JP5990773B2 - Motor position detector - Google Patents

Description

  The present invention relates to light amount control and life calculation of a light emitting element in a motor position detector that performs high resolution by interpolating an analog sine wave from an optical circuit.

  In recent years, FA (Factor Automation) devices have extremely high demands for performance, reliability, and maintainability, and servo motor control devices used there can be used for high speed and high precision positioning performance for a long time. There is a need for high reliability and high maintainability that can detect signs of abnormalities during equipment operation and perform smooth replacement work.

  In general, in a motor position detector used in a servo motor control device, when a light receiving element such as a photodiode receives light output from a light emitting element such as an infrared LED (Light Emitting Diode), Increasing or decreasing the amount of light transmitted depending on the relative position of the slit pattern of the attached slit plate and the mask pattern on the surface of the light receiving element, the two-phase analog signal output by the photoelectric conversion of the light receiving element is pulse converted by the comparator, and the pulse is increased The position information is detected by counting down.

  As a method for achieving high performance, that is, high resolution for this type of motor position detector, there is a method for increasing the pulse count by reducing the pattern interval between the slit and the mask. However, this method limits the processing accuracy of the pattern and interferes with light between adjacent slits, making it difficult to achieve high resolution.In recent years, the amount of light received can be reduced by changing the slit and mask pattern shapes. The mainstream method is to increase the resolution by adjusting the two-phase analog signal into a sine wave shape that is orthogonal, and interpolating between pulse counts by interpolation division processing using the orthogonal two-phase analog sine wave signal. .

  Normally, the interpolation division process performs A / D conversion (analog to digital converter) on an analog sine wave signal and generates angle information by angle conversion using an inverse trigonometric function by digital signal processing. In order to obtain the sine wave signal, a correction process must be performed and normalized before the angle conversion of the sine wave signal. In particular, for analog sine wave signal amplitude, when A / D-converted digital signals are processed and normalized, if the amplitude is small, the signal-to-noise ratio (SNR) decreases and the noise component of the signal is amplified. Furthermore, since the dynamic range for A / D conversion becomes smaller, the resolution becomes coarse. Then, the accuracy of the correction value detected from the digital signal for the correction process is deteriorated, the error included in the normalized signal is increased, and the accuracy of the angle information is greatly deteriorated. Servo controller's motor position detector is required to have high accuracy of angle information and reliable with long time to maintain high accuracy, so the amplitude of analog sine wave is as large as possible and It must be maintained for a long time.

  However, the light intensity of the light emitting element used in the optical circuit decreases due to the surrounding environment and aging, and the required amplitude cannot be maintained. Therefore, by calculating the value of A ^ 2 + B ^ 2 from the magnitudes of the A-phase signal and B-phase signal output from the light-receiving element, and by controlling the current flowing through the light-emitting element so that this is maintained at a constant value, A technique is known that corrects changes in amplitude due to aging of elements and the influence of temperature characteristics without adding a new light receiving element (see, for example, Patent Document 1).

Further, from the viewpoint of maintainability, a light source, a pattern composed of a light transmission part and a light shielding part, a light receiving part that receives light from the light source through the pattern, and outputs a signal corresponding to the movement position of the pattern; Monitoring means for monitoring whether or not the signal level is lower than a determination value set to a value higher than the signal level at which the received light intensity of the light receiving unit decreases and the movement of the pattern becomes unmeasurable; and There is known a technique that has a warning means for giving a warning when a signal falls below the determination value, predicts an abnormality due to deterioration of the encoder, and prompts the replacement before measurement becomes impossible (for example, Patent Document 2).

JP-A-1-94217 JP 2006-284520 A

  However, in the conventional configuration, in order to compensate for the amount of light that has decreased due to deterioration, control is performed to increase the amount of light by increasing the current flowing through the light emitting element (hereinafter referred to as drive current). Since it progresses according to the integration time, when the drive current is increased, the progress speed of deterioration is rapidly accelerated. For this reason, an excessive driving current flows with the passage of time, and the lifetime of the light emitting element is remarkably shortened.

  In addition, when a decrease in the received light intensity of the light receiving unit is monitored and an abnormality due to deterioration is predicted, if the drive current is increased, the received light intensity is maintained until the lifetime of the light emitting element is exhausted, and the deterioration rate immediately before reaching the lifetime is accelerated. As a result, the rate of decrease in received light intensity is large, and the time from reaching the warning output level to the level at which the position cannot be measured is reduced. become.

