A high-precision digital tape measure based on double coding and an implementation method thereof

Abstract

The application discloses a high-precision digital tape measure based on double coding and an implementation method, relates to the technical field of digital tape measures, and solves the technical problem of manual reading error, and comprises a shell, a four-phase photoelectric signal acquisition module mounting shell mounted in the shell, four-phase photoelectric signal acquisition modules mounted on the four-phase photoelectric signal acquisition module mounting shell, a signal processing control circuit board connected with the four-phase photoelectric signal acquisition modules, a tape mounted in the shell, and a liquid crystal display screen mounted on the shell surface and connected with the signal processing control circuit board. The tape is provided with a hook extending out of the shell, and coding stripes A and B are arranged on the two edges of the tape along the extension direction of the tape. The coding stripe A is composed of first color stripes and second color stripes arranged in a cycle interval with equal width, and the coding stripe A and the coding stripe B face the light beam emitting and receiving surfaces of the four-phase photoelectric signal acquisition modules. The application can eliminate the manual reading error, improve the measurement efficiency, and reduce the error rate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of digital tape measure, and particularly relates to a high-precision digital tape measure based on double coding and an implementation method. BACKGROUND

[0002] At present, most of the measuring tools in engineering measurement are traditional steel tape measures, however, in the process of measuring by using the steel tape measure, the measurement error is often caused by personal measurement habits and visual differences. The existing digital display scheme sprays silk printing on the tape, and the displacement reading is realized by a photoelectric door (or an infrared emitting diode and a silicon photo transistor), or the stretching length of the tape is indirectly measured by driving a mechanical encoder or a code disc with coding stripes to rotate by the tape through mechanical transmission or friction. However, the measurement precision of the former is only millimeter level due to the limitation of the light spot diameter, and the measurement precision of the latter is also millimeter level due to the transmission error, backlash and the like, and both of them need to spray a certain interval calibration pattern on the tape for calibration. When the measurement error occurs between the two calibration patterns, it cannot be corrected, and more seriously, if the calibration pattern is worn or adhered with stains, the calibration will be invalid or the correct value will be calibrated as an error value.

[0003] Therefore, a new tape measure scheme needs to be proposed to eliminate the manual measurement error and solve the technical problems of low measurement precision and inability to calibrate in the prior art. SUMMARY

[0004] The application aims to solve the technical problem of providing a high-precision digital tape measure based on double coding and an implementation method to at least solve part of the above technical problems.

[0005] To achieve the above-mentioned purposes, the technical scheme adopted by the application is as follows:

[0006] A high-precision digital tape measure based on double coding comprises an outer shell, a four-phase photoelectric signal acquisition module mounting shell mounted in the outer shell, a four-phase photoelectric signal acquisition module mounted on the four-phase photoelectric signal acquisition module mounting shell, a signal processing control circuit board connected with the four-phase photoelectric signal acquisition module, a tape mounted in the outer shell, and a liquid crystal display screen mounted on the surface of the outer shell and connected with the signal processing control circuit board.

[0007] The tape is provided with a hook extending out of the outer shell, and coding stripes A and B are arranged on both sides of the tape along the extension direction of the tape. The coding stripe A is composed of first color stripes and second color stripes arranged in a cycle interval with equal width, the sum of the widths of two adjacent stripes is L, the part of the coding stripe A close to the hook is a redundant part of the coding stripe A, and the end of the redundant part of the coding stripe A away from the hook is a zero position.

[0008] The encoding stripe B is composed of three continuous parts, the first part is a redundant part of the encoding stripe B, the redundant part of the encoding stripe B is a first color stripe and has the same start and end positions as the redundant part of the encoding stripe A, the second part of the encoding stripe B is a first color stripe with a width equal to 1.125 The third part of the encoding stripe B is composed of a first color stripe and a second color stripe arranged in a cycle interval;

[0009] The encoding stripe A and the encoding stripe B face the light beam emitting and receiving surface of the four-phase photoelectric signal acquisition module.

[0010] Further, the signal processing control circuit board comprises a comparison circuit and a micro control unit connected with the comparison circuit, the comparison circuit is connected with the four-phase photoelectric signal acquisition module, and the micro control unit is connected with the liquid crystal display screen.

