 stops as 20 seconds. Then, the pointer control unit 111 controls the drive circuit 130 to drive the first to third stepping motors 120a, so that pointer 20a advances 20 seconds. As a result, pointer 20a returns to the position indicating the current time. Pointers 20b and 20c also return to the positions indicating the current time. Next, the magnetic sensor control unit 113 disconnects the magnetic sensor 150 and stops measuring the strength of the magnetic field (step S110). Then, the process returns to step S101 and repeats steps S101 to S110.

[0045] For example, Japanese Patent Application Publication No. 2019-49436 discloses an electronic watch having a stepping motor with a rotor, a stator, a coil with a wire wound around a coil core, and a magnetic-resistant plate covering at least a portion of the stepping motor. In the movement of the electronic watch disclosed in Reference 1, if a strong magnetic field is applied, there is a concern that the stepping motor may be affected by the magnetic field from the portion not covered by the magnetic-resistant plate, causing the rotor to stop rotating. Depending on the magnitude of the external magnetic field, there may be situations where the hands cannot be moved even if pulses are output. In such cases, there is a problem of increased power consumption due to the multiple output of correction pulses.

[0046] Another option is to install a magnetic sensor on the electronic watch to measure the external magnetic field using the magnetic sensor, thereby preventing the output of pulses depending on the magnitude of the external magnetic field. However, in such a structure, the magnetic sensor will ultimately remain continuously turned on, resulting in increased power consumption.

[0047] However, according to the pointer drive device 100 of this embodiment, the magnetic sensor 150 is initially set to off. When the rotation determination unit 112 determines that the rotor 61 is not rotating, the magnetic sensor control unit 113 turns the magnetic sensor 150 on. Thus, when the rotor 61 rotates normally, the magnetic sensor 150 is off, thereby reducing power consumption. Furthermore, if the magnetic field strength obtained by the magnetic sensor 150 is determined to be greater than a first reference value, correction pulses are not output to the first to third stepping motors 120a to 120c. This reduces power consumption even when affected by a magnetic field. Furthermore, if the magnetic field strength obtained by the magnetic sensor 150 is determined to be less than the first reference value, correction pulses stronger than the drive pulses are output to the first to third stepping motors 120a to 120c. This allows accurate time indication even when affected by a magnetic field. Furthermore, when the magnetic field intensity detected by the magnetic sensor 150 is determined to be less than the second reference value, the positions of the hands 20a-20c return to the positions indicating the current time based on the period of stopped rotation of the rotor 61, as measured by the timing unit 115. This allows accurate time indication even under the influence of a magnetic field. Furthermore, when the magnetic field intensity detected by the magnetic sensor 150 is determined to be less than the second reference value, the magnetic sensor 150 is turned off, thereby reducing power consumption. Consequently, the pointer driving device 100 can reduce power consumption even under the influence of a magnetic field.

[0048] (Variation)

[0049] In the above embodiment, an example is described in which the positions of the pointers 20a to 20c return to the positions indicating the current time based on the period during which the rotation of the rotor 61 is stopped as measured by the timing unit 115. If the period during which the rotor 61 is stopped becomes longer, then based on the period during which the rotation of the rotor 61 is stopped, even if the rotor 61 is rotated, the positions of the pointers 20a to 20c may not return to the positions indicating the current time. In the case where the period during which the rotation of the rotor 61 is stopped as measured by the timing unit 115 is longer than the reference period, the first to third stepping motors 120a to 120c may be controlled so that the positions of the pointers 20a to 20c are reset to the initial positions (moved to a certain position), and the positions of the pointers 20a to 20c are adjusted to the positions indicating the current time. In this case, as Figure 8As shown, the pointer drive device 100 includes a gear 21a that rotates the shaft of the pointer 20a, which serves as the second hand, and a detection unit 22a that detects the position of the gear 21a. The gear 21a has a detection hole 23a and is rotated by the first stepper motor 120a. The detection unit 22a detects light passing through the detection hole 23a, thereby detecting the initial position of the gear 21a. When the period of rotation stoppage of the rotor 61, as measured by the timing unit 115, is determined to be longer than a reference period, the first stepper motor 120a rotates the gear 21a to a position where the detection unit 22a detects the detection hole 23a. This resets the gear 21a to its initial position. The pointer control unit 111 controls the first stepper motor 120a from this position, adjusting the pointer 20a to a position indicating the current time as measured by the timing circuit 140. The pointers 20b and 20c are similarly adjusted to positions indicating the current time.

