Displacement measuring device

Abstract

To provide a displacement measuring device capable of reducing power consumption in a sleep mode.SOLUTION: As operation modes of a signal processing section, a measurement computation execution mode for obtaining displacement or a position as a measurement value by using a sensor signal from a displacement sensor, and a sleep mode for reducing power consumption much more than the measurement computation execution mode are prepared. In the sleep mode, the signal processing section executes substitution computation processing for obtaining a substitution value related to displacement or a position at a predetermined sampling frequency by using less sensor signals than in the measurement computation execution mode. An operation mode control section cancels the sleep mode by determining detection of a variation in the displacement sensor when a substitution value varies, and switches the signal processing section to the measurement computation execution mode.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a displacement measuring device. [Background technology]

[0002] A digital micrometer is known as an example of a displacement measuring device. In such a displacement measuring device, in addition to a measurement and calculation execution mode in which normal measurement values ​​are obtained, a sleep mode is provided as an operation mode for reducing power consumption when the device is not in use by a user. In general, in the sleep mode, the frequency of detecting the position (angle) of the spindle is reduced compared to the measurement and calculation execution mode to reduce power consumption. For example, the position (angle) is detected at 80 Hz in the measurement and calculation execution mode, but is detected at 40 Hz in the sleep mode. This leads to a longer battery life and reduced maintenance costs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2006-322927 [Patent Document 2] Patent Publication No. 10-47942 Summary of the Invention [Problem to be solved by the invention]

[0004] Even if you want to reduce power consumption in sleep mode, you cannot skip over the rotation of the spindle. When the spindle starts to move due to user operation, you need to immediately switch to measurement and calculation execution mode to track the rotation of the spindle. Therefore, in conventional sleep mode, even if the frequency is reduced, the spindle position (angle) is calculated periodically to detect changes in the position (angle). However, performing all the signal processing required to calculate the position (angle) of the sensor signal in order to determine the spindle position (angle) consumes a lot of power, which shortens battery life. There is a demand for further reductions in power consumption. [Means for solving the problem]

[0005] The displacement measuring device of the present invention comprises: a displacement sensor that outputs a sensor signal having a different period depending on a displacement or a position; a signal processing unit that processes the sensor signal; an operation mode control unit for switching an operation mode of the signal processing unit, The operation mode of the signal processing unit is a measurement calculation execution mode in which a displacement or a position is obtained as a measured value using the sensor signal obtained from the displacement sensor; a sleep mode for reducing power consumption more than the measurement and calculation execution mode; In the sleep mode, the signal processing unit executes a substitute calculation process at a predetermined sampling frequency to obtain a substitute value related to a displacement or a position by using a part of the sensor signals used in the measurement calculation execution mode, When the substitute value fluctuates, the operation mode control unit determines that a fluctuation in the displacement sensor has been detected, cancels the sleep mode, and switches the signal processing unit to the measurement and calculation execution mode. It is characterized by:

[0006] In one embodiment of the present invention, An index number is prepared in advance for the sensor signal to distinguish a pattern of a magnitude relationship of a signal value determined according to a displacement or a position, In the sleep mode, the signal processing unit obtains the index number as the substitute value based on a magnitude comparison of the signal value of the sensor signal. It is preferred.

[0007] In one embodiment of the present invention, The set of sensor signals used in the substitute calculation process is made to differ for each sampling, periodically or non-periodically. It is preferred.

[0008] In one embodiment of the present invention, The operation mode control unit The proxy values ​​obtained by using the same combination of sensor signals are compared as corresponding proxy values, If the substitute value obtained at the current sampling time has changed from the immediately preceding corresponding substitute value, it is determined that a change in the displacement sensor has been detected, and the sleep mode is cancelled and the signal processing unit is switched to the measurement and calculation execution mode. It is preferred.

[0009] In one embodiment of the present invention, In the sleep mode, the signal processing unit obtains an AD converted value of the sensor signal as the substitute value. It is preferred.

[0010] In one embodiment of the present invention, A display unit; a display mode switching unit that switches the mode of the display unit between a display off mode and a display on mode, a display mode switching unit that switches from a display-off mode to a display-on mode by setting in advance a fluctuation amount of the displacement sensor as a display activation threshold value; When a fluctuation of the displacement sensor is detected in the sleep mode and an amount of the fluctuation of the displacement sensor equal to or greater than the display activation threshold is detected, the display mode switching unit cancels the display off mode and switches to a display on mode. It is preferred.

[0011] In one embodiment of the present invention, The displacement sensor includes: A rotor attached to a rotating body and rotating together with the rotating body; a stator disposed opposite the rotor with a predetermined gap therebetween, This is an absolute rotary encoder that can determine the absolute position within one or half rotation of the rotor from sensor signals with different periods. It is preferred.

[0012] In one embodiment of the present invention, A spindle and a main body frame that holds the spindle so that the spindle can be advanced and retreated in an axial direction, The rotor rotates together with the spindle, and the stator is attached to the body frame. In the measurement calculation execution mode, the signal processing unit obtains the displacement or position of the spindle as a measurement value by combining the total number of rotations of the spindle and the absolute position within one rotation or within half a rotation. It is preferred.

[0013] The control device for the displacement measuring device of the present invention comprises: a signal processing unit that receives a sensor signal output from a displacement sensor and has a period that varies depending on a displacement or a position, and processes the sensor signal; an operation mode control unit for switching an operation mode of the signal processing unit, The operation mode of the signal processing unit is a measurement calculation execution mode in which a displacement or a position is obtained as a measured value using the sensor signal obtained from the displacement sensor; a sleep mode for reducing power consumption more than the measurement and calculation execution mode; In the sleep mode, the signal processing unit executes a substitute calculation process at a predetermined sampling frequency to obtain a substitute value related to a displacement or a position by using a part of the sensor signals used in the measurement calculation execution mode, When the substitute value fluctuates, the operation mode control unit determines that a fluctuation in the displacement sensor has been detected, cancels the sleep mode, and switches the signal processing unit to the measurement and calculation execution mode. It is characterized by:

[0014] The control method for the displacement measuring device of the present invention includes the steps of: a signal processing unit that receives a sensor signal output from a displacement sensor and has a period that varies depending on a displacement or a position, and processes the sensor signal; and an operation mode control unit that switches an operation mode of the signal processing unit, The operation mode of the signal processing unit is a measurement calculation execution mode in which a displacement or a position is obtained as a measured value using the sensor signal obtained from the displacement sensor; a sleep mode for reducing power consumption more than the measurement and calculation execution mode; In the sleep mode, the signal processing unit executes a substitute calculation process at a predetermined sampling frequency to obtain a substitute value related to a displacement or a position by using a part of the sensor signals used in the measurement calculation execution mode, When the substitute value fluctuates, the operation mode control unit determines that a fluctuation in the displacement sensor has been detected, cancels the sleep mode, and switches the signal processing unit to the measurement and calculation execution mode. It is characterized by:

[0015] The control program for the displacement measuring device of the present invention comprises: A computer is incorporated in the control device of the displacement measuring device, and the computer is a signal processing unit that receives a sensor signal output from a displacement sensor and has a period that varies depending on a displacement or a position, and processes the sensor signal; an operation mode control unit for switching the operation mode of the signal processing unit; and a control program for the displacement measuring device for realizing the function thereof, The operation mode of the signal processing unit is a measurement calculation execution mode in which a displacement or a position is obtained as a measured value using the sensor signal obtained from the displacement sensor; a sleep mode for reducing power consumption more than the measurement and calculation execution mode; In the sleep mode, the signal processing unit executes a substitute calculation process at a predetermined sampling frequency to obtain a substitute value related to a displacement or a position by using a part of the sensor signals used in the measurement calculation execution mode, When the substitute value fluctuates, the operation mode control unit determines that a fluctuation in the displacement sensor has been detected, cancels the sleep mode, and switches the signal processing unit to the measurement and calculation execution mode. It is characterized by: [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is an external view of a digital micrometer. [Diagram 2] FIG. 2 is a partial cross-sectional view of a digital micrometer. [Diagram 3] FIG. 2 is a diagram illustrating an example of a scale pattern of a rotor of a rotary encoder. [Figure 4] FIG. 2 is a diagram illustrating a detection portion of a stator of a rotary encoder. [Diagram 5] FIG. 2 is a functional block diagram of a control unit. [Figure 6] FIG. 4 is a functional block diagram of a signal processing unit. [Figure 7] FIG. 4 is a functional block diagram of an operation mode control unit. [Figure 8] 4 is a functional block diagram of a display mode control unit. FIG. [Figure 9] 13 is a diagram illustrating an example of how one period of a first rotor pattern is divided into six stages according to index values. FIG. [Figure 10] 5A to 5C are diagrams illustrating two periods of a first sensor signal. [Figure 11] 5A to 5C are diagrams illustrating two periods of a first sensor signal. [Figure 12] 13 is a diagram illustrating an example of how one period of a first sensor signal is divided into 12 stages by index values. FIG. [Figure 13] FIG. 13 is a diagram illustrating an example of how one cycle of a two-phase signal is divided into eight stages. [Figure 14]FIG. 11 is a functional block diagram of a signal processing unit in the second embodiment. [Figure 15] 13 is a diagram illustrating a manner in which index values ​​are obtained alternately from a first rotor pattern and a second rotor pattern in the second embodiment. FIG. [Figure 16] 13 is a diagram illustrating a manner in which index values ​​are obtained alternately from a first rotor pattern and a second rotor pattern in the second embodiment. FIG. [Figure 17] FIG. 13 is a part of a functional block diagram of a signal processing unit according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be illustrated and described with reference to the reference numerals given to the various elements in the drawings. First embodiment A first embodiment of the present invention will be described. FIG. 1 is an external view of a digital micrometer as a displacement measuring device. A digital micrometer is shown as an example of a small portable digital displacement measuring device, but the present invention is not limited to a digital micrometer. The present invention can be widely applied to a displacement measuring device (measuring instrument) that measures the dimensions of a measuring object, includes a fixed element (such as a main frame or a main scale) and a movable element (such as a spindle or a slider) that is movable relative to the fixed element and directly or indirectly abuts against the measuring object, and detects the relative displacement or position between the movable element and the fixed element by a displacement sensor. Examples include digital calipers and digital dial gauges (digital indicators). The present invention is suitable for small portable measuring instruments that use batteries as a power source because it can reduce power consumption, but it is also effective when applied to large measuring machines.

[0018] FIG. 1 is an external view of a digital micrometer. FIG. 2 is a partial cross-sectional view of the digital micrometer. The digital micrometer 1000 includes a main body frame 1100 as a fixed element, a spindle (rotating body) 1200 as a movable element, a displacement sensor 2000, a control unit 3000, and a display unit 1300.

[0019] The main body frame 1100 is U-shaped, has an anvil 1110 at one end, and holds a spindle 1200 at the other end. Note that the main body frame 1100 may not have an anvil 1110, such as a micrometer head.

[0020] The spindle 1200 is screwed into the main body frame 1100 and moves in the axial direction by rotating it. In other words, the spindle 1200 is a rotating body that rotates and is a movable element that moves back and forth in the axial direction by rotating. The spindle 1200 is abutted against the object to be measured, and the dimensions of the object to be measured are obtained from the position of the spindle 1200 when the object to be measured is sandwiched between the anvil 1110 and the spindle 1200.

[0021] The displacement sensor 2000 is a sensor that detects the displacement or position of the spindle (movable element) 1200. In this embodiment, the displacement sensor 2000 is a so-called rotary encoder 2000, and detects the rotation (rotation angle) of the spindle 1200. The displacement sensor 2000 has a rotor (scale) 2100 that is provided so as to rotate integrally with the spindle 1200, and a stator (detection head) 2200 that is disposed opposite the rotor 2100 with a predetermined gap therebetween.

[0022] FIG. 3 is a diagram illustrating an example of a scale pattern of a rotor of a rotary encoder. FIG. 4 is a diagram illustrating a detection portion of a stator of a rotary encoder. Here, an electromagnetic induction type encoder will be described as an example.

[0023] The rotor 2100 is formed in a substantially doughnut-shaped plate shape, and has a scale pattern 2120 with multiple tracks (two tracks in this example) on its surface facing the stator 2200. Specifically, rotor 2100 has rotor substrate 2110, which is a substantially annular insulating substrate, a first rotor pattern (first scale pattern) 2121, and a second rotor pattern (second scale pattern) 2122. First rotor pattern 2121 is a scale pattern whose one pitch (one period) is P1. Second rotor pattern 2122 is a scale pattern whose one pitch (one period) is P2.

[0024] In the case of rotary encoder 2000, the positioning direction (angle measurement direction) is the rotational direction (direction along the circumference), so scale pattern 2120 is arranged in an annular shape along the rotational direction (direction along the circumference). The pitch (period) of first rotor pattern 2121 and the pitch (period) of second rotor pattern 2122 are different from each other. The same combination of the phase of first rotor pattern 2121 and the phase of second rotor pattern 2122 occurs only at one place (one angle) within one rotation of rotor 2100, and by combining both, the rotation angle of rotor 2100 is uniquely determined. Here, the pitch (period) of the first rotor pattern 2121 is finer. That is, the first rotor pattern 2121 is a fine scale pattern (sometimes called a fine scale pattern), and the second rotor pattern 2122 is a coarse scale pattern (sometimes called a sub-scale pattern). Although a continuous rectangular wave-shaped circular coil is shown as an example of the scale pattern 2120, it may be sinusoidal or may be formed of separate coils.

[0025] Here, an electromagnetic induction type encoder is used as an example, so the rotor patterns (scale patterns) 2121, 2122 are coil patterns, but if it is a photoelectric type, they may be light and dark (reflective / non-reflective, transparent / non-transparent) patterns, and if it is a capacitive type, they may be capacitor electrode patterns. Also, since the positioning direction in the case of rotary encoder 2000 is the rotation direction (direction along the circumference), scale pattern 2120 is arranged in a circular ring shape along the rotation direction (direction along the circumference). In the case of a linear encoder, the length measurement direction (positioning direction) is the longitudinal direction of a longitudinal scale, so scale pattern 2120 is arranged linearly along the longitudinal direction.