[0011] Further, the four-phase photoelectric signal acquisition module comprises an encoder A arranged opposite to the encoding stripe A and an encoder B arranged opposite to the encoding stripe B, and the encoder A and the encoder B are symmetrically distributed; the encoder A is composed of a photoelectric gate EA1 close to the hook and a photoelectric gate EA2 away from the hook, and the distance between EA1 and EA2 is (1 / 4+k) L, wherein k represents a position index; the encoder B is composed of a photoelectric gate EB1 close to the hook and a photoelectric gate EB2 away from the hook, and the distance between EB1 and EB2 is (1 / 4+k) L, when the scale tape is in the zero return state, the center point of EA1 is aligned with the zero position; EA1, EA2, EB1 and EB2 are respectively connected with the comparison circuit.

[0012] Further, the micro control unit is connected with the external storage through a USB interface or WiFi.

[0013] Further, the method comprises the following steps:

[0014] S1, when the scale tape is pulled, EA1 collects the light signal of the encoding stripe A to obtain a class sine wave analog electric signal SA1; EA2 collects the light signal of the encoding stripe A to obtain a class sine wave analog electric signal SA2; EB1 collects the light signal of the encoding stripe B to obtain a class sine wave analog electric signal SB1; and EB2 collects the light signal of the encoding stripe B to obtain a class sine wave analog electric signal SB2;

[0015] S2, SA1, SA2, SB1 and SB2 are respectively input into the comparison circuit for waveform shaping, and the corresponding obtained square wave signals are SA1', SA2', SB1' and SB2' respectively;

[0016] S3, SA1', SA2', SB1' and SB2' are input into the micro control unit for automatic counting of the number of edges to obtain the length of the scale tape stretching.

[0017] S4, the micro control unit outputs the tape stretch length to the liquid crystal display for display.

[0018] Further, the phase difference between SA1 and SA2 is (1 / 2+2k)Π, the phase difference between SB1 and SB2 is (1 / 2+2k)Π; the phase difference between SA1' and SA2' is (1 / 2+2k)Π, the phase difference between SB1' and SB2' is (1 / 2+2k)Π; the phase difference between SA1 and SB1 is (1 / 4+2k)Π, the phase difference between SA2 and SB2 is (1 / 4+2k)Π, the phase difference between SA1' and SB1' is (1 / 4+2k)Π, the phase difference between SA2' and SB2' is (1 / 4+2k)Π.

[0019] Further, S3 comprises:

[0020] SC1, input SA1', SA2' to the first encoder interface of the micro control unit, input SB1', SB2' to the second encoder interface of the micro control unit;

[0021] SC2, when the tape stretch length is L, both SA1' and SA2' will have one rising edge and one falling edge, both SB1' and SB2' will have one rising edge and one falling edge;

[0022] If the first encoder interface only counts the rising edge or the falling edge of one of the square wave signals of SA1' and SA2', then the count value changes by 1, and the tape stretch length corresponding to the count value change of 1 is L;

[0023] If the second encoder interface only counts the rising edge or the falling edge of one of the square wave signals of SB1' and SB2', then the count value changes by 1, and the tape stretch length corresponding to the count value change of 1 is L;

[0024] If the first encoder interface counts both the rising edge and the falling edge of SA1' and SA2', then the count value changes by 4, and the tape stretch length corresponding to the count value change of 1 is L / 4;

[0025] If the second encoder interface counts both the rising edge and the falling edge of SB1' and SB2', then the count value changes by 4, and the tape stretch length corresponding to the count value change of 1 is L / 4;

[0026] If the first encoder interface counts both the rising edge and the falling edge of SA1' and SA2' and the second encoder interface counts both the rising edge and the falling edge of SB1' and SB2', then the count value changes by 8, and the tape stretch length corresponding to the count value change of 1 is L / 8.

[0027] Further, the SC2 further comprises: if the second encoder interface counts abnormally, and the difference between the count value of the first encoder interface and the count value when the scale tape is stretched to L is greater than or equal to 3, and the difference between the count value of the second encoder interface and the count value when the scale tape is stretched to L is -1, the scale tape is in a zero-return state; and outputting the information that the scale tape is in the zero-return state to the liquid crystal display for display.

