JP5903690B2 - Digital scale display controller - Google Patents

Description

  The present invention relates to a digital scale display control apparatus suitably used for measuring, for example, the amount of displacement of a moving table in machine tools, the thickness of various industrial materials and parts, surface roughness, and the like.

  In general, it is known to use an optical digital scale to measure the dimensions and surface roughness of industrial parts and to measure the displacement amount of a moving table in a machine tool. This type of conventional optical digital scale includes a measuring unit that moves (displaces) in the axial direction according to the shape or displacement of a measurement object, and a signal generation device that includes a light emitting element and a light receiving element. The signal generator generates two detection signals whose phases are shifted by ¼ pitch according to the displacement of the measurement unit. Since these detection signals change according to the amount of displacement of the measurement unit, they can be taken out as measurement values of the measurement object, and are digitally displayed on a display (for example, see Patent Document 1). ).

  Also, for example, as a relative displacement detection device such as a linear encoder or a rotary encoder, a pseudo sine wave signal from a detector having a predetermined phase difference is input, and pulses having a period shorter than the period of the pseudo sine wave are counted. A method using a resistance division method for calculating the amount of movement displacement is known (see, for example, Patent Document 2).

JP-A-5-248850 JP 2003-214836 A

  By the way, in the prior art according to Patent Document 1, when it is attempted to increase the measurement accuracy of the measurement object, it takes time for the calculation processing for performing display control of the measurement value, the operation speed is slowed down, and the response of the apparatus is improved. There is a problem that it is difficult to plan.

  In the prior art disclosed in Patent Document 2, if the number of divisions of the input waveform is increased in order to improve detection accuracy, the hardware scale of the frequency doubler circuit increases. For example, assuming that the same optical digital scale is used, when the number of waveform divisions is quadrupled, the number of comparators greatly increases from 10 circuits to 40 circuits. In addition, since the number of pulses with respect to the amount of displacement increases by increasing the number of waveform divisions, there is a problem that the upper limit of the change speed that can be normally measured is reduced due to the circuit delay of the frequency doubler circuit.

  Furthermore, since the hysteresis comparator of the comparison means used in the frequency doubler circuit needs to compare voltage differences of several tens to several hundreds mV, it requires highly accurate parts and causes an increase in cost. In addition, because the pseudo-sine waves with different phases are generated by the resistance division method, multiple hysteresis comparators of the comparator may be turned ON / OFF at the same time due to noise in the input waveform, and errors are likely to occur in the input signal. Thus, there is a problem that measurement errors are likely to occur.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to improve the display accuracy in displaying the measurement value of the measurement object, and to improve the operation speed and responsiveness of the apparatus. It is an object of the present invention to provide a digital scale display control device which can be speeded up.

  In order to solve the above-described problem, the present invention measures an object to be measured using an optical digital scale having a displaceable measuring unit, and uses the displacement amount of the measuring unit as a measured value of the measuring object. The present invention is applied to a digital scale display control device for digital display by a display.

A feature of the configuration adopted by the invention of claim 1 is that a signal generator for generating two detection signals whose phases are shifted by 1/4 pitch according to the displacement of the measurement unit, and each detection signal from the signal generator A counter that outputs a measurement value of the measurement object as a counter count value by performing a count-up operation and a count-down operation based on a change in each signal waveform, and operates in parallel with the counter, An A / D converter that A / D converts the signal waveform into a digital waveform, and waveform shaping that performs waveform shaping so that the center voltage and amplitude of the two A / D converted digital signals (VAD, VBD) match. a Department, first based on the phase information and the phase information of the waveform-shaped the two digital signals (VAD, VBD) from the signal of eight sections within one period of the waveform (# 1 to # 8) Displacement correction value and (X2) and phase-correction value calculation unit that calculates a waveform-shaped the absolute value signal values of the two digital signals (VAD, VBD) (| VAD |, | VBD |) compared with Then, the ratio of both signal values is calculated, and when the absolute value (| VAD |, | VBD |) is (| VAD | ≧ | VBD |), the phase information and the absolute value (| VAD |, | VBD The second displacement correction value (X3) finer than the first displacement correction value (X2 ) is calculated based on the ratio of |) (| VAD | / | VBD |), and the absolute value (| VAD When |||| VBD |) is (| VAD | <| VBD |), it is based on the phase information and the ratio (| VBD | / | VAD |) of the absolute values (| VAD |, | VBD |). a displacement correction value calculating unit that calculates the first displacement correction value second displacement correction value finer than (X2) (X3), when the unit by the counter A measurement value display processing unit that calculates an input frequency of each detection signal from a counter count value per hit, and performs display processing of the measurement value in the display unit based on a frequency range of the input frequency, the measurement value display The processing unit determines whether the first displacement correction value (X2) , the second displacement with respect to the displacement amount (X1) based on the count value of the counter, depending on whether the input frequency exceeds a predetermined determination frequency. The displacement correction value (X3) is selectively added, and the display processing of the measured value in the display device is performed according to the total value.

The feature of the configuration adopted by the invention of claim 2 is that a signal generator for generating two detection signals whose phases are shifted by ¼ pitch according to the displacement of the measurement unit, and for each detection signal from the signal generator A counter that outputs a measurement value of the measurement object as a counter count value by performing a count-up operation and a count-down operation based on a change in each signal waveform, and operates in parallel with the counter, An A / D converter for A / D converting the waveform into a digital waveform, and a waveform shaping unit for shaping the waveform so that the center voltages and amplitudes of the two A / D converted digital signals (VAD, VBD) match. Then, phase information within one cycle of the signal waveform and a first displacement correction value (X2) based on the phase information are calculated from the two digital signals (VAD, VBD) that have undergone waveform shaping. A phase / correction value calculation unit and a signal value of the two digital signals (VAD, VBD) having been subjected to waveform shaping are compared, and a second displacement correction value that is finer than the first displacement correction value (X2). A displacement correction value calculation unit for calculating (X3), and an input frequency of each detection signal is calculated from a counter count value per unit time by the counter, and a measured value in the display unit based on a frequency range of the input frequency A measurement value display processing unit that performs the display processing of the second step, and when the input frequency is equal to or higher than zero and equal to or lower than a predetermined determination frequency, the displacement correction value calculation unit performs the second correction correction value calculation unit. By calculating the displacement correction value (X3), the display unit according to the total value (X1 + X3) obtained by adding the second displacement correction value (X3) to the displacement amount (X1) based on the count value of the counter When the measured value display process is performed and the input frequency exceeds the determination frequency, the displacement correction value calculation unit does not calculate the second displacement correction value (X3), and the count value of the counter The display unit displays the measured value according to the total value (X1 + X2) obtained by adding the first displacement correction value (X2) to the displacement amount (X1) based on the above .

According to a third aspect of the present invention, the phase / correction value calculation unit compares the phase information and the first displacement by comparing the signal values of the two digital signals (VAD, VBD) that have undergone waveform shaping. The correction value (X2) is calculated.

According to a fourth aspect of the present invention, the measured value display processing unit is configured to detect the displacement (X1) based on the count value of the counter and the second value when the input frequency is equal to or higher than zero and equal to or lower than the determination frequency. In accordance with the total value (X1 + X3) of the displacement correction value, the measured value is displayed on the display, and when the input frequency exceeds the determination frequency, the displacement amount (X1) based on the count value of the counter And the first displacement correction value (X2) are displayed according to the total value (X1 + X2) of the measured value on the display unit.