[0026] Stator 2200 has a transmitting coil and a receiving coil pattern as a detection unit for detecting the rotation angle (rotational position) of rotor 2100. Specifically, stator 2200 has stator substrate 2210, which is a substantially annular insulating substrate, drive signal transmitting unit 2220, and detection signal receiving unit 2300. Here, drive signal transmitting unit 2220 and detection signal receiving unit 2300 are electrode wires arranged concentrically on stator substrate 2210.

[0027] The drive signal transmitting unit 2220 is a transmitting coil that is magnetically coupled to the first rotor pattern 2121 and the second rotor pattern 2122 of the rotor 2100 to generate induced electromotive forces in the first rotor pattern 2121 and the second rotor pattern 2122. Here, the drive signal transmitting unit 2220 is composed of two annular coils. The transmitting coil that is located near the outer side of the stator substrate 2210 and is coupled to the first rotor pattern 2121 is referred to as the first transmitting coil 2221. The transmitting coil that is located near the inner side of the stator substrate 2210 and is coupled to the second rotor pattern 2122 is referred to as the second transmitting coil 2222.

[0028] The detection signal receiving unit 2300 is a receiving coil that is magnetically coupled to the first rotor pattern 2121 and the second rotor pattern 2122 of the rotor 2100, and reads a sensor signal corresponding to the position (rotational position) from the first rotor pattern 2121 and the second rotor pattern 2122. Here, the detection signal receiving unit 2300 is composed of two sets of annular coils. The receiving coil that is located near the outer side of the stator substrate 2210 and is coupled to the first rotor pattern 2121 is referred to as a first receiving coil 2310. The receiving coil that is located near the inner side of the stator substrate 2210 and is coupled to the second rotor pattern 2122 is referred to as a second receiving coil 2320.

[0029] The first receiver coil 2310 is composed of three phase coils with phases shifted by 120°. The three phase coils constituting the first receiver coil 2310 are a first A-phase receiver coil 2311, a first B-phase receiver coil 2312, and a first C-phase receiver coil 2313. The pitch (period) of the coils of the first receiver coil 2310 (the first A-phase receiver coil 2311, the first B-phase receiver coil 2312, and the first C-phase receiver coil 2313) is the same as the pitch (period) of the first rotor pattern 2121, which is P1.

[0030] The second receiver coil 2320 is composed of three phase coils with phases shifted by 120°. The three phase coils constituting the second receiver coil 2320 are a second A phase receiver coil 2321, a second B phase receiver coil 2322, and a second C phase receiver coil 2323. The coil pitch (period) of the second receiver coil 2320 is the same as the pitch (period) of the second rotor pattern 2122, which is P2.

[0031] In this embodiment, the receiving coils 2310 and 2320 as the detection signal receiving unit 2300 are provided in a sinusoidal shape, but may be rhombic or rectangular. In addition, the first receiving coil 2310 and the second receiving coil 2320 are described as having three phases, but may be one phase, two phases, four phases, or more. In the case of this first embodiment, it can be said that the first receiving coil 2310 needs to have two or more phases in order to obtain a substitute value described later. However, if the absolute position is only detected by combining sensor signals with different periods, each of the first receiving coil 2310 and the second receiving coil 2320 may be one phase. In addition, since the substitute value of the present invention is not limited to this first embodiment, it is not necessary to limit the first receiving coil 2310 to two or more phases in the interpretation of the present invention.

[0032] Here, an electromagnetic induction type encoder is used as an example, so the drive signal transmitting unit 2220 and the detection signal receiving unit 2300 of the stator (detection head) 2200 are electrode wires, but if it is a photoelectric type, it may be a combination of a light source and a light receiving element, and if it is a capacitive type, it may be an electrode pattern of a transmitting electrode and a capacitor.

[0033] When detecting the angle (position) of the rotor 2100, a driving current pulse is applied to the transmitting coils (first transmitting coil 2221, second transmitting coil 2222) of the driving signal transmitting unit 2220. Then, an electromotive force (induced current) is generated in the first rotor pattern 2121 and the second rotor pattern 2122 by coupling with the transmitting coils (first transmitting coil 2221, second transmitting coil 2222). In the first receiving coil 2310 of the stator 2200 that is coupled with the first rotor pattern 2121 of the rotor 2100, an electromotive force (induced current) having a magnitude according to the degree of overlapping between the two is generated, and this is extracted as a sensor signal. Similarly, in the second receiving coil 2320 of the stator 2200 that is coupled with the second rotor pattern 2122 of the rotor 2100, an electromotive force (induced current) having a magnitude according to the degree of overlapping between the two is generated, and this is extracted as a sensor signal. The sensor signal received by the first receiving coil 2310 is defined as a first sensor signal. The sensor signal received by the second receiving coil 2320 is referred to as a second sensor signal. The phase obtained from the sensor signal of the first receiving coil 2310 and the phase obtained from the sensor signal of the second receiving coil 2320 are combined to obtain the absolute position (angle) of the rotor 2100 within one rotation.

[0034] However, even though it is an absolute position detection type rotary encoder 2000, the absolute position can only be obtained within one rotation. Therefore, information on the total number of rotations is required to obtain the position of the spindle 1200, i.e., the total displacement of the spindle 1200. Regarding the number of rotations, when the rotor 2100 rotates once, if it rotates in the positive direction, the number of rotations is counted up, and if it rotates in the negative direction, the number of rotations is counted down.

[0035] In the case of a linear encoder, the number of periods (length periods) for which the absolute position can be obtained is counted. This can be called the number of rotations (number of rotations or number of rounds), the number of cycles, or the number of units. In addition, in the case of an absolute position detection type rotary encoder, if the absolute position can be obtained within half a rotation or within 45° of a rotation of the rotor rather than one rotation (360°) (the period (length period) for which the absolute position can be obtained is 180° or 90°), the half rotation or 45° rotation can be called one full revolution or full rotation (number of rotations or number of rounds), the number of cycles, or the number of units.

[0036] If the rotation speed is skipped, an error will occur in the measurement value by the pitch of the spindle's feed screw (for example, 0.5 mm).

[0037] FIG. 5 is a functional block diagram of the control unit 3000. The control unit 3000 may be a so-called computer having a storage device (ROM, RAM) and a central processing unit (CPU) as hardware. The computer may be operated as each functional unit by executing a program (control program for the displacement measuring device 1000) stored in the storage device (ROM, RAM). Such a control program for the displacement measuring device 1000 may be distributed by recording it on a non-volatile recording medium (CD-ROM, memory card, etc.), or may be made downloadable via an Internet line, etc.

[0038] The control unit 3000 processes the sensor signal from the displacement sensor 2000 and controls the entire operation. The control unit 3000 includes a signal processing unit 3100 , an operation mode control unit 3200 , a display mode control unit 3300 , and a display control unit 3400 .