[0028] Further, the SC2 further comprises: if the first encoder interface counts the rising and falling edges of SA1' and SA2', and the second encoder interface counts the rising and falling edges of SB1' and SB2', and the difference between the count value of the first encoder interface and the count value of the second encoder interface is not equal to 4 or 3 or 5, and the scale tape is not in the zero-return state, one of the coded stripes B and A is abnormal; and outputting the measurement abnormality information to the liquid crystal display for display.

[0029] Further, the SC2 further comprises: when one of the coded stripes B and A is abnormal, correcting the combination of SA1' and SA2' or the combination of SB1' and SB2' by using a filtering algorithm to obtain the scale tape stretching length.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] The present application sets the encoder A opposite to the coded stripe A, and sets the encoder B opposite to the coded stripe B, and the encoder A and the encoder B are symmetrically distributed, wherein the distance between EA1 and EA2 is (1 / 4+k) L, and the distance between EB1 and EB2 is (1 / 4+k) L, and when the scale tape is in the zero-return state, the center point of EA1 is aligned with the zero point position; and the third part of the coded stripe B is set to be the part 1 / 8 L behind the zero point position of the coded stripe A, so that when the scale tape is pulled, the phase difference between the signal SA1 of the coded stripe A collected by EA1 and the signal SB1 of the coded stripe B collected by EB1 is (1 / 4+2k)Π, and the phase difference between the signal SA2 of the coded stripe A collected by EA2 and the signal SB2 of the coded stripe B collected by EB2 is (1 / 4+2k)Π, thereby improving the precision from L / 4 to L / 8, eliminating the artificial reading error, and solving the technical problem of low measurement precision in the prior art.

[0032] The present application further detects whether the second encoder interface counts abnormally and whether a specific state occurs, to determine whether the scale tape is in the zero-return state.

[0033] The application also judges whether one of the encoding stripe B and the encoding stripe A is abnormal by detecting whether the difference between the count value of the first encoder interface and the count value of the second encoder interface is not equal to 4 or 3 or 5, and combining whether the scale tape is in the zero-reset state.

[0034] In the application, if the difference between the count value of the first encoder interface and the count value of the second encoder interface is not equal to 4 or 3 or 5, and the scale tape is not in the zero-reset state, a filtering algorithm is used to correct the combination of SA1' and SA2' or the combination of SB1' and SB2', so as to obtain the scale tape stretching length, thereby solving the technical problem that the prior art cannot calibrate. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The structural diagram of the encoding stripe A and the encoding stripe B on the scale tape of the application.

[0036] Figure 2 The top view of the relationship between the four-phase photoelectric signal acquisition module and the scale tape of the application.

[0037] Figure 3 The step flow chart of the application.

[0038] Corresponding names of the reference signs are as follows:

[0039] 1, four-phase photoelectric signal acquisition module mounting shell; 2, scale tape; 3, hook; 4, encoding stripe A; 5, encoding stripe B; 6, redundant part of the encoding stripe A; 7, redundant part of the encoding stripe B; 8, zero point position; 9, second part of the encoding stripe B; 10, photoelectric gate EA1; 11, photoelectric gate EA2; 12, photoelectric gate EB1; 13, photoelectric gate EB2. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the application clearer, the application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0041] In the description of the application, it should be noted that the terms “first” and “second” are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0042] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; of course, it can also be mechanical connection, or electrical connection; in addition, it can also be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0043] As shown in Figures 1-2 A high-precision digital tape measure based on double coding includes a shell, a four-phase photoelectric signal acquisition module mounting shell 1 mounted in the shell, a four-phase photoelectric signal acquisition module mounted on the four-phase photoelectric signal acquisition module mounting shell, a signal processing control circuit board connected with the four-phase photoelectric signal acquisition module, a tape 2 mounted in the shell, and a liquid crystal display screen connected with the signal processing control circuit board on the shell surface.

[0044] The tape is provided with a hook 3 extending out of the shell, and coding stripes A4 and coding stripes B5 are arranged on both sides of the tape along the extension direction of the tape. The coding stripes A are composed of first color stripes and second color stripes arranged in a cycle interval, the sum of the widths of two adjacent stripes is L, the part of the coding stripes A close to the hook is a redundant part 6 of the coding stripes A, and the end of the redundant part 6 of the coding stripes A away from the hook is a zero position 8.