  According to invention of Claim 5, the said measured value display process part is a structure which switches the display of the measured value in the said display to the display whose lower digit is not a numerical value, when the said input frequency exceeds the said determination frequency. It is said.

  According to a sixth aspect of the present invention, the measurement value display processing unit switches the display of the measurement value on the display so that the lowest digit is not displayed when the input frequency exceeds the determination frequency. It is configured.

  According to the present invention, the first displacement correction value and the second displacement correction value are values in a range of 0 or more and not more than a predetermined pitch with respect to the phase pitch of the optical digital scale.

  According to the present invention, the first displacement correction value and the second displacement correction value are values in a range of 0 or more and ¼ pitch or less with respect to the phase pitch of the optical digital scale.

The invention of claim 1 takes out the measurement value of the measurement object as a counter count value by measuring the measurement object using an optical digital scale. On this, the phase / correction value calculation unit includes: From two digital signals (VAD, VBD) , phase information of eight sections ( # 1 to # 8) within one cycle of a signal waveform and a first displacement correction value (X2) based on the phase information are calculated. can do. The displacement correction value calculation unit compares the signal values of the two digital signals (VAD, VBD) with absolute values (| VAD |, | VBD |) to calculate the ratio of both signal values, and calculates the phase information and the Finer than the first displacement correction value (X2) based on the ratio (| VAD | / | VBD |) or the ratio (| VBD | / | VAD |) of absolute values (| VAD |, | VBD |) The second displacement correction value (X3) , which is a simple value (for example, a numerical value including the lowest digit that is below the decimal point with respect to the μm order), can be calculated. Then, the measurement value display processing unit determines whether the first displacement correction value (X2) , the displacement amount (X1) based on the count value of the counter depends on whether the input frequency by the counter exceeds the determination frequency or not. The second displacement correction value (X3) can be selectively added, and display processing of the measurement value on the display device can be performed according to the total value. The second displacement correction value (X3) is, for example, a correction value including the lowest digit that is less than the decimal point with respect to the μm (micron) order, and the displacement based on the count value of the counter by the measurement value display processing unit. An addition process is performed on the amount (X1), and the measurement value of the measurement object can be corrected.

The invention of claim 2 takes out the measurement value of the measurement object as a counter count value by measuring the measurement object using an optical digital scale. On this, the phase / correction value calculation unit includes: From the two digital signals (VAD, VBD), the phase information within one cycle of the signal waveform and the first displacement correction value (X2) based on the phase information can be calculated. The displacement correction value calculation unit compares the signal values of the two digital signals (VAD, VBD), and has a value finer than the first displacement correction value (X2) (for example, less than the decimal point with respect to the μm order). A second displacement correction value (X3) that is a numerical value including the lowest digit) can be calculated. Then, the measured value display processing unit is the sum of the displacement amount (X1) based on the count value of the counter and the second displacement correction value (X3) when the input frequency by the counter is not less than zero and not more than the determination frequency. According to (X1 + X3), display processing of the measured value on the display can be performed, and when the input frequency exceeds the determination frequency, the displacement amount (X1) based on the count value of the counter and the first displacement correction value According to the total value (X1 + X2) with (X2), the display process of the measured value in the said indicator can be performed .

According to the third aspect of the present invention, the phase / correction value calculating section compares the signal values of the two digital signals (VAD, VBD) with the phase information in one cycle of the signal waveform and the phase information . based first displacement correction value (X2) and can be calculated. First displacement correction value (X2) is, for example, [mu] m (microns) the lowest digit as a decimal as that does not contain the correction value for the order, based on the count of the counter by the measurement value display unit the displacement An addition process is performed on the amount (X1) , and the measurement value of the measurement object can be corrected.

According to the invention of claim 4, the measured value display processing unit has the displacement amount (X1) and the second displacement correction value (X3) based on the count value of the counter when the input frequency is not less than zero and not more than the determination frequency. The measured value can be displayed on the display device in accordance with the total value (X1 + X3) and when the input frequency exceeds the determination frequency, the displacement (X1) based on the count value of the counter and the first In accordance with the total value (X1 + X2) with the displacement correction value (X2) , the measurement value display process on the display can be performed.

According to the invention of claim 5, the measured value display processing unit adds the displacement amount (X1) based on the count value of the counter and the first displacement correction value (X2) when the input frequency exceeds the determination frequency. By displaying the measured value according to the value (X1 + X2) , the display of the measured value on the display unit is switched to the non-numeric display instead of the display of the last decimal place for the μm (micron) order, for example. It is possible to inform the user of the digital scale that the measured value after the decimal point is indeterminate.

  According to the sixth aspect of the present invention, it is possible to actively notify that the measured value after the decimal point is indeterminate, for example, by switching so that the lowermost digit below the decimal point is not displayed.

In the present invention, the first displacement correction value (X2) and the second displacement correction value (X3) are not more than a predetermined pitch with respect to the phase pitch of the optical digital scale, and a value in the range of 0 or more. It can be. Furthermore, in the present invention, the first displacement correction value (X2) and the second displacement correction value (X3) can be set to values in the range of 0 or more and ¼ pitch or less.

1 is an overall configuration diagram showing a digital scale display control apparatus according to an embodiment of the present invention; It is a perspective view which shows typically the signal generator built in the digital scale of FIG. It is a characteristic diagram which shows two detection signals output from a signal generator. It is a control block diagram which shows the internal structure of a display control apparatus. Characteristics of the digital signals VAD and VBD based on the two detection signals, the characteristics of the binary signals LA and LB, the first relative displacement amount X1, the phase information sections # 1 to # 8, and the second and third relative displacement amounts X2, It is a characteristic diagram which shows X3. It is a flowchart which shows the display control processing by the display control apparatus of a digital scale. 7 is a flowchart showing a calculation process of a section (phase information) and a relative displacement amount X2 in FIG. It is a flowchart which shows the frequency determination process in FIG. It is a table figure which shows the relationship between the determination conditions of an area (phase information), and the 2nd relative displacement amount X2. It is a figure which shows the calculation table which calculates 3rd relative displacement amount X3.

  A digital scale display control apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 10 of the accompanying drawings.

  In the figure, reference numeral 1 denotes an optical digital scale employed in the present embodiment. The digital scale 1 includes a scale main body 2 constituting an outer shell thereof and an axial direction from the scale main body 2 (for example, downward in FIG. 1). ) And a spindle 4 as a measuring unit provided so as to protrude downward in the axial direction from the stem 3. The spindle 4 is attached to the stem 3 so as to be displaceable in the axial direction, and is displaced in the direction of arrow A in FIG. 1 according to the shape of the measurement object 100. The measurement object 100 is moved, for example, in the direction indicated by the arrow B in FIG.

  A signal generator 5 schematically shown in FIG. 2 is provided in the scale body 2 of the digital scale 1. The signal generator 5 is fixedly provided in the scale main body 2 and is movable so as to be displaceable in the scale main body 2 so as to be movable relative to the fixed slit 6. The slit 7 includes a pair of light emitting elements 8A and 8B and a pair of light receiving elements 9A and 9B. Here, the pair of light emitting elements 8A and 8B and the pair of light receiving elements 9A and 9B are arranged at positions facing each other with the fixed slit 6 and the movable slit 7 in between. The light emitted from one light emitting element 8A is received by one light receiving element 9A, and the light from the other light emitting element 8B is received by the other light receiving element 9B.