  In general, the product life of the optical motor position detector is dominated by the life of the light emitting element. As a result, the product life is shortened, the maintainability is deteriorated, and the reliability is impaired.

  The present invention solves the above-mentioned conventional problems, and extends the life while maintaining the accuracy of the angle information by combining the control of the driving current and the correction processing of the digital signal processing against the light amount decrease due to the secular change. Therefore, an object of the present invention is to provide a motor position detector that does not impair reliability by calculating lifetime information.

  In order to solve the above-described conventional problems, the motor position detector of the present invention normalizes the light amount control unit that controls the drive current that flows from the light amount to the light emitting element and the two-phase analog original signal that is output from the optical circuit. A signal correction unit that generates a two-phase sine wave signal for conversion and a lifetime calculation unit that calculates and outputs lifetime information of the light emitting element are provided. The light quantity control unit controls the drive current to maintain the light quantity at a constant amount. When the drive current exceeds a preset allowable current value, the light quantity control unit limits the allowable current value and outputs an allowable current arrival signal. The life calculator calculates the remaining life from the drive current and the allowable current value when the allowable current arrival signal is not output, and from the initial information and the signal correction amount when the allowable current arrival signal is output. The remaining life is calculated, and a warning signal that is output when the remaining life falls below the life warning value and an error signal that is output when the remaining life falls below the life limit value are output as life information.

  This limits the drive current with the allowable current value, prevents excessive current from flowing to the light emitting element, maintains the maximum angle conversion accuracy, and calculates the life information that informs the replacement time. Both maintainability and reliability can be improved.

The motor position detector of the present invention further includes a temperature detection unit that detects the ambient temperature of the optical circuit and outputs temperature information, and the life calculation unit corrects the remaining life with the temperature information. .

  As a result, it is possible to accurately determine the replacement time by calculating accurate life information, and to operate with maximum use of the life of the motor position detector, and build a highly reliable system. be able to.

  The motor position detector of the present invention calculates the life information that informs the replacement timing while preventing the excessive current from flowing to the light emitting element by limiting the drive current with the allowable current value and maintaining the maximum angle conversion accuracy. By doing so, it is possible to construct a highly reliable system that achieves both long life and maintainability.

Configuration diagram of a motor position detector according to the first embodiment of the present invention. The figure which shows the relationship between the drive current and light quantity waveform in Embodiment 1 of this invention.

In the first invention, light output from the light emitting element is increased or decreased at a relative position between the slit pattern of the slit plate connected to the motor rotor and the mask pattern on the surface of the light receiving element, and is orthogonalized by photoelectric conversion by the light receiving element. An optical circuit that generates a two-phase analog original signal, an analog pulse signal, and a light amount feedback signal, a light amount control unit that controls a drive current that flows from the light amount feedback signal to the light emitting element, and amplifies and orthogonalizes the analog original signal 2 A signal amplifying unit for generating a phase analog sine wave signal, an A / D conversion unit for generating a two-phase digital sine wave signal by A / D conversion of the analog sine wave signal, and signal processing of the two-phase digital sine wave signal A signal correction unit that generates a two-phase sine wave signal for conversion by correcting the signal, and binarizes the analog pulse signal into a digital pulse A pulse conversion unit for converting to a signal, a position information generation unit for generating position information by interpolating the digital pulse signal with an angle conversion value obtained by inverse trigonometric function of the two-phase sine wave signal for conversion, A life calculation unit that calculates and outputs life information of the light emitting element, a memory unit that stores the motor information of the motor, and a communication unit that performs parallel / serial conversion of the position information and the motor information to communicate with the motor control device And
The light amount control unit maintains the light amount feedback signal at a constant amount by controlling the driving current, and restricts the allowable current value when the driving current exceeds a preset allowable current value and allows an allowable current arrival signal. The life calculation unit averages a signal correction amount used to correct the two-phase digital sine wave signal by the signal correction unit in an initial operation state with a plurality of values of the position information. stored as initial information into said memory section Te, the allowable current when the arrival signal is not outputted to calculating the remaining life from the allowable current value and the drive current, if the allowable current arrival signal is outputted a warning signal is computed the remaining lifetime from the signal correction amount and the initial information, the remaining life is output below the preset lifetime warning value, this life warning With the structure that outputs the error signal output and below the set lifetime threshold lower than the value as the life information, excessive current from flowing to the light emitting element by limiting the drive current allowable current value In addition to maintaining the maximum angle conversion accuracy and calculating the life information that informs the replacement time, it is possible to achieve both long life and maintainability, and to improve reliability.