[0045] The coding stripes B are composed of three parts, the first part is a redundant part 7 of the coding stripes B, the redundant part 7 of the coding stripes B is a first color stripe and has the same start and end positions as the redundant part of the coding stripes A, the second part 9 of the coding stripes B is a first color stripe with a width of 1.125 L, and the third part of the coding stripes B is composed of first color stripes and second color stripes arranged in a cycle interval. In summary, the width of the third part of the coding stripes B lagging behind the part after the zero position of the coding stripes A is 1 / 8 L.

[0046] The coding stripes A and the coding stripes B face the light beam emitting and receiving surface of the four-phase photoelectric signal acquisition module.

[0047] The signal processing control circuit board includes a comparison circuit and a micro control unit connected with the comparison circuit, the comparison circuit is connected with the four-phase photoelectric signal acquisition module, and the micro control unit is connected with the liquid crystal display screen.

[0048] The four-phase photoelectric signal acquisition module comprises an encoder A arranged opposite to the encoding stripe A and an encoder B arranged opposite to the encoding stripe B, and the encoder A and the encoder B are symmetrically distributed; the encoder A is composed of a photoelectric gate EA1 close to the hook and a photoelectric gate EA2 far from the hook, and the interval between the EA1 and the EA2 is (1 / 4+k) L, wherein k represents a position index; that is, the interval between the two photoelectric gates in the same group of encoders is L / 4; the encoder B is composed of a photoelectric gate EB1 close to the hook and a photoelectric gate EB2 far from the hook, and the interval between the EB1 and the EB2 is (1 / 4+k) L, and the center point of the EA1 is aligned with the zero position when the scale tape is in the zero-return state; the EA1, the EA2, the EB1 and the EB2 are respectively connected with a comparison circuit.

[0049] The micro control unit is connected with an external storage through a USB interface or WiFi, and the micro control unit is provided with a FLASH memory.

[0050] In the embodiment, when the scale tape is pulled, the four-phase photoelectric signal acquisition module will acquire analog electrical signals of four-phase sinusoidal waves through the EA1, the EA2, the EB1 and the EB2. For convenience of description, the waveform signal acquired by the EA1 is called SA1, the waveform signal acquired by the EA2 is called SA2, the waveform signal acquired by the EB1 is called SB1, and the waveform signal acquired by the EB2 is called SB2. Because the interval between the EA1 and the EA2 is (1 / 4+k) L, the SA1 and the SA2 are different by (1 / 2+2k)Π in phase, wherein Π represents a circular constant, and the angle unit follows the radian system, and the SB1 and the SB2 are also different by (1 / 2+2k)Π in phase. Since the two groups of encoders are arranged in alignment along the direction perpendicular to the stretching direction of the scale tape, and the interval between the encoding stripe A and the encoding stripe B in the circular arrangement part is 1 / 8 L, so the phase difference between SA1 and SB1 is (1 / 4+2k)Π, and the phase difference between SA2 and SB2 is (1 / 4+2k)Π by analogy; since SA1, SA2, SB1 and SB2 are analog signals of sinusoidal wave, the edges of these signals do not change obviously, which is not conducive to the accurate identification of the micro control unit, therefore, the waveforms of SA1, SA2, SB1 and SB2 are shaped into square wave signals in the same direction or in the opposite direction, i.e. SA1', SA2', SB1' and SB2', and then the shaped square wave signals SA1', SA2', SB1' and SB2' are input to the micro control unit, the micro control unit can obtain the stretching length of the current tape, the zero reset state and whether the measurement error occurs by identifying and processing SA1', SA2', SB1' and SB2', the micro control unit displays the stretching length information, the zero reset state information and the measurement error information of the current tape to the liquid crystal display screen and transmits the stretching length information, the zero reset state information and the measurement error information to the external storage through the USB interface or WiFi, or the stretching length information, the zero reset state information and the measurement error information can be sent to the internal FLASH memory of the micro control unit, which eliminates the manual reading error, improves the measurement efficiency and reduces the error rate.

[0051] As shown in Figure 3 a high-precision digital tape measure based on double encoding, comprising the following steps:

[0052] S1, when pulling the tape, EA1 collects the light signal of the encoding stripe A to obtain a sinusoidal analog signal SA1; EA2 collects the light signal of the encoding stripe A to obtain a sinusoidal analog signal SA2; EB1 collects the light signal of the encoding stripe B to obtain a sinusoidal analog signal SB1; and EB2 collects the light signal of the encoding stripe B to obtain a sinusoidal analog signal SB2;

[0053] S2, input SA1, SA2, SB1 and SB2 into the comparison circuit for waveform shaping, and the corresponding square wave signals are SA1', SA2', SB1' and SB2', respectively;

[0054] S3, input SA1', SA2', SB1' and SB2' into the micro control unit for automatic counting of the edge number to obtain the tape stretching length;

[0055] S4, the micro control unit outputs the tape stretching length to the liquid crystal display for display.