[0039] FIG. 6 is a functional block diagram of the signal processing unit 3100. The signal processing unit 3100 includes a sensor driving unit 3110 , an input unit 3120 , an AD converter 3130 , a phase calculation unit 3140 , a position calculation unit 3161 , a rotation number counter 3150 , a position synthesis unit 3162 , and a substitute calculation processing unit 3170 .

[0040] Here, what will be mainly described in this embodiment is the substitute calculation processing unit 3170 that operates in the sleep mode. The other functional units mainly operate in the measurement calculation execution mode, and are basically known as the signal processing unit 3100 of the displacement sensor 2000.

[0041] The measurement calculation execution mode is the normal operating mode when measuring an object to be measured with a measuring instrument, and is an operating mode in which the displacement or position (rotation angle) of the spindle (movable element) 1200 is detected in real time (or at high frequency) and the position of the spindle (movable element) 1200 is determined every moment. In the case of this embodiment, in the measurement calculation execution mode, it is necessary to detect the rotation of the spindle 1200 at a frequency (frequency) that does not skip at least one rotation of the spindle 1200. Generally, if the thimble 1210 (or the ratchet thimble 1210) of the micrometer 1000 is thin, the user can rotate the spindle 1200 at an extremely fast speed. Here, it is assumed that the minimum time for the user to intentionally rotate the spindle 1200 at a fast speed when measuring the measurement object will not be less than 1 / 80 seconds, and the signal processing unit 3100 performs rotation detection and position calculation at 80 Hz. However, this operation frequency is appropriately adjusted according to the type and size of the measuring device. Note that since the absolute position can be detected within one rotation, it is sufficient not to skip the rotation. Therefore, since intermittent angle detection is sufficient compared to a method of constantly counting the angle change such as an incremental type, the frequency of position (angle) detection can be reduced, and power consumption can be reduced.

[0042] The operation of each functional unit in the measurement and calculation execution mode will now be briefly described. First, a driving current pulse is applied from the sensor driving unit 3110 to the driving signal transmitting unit 2220 (first transmitting coil 2221, second transmitting coil 2222) of the stator 2200. Then, an electromotive force (induced current) is generated in the first rotor pattern 2121 and the second rotor pattern 2122 due to coupling with the transmitting coils (first transmitting coil 2221, second transmitting coil 2222). An electromotive force (induced current) having a magnitude according to the degree of overlapping between the first rotor pattern 2121 of the rotor 2100 is generated in the first receiving coil 2310 of the stator 2200, which is coupled with the first rotor pattern 2121 of the rotor 2100, and this becomes a sensor signal. Similarly, an electromotive force (induced current) having a magnitude according to the degree of overlapping between the second rotor pattern 2122 of the rotor 2100 is generated in the second receiving coil 2320 of the stator 2200, which is coupled with the second rotor pattern 2122 of the rotor 2100, and this becomes a sensor signal.

[0043] The sensor signals from the first receiving coil 2310 and the second receiving coil 2320 are input to the input unit 3120. The input unit 3120 includes a first input unit 3121 and a second input unit 3122. The sensor signal from the first receiving coil 2310 is input to the first input unit 3121, and the sensor signal from the second receiving coil 2320 is input to the second input unit 3122. The input unit 3120, as an input unit for analog signals, performs, for example, signal amplification (amplification) and shaping (filter processing). An AD converter 3130 is disposed as an analog interface after the input unit 3120. The sensor signal digitized by the AD converter 3130 (for example, a sample and hold circuit) at 12 bits or 16 bits is input to the phase calculation unit 3140.

[0044] The sensor signal of the first receiving coil 2310 is processed by the first phase calculation unit 3141 to obtain the first phase. The sensor signal of the second receiving coil 2320 is processed by the second phase calculation unit 3142 to obtain the second phase. The phase calculation unit 3140 obtains the phase from the signal value of the sensor signal by an inverse trigonometric function. For example, a three-phase signal with a phase difference of 120° is treated as a two-phase signal with a phase difference of 90°, and the phase of each is obtained by an inverse trigonometric function (for example, arctan). The first phase obtained from the sensor signal of the first receiving coil 2310 and the second phase obtained from the sensor signal of the second receiving coil 2320 are combined by the position calculation unit 3161. This makes it possible to obtain the absolute position (angle) within one rotation of the rotor 2100.

[0045] Also, for example, one rotation of rotor 2100 and its rotation direction are detected from the sensor signal of first receiving coil 2310, and counted by rotation number counter 3150. When rotor 2100 rotates once, the number of rotations is counted up if the rotation is in the positive direction, and counted down if the rotation is in the negative direction. Position synthesis unit 3162 converts the number of rotations of spindle 1200 and the rotation angle within one rotation into the actual position of spindle 1200 to find the absolute position (measurement value) of spindle 1200.

[0046] If the measurement and calculation execution mode is in the display-on mode, the position (measurement value) of the spindle 1200 is displayed on the display unit 1300. This will be described later.

[0047] (Sleep mode) FIG. 7 is a functional block diagram of the operation mode control unit 3200. The operation mode control unit 3200 includes a current position storage memory 3210 , a timer 3220 , and a substitute value storage memory 3230 .

[0048] The operation mode control unit 3200 controls switching of the operation mode of the signal processing unit 3100 between a measurement calculation execution mode and a sleep mode. A trigger for switching from the measurement calculation execution mode to the sleep mode may be the same as in the past, for example, a user may explicitly select the sleep mode, or the micrometer 1000 may be automatically switched to the sleep mode if it has not been used for a certain period of time or more. The latest position information obtained by the position synthesis unit 3162 is stored in the current position storage memory 3210, and if the timer 3220 is started and the current position does not change for a certain period of time, it is determined that the micrometer 1000 is not being used, and the operation mode control unit 3200 transitions the operation mode of the signal processing unit 3100 to the sleep mode.

[0049] The operation of the signal processing unit 3100 in the sleep mode will be described. The sleep mode is an operation mode for reducing power consumption when the user is not using the micrometer (measuring instrument) 1000. In general, in the sleep mode, the frequency of position (angle) detection by the signal processing unit 3100 is reduced compared to the measurement and calculation execution mode to reduce power consumption. For example, the position (angle) is detected at 80 Hz in the measurement and calculation execution mode, but is detected at 40 Hz in the sleep mode. This method also reduces power consumption to 1 / 2 or less. In this embodiment, in order to further reduce power consumption, instead of completely determining the position (angle), a substitute value related to the displacement or position that can detect the fluctuation of the displacement sensor 2000 (rotary encoder 2000) is used.

[0050] During sleep mode execution, the functional parts of the signal processing unit 3100 that operate are the sensor driving unit 3110, part of the input unit 3120, and the substitute calculation processing unit 3170. The other functional parts do not operate and are in a standby state. This allows a significant reduction in power consumption. Since a considerable amount of power is required for AD conversion of multiple analog signals and the subsequent phase calculation, the effect of reducing power consumption by not performing AD conversion and phase calculation is significant.