  When the spindle 4 shown in FIG. 1 is displaced in the direction of arrow A, the movable slit 7 of the signal generating device 5 follows this and is displaced in the same direction (for example, the direction of arrow A). For this reason, each slit position of the movable slit 7 differs from each slit position of the fixed slit 6 by the displacement of the spindle 4, and the amount of light received by the light receiving elements 9 A and 9 B corresponds to the amount of displacement of the spindle 4. Change. Thereby, the signal generator 5 can extract the signal received by the light receiving element 9A as, for example, a sine wave detection signal VA shown in FIG. 3, and the signal received by the light receiving element 9B can be extracted, for example, as a sine signal shown in FIG. It can be taken out as a wave detection signal VB.

  In other words, the signal generator 5 converts the density of the moire fringes generated by the overlapping of the fixed slit 6 made of a glass plate and the movable slit 7 into a voltage value by the light receiving elements 9A and 9B made of photocells or the like. The sinusoidal detection signals VA and VB shown in FIG. 3 can be output. In this case, when the spindle 4 is displaced in the axial direction according to the shape of the measurement object 100, the moire fringe repeats light and dark with the grating pitch of the movable slit 7 as one period, and the detection signals VA and VB are expressed by the following equation 1, As shown in Formula 2, the phase is adjusted as a sine wave signal whose phase is shifted by ¼ pitch according to the displacement of the measurement unit (ie, spindle 4).

  Here, the detection signals VA and VB in the equations (1) and (2) correspond to the amplitudes Ka and Kb corresponding to the change in shading of the moire fringes and the displacement of the movable part of the optical digital scale 1 (that is, the spindle 4). It is obtained including the relative displacement amount Xs, the length L of the grating pitch, and the offset voltages Vo1 and Vo2. The detection signals VA and VB are sine wave signals whose phases are shifted from each other by a quarter pitch (ie, π / 2). The vertical axis in FIG. 3 is the voltage V, and the horizontal axis is the relative displacement amount Xs.

  In the present embodiment, the length L of the grating pitch is set to 8 μm, and the detection signals VA and VB are sine waves with a period in which one pitch is 8 μm, as shown by the characteristic lines 10A and 10B in FIG. The waveform is repeated. In the characteristic lines 10A and 10B shown in FIG. 3, the line segments forming a vertical stripe pattern in the sine wave indicate the signal values (voltage V) of the detection signals VA and VB with respect to an arbitrary relative displacement amount Xs. The value is taken as a voltage value.

  Reference numeral 11 denotes a display that digitally displays the measurement value of the measurement object 100. The display 11 is configured using, for example, a liquid crystal screen. When the measurement object 100 is measured using the optical digital scale 1, the display 11 has a relative displacement amount Xs corresponding to the displacement amount of the spindle 4 (specifically, the following Equation 11, The relative displacement amount Xr) according to Equation 12 is digitally displayed as a measurement value of the measurement object 100.

  Reference numeral 12 denotes a display control apparatus employed in the present embodiment. The display control apparatus 12 has two low-pass filters 13A for filtering the detection signals VA and VB from the optical digital scale 1, as shown in FIG. , 13B (hereinafter referred to as LPFs 13A, 13B) and the detection signals VA, VB passing through the LPFs 13A, 13B, and binary signals LA, LB as counter inputs (see characteristic lines 28A, 28B shown in FIG. 5) Are configured to include two hysteresis comparators 14A and 14B and a microcontroller 15.

  As shown in FIG. 1, the display control device 12 includes a storage unit 12A including a ROM, a RAM, and / or a nonvolatile memory. The storage unit 12A includes a program for performing software processing in waveform shaping units 20A and 20B, a phase / correction value calculation unit 21, a displacement correction value calculation unit 22, and a measurement value display processing unit 23, which will be described later, FIGS. A processing program corresponding to the flowchart shown in FIG. 8 and maps corresponding to the tables shown in FIGS. 9 and 10 are stored in an updatable manner.

  The microcontroller 15 includes a counter 16, which will be described later, a calculation unit 17 for a relative displacement amount X1, sample hold circuits 18A and 18B, A / D converters 19A and 19B, waveform shaping units 20A and 20B, a phase / correction value calculation unit 21, A displacement correction value calculation unit 22 and a measurement value display processing unit 23 are included.

  The counter 16 having a phase difference pulse count function counts up the binary signals LA and LB (characteristic lines 28A and 28B in FIG. 5) input from the hysteresis comparators 14A and 14B based on changes in the respective signal waveforms. By performing the operation and the countdown operation, the measurement value of the measurement object 100 is output as a counter count value (hereinafter referred to as a count value Cn).

  The count value Cn is a count value having a minimum unit of 1/4 of the length L of the lattice pitch (for example, L = 8 μm and L / 4 = 2 μm). The calculation unit 17 for the relative displacement amount X1 uses the counter 16 to calculate the first relative displacement amount X1 that determines the outline of the measurement value (relative displacement amount Xr) of the measurement object 100, as shown in the following equations 11 and 12. Based on the counted value Cn, the following equation 3 is used.

  The sample hold circuits 18A and 18B and the A / D converters 19A and 19B operate in parallel (in parallel) with the counter 16, and convert the waveforms of the detection signals VA and VB that have passed through the LPFs 13A and 13B into digital waveforms. D-convert. The two digital signals VAD and VBD A / D converted by the A / D converters 19A and 19B are expressed by the following equations (4) and (5). The digital signals VAD and VBD can be described as follows by scaling the amplitudes Ka and Kb in the equations (1) and (2) by software processing and setting the offset voltages Vo1 and Vo2 to zero. The amplitude value Kd is based on software processing.

  The waveform shaping sections 20A and 20B perform waveform shaping by software processing so that the center voltages and amplitudes of the digital signals VAD and VBD are matched. A waveform shaping method for scaling and offset removal by software processing can be performed using a known technique as described in, for example, Japanese Patent Application Laid-Open No. 2007-178170. As shown in FIG. 1, there is also a method of determining the correction count and the like by performing calibration or the like individually in a state where the optical digital scale 1 is connected to the display control device 12.

  Although the digital signals VAD and VBD in FIG. 5 are shown as sinusoidal curves along the characteristic lines 29A and 29B, the signal values of the digital signals actually forming a vertical stripe pattern (see the signal values in FIG. 3). It is expressed as Further, characteristic lines 30A and 30B in FIG. 5 represent characteristics of digital signals -VAD and -VBD obtained by inverting the positive and negative of the digital signals VAD and VBD.

  The phase / correction value calculation unit 21 compares the signal values of the two digital signals VAD and VBD that have undergone waveform shaping, so that they are within one period of the signal waveform (for example, the length L = 8 μm of the grating pitch). Eight sections # 1 to # 8 (see FIGS. 5 and 9) as phase information at the second and second displacement correction values based on the respective sections # 1 to # 8 (phase information). Relative displacement amount X2 is calculated. The phase / correction value calculation unit 21 calculates a section (phase information) and a second relative displacement amount X2 along a flowchart shown in FIG.