[0056] The phase difference between SA1 and SA2 is (1 / 2+2k)Π, the phase difference between SB1 and SB2 is (1 / 2+2k)Π; the phase difference between SA1' and SA2' is (1 / 2+2k)Π, the phase difference between SB1' and SB2' is (1 / 2+2k)Π; the phase difference between SA1 and SB1 is (1 / 4+2k)Π, the phase difference between SA2 and SB2 is (1 / 4+2k)Π, the phase difference between SA1' and SB1' is (1 / 4+2k)Π, and the phase difference between SA2' and SB2' is (1 / 4+2k)Π.

[0057] S3 includes:

[0058] SC1, input SA1', SA2' into the first encoder interface of the micro control unit, and input SB1', SB2' into the second encoder interface of the micro control unit;

[0059] SC2, when the length of the tape is L, both SA1' and SA2' will have a rising edge and a falling edge, and both SB1' and SB2' will have a rising edge and a falling edge;

[0060] If the first encoder interface only counts the rising edge or the falling edge of one of the square wave signals of SA1' and SA2', the count value changes by 1, and the length of the tape corresponding to the change of the count value by 1 is L;

[0061] If the second encoder interface only counts the rising edge or the falling edge of one of the square wave signals of SB1' and SB2', the count value changes by 1, and the length of the tape corresponding to the change of the count value by 1 is L;

[0062] If the first encoder interface counts both the rising edge and the falling edge of SA1' and SA2', the count value changes by 4, and the length of the tape corresponding to the change of the count value by 1 is L / 4, realizing 4 times frequency, i.e. improving the measurement accuracy of the tape by 4 times;

[0063] If the second encoder interface counts both the rising edge and the falling edge of SB1' and SB2', the count value changes by 4, and the length of the tape corresponding to the change of the count value by 1 is L / 4, realizing 4 times frequency, i.e. improving the measurement accuracy of the tape by 4 times;

[0064] If the first encoder interface counts both the rising edge and the falling edge of SA1' and SA2' and the second encoder interface counts both the rising edge and the falling edge of SB1' and SB2', the count value changes by 8, and the length of the tape corresponding to the change of the count value by 1 is L / 8, realizing 8 times frequency, i.e. improving the measurement accuracy of the tape by 8 times;

[0065] The SC2 further comprises: if the second encoder interface counts abnormally, and the difference between the count value of the first encoder interface and the count value when the scale tape is stretched to a length L is greater than or equal to 3, and the difference between the count value of the second encoder interface and the count value when the scale tape is stretched to a length L is -1, the scale tape is in a zero-return state; the information that the scale tape is in the zero-return state is output to the liquid crystal display for display; if there is a count error between the first encoder and the second encoder at this time, the count values of the first encoder and the second encoder can also be forcibly cleared to zero. Because the encoding stripe B is cyclically encoded 1.125 L behind the encoding stripe A, the count value of the first encoder interface normally decreases in the last 1.125 periods when the scale tape is retracted, and the second encoder interface enters an abnormal encoding state, and the count value thereof will change between 0 and 1; the difference between the count value of the first encoder interface and the count value at the fourth time in the past is greater than or equal to 3 when the scale tape is in the zero-return state, and thus the zero-return can be realized.

[0066] The SC2 further comprises: if the first encoder interface counts the rising and falling edges of SA1' and SA2', and the second encoder interface counts the rising and falling edges of SB1' and SB2', and the difference between the count value of the first encoder interface and the count value of the second encoder interface is not equal to 4 or 3 or 5, and the scale tape is not in the zero-return state, one of the encoding stripe B and the encoding stripe A is abnormal; the measurement abnormality information is output to the liquid crystal display for display.

[0067] The SC2 further comprises: when one of the encoding stripe B and the encoding stripe A is abnormal, a filtering algorithm is used to correct the combination of SA1' and SA2' or the combination of SB1' and SB2', to obtain the scale tape stretching length.

