JP2005292078A - Incremental type displacement measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an increment type displacement measuring instrument, capable of aligning reference positions (origin positions), when positioning from a going direction and when positioning from a returning direction, in reference positioning (origin positioning) for incremental measurement. <P>SOLUTION: In a reference positioning operation for an optical encoder concerned in this increment type displacement measuring instrument, a counter circuit is zero-set using a reference signal ψR2 as a trigger in the going direction (S1); where as the counter circuit is zero-set, by using a reference signal ψR3 which becomes active with a lag to the reference signal ψR2, as a trigger, in the returning direction (S2). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an incremental-type displacement measuring apparatus, and relates to, for example, improvement of zero set and preset functions.

  Conventionally, a displacement measuring device such as an encoder has been used for precise measurement such as linear displacement. As a method of the displacement measuring device, there are an optical type, an electromagnetic induction type, a capacitance type, and the like. The optical encoder includes, for example, a main scale provided with an optical grating and a sensor head that can move on the scale. The sensor head includes an index scale that is arranged opposite to the main scale and provided with an optical grating, a light source having a light emitting diode, and a light receiving unit having a photodiode.

  When the sensor head is moved in a state where the light-emitting diode is turned on, a light / dark pattern of light is generated by the optical grating provided on the main scale and the optical grating provided on the index scale. This light / dark pattern is detected by a photodiode and converted into an electrical signal, and the amount of displacement is calculated based on this signal.

  Of the displacement measuring devices, the incremental type measures the amount of displacement by counting pulses generated by interpolating the electric signal (main signal). For this reason, the measurement can be started only after the sensor head is passed through the origin on the main scale and the origin is detected. This operation of detecting the origin is called origin retrieval.

Although the sensor head can move on the main scale in the forward direction and the return direction opposite to this, there is an encoder that can take the origin only from one direction (Patent Document 1). For example, when the origin can only be obtained from the forward direction, the measurement cannot be started unless the sensor head is moved in the forward direction to pass the origin on the main scale.
JP 2000-97726 A (FIG. 4)

  It is convenient if the origin can be obtained from both the forward direction and the return direction (hereinafter referred to as “reference position acquisition of incremental measurement”). However, if there is a difference in the detection of the origin between the forward direction and the return direction, there is a disadvantage that the amount of displacement differs between when measured from the forward direction and when measured from the return direction.

  An object of the present invention is to provide an incremental displacement measuring apparatus capable of aligning a reference position in a case where the reference position of the incremental measurement is taken from one direction and the other direction opposite thereto. And

  One aspect of the incremental displacement measuring apparatus according to the present invention is a main scale, and is movable relative to the main scale along a measurement axis in one direction and the other direction opposite to the main scale. An index scale disposed opposite to the main scale, an optical grating for main signal provided on the main scale and the index scale, and for generating a main signal as a basis of a pulse for counting for incremental measurement, and the main scale A reference signal optical grating for generating a reference signal for specifying a reference position in the incremental measurement, and the reference signal optical grating by relative movement of the index scale with respect to the main scale. Based on the main signal and asynchronous A first reference signal generation circuit that generates a first reference signal that is a reference signal, and a second reference signal that is a reference signal that is active in different directions in the one direction and the other direction. A second reference signal generation circuit that generates the active signal so as to be synchronized with the main signal, and a third reference that is synchronized with the second reference signal and is activated later than the second reference signal becomes active A third reference signal generation circuit for generating a signal, and a trigger for setting a reference value for counting the number of pulses for counting the incremental measurement generated based on a main signal and indicating a reference position for the incremental measurement, A counter circuit that is a second or third reference signal when measuring displacement from one direction and a third reference signal when measuring displacement from the other direction , Characterized in that it comprises a.

  According to one aspect of the present invention, the trigger of the reference value set of the counter circuit is the second or third reference signal in one direction and the third reference signal in the other direction. Since the third reference signal becomes active after the second reference signal becomes active, the reference positions can be aligned in one direction and the other direction.