  The detection signals VA and VB according to the equations (1) and (2) are waveforms having the grating pitch length L as one cycle with respect to the true relative displacement amount Xs, and the arbitrary relative displacement amount Xs is an integer value N. (For example, N = 0, 1, 2, 3,...) And a relative displacement amount Xo that is less than or equal to the lattice pitch length L (for example, L = 8 μm), can be expressed by the following equation (6)

  By comparing the signal values (voltage values) of the digital signals VAD and VBD according to the flowchart of FIG. 7 to be described later, the relative displacement amount Xo is, for example, as shown in the table 31 of FIG. Which of the sections # 1 to # 8 obtained by dividing the length L into eight can be obtained as phase information. The phase / correction value calculation unit 21 specifies phase information (that is, sections # 1 to # 8 of the table 31 shown in FIG. 9), and then calculates a relative displacement amount X2 equal to or lower than the detection accuracy of the relative displacement amount X1 by the counter 16. The table 31 is calculated for each section # 1 to # 8.

  The count value Cn by the counter 16 increases or decreases with the lattice pitch length L / 4 as a minimum unit, and therefore the relative displacement amount X2 is set to either the value 0 or the value L / 8. For example, L = 8 μm, section # 2 “L / 8 ≦ Xo <2L / 8” in FIG. 9, section # 4 “3L / 8 ≦ Xo <4L / 8”, section # 6 “5L / 8 ≦ Xo < In the case of “6L / 8” and section # 8 “7L / 8 ≦ Xo <L”, the relative displacement amount X2 is 1 μm (X2 = L / 8 = 1 μm). In FIG. 9, section # 1 “0 ≦ Xo <L / 8”, section # 3 “2L / 8 ≦ Xo <3L / 8”, section # 5 “4L / 8 ≦ Xo <5L / 8”, section In the case of # 7 “6L / 8 ≦ Xo <7L / 8”, the relative displacement amount X2 is 0 μm (X2 = 0 μm).

  Since the calculation process of the relative displacement amount X2 can be realized by a relatively simple algorithm, it can be processed within 1 microsecond (μsec) using an embedded microcomputer with a 100 MHz clock, and the relative use range is within the normal use range. It is possible to deal with displacement speeds up to 1 m / sec. When a calculation error occurs in the process (step 50) in FIG. 7, the signal values of the digital signals VAD and VBD do not follow the above equations 4 and 5 due to input noise, so the relative displacement amount X2 in this case is calculated the previous time. Keep the value.

  The second relative displacement amount X2 as the first displacement correction value is a correction value that corrects the first relative displacement amount X1 by the counter 16 by summing up the relative displacement amount Xr by the equation 12 described later, For example, the first relative displacement amount X1 is corrected as a numerical value (relative displacement amount Xr) that does not include the lowest digit that is less than the decimal point with respect to the μm (micron) order. In the present embodiment, the relative displacement amount X2 is set to either value 0 or value L / 8. However, the present invention is not limited to this, and the second relative displacement amount X2 is equal to or less than a predetermined pitch with respect to the phase pitch of the optical digital scale 1, that is, the length L (L = 8 μm) of the grating pitch. It is set to a value within a range, preferably within a range of 1/4 pitch or less.

  The displacement correction value calculation unit 22 compares the signal values (voltage values) of the two digital signals VAD and VBD that have been waveform-shaped as described above, and determines the ratio Ra between the two signal values according to the following formula 7 or formula 8. Calculate as follows. Based on the signal value ratio Ra and the phase information (i.e., sections # 1 to # 8 of the table 31 shown in FIG. 9), the displacement correction value calculation unit 22 uses the calculation table 32 shown in FIG. A second displacement correction value finer than the second relative displacement amount X2 (first displacement correction value) is calculated as the third relative displacement amount X3.

  However, the ratio Ra is expressed by a numerical value of Ra ≧ 1, and when the absolute value of the digital signal VAD is larger than the absolute value of the digital signal VBD, that is, when | VAD |> | VBD | The ratio Ra is obtained by the equation (7). Further, when the absolute value of the digital signal VBD is larger than the absolute value of the digital signal VAD, that is, in the case of | VBD |> | VAD |, the ratio Ra is obtained by the equation (8).

  The calculation table 32 shown in FIG. 10 is created in advance by performing calculation according to the following equation (9). Since the count value Cn of the counter 16 increases or decreases with the length L / 4 of the lattice pitch as a minimum unit, the relative displacement amount X3 as the second displacement correction value is in a range (0 ≦ X3 <L / 4), that is, , 0 ≦ X3 <2 to determine the value. Further, in order to speed up the calculation, a value is determined for each phase information described above (that is, the section of the table 31 shown in FIG. 9).

  The calculation table 32 shown in FIG. 10 shows 20 numerical examples (1.081Δ ≦ Ra ≦ 25.45Δ) in total as numerical values of the ratio Ra. However, these numerical examples are only a part of the numerical examples. For example, about 80 to 160 numerical values (the numerical values obtained by the calculations of the equations 7 and 8) are written in the column of the ratio Ra. The calculation table 32 is created in advance including these numerical values.

  The third relative displacement amount X3 as the second displacement correction value is a correction value that corrects by adding the first relative displacement amount X1 by the counter 16 as a relative displacement amount Xr by Equation 11 described later. For example, the first relative displacement amount X1 is corrected as a numerical value (relative displacement amount Xr) including the lowest digit that is below the decimal point with respect to the μm (micron) order. The third relative displacement amount X3 is a value in a range equal to or less than a predetermined pitch with respect to the phase pitch of the optical digital scale 1, that is, the length L (L = 8 μm) of the grating pitch, preferably ¼ pitch. The value is set in the following range.

  The measured value display processing unit 23 calculates the input frequency f of each detection signal (that is, the binary signals LA and LB by the characteristic lines 28A and 28B in FIG. 5) from the counter count value per unit time by the counter 16. Based on the frequency range of the input frequency f, the display unit 11 performs display processing of the measured value. Here, the measured value display processing unit 23 includes a frequency determination unit 24, a correction value selection unit 25, an addition processing unit 26, and a display processing unit 27, as shown in FIG.

  The frequency determination unit 24 performs a frequency determination process shown in FIG. 8 described later as a subroutine, and when the input frequency f exceeds a predetermined determination frequency fa (hereinafter referred to as a determination value fa), the lowest digit invalid flag F is output as F = 1. When the optical digital scale 1 is used, in order to ensure detection accuracy on the order of 0.1 μm, the relative displacement amount X3 is the minimum unit of L / 80 with respect to the lattice pitch length L (L = 8 μm). Design to The calculation of the relative displacement amount X3 is, for example, processing within 10 μsec using a built-in microcomputer with a 100 MHz clock. Is possible.

  For example, the frequency determination unit 24 acquires the count value Cn of the counter 16 every 0.1 second (sec), and the relative displacement amount when the difference between the previous and subsequent count values Cn exceeds 5000 counts / sec, for example. It is determined that the calculated value of X3 is invalid, and the lowest digit (0.1 μm digit) invalid flag F is output as “F = 1”. For example, when the shape of the measuring object 100 changes greatly and the spindle 4 of the digital scale 1 is greatly displaced greatly, the input frequency f may exceed the determination value fa.

  According to the present embodiment, the counter 16 is incremented by the count value Cn every 2 μm and one period is set to 8 μm, so that the input frequency f is determined by the determination value fa (for example, fa = 5000 × 2 / 8 = 1250 Hz), the lowest digit invalid flag F is output as “F = 1”. When the input frequency f is greater than or equal to zero and less than or equal to the determination value fa, it is determined that the calculated value of the relative displacement amount X3 is valid, and the lowest digit invalid flag F is output as “F = 0”.