  In a second aspect of the invention, in particular, the motor position detector of the first aspect of the invention further includes a temperature detection unit that detects the ambient temperature of the optical circuit and outputs temperature information, and the lifetime calculation unit calculates the remaining lifetime as a temperature. By adopting a configuration that corrects with information, it is possible to accurately determine the replacement time by calculating accurate life information, and it is possible to operate with the maximum life of the motor position detector, resulting in high reliability. You can build a system with it.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a configuration diagram of a motor position detector according to the first embodiment of the present invention.

  In FIG. 1, the motor position detector is generally called an encoder, and includes an optical circuit 100 comprising a light emitting element 1, a slit plate 2, and a light receiving element 3, a light quantity control unit 4, a signal amplification unit 5, an A / D conversion unit 6, and signal correction. 7, a pulse conversion unit 8, a position information generation unit 9, a life calculation unit 10, a temperature detection unit 11, a memory unit 12, and a communication unit 20, and the communication unit 20 is a motor control device using bidirectional serial communication means such as RS485. 21 transmits and receives information.

  The light-emitting element 1 is a light source such as an infrared LED or a semiconductor laser. In general, an FA servomotor uses an inexpensive and highly reliable infrared LED, and an ultra-high resolution angle measuring encoder uses a semiconductor laser. . The slit plate 2 is a plate made of glass or resin material that transmits light, provided with a grid-like slit pattern that blocks light or an open pattern that transmits the entire circumference, or a thin plate of stainless steel. What perforated the permeation | transmission part or the thing which formed the reflecting film in the permeation | transmission part is used. A photodiode or a phototransistor is used as the light receiving element 3, and a lattice mask pattern, an opening for detecting the amount of received light, and the like are arranged on the surface of the light receiving element.

  The optical circuit is arranged so that the light 1A from the light emitting element 1 passes through the slit plate 2 to become transmitted light 2A and is received by the light receiving element 3, and the slit plate is connected to the encoder shaft connected to the motor rotor. is set up.

  When the encoder shaft rotates, the relative position of the slit pattern on the slit plate and the mask pattern applied to the surface of the light receiving element changes, and the signal generation pattern on the surface of the slit plate and the light receiving element causes a sine wave orthogonal from the light receiving element. An original signal 3B and an analog pulse signal 3C are output, and a light amount feedback signal 3A indicating a light amount received by the light receiving element is output from the open pattern of the slit plate and the opening of the light receiving element. As for the analog pulse signal 3C, a two-phase pulse and an origin pulse are output in an incremental type encoder, and a code pulse capable of determining an absolute address such as an M code or a gray code is output in an absolute type encoder.

The light quantity control unit 4 feedback-controls the drive current 4A of the light emitting element so that the light emission quantity of the light emitting element 1 is maintained at a constant amount based on the light quantity feedback signal 3A from the light receiving element 3, and the drive current is allowed. When the current value is exceeded, the output of the allowable current arrival signal 4B is switched from Low to High after being limited by the allowable current value. The light amount feedback signal is A / D converted and a DSP (Digital Signal Processor). ), Microcomputer, ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), and calculate the command value of the drive current by digital feedback processing of software or logic circuit , A command value PWM (Pulse Width
It may be configured to output by modulation or D / A conversion (Digital to Analog Converter) and convert to drive current by a transistor, or may be configured by an analog circuit using an operational amplifier and a transistor.

The allowable current value may be a value that gives a margin by multiplying the absolute maximum rated current value of the light emitting element by a certain ratio so that the drive current does not become excessive, or a range that does not exceed the absolute maximum rated current The current value immediately after startup may be multiplied by a constant magnification. The allowable current value may be a fixed value in advance, may be arbitrarily set using the memory unit 12, or may be set from the motor control device 21 via the communication unit.