  In one aspect of the present invention, when measuring displacement from the one direction, the second reference signal serves as a trigger for the set of reference values, and the reference value in the one direction when the second reference signal is used as a trigger. A count number between the position of the set and the position of the reference value set in the other direction is obtained in advance, and the delay of the third reference signal can be set based on this count number. . More specifically, an UP / DOWN counter that outputs an active third reference signal when the second reference signal is triggered and a number corresponding to the delay of the third reference signal is counted can be provided. According to this, even if the relative movement direction of the index scale is changed to the opposite direction due to vibration or the like during the reference position setting, the influence can be eliminated.

  In another aspect of the incremental displacement measuring apparatus according to the present invention, the main scale is movable relative to the main scale along the measurement axis in one direction and the other direction opposite to the main scale. An index scale disposed opposite to the scale; a main signal optical grating provided on the main scale and the index scale and generating a main signal as a basis of pulses for counting for incremental measurement; and the main scale A reference signal optical grating provided on the scale and the index scale and for generating a reference signal for specifying a reference position in the incremental measurement, and the reference signal optical by relative movement of the index scale with respect to the main scale. Asynchronous with main signal based on lattice A first reference signal generation circuit that generates a first reference signal that is a reference signal, and a second reference signal that is a reference signal that is active at different positions in the one direction and the other direction, A second reference signal generation circuit that is generated so as to be synchronized with the main signal during active, and counts the number of pulses for counting the incremental measurement generated based on the main signal, and the second reference signal is used as a trigger. A counter circuit in which an initial value is set, and when the displacement is measured from the one direction, the initial value is a reference value indicating a reference position of the incremental measurement or a value reverted from the reference value, The initial value when the displacement is measured from the other direction is a value that is reversed from the reference value.

  According to another aspect of the present invention, the initial value set in the counter circuit is a reference value in one direction or a value back from this, and a value back from the reference value in the other direction. Yes. For this reason, it is possible to align the reference positions in one direction and the other direction.

  In another aspect of the invention, the initial value when the displacement is measured from the one direction is the reference value, and the backward value that is the initial value when the displacement is measured from the other direction is In this case, it is set based on a count number obtained in advance between the trigger occurrence in the one direction and the trigger occurrence in the other direction.

  In one aspect and another aspect of the present invention, an assembly assembled with the main scale and the index scale as parts, and a counter device in which the counter circuit is incorporated and connected to the assembly by a cable, Can be. In addition, the counter circuit may be incorporated in an assembly in which the main scale and the index scale are assembled as parts.

  According to the incremental displacement measuring apparatus of the present invention, the reference position is aligned between the case where the reference position of the incremental measurement is taken from one direction and the other direction opposite thereto, that is, the reference position is the same. It becomes possible to. Therefore, it is not necessary to restrict the reference positioning operation from one direction, and the convenience of measurement can be improved.

  Hereinafter, an incremental displacement measuring apparatus (sometimes referred to as “displacement measuring apparatus”) according to the present embodiment will be described with reference to the drawings. In the figure, the same reference numerals are used to designate the same elements as those shown in the drawings already described, and the description thereof is omitted.

First, reference positions and reference values used in this specification will be described. There are zero set and preset for the origin. Zero set is to make the display value zero at an arbitrary position. The preset is to set an arbitrary numerical value on the display unit. Accordingly, measurement is started with zero set as the origin and zero as the preset with the above-mentioned arbitrary numerical value as the origin. As described above, since the origin in the origin determination is not necessarily zero, in this specification, the expression “reference position in incremental measurement” is used instead of “origin”, and “reference position acquisition” is used instead of “origin acquisition”. The expression is used. A value corresponding to the reference position is a reference value, and zero in the zero set and the above arbitrary numerical value in the preset are the reference values.
[First Embodiment]
FIG. 1 is a perspective view showing a schematic configuration of an optical incremental displacement measuring apparatus 1 according to the first embodiment. Specific examples of the displacement measuring apparatus 1 include a linear scale, a linear gauge, and a dial gauge with a digital display. The displacement measuring apparatus 1 includes a long main scale 3 extending along the measuring axis X of the apparatus 1, a forward direction (one example of one direction) with respect to the scale 3, and a return direction (the other direction) opposite thereto. Sensor head 5 that is movable along the measurement axis X in an example of a direction).