  The correction value selection unit 25 determines the relative displacement amount X2 as the first and second displacement correction values depending on whether the lowest digit invalid flag F output from the frequency determination unit 24 is “0” or “1”. One of X3 is selected as a correction value. That is, when the lowest digit invalid flag F is F = 0, the relative displacement amount X3 is selected as a correction value, and when F = 1, the relative displacement amount X2 is selected as a correction value. At this time, the addition processing unit 26 performs addition processing according to the following formulas 11 and 12 according to the selection processing of the correction value selection unit 25, and the measured value to be digitally displayed on the display 11 from the relative displacement amounts X1, X2, and X3. The relative displacement amount Xr is calculated.

  Here, the relative displacement amount Xr represents a numerical value that can be digitally displayed on the display 11 with respect to the true relative displacement amount Xs in the above-described equations 4 and 5, and an approximate value (Xs) with respect to the true relative displacement amount Xs. ≈Xr), and the measured value of the measuring object 100 is digitally displayed on the display 11 via the display processing unit 27. The display processing unit 27 causes the display 11 to digitally display the relative displacement amount Xr according to the processing result of the addition processing unit 26. Thus, the measured value display processing unit 23 calculates the input frequency f of each detection signal (the binary signals LA and LB in FIG. 5) from the counter count value per unit time by the counter 16, and this input frequency f Based on the frequency range, the display unit 11 performs display processing of the measured value.

  The display control device 12 of the optical digital scale 1 according to the present embodiment has the above-described configuration. Next, a control operation when measuring the measuring object 100 using the optical digital scale 1 will be described. explain.

  First, when the measurement object 100 is measured using the optical digital scale 1, the zero point adjustment is performed in advance, and when the true relative displacement amount Xs is zero (Xs = 0), the digital signal according to Equation 4 is used. Adjustment is made so that the signal value (voltage) of VAD becomes zero and the signal value (voltage) of the digital signal VBD according to Equation 5 becomes the maximum value, and the count value Cn of the counter 16 is set as Cn = 0. .

  Next, when the measuring object 100 is moved in the direction of arrow B in FIG. 1, the spindle 4 of the digital scale 1 is displaced in the direction of arrow A following this. Accordingly, the signal generator 5 of the digital scale 1 outputs sine wave detection signals VA and VB, for example, as indicated by characteristic lines 10A and 10B shown in FIG. In this case, the detection signals VA and VB are adjusted as sine wave signals whose phases are shifted by ¼ pitch in accordance with the displacement of the measuring section (ie, the spindle 4) as in the equations (1) and (2).

  The display control device 12 shown in FIG. 4 shapes the detection signals VA and VB passed through the LPFs 13A and 13B by the two hysteresis comparators 14A and 14B, and converts the binary signals LA and LB to the characteristic lines 28A and 28B shown in FIG. This is generated and output to the counter 16. The counter 16 outputs a count value Cn based on the change in the signal waveform of the binary signals LA and LB, and the first relative displacement amount X1 based on the count value Cn of the counter 16 is calculated by the next arithmetic unit 17 as described above. As shown in Equation 3, X1 = 2Cn is calculated.

  Here, the display control processing of the display control device 12 that displays the measurement value of the optical digital scale 1 will be described with reference to FIGS.

  When the processing operation of FIG. 6 starts, the count value Cn of the counter 16 is read in step 1, and in the next step 2, the first relative displacement amount X1 is calculated as X1 = 2Cn as shown in Equation 3. In the next step 3, the digital signals VAD and VBD according to the equations 4 and 5 are read. Then, in the next step 4, the calculation process of the section (phase information) and the second relative displacement amount X2 by the phase / correction value calculator 21 is executed according to the flowchart shown in FIG.

  In the next step 5, the determination process by the frequency determination unit 24 of the measurement value display processing unit 23 is executed according to a flowchart shown in FIG. In the next step 6, it is determined whether or not the lowest digit invalid flag F is F = 0, and when it is determined to be “YES”, the lowest digit (order of 0.1 μm) is displayed effectively. Thus, since the calculation speed or the calculation time can be ensured, the process proceeds to the next step 7.

  In step 7, the absolute values of the digital signals VAD and VBD are compared and a determination process is performed. If “YES” is determined, the absolute value of the digital signal VAD is larger than the absolute value of the digital signal VBD (| VAD |> | VBD |), the ratio Ra according to Equation 7 is obtained in the next step 8. If “NO” is determined in step 7, the absolute value of the digital signal VBD is larger than the absolute value of the digital signal VAD (| VBD |> | VAD |). The ratio Ra according to Equation 8 is obtained.

  In the next step 10, the relative displacement amount X3 as the second displacement correction value is calculated from the ratio Ra and the section (phase information) using the calculation table 32 shown in FIG. Here, since the value of the third relative displacement amount X3 is determined for each of the phase information (that is, the sections # 1 to # 8 of the table 31 shown in FIG. 9), the time required for the calculation is shortened. Calculation can be speeded up.

  In the next step 11, a relative displacement amount Xr as a measured value that can be digitally displayed on the display 11 is calculated as Xr = X1 + X3 according to the equation (11). In the next step 12, the relative displacement amount Xr at this time is digitally displayed on the display 11 as a measured value, and the process returns in the next step 13.

  On the other hand, when “NO” is determined in Step 6, the lowest digit invalid flag F becomes F = 1, it can be determined that the calculated value of the relative displacement amount X3 is invalid, and the lowest digit (0.1 μm Display accuracy). Therefore, in this case, in the next step 14, the relative displacement amount Xr as a measurement value that can be digitally displayed by the display 11 is calculated as Xr = X1 + X2 according to the equation (12). In the next step 12, the relative displacement amount Xr at this time is digitally displayed on the display 11 as a measured value, and the process returns in the next step 13.

  Next, the calculation process of the section (phase information) and the second relative displacement amount X2 by the phase / correction value calculator 21 will be described with reference to FIG. In the following description, the signal values of the digital signals VAD and VBD are simplified and described as signals VAD and VBD.

  First, in step 21, it is determined whether or not the signal VAD read in step 3 is a positive value (VAD> 0). If “YES” is determined, the signal VBD is positive in the next step 22. It is determined whether or not (VBD> 0). If “YES” is determined in the step 22, it is determined in a next step 23 whether or not the signal VAD is smaller than the signal VBD (VAD <VBD).

  If “YES” is determined in the step 23, the phase information (that is, the section # 1 shown in FIGS. 5 and 9) is specified as “0 ≦ Xo <L / 8” in the next step 24, and the next In step 25, the second relative displacement amount X2 as the first displacement correction value is calculated as X2 = 0 μm. Thereafter, the process returns at step 26.

  Further, when “NO” is determined in step 23, the signal VAD is equal to or higher than the signal VBD (VAD ≧ VBD). Therefore, in the next step 27, the phase information (that is, the section # 2 shown in FIGS. 5 and 9) is specified as “L / 8 ≦ Xo <2L / 8”, and in the next step 28, the second relative The displacement amount X2 is calculated as X2 = 1 μm. Thereafter, the process returns at step 26.