  The signal amplifying unit 5 is composed of an analog amplifying circuit such as an operational amplifier or a transistor, and a magnification obtained by matching the input two-phase analog original signal 3B from the light receiving element 3 with the input range of the A / D converting unit 6 at the subsequent stage. To output a two-phase analog sine wave signal 5A.

  The A / D converter 6 samples the two-phase analog sine wave signal 5A at a constant period and quantizes it to generate a two-phase digital sine wave signal 6A. Generally, A / D converters built into DSPs, microcomputers, and ASICs are used, but if a high sampling period is required, parallel output type converters may be used. If the number of bits is required, a serial output type converter may be used. In order to reduce the influence of noise, a signal obtained by averaging the converted digital signal a plurality of times may be used.

The signal correction unit 7 is configured by software or a logic circuit, and calculates and outputs a signal correction amount 7B to correct offset, amplitude, phase shift and fluctuation included in the two-phase digital sine wave signal 6A, and performs correction processing. A normalized two-phase sine wave signal 7A for conversion is output. In addition, the signal correction unit independently switches the validity / invalidity of each correction based on the allowable current arrival signal 4B so that the angle conversion accuracy can be maintained to the maximum.
For example, when the allowable current arrival signal is Low, the correction processing is performed with the amplitude correction disabled and other corrections enabled, and when the correction signal is High, the correction processing is performed with all the corrections enabled. Alternatively, all corrections may be invalidated when the allowable current arrival signal is Low, and valid when the signal is High.

  Instead of switching between valid / invalid, different correction processing may be performed for each of Low and High.

  The pulse converter 8 is constituted by a comparison amplifier such as a comparator, and binarizes the analog pulse signal 3C and outputs a digital pulse signal 8A. In general, an incremental type encoder is constituted by a general-purpose comparison amplifier, and an absolute type encoder is constituted by a dedicated custom analog IC because a large number of comparison amplifiers are required.

  The position information generation unit 9 is configured by software or a logic circuit, counts the digital pulse signal 8A, interpolates between pulses by interpolation processing by angle conversion using an inverse trigonometric function from the conversion two-phase sine wave signal 7A, The high-resolution position information 9A is generated. The digital pulse signal count operation is an operation that counts up / down two-phase pulses in the incremental type and resets the count when the origin pulse is input. In the absolute type, the code pulse is used with a logic circuit or ROM table. The absolute position is calculated by the conversion process. In the interpolation processing, the angle of the two-phase sine wave may be directly converted by inverse tangent, or the angle of each of the two-phase sine waves may be converted by the inverse sine / inverse cosine and the result of the synthesis process using the weighting function may be used.

The life calculation unit 10 is configured by software or a logic circuit, and in the initial state immediately after the operation starts, the signal correction amount 7B is sampled a plurality of times and averaged and output to the memory unit 12 as initial information 10B to execute writing. . Here, sampling multiple times is performed in order to reduce periodic fluctuations in the signal correction amount due to motor rotation, and a plurality of specific positions may be taken based on the position information 9A, or signal correction for one rotation of the motor. An intermediate value between the maximum value and the minimum value of the quantity may be taken. The write timing of the initial information may be written by judging that the initial state is in the life calculation unit or when the life calculation unit control signal 20B is received from the motor control device 21 via the communication unit 20. But you can.

  The life calculation unit calculates the remaining life of the light-emitting element 1 from the drive current 4A, the allowable current arrival signal 4B, the signal correction amount 7B, and the initial information 10B after the initial information is written, and the remaining life is a life warning value. The warning signal that is output when the remaining life is less than the value and the error signal that is output when the remaining life is less than the life limit value are output as the life information 10A. The life warning value and the life limit value may be fixed in advance, may be arbitrarily set using the memory unit 12, or may be set from the motor control device 21 via the communication unit. Good.

  The memory unit 12 includes a nonvolatile memory such as an EEPROM and a controller that controls writing and reading by software or a logic circuit, and writing and reading of initial information 10B from the life calculation unit 10 or motor information 12A from the communication unit 20. I do. Writing and reading are executed at an arbitrary timing from the life calculation unit and the communication unit.

  The communication unit 20 is connected to the motor control device 21 via a serial communication line such as RS485, and performs bidirectional communication using a general-purpose or dedicated communication protocol. The communication unit receives the request from the motor control device, converts the read data of the position information 9A, the life information 10A, and the motor information 12A from parallel to serial according to the contents of the request, and returns the response. A control signal is output, and write data of motor information is output to the memory unit 12. Here, the motor information includes parameters necessary for the motor control device to identify and drive the motor, such as the motor model name, serial number, and motor constant.