  The main scale 3 is made of a transparent material such as glass. An optical grating 7 (an example of an optical grating for main signals) having a predetermined pitch is formed on the scale 3 along the longitudinal direction of the scale 3. Further, an optical grating 9 (an example of an optical grating for reference signal) is formed at a reference position in the incremental measurement of the scale 3.

  The sensor head 5 includes an index scale 11 disposed on one surface side of the main scale 3 so as to face the scale 3. Since the scale 11 is disposed on the sensor head 5, it can move on the main scale 3 along the measurement axis X in the forward direction and the return direction. The scale 11 is made of a transparent material such as glass. On the scale 11, four optical gratings 13 (an example of a main signal optical grating) having the same pitch as the optical grating 7 are formed so as to face the optical grating 7.

  When the phase space of the optical grating 13a is 0 degree, the phase space of the optical grating 13b is 90 degrees, the phase space of the optical grating 13aa is 180 degrees, and the phase space of the optical grating 13bb is 270 degrees. The pitch is specified. The scale 11 is formed with an optical grating 15 (an example of a reference signal optical grating) corresponding to the optical grating 9 of the main scale 3.

  The sensor head 5 includes a light source 17 and a light receiving unit 19 that are arranged so as to face each other across the scales 3 and 11. The light source 17 includes a light emitting diode and is disposed on the main scale 3 side. The light receiving unit 19 is disposed on the index scale 11 side. The light receiving unit 19 includes four photodiodes 21 and one photodiode 23. The diodes 21a, 21b, 21aa, and 21bb are opposed to the optical gratings 13a, 13b, 13aa, and 13bb, respectively. The diode 23 faces the optical grating 15 of the index scale 11.

  Now, measurement of displacement is performed by moving the sensor head 5 on the main scale 3 along the measurement axis X in a state where the light L from the light source 17 is irradiated onto the index scale 11 via the main scale 3. Is done. At this time, the light / dark pattern of sinusoidal light generated by irradiating the optical grating 7 and the optical grating 13a with the light L is received by the photodiode 21a and output as the main signal φa.

  Similarly, a light / dark pattern of sinusoidal light generated by irradiating the light L onto the optical grating 7 and the optical grating 13b (13aa, 13bb) is received by the diode 21b (21aa, 21bb), and the main signal φb It is output as (φaa, φbb). Further, the light / dark pattern of the light generated by irradiating the optical grating 9 and the optical grating 15 with the light L is received by the photodiode 23 and output as the reference signal φr.

  The main signal is a signal that is a basis of a pulse for counting the incremental measurement, and is generated using the optical gratings 7 and 13 (an example of the optical grating for the main signal). A displacement amount is calculated from the number of pulses. The main signal φa is a phase (0 degree) signal. The main signal φb is a b-phase (90 degrees) signal that is 90 degrees out of phase with the a phase, the main signal φaa is an aa phase (180 degrees) signal that is 180 degrees out of phase with the a phase, The main signal φbb is a bb phase (270 degrees) signal that is 270 degrees out of phase with respect to the a phase.

  The reason why the a-phase and b-phase signals are used is to determine whether the moving direction of the sensor head 5 is the forward direction or the return direction, depending on which of them is advanced by 90 ° with respect to the other party. In addition, the aa phase and the bb phase obtained by inverting these in addition to the a phase and the b phase are used to remove the DC component contained in the signals of the a phase and the b phase, as well as signal reliability and high-speed tracking. This is to ensure sex.

  The reference signal is a signal for specifying the reference position in the incremental measurement, and is generated by using the optical gratings 9 and 15 (an example of the reference signal optical grating). Among the reference signals, the reference signal φr is a signal generated asynchronously with the main signal based on the optical gratings 9 and 15 by the relative movement of the index scale 11 with respect to the main scale 3.

  FIG. 2 is a waveform diagram of the main signal and the reference signal. The main signal φA1 is a sinusoidal signal obtained by synthesizing the main signal φa and the main signal φaa. The main signal φB1 is a sinusoidal signal obtained by synthesizing the main signal φb and the main signal φbb, and is 90 degrees out of phase with the main signal φA1.

  The reference signal φR1 (an example of the first reference signal) is a signal obtained by binarizing the reference signal φr. Similarly to the signal φr, the signal φR1 is a signal generated asynchronously with the main signal based on the optical gratings 9 and 15 by the relative movement of the index scale 11 with respect to the main scale 3.