[0068] In the embodiment, whether the scale tape is in the zero-return state is determined by detecting whether the count of the second encoder interface is abnormal and whether a specific state occurs. Whether one of the encoding stripe B and the encoding stripe A is abnormal is determined by detecting whether the difference between the count value of the first encoder interface and the count value of the second encoder interface is not equal to 4 or 3 or 5, and combining whether the scale tape is in the zero-return state.

[0069] In the embodiment, if it is detected that the difference between the count value of the first encoder interface and the count value of the second encoder interface is not equal to 4 or 3 or 5, and the scale tape is not in the zero-return state, a filtering algorithm is used to correct the combination of SA1' and SA2' or the combination of SB1' and SB2', to obtain the scale tape stretching length, thereby solving the technical problem that the prior art cannot be calibrated.

[0070] Finally, it should be noted that: the above embodiments are merely the preferred embodiments of the present application to illustrate the technical solutions of the present application, rather than limit, of course, is not to limit the scope of the patent of the present application; although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still be modified to the technical solutions recorded in the foregoing embodiments, or part or all of the technical features are replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application; that is to say, but whatever is made in the main design idea and spirit of the present application has no substantial significance of the change or polish, the technical problem solved is still consistent with the present application, and should be included in the protection scope of the present application; in addition, the technical solutions of the present application are directly or indirectly applied to other related technical fields, which are also included in the patent protection scope of the present application.

Claims

1. A high-precision digital measuring tape based on dual encoding, characterized in that, Includes an outer casing, a four-phase photoelectric signal acquisition module mounting shell (1) installed inside the outer casing, a four-phase photoelectric signal acquisition module installed on the four-phase photoelectric signal acquisition module mounting shell, a signal processing control circuit board connected to the four-phase photoelectric signal acquisition module, a ruler (2) installed inside the outer casing, and an LCD screen installed on the outer casing surface and connected to the signal processing control circuit board. The tape is provided with a hook (3) extending out of the outer shell. The tape is provided with coded stripes A (4) and B (5) on both sides along the tape extension direction. The coded stripe A is composed of a first color stripe and a second color stripe of equal width arranged in a cyclical interval. The sum of the widths of two adjacent stripes is L. The part of the coded stripe A close to the hook is the redundant part of the coded stripe A (6). The end of the redundant part (6) of the coded stripe A away from the hook is the zero point position (8). The coded stripe B consists of three continuous parts. The first part is the redundant part (7) of the coded stripe B. The redundant part (7) of the coded stripe B is the first color stripe and has the same start and end positions as the redundant part of the coded stripe A. The second part (9) of the coded stripe B has a width of 1.

125. The first color stripe of L, and the third part of the coded stripe B are composed of the first color stripe and the second color stripe arranged in a cyclical interval; Encoded stripes A and B face the beam emission and reception surfaces of the four-phase photoelectric signal acquisition module.

2. The high-precision digital measuring tape based on dual encoding according to claim 1, characterized in that, The signal processing control circuit board includes a comparator circuit and a microcontroller unit connected to the comparator circuit. The comparator circuit is connected to a four-phase photoelectric signal acquisition module, and the microcontroller unit is connected to an LCD screen.

3. A high-precision digital measuring tape based on dual encoding according to claim 2, characterized in that, The four-phase photoelectric signal acquisition module includes encoder A, which is set opposite to the coded stripe A, and encoder B, which is set opposite to the coded stripe B. Encoder A and encoder B are symmetrically distributed. Encoder A consists of photoelectric gate EA1 (10) close to the hook and photoelectric gate EA2 (11) far from the hook. The distance between EA1 and EA2 is (1 / 4+k). L, where k represents the position index; encoder B consists of photoelectric gate EB1 (12) close to the hook and photoelectric gate EB2 (13) far from the hook, with a distance of (1 / 4+k) between EB1 and EB2. L, when the tape is in the zero state, the center point of EA1 is aligned with the zero position; EA1, EA2, EB1, and EB2 are respectively connected to the comparator circuit.

4. A high-precision digital measuring tape based on dual encoding according to claim 3, characterized in that, The microcontroller connects to external storage via USB or WiFi.