  Next, the operation of the light quantity control unit 4 and the remaining life calculation of the life calculation unit 10 will be described with reference to FIG. FIG. 2 shows the relationship between the drive current 4 </ b> A of the light quantity control unit 4 and the light quantity L of the light emitting element 1. The drive current 201 of the conventional configuration increases the drive current so as to compensate for the light amount decrease due to deterioration of the light emitting element as time elapses. Therefore, as shown in the light emission element light amount 301 of the conventional configuration, the fixed time exceeding the allowable current value is Although the initial light amount Ls can be maintained, the drive current exceeds the allowable current value and becomes an excessive amount of current, so that the deterioration rate of the light emitting element is accelerated and the light amount rapidly decreases.

  When the amount of light decreases, the signal level of the two-phase analog original signal 3B also decreases, so the signal correction amount 7B of the signal correction unit 7 increases. As the signal correction amount increases, the error component of the position information also increases. When the correction limit light quantity Lm is reached at time T1, the required accuracy cannot be satisfied and the motor position detector reaches the end of its life. On the other hand, the drive current 202 of the present invention is controlled so that the drive current does not increase beyond the allowable current value. Therefore, after the time T0 when the drive current reaches the allowable current value, the light amount decreases due to the deterioration of the light emitting element, but the deterioration rate is Since it does not change without accelerating, the decrease rate of the light amount becomes smaller and constant than in the conventional configuration, and as a result, the required accuracy of the position information can be maintained until time T2 (> T1) when the light amount reaches the correction limit light amount. .

  The life calculator 10 first calculates time T0, time T2, the amount of change in the drive current 4A, and the amount of change in the signal correction amount 7B. The light quantity L of the light emitting element 1 is generally expressed as (Equation 1) using the constant K proportional to the structure of the light emitting element, the drive current, and the initial light quantity Ls.

The amount of light decreases with time according to (Equation 1), and the light amount control unit 4 controls the drive current to keep the decreased amount of light constant. Usually, the light emitting element, the amount of light, and the drive current are proportional, and the drive current is calculated from (Equation 2) using the natural number n from the relationship.

Is is an initial current value of the drive current, K _n−1 is a constant K when the current value is I _n−1 , and Δt is a calculation cycle. The calculation cycle may be set to a length that allows the change during the constant Kn _-1 cycle to be ignored. If a natural number n when I _n becomes the allowable current value It is assumed to be _{n T0,} time T0 is (Equation 3).

Time T0 after the drive current becomes a constant value because it is limited by the allowable current value It, the light quantity when the constant K in this case the K _IT is (Equation 4).

For example, in the case of amplitude correction, when the light amount decreases, the amplitude of the two-phase digital sine wave signal 6A also decreases and the correction amount increases. Since the relationship between the light amount and the correction amount signal is uniquely determined in this way, the light amount can be determined in advance from the correction amount signal. As a determination method, what is obtained by an arithmetic expression obtained by an arithmetic simulation or an evaluation test may be calculated on software or a logic circuit, or may be constituted by a ROM table. When the light quantity decreases according to (Equation 4) and reaches the correction limit light quantity Lm, the required accuracy of the position information cannot be maintained and the service life is reached, and the time T2 can be calculated by (Equation 5).

The remaining life calculation is switched at the high / low level of the allowable current arrival signal 4B, and when the allowable current arrival signal is low, the detection current Id of the drive current 4A is detected (expression 2), and n is calculated such that In = Id. Then, the remaining life is obtained by T2−n × Δt. When the allowable current arrival signal is High, the light amount Ld is determined from the signal correction amount 7B (Equation 4), and the time Td is calculated from (Equation 4) to obtain the remaining life (Equation 6). Ask for.

Based on the obtained remaining life, a warning signal is generated when the remaining life falls below the life warning value determined from the period in which only the motor or encoder can be replaced or the periodic inspection cycle, and the light intensity is the correction limit light intensity Lm An error signal is generated when a time T2 that is less than 10 lapses, and the remaining life, warning signal, and error signal are output as life information 10A. The calculation of the life calculation unit 10 may be performed in the motor control device by transmitting necessary information to the motor control device 21 via the communication unit 20.