  Reference signal φR2 (an example of a second reference signal) is a signal generated so as to be synchronized with main signals φA1 and φB1 while reference signal φR1 is active. Specifically, the signal φR2 becomes active (rising) when one of the main signals φA1 and φB1 first reaches the maximum value after the signal φR1 becomes active (after rising), and then becomes the maximum value. Becomes inactive (falls) when

  The reference signals φr, φR1, and φR2 are signals obtained when the optical grating 15 of the index scale 11 passes over the optical grating 9 of the main scale 3 in FIG. The reference signal is mainly used as a trigger for taking a reference position in incremental measurement at the time of power-on or at an arbitrary time in an incremental displacement measuring apparatus. That is, the reference signal is used as a trigger when setting a reference value (for example, zero in the case of zero set) indicating the reference position in the counter circuit that counts the number of pulses generated based on the main signal.

  Next, the block of the circuit unit provided in the displacement measuring apparatus 1 will be described. FIG. 3 is a block diagram showing this. The main signal φa and the main signal φaa are input to the combining circuit 25, combined, and output as the main signal φA1. Similarly, main signal φb and main signal φbb are output as main signal φB1.

  The main signals φA1 and φB1 composed of these two-phase sine waves are amplified by the amplifier circuit 27 and then input to the interpolation circuit 29. Here, a predetermined number of periods of the main signals φA1 and φB1 are divided to generate two-phase pulses φA2 and φB2 (an example of an incremental measurement counting pulse). For example, if the grating pitch of the optical gratings 7 and 13 of the scales 3 and 11 in FIG. 1 is 20 μm, the interpolation circuit 29 divides this into 100, so that a pulse φA2, having a resolution of 0.05 μm at a 0.2 μm pitch. φB2 is generated. The pulses φA2 and φB2 are input to the counter circuit 31, where the number of pulses is counted.

  On the other hand, the reference signal φr is input to the generation circuit 33 (an example of the first reference signal generation circuit) of the reference signal φR1. The circuit 33 includes a comparator circuit, whereby the reference signal φr is binarized and output as the reference signal φR1. This signal φR1 is input to the generation circuit 35 of the reference signal φR2 (an example of a second reference signal generation circuit). The circuit 35 includes a synchronization processing circuit. As shown in FIG. 2, the reference signal φR2 (second reference signal) is synchronized with the main signals φA1 and φB1 while the reference signal φR1 (an example of the first reference signal) is active. Example) is generated.

  Incidentally, as shown in FIG. 2, since the reference signal φR1 is a pulse, the width inevitably occurs in the active state. Accordingly, the reference signal φR2 (an example of the second reference signal) generated based on the reference signal φR1 is different in an active position in the forward direction and the return direction. Since the rising edge of the reference signal is used for the trigger of the reference value set of the counter circuit 31 (FIG. 3), when the trigger is the reference signal φR2, the distance between the rising edge in the forward direction and the rising edge in the return direction The reference position is shifted by D. Therefore, there is a difference in the measured value between when measured from the forward direction and when measured from the return direction.

  As a comparison with the first embodiment, a case where the counter circuit 31 is set to zero using the reference signal φR2 as a trigger in both the forward direction and the return direction will be described with reference to FIGS. FIG. 4 is a diagram showing the relationship between the position on the measurement axis X and the rise of the reference signal φR2 in this comparative embodiment. The distance between the zero-set position in the forward direction and the zero-set position in the return direction corresponds to 12 counts of the counter circuit 31. Thus, since the rising position of the reference signal φR2 is different between the forward direction and the return direction, the position of the zero set is different. Therefore, there is a restriction that the zero set operation must be unified in one direction.

  On the other hand, in the first embodiment, the reference signal φR2 (an example of the second reference signal) is used for the trigger in the forward direction, and the reference signal φR3 (an example of the third reference signal) is used for the trigger in the return direction. The direction and the return direction are set so that the positions on the measurement axis X when zero setting is the same. That is, the process of correcting the position of the zero set in the return direction is performed.