  On the other hand, if “NO” is determined in the step 22, it is determined in a next step 29 whether or not the signal VAD is larger than the signal −VBD (VAD> −VBD). If “YES” is determined in the step 29, the phase information (that is, the section # 3 shown in FIGS. 5 and 9) is specified as “2L / 8 ≦ Xo <3L / 8” in the next step 30, In the next step 31, the second relative displacement amount X2 is calculated as X2 = 0 μm. Thereafter, the process returns at step 26.

  Further, when “NO” is determined in step 29, the signal VAD is equal to or lower than the signal −VBD (VAD ≦ −VBD). Therefore, in the next step 32, it is determined whether or not the signal VBD is a negative value (VBD <0). If “YES” is determined in the step 32, the phase information (that is, the section # 4 shown in FIGS. 5 and 9) is specified as “3L / 8 ≦ Xo <4L / 8” in the next step 33, In the next step 34, the second relative displacement amount X2 is calculated as X2 = 1 μm. Thereafter, the process returns at step 26.

  On the other hand, if “NO” is determined in step 32, the signal VBD is zero or a positive value (VBD ≧ 0) and there is no corresponding section. In this case, the process proceeds to step 50 described later and is processed as a calculation error. To do. That is, in this case, the signals VAD and VBD are not in accordance with the equations (4) and (5) due to the influence of input noise and the like, and the relative displacement amount X2 in this case maintains the previously calculated value.

  On the other hand, if “NO” is determined in the step 21, it is determined in a next step 35 whether or not the signal VAD is a negative value (VAD <0). If “YES” is determined in the step 35, it is determined in a next step 36 whether or not the signal VBD is a negative value (VBD <0). If “YES” is determined in the step 36, it is determined in a next step 37 whether or not the signal VAD is larger than the signal VBD (VAD> VBD). If “YES” is determined in the step 37, the phase information (that is, the section # 5 shown in FIGS. 5 and 9) is specified as “4L / 8 ≦ Xo <5L / 8” in the next step 38, In the next step 39, the second relative displacement amount X2 is calculated as X2 = 0 μm. Thereafter, the process returns at step 26.

  On the other hand, if “NO” is determined in the step 37, the signal VAD is equal to or lower than the signal VBD (VAD ≦ VBD), so that the phase information (that is, the section # 6 shown in FIGS. 5 and 9) is determined in the next step 40. ) Is specified as “5L / 8 ≦ Xo <6L / 8”, and in the next step 41, the second relative displacement amount X2 is calculated as X2 = 1 μm. Thereafter, the process returns at step 26.

  On the other hand, when “NO” is determined in step 36, the signal VBD is zero or a positive value (VBD ≧ 0). Therefore, in the next step 42, the signal −VAD is larger than the signal VBD (−VAD> VBD). ) Or not. If “YES” is determined in the step 42, the phase information (that is, the section # 7 shown in FIGS. 5 and 9) is specified as “6L / 8 ≦ Xo <7L / 8” in the next step 43, In the next step 39, the second relative displacement amount X2 is calculated as X2 = 0 μm. Thereafter, the process returns at step 26.

  On the other hand, when “NO” is determined in step 42, since the signal −VAD is equal to or lower than the signal VBD (−VAD ≦ VBD), the signal VBD is a positive value (VBD> 0) in the next step 45. It is determined whether or not. If “YES” is determined in the step 45, the phase information (that is, the section # 8 shown in FIGS. 5 and 9) is specified as “7L / 8 ≦ Xo <L” in the next step 46, and the next In step 47, the second relative displacement amount X2 is calculated as X2 = 1 μm. Thereafter, the process returns at step 26.

  If “NO” is determined in step 45, the signal VBD is zero (VBD = 0). In this case, too, there is no corresponding section. Therefore, the process proceeds to step 50 to process as a calculation error, and the second relative displacement is detected. The quantity X2 maintains the previously calculated value. Thereafter, the process returns at step 26.

  On the other hand, when “NO” is determined in step 35, the signal VAD is zero (VAD = 0), and the process proceeds to the next step 48 to determine whether or not the signal VBD is a positive value (VBD> 0). Determine. If “YES” is determined in the step 48, the process proceeds to the step 24 to specify the phase information (that is, the section # 1 shown in FIGS. 5 and 9) as “0 ≦ Xo <L / 8”. In step 25, the second relative displacement amount X2 is calculated as X2 = 0 μm.

  If “NO” is determined in step 48, the signal VBD is zero or a negative value (VBD ≦ 0), and whether or not the signal VBD is a negative value (VBD <0) in the next step 49. Determine. If “YES” is determined in the step 49, the process proceeds to the step 38 to specify the phase information (that is, the section # 5 shown in FIGS. 5 and 9) as “4L / 8 ≦ Xo <5L / 8”. In the next step 39, the second relative displacement amount X2 is calculated as X2 = 0 μm.

  If “NO” is determined in step 49, the signal VBD is zero (VBD = 0). In this case as well, since there is no corresponding section, the process proceeds to step 50 to process as a calculation error, and the second relative displacement. The quantity X2 maintains the previously calculated value. Thereafter, the process returns at step 26.

  Next, with reference to FIG. 8, the determination process by the frequency determination part 24 of the measured value display process part 23 is demonstrated.

  First, when the frequency determination process starts, the input frequency f is read in step 51. This input frequency f is calculated by the counter count value per unit time by the counter 16 (that is, the count values of the binary signals LA and LB by the characteristic lines 28A and 28B in FIG. 5). In the next step 52, it is determined whether or not the input frequency f is 0 ≦ f ≦ fa with respect to the determination value fa.

  If "YES" is determined in the step 52, the least significant digit invalid flag F is output as "F = 0" in the next step 53, and thereafter, the process returns in the step 54. On the other hand, when “NO” is determined in step 52, for example, the shape of the measurement object 100 is greatly changed, and the spindle 4 of the digital scale 1 is suddenly displaced, so that the input frequency f exceeds the determination value fa. Therefore, the process proceeds to the next step 55, and the lowest digit invalid flag F is switched to “F = 1”.

  Thus, according to the present embodiment, when the lowest digit invalid flag F is “F = 0”, the relative displacement amount Xr as a measured value that can be digitally displayed on the display 11 is expressed as Xr = It can be calculated as X1 + X3. On the other hand, when the lowest digit invalid flag F is switched to “F = 1”, there is a high possibility that the calculated value of the relative displacement amount X3 becomes invalid, and the display accuracy of the lowest digit (on the order of 0.1 μm) is improved. There are cases where it cannot be secured. Therefore, in such a case, the relative displacement amount Xr as a measured value that can be digitally displayed by the display 11 can be calculated as Xr = X1 + X2 according to the equation (12).

  Next, the display control process of the display control device 12 according to the present embodiment will be described in the case where the measurement value of the measurement object 100 is shown as an example.

  For example, the measured value shown in FIG. 5 indicates the case where the relative displacement amount Xs is “11.33... Μm”, and the measured value of the measurement object 100 is the vertical straight line 33 indicated by the solid line in FIG. It has become the position. In this case, the counter 16 becomes the count value Cn = 5 due to the rise and fall of the binary signals LA and LB, and this count value Cn is incremented every 2.0 μm. Relative displacement amount X1 is calculated as X1 = 10 μm.

  Further, the measurement value of the measurement object 100 is at the position of the straight line 33 in FIG. 5, and the signal values of the digital signals VAD and VBD are VAD> 0, VBD <0, VAD ≦ −VBD. The section of the phase information that satisfies the condition is shown as “# 4”, and the section “3 / 8L ≦ Xo <4 / 8L” is satisfied in FIG. Thereby, also from the table 31 shown in FIG. 9, the second relative displacement amount X2 which is the first displacement correction value is calculated as X2 = 1 μm.