[0051] In the sleep mode, the signal processing unit 3100 applies a driving current from the sensor driving unit 3110 to the driving signal transmitting unit 2220 of the stator 2200 at a frequency of 40 Hz. The operation frequency of 40 Hz is merely an example, and any frequency (predetermined sampling frequency) lower than that of the measurement calculation execution mode may be used. The fewer the number of operations, the more power consumption can be reduced. However, since the power required for one operation in the sleep mode of this embodiment is significantly less than that of the "measurement calculation execution mode", the power consumption reduction can be achieved even if the operation frequency is the same (80 Hz), and more specifically, the purpose of power consumption reduction can be achieved even if the operation frequency is increased. Therefore, the sampling frequency in the sleep mode does not necessarily exclude the case where it is higher than the sampling frequency in the measurement calculation execution mode.

[0052] Even if you want to reduce power consumption in the sleep mode, you must not skip the rotation of the spindle 1200. When it is detected that the spindle 1200 has started to rotate, that is, when it is detected that there is a change in the rotary encoder (displacement sensor) 2000, it is necessary to immediately switch to the measurement and calculation execution mode to track the rotation of the spindle 1200. It is unlikely that a user would suddenly rotate a measuring instrument in the sleep mode at high speed, but the spindle 1200 must not rotate more than once before returning from the sleep mode to the measurement and calculation execution mode and determining the rotation position of the spindle 1200. The operation frequency in the sleep mode is adjusted appropriately depending on the properties of the substitute value (resolution at which the fluctuation can be detected), which will be described later, the properties of the measuring instrument and the displacement sensor 2000 (for example, the difference between the micrometer 1000 and the caliper), the characteristics and preferences of the user, and the like.

[0053] In this embodiment, the rotor 2100 has a scale pattern 2120 with multiple tracks (two tracks in this embodiment), but in the sleep mode, it is not necessary to read all the tracks of the rotor 2100, and information on fewer tracks is read. Even if the rotor 2100 has N tracks, in the sleep mode, information on M tracks, which is less than N, is read. Here, N and M are integers that satisfy N>M≧1. Here, the rotor 2100 has a first rotor pattern 2121 (first scale pattern) and a second rotor pattern 2122 (second scale pattern). In the sleep mode of this embodiment, only the first rotor pattern 2121 (first scale pattern) with a dense pitch is used. This is because the first rotor pattern 2121 (first scale pattern) with a dense pitch is considered to be more advantageous for detecting fluctuations. When applying a drive current from the sensor driving section 3110 to the drive signal transmitting section 2220 of the stator 2200, if the first transmitting coil 2221 and the second transmitting coil 2222 can be driven separately and independently, then the drive current may be applied to the first transmitting coil 2221.

[0054] A drive current is applied to the first transmitting coil 2221 from the first sensor driving unit of the sensor driving unit 3110. Then, an electromotive force (induced current) is induced in the first rotor pattern 2121 coupled with the first transmitting coil 2221. An electromotive force (induced current) having a magnitude according to the degree of overlap between the first rotor pattern 2121 and the first receiving coil 2310 of the stator 2200 coupled with the first rotor pattern 2121 is generated. Since the first receiving coil 2310 has three phases, namely, a first A-phase receiving coil 2311, a first B-phase receiving coil 2312, and a first C-phase receiving coil 2313, a three-phase sensor signal is input to the first input unit 3121 of the signal processing unit 3100. After amplification and shaping processing in the first input unit 3121, the three-phase signal is input to the substitute calculation processing unit 3170.

[0055] In the substitute calculation processing unit 3170, one cycle is divided into several sections based on the magnitude relationship of the three-phase signals. The first rotor pattern 2121 of the rotor 2100 shown in FIG. 3 divides one revolution (360°) into 16 cycles from 0 to 15 (see FIG. 9). Furthermore, one cycle can be divided into six sections by a simple magnitude comparison pattern of the three-phase signals with a phase difference of 120°. The sensor signal received by the first receiving coil 2310 is defined as a first sensor signal. 10 and 11 are diagrams showing two periods of the first sensor signal. The signal from the phase 1A receive coil 2311 is referred to as a phase 1A signal. The signal from the phase 1B receive coil 2312 is referred to as a phase 1B signal. The signal from the phase 1C receive coil 2313 is referred to as a phase 1C signal.

[0056] The substitute calculation processor 3170 performs a magnitude comparison (eg, a comparison using a comparator) of the three-phase analog signals, and further outputs an index value based on a combination of the results.

[0057] An example of the relationship between the magnitude relationship of the three-phase analog signals and the index values ​​is as follows. "1A phase signal ≧ 1B phase signal ≧ 1C phase signal, 1A phase signal ≧ 1C phase signal" → Index value: "0" "1A phase signal < 1B phase signal ≧ 1C phase signal, 1A phase signal ≧ 1C phase signal" → Index value: "1" "1A phase signal < 1B phase signal ≥ 1C phase signal, 1A phase signal < 1C phase signal" → Index value: "2" "1A phase signal < 1B phase signal < 1C phase signal, 1A phase signal < 1C phase signal" → Index value: "3" "1A phase signal ≧ 1B phase signal < 1C phase signal, 1A phase signal < 1C phase signal" → Index value: "4" "1A phase signal ≧ 1B phase signal < 1C phase signal, 1A phase signal ≧ 1C phase signal" → Index value: "5"

[0058] The index value found by the substitute calculation processing unit 3170 is stored in the substitute value storage memory 3230 of the operation mode control unit 3200. In this way, substitute values ​​are obtained at 40 Hz, and their fluctuations are monitored. If the user is not using the measuring instrument (micrometer 1000), there should be no change in the index value. When the user starts to use the measuring instrument (micrometer 1000), the rotor 2100 rotates together with the spindle 1200, and the index value also changes. The operation mode control unit 3200 is triggered by the change in the index value and immediately switches the operation mode of the signal processing unit 3100 to the measurement calculation execution mode.

[0059] That is, as internal processing in the signal processing unit 3100, all functional units of the signal processing unit 3100 that were on standby are started up, the position (angle) of the displacement sensor (rotary encoder) 2000 is obtained, and the number of rotations is also counted. In this way, the absolute position of the spindle 1200 is obtained. Therefore, there is no risk of skipping the rotation of the spindle 1200, and the correct absolute position of the spindle 1200 can be obtained reliably. Furthermore, whether or not to display on the display unit 1300 will be described later.

[0060] In the above example, for example, the position of index value "0" in the 0th cycle and the position of index value "0" in the 1st cycle of the adjacent cycle cannot be distinguished from the index value alone. Therefore, in this case, if 1 / 16 rotation occurs in 1 / 40 seconds, this index value cannot detect fluctuations in the displacement sensor 2000. Taking this into consideration, the frequency of index value detection in sleep mode is determined with consideration given to the fineness of the scale pattern 2120. The index value needs to be monitored at a frequency faster than the speed at which the user rotates the spindle 1200 by 1 / 16 rotation (1 rotation divided by "the number of cycles of the scale pattern included in the range for which the absolute position can be obtained").