  FIG. 5 is a diagram showing the relationship between the position on the measurement axis X and the rise of the reference signals φR2 and φR3 in the first embodiment, and corresponds to FIG. In the forward direction, as in the comparative example, the reference signal φR2 is used as a trigger to set to zero (S1). On the other hand, in the return direction, the reference signal φR3, which becomes active later than the reference signal φR2 becomes active, is set to zero as a trigger (S2).

  The delay of the reference signal φR3 corresponds to 11 counts of the counter circuit 31. As shown in FIG. 4, the count number (12 counts) between the zero-set position in the forward direction and the zero-set position in the return direction when the reference signal φR2 is used as a trigger is obtained in advance. It is determined based on this count number. Thereby, the position of the zero set (S2) in the return direction can be aligned with the position of the zero set (S1) in the forward direction. The 11-count measurement is started by using the active reference signal φR2 as a trigger, and the reference signal φR3 is activated by the 11-count measurement. Therefore, the reference signal φR3 is synchronized with the reference signal φR2.

  The delay (11 counts) of the reference signal φR3 is counted by the UP / DOWN counter. The UP / DOWN counter outputs an active reference signal φR3 when the reference signal φR2 is triggered and the number corresponding to the delay of the reference signal φR3 is counted. The 11-count setting corresponding to the delay of the reference signal φR3 is performed by the manufacturer before shipment of the displacement measuring device. This 11 count may be set by a DIP switch or may be stored in the memory of the microcomputer. The active period of the reference signal φR3 can be arbitrarily set by an UP / DOWN counter or the like.

  The UP / DOWN counter 37 that counts the delay of the reference signal φR3 is included in the reference signal φR3 generation circuit 39 (an example of a third reference signal generation circuit) shown in FIG. Main signals φA2 and φB2 are added to the counter 37, and UP / DOWN counting is performed. A reference signal φR3 is output from the output terminal. The counter 37 starts counting with the reference signal φR2 as a trigger, and activates the reference signal φR3 when counting “+11”.

  By using the UP / DOWN counter 37, even if the sensor head 5 in FIG. Will be counted. Thereby, it is possible to prevent the return direction zero set (S2) from being performed before the position of the forward direction zero set (S1). That is, the influence of vibration or the like can be eliminated.

  The generation circuit 39 of the reference signal φR3 includes a count direction discrimination circuit 41. The discrimination circuit 41 can be composed of a logic circuit such as a D flip-flop as shown in FIG. In the example of FIG. 6, the main signal φA2 is applied to the D input terminal, and the main signal φB2 is applied to the clock CK input terminal.

  As shown in FIG. 6, when the phase of the main signal φA2 is advanced by 90 degrees from the phase of the main signal φB2, a signal at H level is output from the output terminal Q. This is a φA binary phase, and normally indicates that the sensor head 5 in FIG. 1 is moving in the forward direction (the counter circuit 31 is UP-counted). Conversely, when the phase of the main signal φB2 is advanced by 90 degrees from the phase of the main signal φA2, an L level signal is output from the output terminal Q (φB2 phase advance). The φB binary phase usually indicates that the sensor head 5 is moving in the return direction (the counter circuit 31 is DOWN count).

  The switch circuit 43 is controlled by the output signal of the discrimination circuit 41. The switch circuit 43 includes an input terminal 45 to which a reference signal φR2 is applied, an input terminal 47 to which a reference signal φR3 is applied, and an output terminal 49 connected to a clear CLR terminal (a preset terminal in the case of preset).

  When the sensor head 5 of FIG. 1 is moving in the forward direction, the input terminal 45 is connected to the output terminal 49 by the output signal of the discrimination circuit 41. As a result, the reference signal φR2 is input to the clear CLR terminal of the counter circuit 31. Conversely, when the sensor head 5 is moving in the return direction, the input terminal 47 is connected to the output terminal 49 by the output signal of the discrimination circuit 41. Therefore, the reference signal φR3 is input to the clear CLR terminal of the counter circuit 31.

  The measured value is calculated based on the pulses counted by the counter circuit 31 set to zero by using the reference signal φR2 as a trigger for the forward direction and the reference signal φR3 for the return direction. This result is displayed on the LCD 51. Although the case of zero set as the reference position has been described, in the case of preset, an arbitrary numerical value is set in the counter circuit in place of zero in zero sets S1 and S2 of FIG.