[0050] In the above embodiment, an example is described in which the first to third stepping motors 120a to 120c are controlled to stop rotating when the magnetic field strength obtained by the magnetic sensor 150 is determined to be greater than the first reference value. The magnetic field strength obtained by the magnetic sensor 150 can also be used for purposes other than stopping the rotation of the first to third stepping motors 120a to 120c. For example, Figure 9 As shown, when the magnetic field strength detected by the magnetic sensor 150 is determined to be above a third reference value, the user may be notified that a strong magnetic field is being applied. The third reference value is a value at which the electronic watch 1 may malfunction or experience other abnormalities. In this case, the electronic watch 1 includes a display unit 70 that displays characters, such as through a liquid crystal display, and the control unit 110 may cause the display unit 70 to display an error message indicating that a strong magnetic field is being applied. The error message may be, for example, "mag.error." In this case, the third reference value may be set to a value greater than the first reference value. The user can determine whether maintenance is required by observing the error display. Alternatively, if the magnetic field strength detected by the magnetic sensor 150 is determined to be above the third reference value, the user may be notified by sound, such as a buzzer, or by vibration. In this case, the third reference value may be set to a value equal to or smaller than the first reference value. This allows the user to be aware of the effects of the magnetic field on the electronic watch 1 and to move the electronic watch 1 to a location less affected by the magnetic field.

[0051] In the above embodiment, when the magnetic field strength is determined to be less than the first reference value, a correction pulse stronger than the drive pulse is output. Alternatively, the pointer control unit 111 may stepwise change at least one of the applied voltage and pulse width of the correction pulse based on the magnetic field strength obtained by the magnetic sensor 150.

[0052] In the above embodiment, the rotation determination unit 112 outputs a current difference detection pulse to the coil 63, detecting the coil current I1 to determine whether the rotors 61 of the first to third stepping motors 120a to 120c are rotating. The rotation determination unit 112 can be used as long as it can determine whether the rotors 61 of the first to third stepping motors 120a to 120c are rotating. A potentiometer that converts the rotation angle into an electrical signal such as a voltage and outputs it may also be used. Alternatively, an optical rotation detection device may be used that detects rotation by irradiating light onto a rotating body, such as a rotating shaft, that rotates with the rotation of the rotor 61 and detecting the light reflected by the rotating body.

[0053] In the above embodiment, the hands 20a to 20c are driven by the first to third stepping motors 120a to 120c, respectively. However, the hands 20a to 20c may also be driven by a single stepping motor. In this case, multiple gears are used to adjust the movement so that if the second hand 20a rotates 60 times, the minute hand 20b rotates once, and if the minute hand 20b rotates 12 times, the hour hand 20c rotates once.

[0054] In the above embodiment, the hands 20a-20c are driven by the first to third stepping motors 120a-120c. However, the hands 20a-20c may be driven by a motor other than a stepping motor, such as a servo motor, as long as they are driven to a position indicating the time. In this case, when the magnetic field intensity detected by the magnetic sensor 150 is determined to be below the first reference value, the motor may be rotated with a higher current or voltage.

[0055] In the above embodiment, the pointer 20a is a second hand indicating seconds, the pointer 20b is a minute hand indicating minutes, and the pointer 20c is an hour hand indicating time. The pointers 20a to 20c may indicate other than time, and may also indicate temperature, air pressure, direction, etc.

[0056] Furthermore, the portion of the pointer drive device 100 that is comprised of a CPU, RAM, ROM, and the like, which is central to the movement control processing, does not rely on a dedicated system and can be executed using a conventional portable information terminal (smartphone, tablet PC), personal computer, or the like. For example, a computer program for executing the aforementioned actions may be stored on a computer-readable recording medium (floppy disk, CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), etc.) and distributed, and the computer program may be installed in a portable information terminal, etc., thereby constituting an information terminal that executes the aforementioned processing. Alternatively, the computer program may be stored in a storage device of a server device on a communication network such as the Internet, and downloaded from a conventional information processing terminal, etc., thereby constituting an information processing device.

[0057] Furthermore, when the pointer driving device 100 is implemented by sharing the tasks between an OS (Operating System) and an application program, or by collaboration between the OS and the application program, only the application program portion may be stored in a recording medium or a storage device.

[0058] Alternatively, the computer program may be superimposed on a carrier wave and distributed via a communication network. For example, the computer program may be posted on a bulletin board (BBS) on a communication network and distributed via the network. Furthermore, the computer program may be activated and executed under the control of the OS in the same manner as other application programs, thereby enabling the aforementioned processing to be performed.

[0059] As mentioned above, although the preferred embodiment was described, the present invention is not limited to the specific embodiment described above, and the present invention includes the invention described in the claims and the equivalent scope thereof.

Claims

1. A pointer driving device, characterized in that: The pointer driving device has: an electric motor, which moves the pointer; a drive circuit configured to drive the motor by inputting into the motor either a drive pulse having a predetermined current value or voltage value set thereto or a correction pulse having at least one of an input voltage and a pulse width greater than that of the drive pulse; a magnetic sensor that measures a magnetic field in a predetermined area; as well as processor, If the processor determines that the magnetic field intensity measured by the magnetic sensor is greater than a first reference value, the processor controls the drive circuit to not output the drive pulse and the correction pulse, and adds and stores a period during which the rotation is stopped. The processor controls the drive circuit to input the correction pulse, which is stronger than the drive pulse, into the motor in place of the drive pulse, when the drive circuit detects that the motor is not driven despite inputting the drive pulse to the motor, and when the magnetic field intensity measured by the magnetic sensor is less than the first reference value at which the motor can be driven by the correction pulse and is greater than a second reference value that is smaller than the first reference value. If the processor determines that the magnetic field strength measured by the magnetic sensor is less than the second reference value, it controls the drive circuit to drive the motor based on the period when the rotation of the motor stops, and after stopping the measurement of the magnetic sensor, controls the drive circuit to input the drive pulse into the motor.