[0061] Here are some variations on the index value. If three-phase signals with a phase difference of 120° are directly compared in magnitude, one period can be divided into six sections. Furthermore, if an inverted three-phase signal is added to the three-phase signal to make a six-phase signal, one period can be divided into 12 sections. An example of this relationship is shown in Figure 12. If the index value can be calculated more precisely, even slight fluctuations in the displacement sensor 2000 can be detected immediately.

[0062] The index value can be calculated not only for three-phase signals, but also for two-phase signals. If the sensor signal is a two-phase signal with a phase difference of 90 degrees, one period can be divided into four parts. Alternatively, by adding an inverted two-phase signal that is the inversion of the two-phase signal and comparing the magnitude of the four-phase signals, one period can be divided into eight parts. An example of this relationship is shown in Figure 13.

[0063] (Display Control) The display mode control unit 3300 switches the display of the display unit 1300 between on and off. In other words, the display mode control unit 3300 causes the display control unit 3400 to switch between a display on mode and a display off mode. Here, the display on mode is a display on mode in which the display unit 1300 displays the measurement value (spindle position). The display off mode is a display off mode in which the display unit 1300 does not display the measurement value (spindle position), that is, no display is performed.

[0064] FIG. 8 is a functional block diagram of the display mode control unit 3300. The display mode control unit 3300 includes a display activation threshold memory 3310 and a sleep position storage memory 3320 .

[0065] In the display activation threshold memory 3310, the displacement amount of the movable element (here, the spindle 1200) is set as a threshold for returning the display of the display unit 1300 from the sleep mode. For example, 1 / 4 rotation (or a displacement amount equivalent to 1 / 4 rotation) of the spindle 1200 is set as the display activation threshold. Of course, the display activation threshold may be 1 / 6 rotation or 1 / 8 rotation. The manufacturer may set it at the time of shipment, or the user may set this threshold (display activation threshold) according to his / her preference. Note that, even if the signal processing unit 3100 is internally activated and performing the detection operation of the displacement sensor 2000, if the display unit 1300 does not light up (return), it appears to the user that the sleep mode continues. Therefore, the user will understand this threshold (display activation threshold) as the amount of operation required to return from the sleep mode to the normal measurement and calculation execution mode.

[0066] When the sleep mode is entered, the sleep position storage memory 3320 stores the position information of the spindle (movable element) 1200 at that time as the sleep position. As described above, the operation mode control unit 3200 causes the operation mode of the signal processing unit 3100 to transition to the sleep mode. When entering this sleep mode, the display mode control unit 3300 stores the position information in the sleep position storage memory 3320 as the sleep position.

[0067] When the operation mode control unit 3200 causes the operation mode of the signal processing unit 3100 to transition to the sleep mode, the display mode control unit 3300 also transitions the operation mode of the display control unit 3400 to the display off mode. Meanwhile, the display mode control unit 3300 has another threshold for returning from the display off mode to the display on mode, separate from the transition of the operation mode of the signal processing unit 3100. After the signal processing unit 3100 transitions (returns) to the measurement calculation execution mode, the display mode control unit 3300 receives the latest information on the spindle position from the position synthesis unit 3162. The display mode control unit 3300 compares the latest spindle position with the stored sleep position. Then, when there is a displacement of the spindle 1200 that is equal to or greater than the display activation threshold, the display mode control unit 3300 transitions the operation mode of the display control unit 3400 to the display on mode. Then, the display control unit 3400 executes display control so that the measured value and other necessary information are displayed on the display unit 1300.

[0068] In order not to miss any rotation of the spindle 1200, the signal processor 3100 is activated immediately to monitor the spindle position if there is even a slight fluctuation in the displacement sensor 2000. However, there are cases where the user does not intentionally move the spindle 1200 to start a measurement, but simply wants to move the measuring instrument (micrometer 1000). If the display is also restored in response to an unintentional fluctuation in the displacement sensor 2000, this will result in unnecessary power consumption. According to this embodiment, the display unit 1300 is turned on only when the user operates the measuring instrument (micrometer 1000) to intentionally restore it from sleep mode. This prevents unnecessary consumption of display power for the user, which leads to a longer battery life and reduced maintenance costs.

[0069] The display off mode is not limited to displaying nothing at all on the display unit 1300. In the display on mode, the position of the spindle 1200 is displayed on the display unit 1300 and the display is updated in real time, whereas in the display off mode, this information is not displayed completely. In the display off mode, for example, a message such as "Display off mode" or "Please rotate X degrees further until start-up" may be displayed on the display unit 1300.

[0070] In the first embodiment, the rotary encoder (displacement sensor) 2000 outputs two sets of sensor signals, and in the sleep mode, one of the sensor signals (here, the first sensor signal) is used to monitor the fluctuation of the displacement sensor 2000. As an absolute position measurement method, there is also a method of using three or more sets of sensor signals with different periods from a scale pattern 2120 of three or more tracks with different periods. In this case, instead of using all three sets, an index value may be obtained from each of the sensor signals of one or two of the sets. Alternatively, two sets of sensor signals may be combined to obtain one index value. If one set is a three-phase sensor signal, one index value may be obtained by comparing the magnitude of the signal values ​​of the two sets of sensor signals, i.e., six-phase sensor signals, and the fluctuation of the index value may be observed.

[0071] Second Embodiment In the first embodiment, only the first rotor pattern (first scale pattern) 2121 is used to calculate the index value. Here, as a second embodiment, it is proposed to alternately use the first rotor pattern (first scale pattern) 2121 and the second rotor pattern (second scale pattern) 2122 to calculate the index value. In this case, the sensor driving unit 3110 applies driving signals alternately to the first transmitting coil 2221 and the second transmitting coil 2222 from the first sensor driving unit 3111 and the second sensor driving unit 3112. The substitute calculation processing unit 3170 in FIG. 14 is adapted to receive not only the output of the first input unit 3121 but also the output of the second input unit 3122.

[0072] The process of obtaining the index value is the same as that of the first embodiment, and the index value is obtained by, for example, simply comparing the magnitudes of the three-phase sensor signals. As illustrated in FIG. 15, the first rotor pattern 2121 and the second rotor pattern 2122 are read alternately at a certain frequency (for example, 40 Hz). In FIG. 15, F should be interpreted as meaning the first rotor pattern 2121, which is a dense track, and S should be interpreted as meaning the second rotor pattern 2122, which is a sub-track. That is, the first index value based on the first sensor signal and the second index value based on the second sensor signal are obtained alternately. The first index value and the second index value thus obtained are sequentially stored in the substitute value storage memory 3230, and are compared with the corresponding values ​​from the previous time to see if there is any change. If there is a change in either the first index value or the second index value, it is determined that the displacement sensor 2000 has fluctuated, and the operation mode control unit 3200 returns the operation mode of the signal processing unit 3100 to the measurement calculation execution mode.