  As described above, in the first embodiment, the zero-set trigger of the counter circuit 31 is not the reference signal φR2 in both the forward direction and the return direction, but the forward direction is the reference signal φR2 and the return direction is the reference signal φR3. ing. Since the reference signal φR3 becomes active later than the reference signal φR2 becomes active, the zero set position can be aligned in the forward direction and the return direction. Therefore, it is not necessary to limit the reference positioning operation from one direction, and the convenience of measurement can be improved.

  As shown in FIG. 5, the reference signal φR3 becomes active based on the active reference signal φR2, and therefore, when performing the standard positioning operation from the return direction, the reference signal φR2 is further before the position where the reference signal φR2 becomes active. The reference positioning operation must be started from (return direction).

Also, the zero-set trigger may be the reference signal φR3 for the forward direction and the reference signal φR2 for the return direction. Further, the zero-set trigger can be set to the reference signal φR3 in both the forward direction and the return direction. This will be described with reference to FIG. FIG. 7 is a modification of the first embodiment, and is a diagram showing the relationship between the position on the measurement axis X and the rise of the reference signals φR2 and φR3, and corresponds to FIG. In the forward direction, the reference signal φR3 becomes active when the UP / DOWN counter counts five, and when the return direction counts six, the reference signal φR3 becomes active. Also according to this modification, the zero set position can be aligned in the forward direction and the return direction.
[Second Embodiment]
In the second embodiment, the trigger for zero setting is the reference signal φR2 in both the forward direction and the return direction. A value (initial value) set in the counter circuit with the reference signal φR2 as a trigger is a value obtained by setting the forward direction to zero and the return direction to return from zero. The value set in the counter circuit of the first embodiment is zero, but a value other than zero is also set in the counter circuit of the second embodiment. Therefore, in the second embodiment, the expression “initial value” is used as the value set in the counter circuit. Hereinafter, the second embodiment will be described focusing on differences from the first embodiment.

  FIG. 8 is a diagram showing the relationship between the position on the measurement axis X and the rise of the reference signal φR2 in the second embodiment, and corresponds to FIG. The number of counts (12 counts) between the generation of the trigger in the forward direction and the generation of the trigger in the return direction is obtained in advance. When the displacement measuring device is set to zero, the counter direction is set so that zero is set as the initial value for the forward direction, while the return direction is not zero in the counter circuit, but a value that is set back from zero. Is set to be set as an initial value (subtract the number corresponding to the distance between the trigger occurrence in the forward direction and the trigger occurrence in the return direction). Thereby, the position of the zero set when measuring the displacement from the return direction can be corrected and aligned with the position of the zero set in the forward direction. Further, in the zero set from the return direction, it is possible to align with the zero set position in the forward direction without reaching the zero set position in the forward direction (that is, the stage where “+11” is set as the initial value) The zero set is completed and the measurement can be started.) Therefore, it is not necessary to limit the reference positioning operation from one direction, and the convenience of measurement is improved.

  The backward value is a value larger than zero (reference value) because the counter circuit counts down in the return direction. On the other hand, in the forward direction, the counter circuit counts up, so the value is smaller than zero (reference value).

  FIG. 9 is a block diagram of a circuit unit provided in the displacement measuring apparatus according to the second embodiment, and corresponds to FIG. Differences from the block diagram of FIG. 3 will be mainly described. An output signal from the count direction discrimination circuit 41 is input to the initial value selection circuit 53. When the output signal from the circuit 41 indicates the forward direction, a reference value (zero in the case of FIG. 8) is selected, and when the return signal indicates the return direction, a return value that is a value reversed from the reference value (in the case of FIG. 8). “+11”).

  When the rising edge of the reference signal φR2 is input to the LOAD terminal of the counter circuit 31, zero is set in the counter circuit 31 when the reference position is taken from the forward direction, and “+11” is set in the return direction. Is started. Therefore, the second embodiment can also make the zero set position the same in the forward direction and the return direction.

  In both the forward direction and the return direction, a value returned from zero (reference value) can be set as the initial value. This will be described as a modification. FIG. 10 is a diagram illustrating the relationship between the position on the measurement axis X and the rise of the reference signal φR2 in the modification of the second embodiment.