  At the position of the measurement value of the measurement object 100 (straight line 33 in FIG. 5), the signal values of the digital signals VAD and VBD according to the equations 4 and 5 are VAD = 255, where the amplitude value Kd is Kd = 511. VBD = −442. Then, the ratio Ra is calculated as | VBD | ÷ | VAD | = 1.7333 by the equation (8). Further, the section of the phase information is indicated as “# 4”, and the section is “3 / 8L ≦ Xo <4 / 8L” in FIG.

  Accordingly, a reference value with a ratio Ra of “1.7333” and a section of “3 / 8L ≦ Xo <4 / 8L” is obtained as “1.33” from the calculation table 32 shown in FIG. From the reference value “1.33”, the third relative displacement amount X3 can be calculated as X3 = 1.3 μm. When the lowest digit invalid flag F is F = 0, the relative displacement amount Xr as a measured value that can be digitally displayed on the display 11 is set to Xr = X1 + X3, that is, Xr = 11.3 μm according to the equation (11). Can be calculated. In this case, the digital display by the display 11 can be displayed as “11.3 μm” or “0.0113 mm” based on the relative displacement amount Xr.

On the other hand, when the lowest digit invalid flag F is switched to “F = 1”, the relative displacement amount Xr as a measured value that can be digitally displayed by the display 11 is expressed as Xr = X1 + X2, That is, it can be calculated as Xr = 11.0 μm. In this case, the digital display by the display 11 is “11. μm ”or“ 0.011 ” “mm” can be an underbar display in which the lowest digit is invalid.

  In the present embodiment, for example, even when the amplitudes of the detection signals VA and VB which are input signals are reduced, for example, by using the 12-bit A / D converters 19A and 19B, sufficient accuracy can be captured. Since the phase can be calculated from a plurality of input points by using interpolation by a program, it is resistant to changes in the amplitudes of the detection signals VA and VB of the optical digital scale 1 due to changes over time. There is.

  Thus, according to the present embodiment, by measuring the measurement object 100 using the optical digital scale 1, the measurement value of the measurement object 100 is taken out as the counter count value, and the first equation (3) is used. Relative displacement amount X1 can be calculated. The phase / correction value calculation unit 21 compares the signal values of the two digital signals VAD and VBD to obtain phase information (sections # 1 to # 8) within one cycle of the signal waveform, The first displacement correction value (that is, the second relative displacement amount X2) based on the sections # 1 to # 8 can be calculated.

  The displacement correction value calculator 22 compares the signal values of the two digital signals VAD and VBD to calculate the ratio Ra of both signal values, and the ratio Ra of the signal value and the phase information (sections # 1 to # 8). Based on the above, the second displacement correction value (that is, the third relative displacement amount X3) that is finer than the first displacement correction value and that can ensure the detection accuracy, for example, on the order of 0.1 μm is calculated. can do.

  In other words, the third relative displacement amount X3 has L / 80 as a minimum unit with respect to the length L (L = 8 μm) of the grating pitch in order to ensure detection accuracy on the order of 0.1 μm. Is set to Then, the measured value display processing unit 23 counts the counter value Cn (that is, the first relative displacement amount X1) depending on whether or not the input frequency f by the counter 16 exceeds the determination frequency (that is, the determination value fa). The second and third relative displacement amounts X2 and X3 can be selectively added, and the display processing of the measured value on the display 11 can be performed according to the total value.

  In this case, when the input frequency f is greater than or equal to zero and less than or equal to the determination value fa, the measured value display processing unit 23 follows the total value of the first relative displacement amount X1 and the third relative displacement amount X3 by the counter 16. A relative displacement amount Xr (Xr = X1 + X3) as a measured value that can be digitally displayed can be displayed on the display 11. On the other hand, when the input frequency f exceeds the determination value fa, the relative displacement amount Xr (Xr = X1 + X2) as a measured value is determined according to the total value of the first relative displacement amount X1 and the second relative displacement amount X2 by the counter 16. ) Can be displayed on the display 11.

  As described above, the measured value display processing unit 23, when the input frequency f exceeds the determination value fa, the first relative displacement amount X1 and the second relative displacement amount X2 (the first relative displacement amount X2 based on the count value Cn of the counter 16). By displaying the measured value according to the total value with the displacement correction value), the display of the measured value on the display 11 is, for example, the numerical value indicating the lowest digit that is below the decimal point for the μm (micron) order. No display, for example, the lowest digit can be switched to an underbar display, and the user of the digital scale 1 can be notified that the measured value after the decimal point is indeterminate.

  In the embodiment, when the input frequency f exceeds the predetermined determination value fa, the case where the lowest digit of the display of the measurement value on the display 11 is displayed as an underbar is taken as an example. explained. However, the present invention is not limited to this. For example, the least significant digit below the decimal point may be switched so as not to be displayed on the order of μm (microns), and a configuration other than the numerical value may be displayed. Thereby, the user of the digital scale 1 can be positively notified that the measured value after the decimal point is indefinite.

  In addition, the case where the determination value fa as the determination frequency is 1250 Hz, for example, has been described as an example, but the determination frequency is not limited to this, and depends on the calculation processing speed of the displacement correction value calculation unit 22 to the last. The determination frequency may be changed as appropriate.

  On the other hand, in the above embodiment, the case where the eight sections # 1 to # 8 (see FIGS. 5 and 9) are set as the phase information by the phase / correction value calculation unit 21 has been described as an example. However, the present invention is not limited to this, and for example, a section of phase information is provided for a period of one period of the signal waveform of the digital signals VAD and VBD (grating pitch length L = a μm, where a is a positive integer). It is good also as a structure set as.

  In the above-described embodiment, the calculation or detection accuracy of the relative displacement amount X3 calculated by the displacement correction value calculation unit 22 is expressed as “1/1 of the grid pitch length L when the change speed is 0.01 m / sec or less. The case where it is configured as “80” has been described as an example. However, the present invention is not limited to this. For example, the numerical accuracy of the table shown in FIG. 9 may be improved according to the processing speed of the CPU, or the higher change speed may be followed.

  In the above embodiment, the case where the relative displacement amount X3 is calculated by the displacement correction value calculation unit 22 using the calculation table 32 calculated in advance has been described as an example. However, the present invention is not limited to this. For example, a method of calculating the relative displacement amount X3 as the second displacement correction value using a means such as a series expansion method of a trigonometric function by a hardware multiplier / divider. It may be adopted.

  Furthermore, in the above-described embodiment, the phase / correction value calculation unit 21 uses the phase information within one cycle of the signal waveform and the first displacement correction value (second relative displacement amount X2) based on the phase information. The case of calculating is described as an example. However, the present invention is not limited to this. For example, the phase calculation unit that calculates only the phase information without calculating the first displacement correction value (second relative displacement amount X2) is replaced with the phase / correction value calculation unit 21. It can also be set as the structure provided instead of. In this case, the displacement correction value (third relative displacement amount X3) calculated by the displacement correction value calculation unit 22 is added to the first relative displacement amount X1 by the counter 16 as shown in the equation 11 to obtain a relative value. The displacement amount Xr may be calculated, and the display processing unit (that is, the measurement value display processing unit) may be configured to digitally display the relative displacement amount Xr with a display.