[0073] First, since there is only one combination pattern of the first index value and the second index value within one rotation, the rotation angle can be roughly determined within one rotation by obtaining the first index value and the second index value, although it is the resolution of the index value. The current position of the spindle 1200 is stored in the current position storage memory 3210. The combination of the two index values ​​should match the current position of the spindle 1200. If the two do not match, some kind of error may have occurred during the sleep mode. Also, as described above, it is not possible to determine which period the index value corresponds to by only one index value (for example, the first index value). By unfortunate coincidence, as illustrated in FIG. 16, if the rotation is performed by 1 / 16 at exactly 40 Hz, for example, this fluctuation may not be recognized by the first index value. However, it should be possible to detect that the second index value has changed at the next detection timing. Therefore, it becomes possible to more reliably detect the fluctuation of the displacement sensor 2000.

[0074] In the above example, the first rotor pattern (first scale pattern) 2121 and the second rotor pattern (second scale pattern) 2122 are used alternately, but this is not limited to "alternate." For example, a first substitute value based on the first rotor pattern (first scale pattern) 2121 may be obtained nine times in succession, and then a second substitute value based on the second rotor pattern (second scale pattern) 2122 may be obtained once, and this acquisition pattern may be repeated. The number of times the first substitute value is continuously obtained does not have to be a fixed cycle, but may be determined randomly. By occasionally obtaining a second substitute value different from the first substitute value, it is possible to supplement information that cannot be recognized by the first substitute value alone (such as a rough absolute position or the presence or absence of an internal error).

[0075] When three or more sets of sensor signals with different periods are obtained from scale pattern 2120 of three or more tracks having different periods, the index value may be obtained by switching the sets in order or in a fixed order for each sampling. Also, when four sets of sensor signals are obtained from four tracks, the index value may be obtained using only two or three sets instead of using all four.

[0076] Just to be sure, I'll add a little more detail. In a displacement sensor that obtains a plurality of sets of sensor signals with different periods from scale patterns of a plurality of tracks having different periods, in a measurement calculation execution mode, a plurality of sensor signals are obtained simultaneously at the same timing in one sampling for obtaining a measurement value, and one measurement value is obtained by combining the thus synchronized sensor signals. In the first embodiment, the rotary encoder (displacement sensor) 2000 outputs two sets of sensor signals, and in the sleep mode, one of the sensor signals is used to monitor the fluctuation of the displacement sensor 2000. In the second embodiment, a first index value based on the first sensor signal and a second index value based on the second sensor signal are obtained, but the first sensor signal and the second sensor signal are not obtained simultaneously in one sampling, but are obtained one by one in one sampling. The pair of the first sensor driving unit 3111 and the first input unit 3121 and the pair of the second sensor driving unit 3112 and the second input unit 3122 are activated / stopped alternately. In the present invention including the first and second embodiments, the substantial functions of the signal processing unit 3100 are not all activated simultaneously at any timing during the sleep mode. The proxy value for monitoring the fluctuation of the displacement sensor during the sleep mode is obtained using fewer sensor signals than the sensor signals acquired in one sampling in the measurement and calculation execution mode.

[0077] Third embodiment In the above first and second embodiments, index values ​​are used as substitute values. In the third embodiment, it is proposed to use an AD converted value of a sensor signal as a substitute value. Fig. 17 is a part of a functional block diagram of a signal processing unit 3100 in the third embodiment. In Fig. 17, a substitute value acquisition unit acquires an AD conversion value from one of the AD converters.

[0078] The operation in the sleep mode will now be described. During execution of the sleep mode, the functional parts of the signal processing unit 3100 that operate are a part of the sensor driving unit 3110 (first sensor driving unit 3111), a part of the input unit 3120, a part of the AD converter 3130, and the substitute value acquisition unit 3180. The other functional parts do not operate and are in a standby state. In this embodiment, a three-phase sensor signal is input to the first input unit 3121 as the first sensor signal, but amplification, shaping, and AD conversion in the input unit 3120 are performed only for one phase, and other signals are not processed. In other words, AD conversion is performed only for one phase.

[0079] In the sleep mode, the signal processing unit 3100 applies a driving current from the sensor driving unit 3110 (first sensor driving unit 3111) to the driving signal transmitting unit 2220 (first transmitting coil 2221) of the stator 2200 at a frequency of 40 Hz. An electromotive force (induced current) is induced in the first rotor pattern 2121 coupled with the first transmitting coil 2221, and an electromotive force (induced current) of a magnitude according to the degree of overlap between the first rotor pattern 2121 and the first receiving coil 2310 of the stator 2200 coupled with the first rotor pattern 2121 is generated. The first receiving coil 2310 has three phases, a first A-phase receiving coil 2311, a first B-phase receiving coil 2312, and a first C-phase receiving coil 2313, so that a three-phase sensor signal is input to the first input unit 3121 of the signal processing unit 3100. Only one of the phases (for example, a first C-phase signal) is amplified and shaped, and input to the AD converter 3130.

[0080] The AD converter 3130 has a first AD converter 3131 and a second AD converter 3132. Furthermore, the first AD converter 3130 has AD converters 3131A, 3131B, and 3131C corresponding to the 1A-phase signal, the 1B-phase signal, and the 1C-phase signal, respectively. One AD converter 3131C digitally converts the 1C-phase signal, for example, at 12 bits or 16 bits. The digitally converted sensor signal value is input to a substitute value acquisition unit 3180, and is further stored in a substitute value storage memory 3230 of the operation mode control unit 3200. In this case, the AD conversion process may be considered to correspond to a "substitute calculation process for obtaining a substitute value." The operation mode control unit 3200 uses the digitally converted sensor signal value as an index value and monitors fluctuations in this index value. If there is a fluctuation in the digitally converted sensor signal value, this is used as a trigger to immediately switch the operation mode of the signal processing unit 3100 to a measurement calculation execution mode.

[0081] For example, a 16-bit digital value can distinguish the value of the sensor signal into 65,536 steps. If the rotor 2100 moves to the same index value in the adjacent cycle before the next sampling, this cannot be detected, just like the index value in the first embodiment. However, it is almost impossible for the rotor 2100 to move exactly to the same index value distinguished into 65,536 steps at the next sampling timing. Therefore, by using a digitally converted value of one of the sensor signals as an index value and monitoring this, fluctuations in the displacement sensor 2000 can be reliably detected.

[0082] It is preferable that the AD converter for determining the substitute value is the same as the AD converter that the signal processing unit 3100 has for determining the position (angle) of the spindle (movable element) 1200 in the measurement calculation execution mode. The AD converter is, for example, 8-bit, 12-bit, 16-bit or more, depending on the resolution of the position (angle) calculation, and is used for the "substitute calculation process for determining a substitute value."

[0083] In obtaining the AD converted value as the substitute value, as described in the second embodiment, the sensor signal from a different receiving coil may be AD converted for each sampling, and the values ​​may be compared with the corresponding values ​​from the previous time to see if there are any changes.