When measuring from the forward direction, “−5” is set in the counter circuit 31 with the reference signal φR2 as a trigger. In this case, since the counter circuit 31 counts up, a value smaller than zero (reference value) becomes a backward value. On the other hand, when measuring from the return direction, “+6” is set. As described above, the position of the zero set in the forward direction can be made the same as that in the return direction.
[Aspects to which the present invention is applicable]
The counter circuit 31 may be separated from the assembly composed of the main scale and the sensor head (separated type), or may be incorporated in the assembly (integrated type). FIG. 11 is a diagram showing a separation-type displacement measuring apparatus and corresponds to FIG. The displacement measuring device 1 includes an assembly 55 assembled with the main scale 3 and the sensor head 5 as parts, and a count / display device 59 (an example of a counting device) that can be connected to the assembly 55 by a cable 57. The device 59 may incorporate the counter circuit 31 and the LCD 51 shown in FIG. 3 (first embodiment), or the counter circuit 31 and the count direction discrimination circuit shown in FIG. 9 (second embodiment). 41, the initial value selection circuit 53 and the LCD 51 may be incorporated.

  On the other hand, FIG. 12 is a view showing an integrated displacement measuring device, which corresponds to FIG. The counter head 31 and the LCD 51 shown in FIGS. 3 and 9 are incorporated in the sensor head 5.

  Further, as shown in FIG. 1, the case where the sensor head 5 including the index scale 11 moves on the main scale 3 has been described. Conversely, the main scale 3 may move on the sensor head 5. Therefore, in the present invention, it can be said that the index scale can be moved relative to the main scale.

  Further, the light L from the light source 17 has been described as a type (transmission type) that is transmitted through the main scale 3 and irradiated onto the index scale 11. However, the present invention can also be applied to a type (reflective type) in which light from a light source is reflected on a main scale and irradiated on an index scale.

1 is a perspective view showing a schematic configuration of an optical incremental displacement measuring device according to a first embodiment. It is a wave form diagram of the main signal and reference signal which concern on 1st Embodiment. It is a block diagram of the circuit part with which the displacement measuring device concerning a 1st embodiment is equipped. In a comparison form, it is a figure which shows the relationship between the position on the measurement axis | shaft X, and rising of reference signal (phi) R2. In 1st Embodiment, it is a figure which shows the relationship between the position on the measurement axis | shaft X, and starting of reference signal (phi) R2, (phi) R3. It is a figure which shows D flip-flop contained in the production | generation circuit of the reference signal (phi) R3 which concerns on 1st Embodiment. In the modification of 1st Embodiment, it is a figure which shows the relationship between the position on the measurement axis | shaft X, and starting of reference signal (phi) R2, (phi) R3. In 2nd Embodiment, it is a figure which shows the relationship between the position on the measurement axis | shaft X, and rising of reference signal (phi) R2. It is a block diagram of the circuit part with which the displacement measuring device concerning a 2nd embodiment is equipped. In the modification of 2nd Embodiment, it is a figure which shows the relationship between the position on the measurement axis | shaft X, and starting of reference signal (phi) R2. It is a perspective view which shows schematic structure of the counter circuit separated type displacement measuring apparatus which concerns on 1st and 2nd embodiment. It is a perspective view which shows schematic structure of the displacement measuring device of the counter circuit integrated type.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Incremental type displacement measuring apparatus, 3 ... Main scale, 5 ... Sensor head, 7 ... Optical grating (an example of the optical grating for main signals), 9 ... Optical grating (for reference signals) Example of optical grating), 11... Index scale, 13, 13a, 13b, 13aa, 13bb... Optical grating (an example of optical grating for main signal), 15. Example), 17 ... light source, 19 ... light receiving unit, 21a, 21b, 21aa, 21bb, 23 ... photodiode, 25 ... compositing circuit, 27 ... amplifier circuit, 29 ... inside Insertion circuit, 31... Counter circuit, 33... Reference signal φR1 generation circuit (an example of a first reference signal generation circuit), 35... Reference signal φR2 generation circuit (an example of a second reference signal generation circuit), 37 ... UP / D OWN counter, 39... Reference signal φR3 generation circuit (an example of a third reference signal generation circuit), 41... Count direction discrimination circuit, 43... Switch circuit, 45 and 47. ..Output terminal, 51... LCD, 53... Initial value selection circuit, 55... Assembly, 57 .. Cable, 59. ..Light, φa, φb, φaa, φbb ... main signal (before synthesis processing), φr ... reference signal (before binarization processing), φA1, φB1 ... main signal (after synthesis processing), φR1... reference signal (an example of a first reference signal), φR2... a reference signal (an example of a second reference signal), φA2, φB2... pulse (an example of a pulse for incremental measurement counting), D ... Rising edge of reference signal φR2 in the forward direction Distance from the rising edge in the vertical direction, φR3... Reference signal (an example of a third reference signal), S1... Zero set triggered by reference signal φR2, S2... Zero triggered by reference signal φR3 set