2. The pointer driving device according to claim 1, characterized in that: If a correction pulse stronger than a driving pulse is output to the motor, the first reference value is an upper limit value of the magnetic field strength at which a rotor having a magnet can rotate.

3. The pointer driving device according to claim 1, wherein: The motor is a stepping motor having a rotor having a magnet and a stator having a coil for rotating the rotor. When the current difference detection pulse output by the drive circuit is input to the coil and the peak value of the current flowing through the coil is below a threshold value, the processor detects that the rotor is rotating and the motor is driving. When the peak value of the current flowing through the coil is greater than the threshold value, the processor detects that the rotor is not rotating and the motor is not driving.

4. The pointer driving device according to claim 1, wherein: The processor changes at least one of an input voltage and a pulse width of a correction pulse input from the drive circuit to the motor, based on the magnetic field strength obtained by measurement by the magnetic sensor.

5. The pointer driving device according to claim 1, wherein: The predetermined area is the vicinity of the electric motor.

6. An electronic watch, characterized in that: This electronic watch has: The pointer driving device according to any one of claims 1 to 5; and A pointer is driven by the pointer driving device.

7. A pointer driving method of a pointer driving device, The pointer driving device has: an electric motor, which moves the pointer; a driving circuit that drives the motor by inputting into the motor any one of a driving pulse having a predetermined current value or voltage value set, and a correction pulse having at least one of an input voltage and a pulse width greater than that of the driving pulse; and a magnetic sensor that measures a magnetic field in a predetermined area, The pointer driving method is characterized by: a detecting step of detecting whether the motor is driving; and A control step, if it is determined that the magnetic field strength measured by the magnetic sensor is greater than a first reference value, controlling the drive circuit not to output the drive pulse and the correction pulse, adding and storing the period of rotation stoppage, and in a case where the drive circuit detects that the motor is not driven even though it inputs the drive pulse to the motor, and the magnetic field strength measured by the magnetic sensor is less than the first reference value at which the motor can be driven by the correction pulse and is greater than a second reference value smaller than the first reference value, controlling the drive circuit so that the correction pulse stronger than the drive pulse is input to the motor instead of the drive pulse, and if it is determined that the magnetic field strength measured by the magnetic sensor is less than the second reference value, controlling the drive circuit to drive the motor based on the period of rotation stoppage of the motor, and controlling the drive circuit to input the drive pulse to the motor after the magnetic sensor stops measuring.

8. The pointer driving method according to claim 7, characterized in that: If a correction pulse stronger than a driving pulse is output to the motor, the first reference value is an upper limit value of the magnetic field strength at which a rotor having a magnet can rotate.

9. The pointer driving method according to claim 7, characterized in that: The motor is a stepping motor having a rotor having a magnet and a stator having a coil for rotating the rotor. When the current difference detection pulse output by the drive circuit is input to the coil and the peak value of the current flowing through the coil is below a threshold value, it is detected that the rotor is rotating and the motor is driving. When the peak value of the current flowing through the coil is greater than the threshold value, it is detected that the rotor is not rotating and the motor is not driving.

10. The pointer driving method according to claim 7, characterized in that: At least one of an input voltage and a pulse width of a correction pulse input from the drive circuit to the motor is changed based on the magnetic field intensity obtained by the measurement of the magnetic sensor.

11. The pointer driving method according to claim 7, characterized in that: The predetermined area is the vicinity of the electric motor.

12. A computer-readable recording medium storing a program, characterized in that: The program causes a computer including a motor, a drive circuit, a magnetic sensor, and a processor to perform the following functions: If the processor determines that the magnetic field intensity measured by the magnetic sensor is greater than a first reference value, the processor controls the drive circuit to not output a drive pulse and a correction pulse, and adds and stores a period during which the rotation is stopped. The processor controls the drive circuit to input the correction pulse, which is stronger than the drive pulse, into the motor in place of the drive pulse, when the drive circuit detects that the motor is not driven despite inputting the drive pulse to the motor, and when the magnetic field intensity measured by the magnetic sensor is less than the first reference value at which the motor can be driven by the correction pulse and is greater than a second reference value that is smaller than the first reference value. If the processor determines that the magnetic field strength measured by the magnetic sensor is less than the second reference value, the processor controls the drive circuit to drive the motor based on the period during which the rotation of the motor is stopped, and controls the drive circuit to input the drive pulse into the motor after stopping the measurement by the magnetic sensor, wherein: The motor moves the pointer. The drive circuit drives the motor by inputting into the motor either the drive pulse having a predetermined current value or voltage value or the correction pulse having at least one of an input voltage and a pulse width greater than the drive pulse. The magnetic sensor measures a magnetic field in a predetermined area.

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