An anti-tamper encoded read sensor and method for a water meter

Abstract

This invention relates to the field of metering instrument data acquisition technology, specifically to an anti-interference coded reading sensor and reading method for water meters. The method involves mapping the resistance value of each code disk area to three mechanical connection states, corresponding to different operating conditions of the water meter's discontinuous gear mechanism. The width of the dividing line between the digits 9 and 0 on the code disk is greater than the width of the dividing lines between other digits. This results in a shorter time window and later triggering of the brush when passing through this critical zone, providing a clear timing distinction window for the carry-over action of the higher-order digits and effectively avoiding misjudgments when multiple digits carry over simultaneously. During reading, the resistance corresponding to different digits is measured, and a software algorithm based on gear rules and water flow constraints is used for state verification, eliminating illegal reading combinations caused by mechanical intermittents or water hammer reversal. This solves the problem of code skipping and errors in the carry-over critical zone of existing direct-reading sensors, improving the reliability and accuracy of electronic readings.

Description

Technical Field

[0001] This invention relates to the field of metering instrument data acquisition technology, and in particular to an anti-interference coded reading sensor and reading method for water meters. Background Technology

[0002] Common coded water meters use photoelectric or magnetic elements to sense changes in the physical characteristics of the code disk pattern, calculate a unique fixed code corresponding to the position of each digit, and identify the water meter reading.

[0003] Passive direct-reading sensors typically employ a "position-determination" principle. For example, the technical solution disclosed in Chinese Patent Application No. CN03112885.8, entitled "Data Acquisition Sensor," involves setting a data acquisition plate with electrodes (or conductive patterns) next to the digit wheel. Springs or brushes synchronized with the digit wheel contact the electrodes at different positions, converting the mechanical position into an electrical signal to directly read the digit wheel's position. This solves the problems of high power consumption, susceptibility to interference, and high maintenance requirements of active pulse meter reading systems, achieving passive, stable, and direct reading acquisition.

[0004] However, since the existing water meter digit wheel reading is a mechanical non-continuous gear structure, the non-continuous gear used to drive the next digit wheel to rotate the previous digit wheel has mechanical intermittent. Specifically, the lower digit wheel only drives the higher digit wheel to rotate one tooth pitch through an isolated convex tooth at the moment it turns from the number "9" to "0", completing the "carry-over" when it reaches ten.

[0005] This mechanical structure exhibits significant critical regions of reading uncertainty at two locations:

[0006] 1) When multiple digit wheels are simultaneously in the "9→0" carry-over critical state (for example, when the reading is "199", both the units digit and the tens digit are in the carry-over process);

[0007] 2) Due to the water hammer effect in the pipeline, when the character wheel undergoes slight forward or reverse rotation, the mechanical position becomes ambiguous in the critical region, causing the brush to potentially contact two code areas simultaneously or resulting in unstable contact. Existing equally divided electrode or code disk designs cannot distinguish between subtle states such as "about to carry over," "carrying over in progress," and "carry over completed," making it highly susceptible to abrupt reading errors under these two conditions (e.g., misreading "199" as "100" or "200").

[0008] To address the problems in the prior art, this invention provides an anti-interference coded reading sensor and reading method for water meters. Summary of the Invention

[0009] The purpose of this invention is to provide an anti-interference coded reading sensor and reading method for water meters, so as to solve the technical problem of fuzzy reading caused by the non-continuous gear progression of water meter digits in the prior art.

[0010] The technical solution of the present invention is: an anti-interference coded reading sensor for water meters, comprising a main control board, a flexible circuit board, and a sensing unit corresponding to each water meter digit wheel. The sensing unit includes a digit wheel and a code disk that are arranged one-to-one on the water meter, and a brush mounted on a substrate and rotating with the digit wheel; multiple sensing units are arranged in descending order of the number of bits.

[0011] Each of the code disks is divided into N regions, and each region is connected to a resistor. The brushes follow the character wheel and contact a region of the code disk corresponding to the current character wheel.

[0012] Each of the code wheels and its connected resistors is configured such that the resistance value presented when the brush contacts different areas represents three mechanical connection states of the character wheel relative to the adjacent higher character wheel: a state connected to the higher character wheel code wheel circuit, an independent state, and a state connected to the lower character wheel code wheel circuit.