  Furthermore, in the above-described embodiment, the case has been described in which the visually observable indicator 11 is disposed at a position close to the measurement work place of the measurement object using the optical digital scale 1. However, the present invention is not limited to this. For example, the measurement result data may be transmitted to a personal computer (information terminal) or the like provided at an external remote location by wired or wireless communication. As an example, when a BCD code generally used in a measuring instrument is used, only numbers in the range of “0” to “9” can be used. For this reason, it is good also as a structure which adds the numerical value which shows the lowest digit invalid flag F to a measurement result. For example, when the lowest digit invalid flag F is “F = 1” with respect to the relative displacement amount Xr = 0.113 mm representing the measurement result, the BCD code “00”-“11”-“01” ”. When the lowest digit invalid flag F is “F = 0”, the BCD code “00”-“11”-“30” ”is transmitted. Thereby, the measurement result of the measuring object by the optical digital scale can be displayed on a display device such as an information terminal by remote control.

1 Digital scale 4 Spindle (measuring unit)
5 Signal generator 10A, 10B Characteristic line (Detection signal characteristic line)
DESCRIPTION OF SYMBOLS 11 Display 12 Display control apparatus 16 Counter 19A, 19B A / D converter 20A, 20B Waveform shaping part 21 Phase / correction value calculation part 22 Displacement correction value calculation part 23 Measurement value display process part 28A, 28B Characteristic line (2 values) Signal characteristic line)
29A, 29B Characteristic line (Digital signal characteristic line)
31 Table 32 Calculation table 100 Measurement object Cn Count value f Input frequency fa Judgment value (judgment frequency)
L Lattice pitch length (phase pitch)
VA, VB detection signal VAD, VBD digital signal X1 first relative displacement amount X2 second relative displacement amount (first displacement correction value)
X3 Third relative displacement amount (second displacement correction value)
Xr Relative displacement (total value)
Xs Relative displacement (true relative displacement)
# 1 to # 8 section (phase information)

Claims (6)

A display controller for a digital scale that measures an object to be measured using an optical digital scale having a displaceable measuring unit and digitally displays a displacement amount of the measuring unit as a measured value of the measuring object by a display In
A signal generator for generating two detection signals whose phases are shifted by 1/4 pitch according to the displacement of the measurement unit;
A counter that outputs a measurement value of the measurement object as a counter count value by performing a count-up operation and a count-down operation based on a change in each signal waveform for each detection signal from the signal generator;
An A / D converter that operates in parallel with the counter and A / D converts the waveform of each detection signal into a digital waveform;
A waveform shaping unit that performs waveform shaping so that the center voltage and amplitude of two digital signals (VAD, VBD) subjected to A / D conversion are matched;
Phase information of eight sections ( # 1 to # 8) in one cycle of the signal waveform from the two digital signals (VAD, VBD) that have undergone waveform shaping, and a first displacement correction value based on the phase information A phase / correction value calculation unit for calculating (X2) ;
The signal values of the two digital signals (VAD, VBD) that have undergone waveform shaping are compared with absolute values (| VAD |, | VBD |) to calculate the ratio of both signal values, and the absolute values (| VAD |, When | VBD |) is (| VAD | ≧ | VBD |), it is determined based on the phase information and the ratio (| VAD | / | VBD |) of the absolute values (| VAD |, | VBD |) . The second displacement correction value (X3) finer than the displacement correction value (X2) of 1 is calculated, and when the absolute values (| VAD |, | VBD |) are (| VAD | <| VBD |), A second displacement correction that is finer than the first displacement correction value (X2) based on the phase information and the ratio (| VBD | / | VAD |) of the absolute values (| VAD |, | VBD |). A displacement correction value calculation unit for calculating a value (X3) ;
A measurement value display processing unit that calculates an input frequency of each detection signal from a counter count value per unit time by the counter and performs display processing of the measurement value in the display unit based on a frequency range of the input frequency. ,
The measurement value display processing unit determines the first displacement correction value (X2 ) with respect to the displacement amount (X1) based on the count value of the counter depending on whether or not the input frequency exceeds a predetermined determination frequency. ) , A display controller for a digital scale, wherein the second displacement correction value (X3) is selectively added, and the display unit displays the measured value according to the total value. A display controller for a digital scale that measures an object to be measured using an optical digital scale having a displaceable measuring unit and digitally displays a displacement amount of the measuring unit as a measured value of the measuring object by a display In
A signal generator for generating two detection signals whose phases are shifted by 1/4 pitch according to the displacement of the measurement unit;
A counter that outputs a measurement value of the measurement object as a counter count value by performing a count-up operation and a count-down operation based on a change in each signal waveform for each detection signal from the signal generator;
An A / D converter that operates in parallel with the counter and A / D converts the waveform of each detection signal into a digital waveform;
A waveform shaping unit that performs waveform shaping so that the center voltage and amplitude of two digital signals (VAD, VBD) subjected to A / D conversion are matched;
Phase / correction value for calculating phase information within one cycle of the signal waveform and a first displacement correction value (X2) based on the phase information from the two digital signals (VAD, VBD) that have undergone waveform shaping A calculation unit;
Displacement correction for calculating a second displacement correction value (X3) finer than the first displacement correction value (X2) by comparing the signal values of the two digital signals (VAD, VBD) that have undergone waveform shaping. A value calculator,
A measurement value display processing unit that calculates an input frequency of each detection signal from a counter count value per unit time by the counter and performs display processing of the measurement value in the display unit based on a frequency range of the input frequency. ,
The measurement value display processing unit calculates the second displacement correction value (X3) by the displacement correction value calculation unit when the input frequency is not less than zero and not more than a predetermined determination frequency. Display the measured value in the display according to the total value (X1 + X3) obtained by adding the second displacement correction value (X3) to the displacement amount (X1) based on the count value of the counter;
  When the input frequency exceeds the determination frequency, the displacement amount (X1) based on the count value of the counter is not calculated by the displacement correction value calculation unit without calculating the second displacement correction value (X3). The digital scale display control apparatus is characterized in that display processing of the measured value in the display device is performed according to a total value (X1 + X2) obtained by adding the first displacement correction value (X2) to the display. The phase / correction value calculation unit calculates the phase information and the first displacement correction value (X2) by comparing the signal values of the two digital signals (VAD, VBD) whose waveforms have been shaped. 3. The display control apparatus for a digital scale according to claim 1, wherein the display control apparatus is configured as described above. The measured value display processing unit calculates a displacement amount (X1) based on the count value of the counter and the second displacement correction value (X3) when the input frequency is greater than or equal to zero and less than or equal to the determination frequency. When the input value exceeds the determination frequency, the displacement value (X1) based on the count value of the counter and the first displacement correction are performed when the measured value is displayed on the display device according to the total value (X1 + X3). The display control apparatus for a digital scale according to claim 1, wherein display processing of the measured value in the display device is performed according to a total value (X1 + X2) with the value (X2) .   The measurement value display processing unit is configured to switch the display of the measurement value on the display to a display whose lowest digit is not a numerical value when the input frequency exceeds the determination frequency. 5. A digital scale display control device according to 3 or 4. The measurement value display processing unit is configured to switch the display of the measurement value on the display so that the lowest digit is not displayed when the input frequency exceeds the determination frequency. , 3 or 4 digital scale display control device.

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