  With the above configuration, the number of replacements can be minimized by extending the life of the motor position detector, and by providing the life calculation unit 10, replacement parts can be prepared in advance from the life information. Since it is possible to predict the replacement time, it is possible to plan the replacement work, and it is possible to reduce or eliminate the dead time in the replacement and to improve the reliability of the entire system.

  Further, the motor position detector including the temperature detection unit 11 includes a temperature detection sensor such as a temperature detection IC or a thermistor, measures the ambient temperature of the motor position detector or the light emitting element, and outputs it as temperature information 11A. To do. The life calculator 10 can correct and output the life information from the temperature information using the Arrhenius theorem.

  With the above configuration, the provision of the temperature detector increases the accuracy of the life information and can further increase the reliability.

  As described above, the motor position detector according to the present invention can increase the lifetime by preventing an excessive current from flowing through the light emitting element, and can improve the reliability by calculating the lifetime information. Therefore, it can be applied to uses such as a laser printer and a scanner for controlling the light amount of the light emitting element.

DESCRIPTION OF SYMBOLS 100 Optical circuit 1 Light emitting element 1A Light 2 Slit board 2A Transmitted light (reflected light)
3 Photodetector 3A Light quantity feedback signal 3B Two-phase analog original signal 3C Analog pulse signal 4 Light quantity controller 4A Drive current 4B Allowable current arrival signal 5 Signal amplifier 5A Two-phase analog sine wave signal 6 A / D converter 6A Two-phase digital Sine wave signal 7 Signal correction unit 7A Two-phase sine wave signal for conversion 7B Signal correction amount 8 Pulse conversion unit 8A Digital pulse signal 9 Position information generation unit 9A Position information 10 Life calculation unit 10A Life information 10B Initial information 11 Temperature detection unit 11A Temperature information 12 Memory unit 12A Motor information 20 Communication unit 20A Two-way communication signal 20B Life calculation unit control signal 21 Motor controller 201 Driving current of conventional configuration 202 Driving current of the present invention 301 Light emitting element light amount of conventional configuration 302 Light emission of the present invention Element light intensity

Claims (2)

Two-phase analog original signal orthogonal to each other by increasing / decreasing the light output from the light emitting element at the relative position of the slit pattern of the slit plate connected to the motor rotor and the mask pattern on the surface of the light receiving element, and performing photoelectric conversion by the light receiving element. An optical circuit that generates an analog pulse signal and a light amount feedback signal, a light amount control unit that controls a drive current that flows from the light amount feedback signal to the light emitting element, and a two-phase analog sine wave signal that amplifies and orthogonalizes the analog original signal A signal amplifying unit for generating the analog sine wave signal, an A / D conversion unit for generating a two-phase digital sine wave signal by A / D conversion, and correcting and converting the two-phase digital sine wave signal by signal processing A signal correction unit that generates a two-phase sine wave signal for use, and binarizes the analog pulse signal to convert it into a digital pulse signal A pulse conversion unit, a position information generation unit that generates position information by interpolating the digital pulse signal with an angle conversion value obtained by inverse trigonometric function of the two-phase sine wave signal for conversion, and a lifetime of the light emitting element A life calculation unit that calculates and outputs information, a memory unit that stores motor information of the motor, and a communication unit that performs parallel / serial conversion of the position information and motor information to communicate with a motor control device,
The light amount control unit maintains the light amount feedback signal at a constant amount by controlling the driving current, and restricts the allowable current value when the driving current exceeds a preset allowable current value and allows an allowable current arrival signal. The life calculation unit averages a signal correction amount used to correct the two-phase digital sine wave signal by the signal correction unit in an initial operation state with a plurality of values of the position information. Stored as initial information in the memory unit,
When the allowable current arrival signal is not output, the remaining life is calculated from the drive current and the allowable current value,
When said allowable current arrival signal is outputted to calculating the remaining lifetime from the signal correction amount and the initial information, and warning signals this residual life is output below the preset lifetime warning value, motor position detector and outputting an error signal output and below the set lifetime threshold below this life warning value as the life information. The motor position detector according to claim 1, further comprising a temperature detection unit that detects ambient temperature of the optical circuit and outputs temperature information, wherein the lifetime calculation unit corrects the remaining lifetime with temperature information. .

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