Claims (7)

The main scale,
An index scale that is movable relative to the main scale along the measurement axis in one direction and the other direction opposite thereto, and disposed opposite the main scale;
An optical grating for a main signal provided on the main scale and the index scale and for generating a main signal that is a basis of a pulse for counting an incremental measurement;
A reference signal optical grating provided on the main scale and the index scale and for generating a reference signal for specifying a reference position in the incremental measurement;
A first reference signal generation circuit that generates a first reference signal that is an asynchronous reference signal to the main signal based on the reference signal optical grating by relative movement of the index scale with respect to the main scale;
A second reference signal generation circuit configured to generate a second reference signal, which is a reference signal having different active positions in the one direction and the other direction, in synchronization with the main signal while the first reference signal is active; ,
A third reference signal generation circuit that generates a third reference signal that is a reference signal that becomes active later than the second reference signal becomes active while being synchronized with the second reference signal;
When the number of pulses for counting the incremental measurement generated based on the main signal is counted and the trigger of the reference value set indicating the reference position of the incremental measurement measures the displacement from the one direction, the second is used. Or a counter circuit that is a third reference signal and that is a third reference signal when displacement is measured from the other direction. An incremental displacement measuring apparatus. When measuring displacement from the one direction, the second reference signal triggers the set of reference values,
When the second reference signal is used as a trigger, a count number between the position of the reference value set in the one direction and the position of the reference value set in the other direction is obtained in advance, and this count number is used as a basis. To set the delay of the third reference signal,
The incremental displacement measuring apparatus according to claim 1. An UP / DOWN counter that outputs an active third reference signal when the second reference signal is triggered and the number corresponding to the delay of the third reference signal is counted;
The incremental displacement measuring device according to claim 2. The main scale,
An index scale that is movable relative to the main scale along the measurement axis in one direction and the other direction opposite thereto, and disposed opposite the main scale;
An optical grating for a main signal provided on the main scale and the index scale and for generating a main signal that is a basis of a pulse for counting an incremental measurement;
A reference signal optical grating provided on the main scale and the index scale and for generating a reference signal for specifying a reference position in the incremental measurement;
A first reference signal generation circuit that generates a first reference signal that is an asynchronous reference signal to the main signal based on the reference signal optical grating by relative movement of the index scale with respect to the main scale;
A second reference signal generation circuit configured to generate a second reference signal, which is a reference signal having different active positions in the one direction and the other direction, in synchronization with the main signal while the first reference signal is active; ,
A counter circuit that counts the number of pulses for counting the incremental measurement generated based on a main signal and that is set with an initial value triggered by a second reference signal;
The initial value in the case of measuring displacement from the one direction is a reference value indicating a reference position of the incremental measurement or a value backward from the reference value,
When the displacement is measured from the other direction, the initial value is a value that is reversed from the reference value.
Incremental displacement measuring apparatus characterized by the above. The initial value when measuring displacement from the one direction is the reference value;
The backward value, which is the initial value when measuring the displacement from the other direction, is based on a count number obtained in advance between the trigger occurrence in the one direction and the trigger occurrence in the other direction. Set as
The incremental displacement measuring device according to claim 4. An assembly assembled with the main scale and the index scale as parts;
The incremental displacement measuring device according to any one of claims 1 to 5, further comprising a counting device in which the counter circuit is incorporated and connected to the assembly by a cable. The counter circuit is incorporated in an assembly in which the main scale and the index scale are assembled as parts.
An incremental displacement measuring apparatus according to any one of claims 1 to 5, wherein

Images