5. The method for implementing a high-precision digital measuring tape based on dual encoding according to claim 3, characterized in that, Includes the following steps: S1. When the tape is pulled, EA1 collects the optical signal of the coded stripe A to obtain a sinusoidal analog electrical signal SA1; EA2 collects the optical signal of the coded stripe A to obtain a sinusoidal analog electrical signal SA2; EB1 collects the optical signal of the coded stripe B to obtain a sinusoidal analog electrical signal SB1; EB2 collects the optical signal of the coded stripe B to obtain a sinusoidal analog electrical signal SB2. S2. Input SA1, SA2, SB1, and SB2 into the comparator circuit for waveform shaping, and the resulting square wave signals are SA1′, SA2′, SB1′, and SB2′, respectively. S3. Input SA1′, SA2′, SB1′, and SB2′ into the microcontroller unit to automatically count the number of edges and obtain the tape stretching length; S4. The microcontroller outputs the stretching length of the tape to the LCD screen for display.

6. The method for implementing a high-precision digital measuring tape based on dual encoding according to claim 5, characterized in that, The phase difference between SA1 and SA2 is (1 / 2+2k)Π, the phase difference between SB1 and SB2 is (1 / 2+2k)Π; the phase difference between SA1′ and SA2′ is (1 / 2+2k)Π, the phase difference between SB1′ and SB2′ is (1 / 2+2k)Π; the phase difference between SA1 and SB1 is (1 / 4+2k)Π, the phase difference between SA2 and SB2 is (1 / 4+2k)Π, the phase difference between SA1′ and SB1′ is (1 / 4+2k)Π, and the phase difference between SA2′ and SB2′ is (1 / 4+2k)Π, where Π represents pi, and the unit of angle follows the radian system.

7. The method for implementing a high-precision digital measuring tape based on dual encoding according to claim 6, characterized in that, S3 include: SC1. Input SA1′ and SA2′ into the first encoder interface of the microcontroller, and input SB1′ and SB2′ into the second encoder interface of the microcontroller. SC2. When the stretching length of the tape is L, SA1′ and SA2′ will each have a rising edge and a falling edge, and SB1′ and SB2′ will each have a rising edge and a falling edge. If the first encoder interface counts only the rising or falling edge of one of the square wave signals SA1′ and SA2′, the count value changes by 1, and the tape stretching length corresponding to the count value change of 1 is L. If the second encoder interface counts only the rising or falling edge of one of the square wave signals SB1′ and SB2′, the count value changes by 1, and the tape stretching length corresponding to the count value change of 1 is L. If the first encoder interface counts both the rising and falling edges of SA1′ and SA2′, the count value changes by 4, and the tape stretching length corresponding to the count value change of 1 is L / 4. If the second encoder interface counts both the rising and falling edges of SB1′ and SB2′, the count value changes by 4, and the tape stretching length corresponding to the count value change of 1 is L / 4. If the first encoder interface counts both the rising and falling edges of SA1′ and SA2′, and the second encoder interface counts both the rising and falling edges of SB1′ and SB2′, then the count value changes by 8. The tape stretching length corresponding to the count value change of 1 is L / 8.

8. The method for implementing a high-precision digital measuring tape based on dual encoding according to claim 7, characterized in that, SC2 also includes: if the second encoder interface count is abnormal, and the difference between the count value of the first encoder interface and the count value when the tape stretch length is L is greater than or equal to 3, and the difference between the count value of the second encoder interface and the count value when the tape stretch length is L is -1, then the tape is in a zero state; the tape is in a zero state information output to the LCD screen for display.

9. The method for implementing a high-precision digital measuring tape based on dual encoding according to claim 7, characterized in that, SC2 further includes: if the first encoder interface counts both the rising and falling edges of SA1′ and SA2′ and the second encoder interface counts both the rising and falling edges of SB1′ and SB2′, and if the difference between the count value of the first encoder interface and the count value of the second encoder interface is not equal to 4, 3, or 5, and the tape is not in a zero-return state, then one of the coded stripes B and A is abnormal; the measurement abnormality information is output to the LCD screen for display.

10. The method for implementing a high-precision digital measuring tape based on dual encoding according to claim 9, characterized in that, SC2 also includes: when one of the coded stripes B and A is abnormal, a filtering algorithm is used to correct the combination of SA1′ and SA2′ or the combination of SB1′ and SB2′ to obtain the tape stretching length.

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