[0084] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0085] 1000 Displacement measuring device (digital micrometer) 1100 Main frame 1110 Anvil 1200 Spindle (moving element, rotating body) 1210 Thimble 1300 Display section 2000 Rotary Encoder (Displacement Sensor) 2100 Rotor 2110 Rotor Board 2120 scale pattern 2121 First rotor pattern 2122 Second rotor pattern 2200 Stator 2210 Stator board 2220 Drive signal transmission unit 2221 First transmitting coil 2222 Second transmitting coil 2300 Detection signal receiver 2310 First receiving coil 2311 Phase 1A receiving coil 2312 Phase 1B receiver coil 2313 Phase 1C receiver coil 2320 Second receiving coil 2321 Phase 2A receiver coil 2322 Phase 2B receiver coil 2323 Phase 2 C receiver coil 3000 Control Unit 3100 Signal Processing Unit 3110 Sensor drive unit 3111 First sensor drive unit 3112 Second sensor drive unit 3120 Input section 3121 First input section 3122 Second input section 3130 A / D Converter 3131 First AD converter 3132 Second AD Converter 3140 Phase calculation section 3141 First phase calculation section 3142 Second phase calculation section 3150 RPM Counter 3161 Position calculation section 3162 Position synthesis section 3170 Substitute Calculation Processing Unit 3180 Substitute Value Acquisition Unit 3200 Operation mode control unit 3210 Current position memory 3220 Timer 3230 Substitute value storage memory 3300 Display mode control section 3310 Display activation threshold memory 3320 Sleep position memory 3400 Display control unit

Claims

1. a displacement sensor that outputs a sensor signal having a different period depending on a displacement or a position; a signal processing unit that processes the sensor signal; an operation mode control unit for switching an operation mode of the signal processing unit, The operation mode of the signal processing unit is a measurement calculation execution mode in which a displacement or a position is obtained as a measured value using the sensor signal obtained from the displacement sensor; a sleep mode for reducing power consumption more than the measurement and calculation execution mode; In the sleep mode, the signal processing unit executes a substitute calculation process at a predetermined sampling frequency to obtain a substitute value related to a displacement or a position by using a part of the sensor signals used in the measurement calculation execution mode, When the substitute value fluctuates, the operation mode control unit determines that a fluctuation in the displacement sensor has been detected, cancels the sleep mode, and switches the signal processing unit to the measurement and calculation execution mode. A displacement measuring device comprising:

2. The displacement measuring device according to claim 1, An index number is prepared in advance for the sensor signal to distinguish a pattern of a magnitude relationship of a signal value determined according to a displacement or a position, In the sleep mode, the signal processing unit obtains the index number as the substitute value based on a magnitude comparison of the signal value of the sensor signal. A displacement measuring device comprising:

3. The displacement measuring device according to claim 1, The set of sensor signals used in the substitute calculation process is made to differ for each sampling, periodically or non-periodically. A displacement measuring device comprising:

4. In the displacement measuring device according to claim 3, The operation mode control unit is The proxy values ​​obtained by using the same combination of sensor signals are compared as corresponding proxy values, If the substitute value obtained at the current sampling time has changed from the immediately preceding corresponding substitute value, it is determined that a change in the displacement sensor has been detected, and the sleep mode is cancelled and the signal processing unit is switched to the measurement and calculation execution mode. A displacement measuring device comprising:

5. The displacement measuring device according to claim 1, In the sleep mode, the signal processing unit obtains an AD converted value of the sensor signal as the substitute value. A displacement measuring device comprising:

6. The displacement measuring device according to claim 1, A display unit; a display mode switching unit that switches the mode of the display unit between a display off mode and a display on mode, a display mode switching unit that switches from a display-off mode to a display-on mode by setting in advance a fluctuation amount of the displacement sensor as a display activation threshold value, When a fluctuation of the displacement sensor is detected in the sleep mode and an amount of the fluctuation of the displacement sensor equal to or greater than the display activation threshold is detected, the display mode switching unit cancels the display off mode and switches to a display on mode. A displacement measuring device comprising:

7. The displacement measuring device according to claim 1, The displacement sensor includes: A rotor attached to a rotating body and rotating together with the rotating body; a stator disposed opposite the rotor with a predetermined gap therebetween, This is an absolute rotary encoder that can determine the absolute position within one or half rotation of the rotor from sensor signals with different periods. A displacement measuring device comprising:

8. The displacement measuring device according to claim 7, A spindle and a main body frame that holds the spindle so that the spindle can be advanced and retreated in an axial direction, The rotor rotates together with the spindle, and the stator is attached to the body frame. In the measurement calculation execution mode, the signal processing unit obtains the displacement or position of the spindle as a measurement value by combining the total number of rotations of the spindle and the absolute position within one rotation or within half a rotation. A displacement measuring device comprising:

9. a signal processing unit that receives a sensor signal output from a displacement sensor and has a period that varies depending on a displacement or a position, and processes the sensor signal; an operation mode control unit for switching an operation mode of the signal processing unit, The operation mode of the signal processing unit is a measurement calculation execution mode in which a displacement or a position is obtained as a measured value using the sensor signal obtained from the displacement sensor; a sleep mode for reducing power consumption more than the measurement and calculation execution mode; In the sleep mode, the signal processing unit executes a substitute calculation process at a predetermined sampling frequency to obtain a substitute value related to a displacement or a position by using a part of the sensor signals used in the measurement calculation execution mode, When the substitute value fluctuates, the operation mode control unit determines that a fluctuation in the displacement sensor has been detected, cancels the sleep mode, and switches the signal processing unit to the measurement and calculation execution mode. A control device for a displacement measuring device.

10. a signal processing unit that receives a sensor signal output from a displacement sensor and has a period that varies depending on a displacement or a position, and processes the sensor signal; and an operation mode control unit that switches an operation mode of the signal processing unit, The operation mode of the signal processing unit is a measurement calculation execution mode in which a displacement or a position is obtained as a measured value using the sensor signal obtained from the displacement sensor; a sleep mode for reducing power consumption more than the measurement and calculation execution mode; In the sleep mode, the signal processing unit executes a substitute calculation process at a predetermined sampling frequency to obtain a substitute value related to a displacement or a position by using a part of the sensor signals used in the measurement calculation execution mode, When the substitute value fluctuates, the operation mode control unit determines that a fluctuation in the displacement sensor has been detected, cancels the sleep mode, and switches the signal processing unit to the measurement and calculation execution mode.

23. A method for controlling a displacement measuring device comprising the steps of:

11. A computer is incorporated in the control device of the displacement measuring device, and the computer is a signal processing unit that receives a sensor signal output from a displacement sensor and has a period that varies depending on a displacement or a position, and processes the sensor signal; an operation mode control unit for switching the operation mode of the signal processing unit; and a control program for the displacement measuring device for realizing the function thereof, The operation mode of the signal processing unit is a measurement calculation execution mode in which a displacement or a position is obtained as a measured value using the sensor signal obtained from the displacement sensor; a sleep mode for reducing power consumption more than the measurement and calculation execution mode; In the sleep mode, the signal processing unit executes a substitute calculation process at a predetermined sampling frequency to obtain a substitute value related to a displacement or a position by using a part of the sensor signals used in the measurement calculation execution mode, When the substitute value fluctuates, the operation mode control unit determines that a fluctuation in the displacement sensor has been detected, cancels the sleep mode, and switches the signal processing unit to the measurement and calculation execution mode. A control program for a displacement measuring device comprising:

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