[0013] The resistors of the multiple code disks are connected in parallel to a common terminal; the brush serves as a signal output terminal and is connected to a signal processing circuit, which reads the reading corresponding to the position of the character wheel through AD sampling;

[0014] The three mechanical connection states specifically correspond to the following operating conditions of the water meter's discontinuous gear mechanism:

[0015] When the area contacted by the low-position brush corresponds to the boundary area from the digit "9" to "0", it is in the state of forward carry connection of the high-position character wheel code disk circuit;

[0016] When the area of ​​contact of the low-position brush corresponds to the numbers "0" to "9", it presents an independent state;

[0017] When the area of ​​contact of the low-position brush is in the boundary area of ​​the digit "0" close to "9", it presents the state of the high-position character wheel code disk circuit reversing carry connection;

[0018] On the code disk, the carry area corresponding to the digit "9" turning into the digit "0" has a physical width. Larger than the width of the separator lines between other numbers The widened isolation zone;

[0019] The width of the widened isolation zone Width of other number separator lines The ratio satisfies: .

[0020] Preferably, the sensing unit is configured as: a code disk that corresponds one-to-one with the character wheel, with the axis of the character wheel as the center, and the spacing width between adjacent character wheel numbers on the code disk is equal;

[0021] The other ends of all the resistors on the sensing unit corresponding to the highest bit wheel are connected in parallel to serve as the first signal terminal, which is led out through the first trace of the flexible circuit board.

[0022] The brush of the sensing unit corresponding to the highest-ranking character wheel serves as the second signal terminal, and is connected to the parallel terminal of all resistors in the sensing unit corresponding to the adjacent lower-ranking character wheel through the second trace of the flexible circuit board.

[0023] Connect all the sensor units corresponding to the character wheels in a daisy chain manner, up to the lowest character wheel;

[0024] The brush of the sensing unit corresponding to the lowest bit wheel is connected to a common reference level through the flexible circuit board.

[0025] Preferably, the signal processing circuit includes a microprocessor, which is used to execute the following reading logic:

[0026] a. Measure the electrical parameters between the signal output terminal and the common terminal;

[0027] b. Calculate the candidate state combinations for each word wheel based on the pre-stored mapping relationship, wherein the state includes a determined digital value and a carry critical state;

[0028] c. Apply verification rules based on discontinuous gear carry rules and water flow physical constraints to perform legality verification and screening of candidate state combinations;

[0029] d. Output the verified and valid reading.

[0030] Preferably, the verification rule includes at least the following: when a certain high-order word wheel is calculated to be in the "carried" state, the state of its adjacent low-order word wheel is the "carried critical state" or the result state after the carried critical state is completed.

[0031] Preferably, the microprocessor is further configured to: when a state change that does not conform to the volume cumulative monotonicity is detected within a short period of time, determine it as a water hammer reversal interference, and maintain the previous stable reading unchanged.

[0032] A reading method for an anti-interference coded reading sensor for a water meter, comprising:

[0033] Obtain the total resistance value of the anti-interference coded reading sensor;

[0034] Based on a pre-stored mapping table of encoder resistance arrangement, the total resistance value is calculated into a combination of candidate reading states for each character wheel. The states include: determining the digital value, 9-0 carry critical positive, and 9-0 carry critical negative.

[0035] The candidate combinations are filtered using state transition verification rules: if the state of the higher-order word wheel is "carried", then the state of its adjacent lower-order word wheel must be "9-0 carry critical positive" or its result; illegal combinations that do not conform to the state transition verification rules and other combinations that do not conform to physical laws are eliminated.

[0036] After filtering, if only one valid combination remains, the corresponding reading for that valid combination will be output; if multiple combinations remain, the combination with the smallest change in the previous historical reading will be selected for output.

[0037] Store the valid reading of this output for use in the next logical judgment.

[0038] A water meter includes the aforementioned anti-interference coded reading sensor for the water meter.

[0039] A meter reading system includes the aforementioned water meter and a meter reading terminal or concentrator that is communicatively connected to the water meter.

[0040] Compared with the prior art, the advantages of the present invention are:

[0041] This invention directly maps the resistance value to the three physical connection states of the "discontinuous gear", making the electronic reading logic consistent with the mechanical action, thereby improving the rationality of the encoding and the anti-interference ability.

[0042] The code disk of this invention has a widened isolation zone at the 9-0 position, and the least significant critical bit is kept in a large state for a shorter time, thus avoiding the problem of overlapping critical states and reading errors.

[0043] The rule-based state verification algorithm effectively identifies and filters out transient and erroneous electrical signal combinations caused by mechanical gaps and water hammer reversal, ensuring the final stability and accuracy of readings under complex real-world operating conditions. Without altering the original mechanical metering core of the water meter, it significantly improves the reliability of direct-reading electronic readings, making it particularly suitable for remote meter reading scenarios where reading stability is extremely critical. Attached Figure Description

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0045] Figure 1 This is a schematic diagram of the anti-interference coded reading sensor system structure described in this invention;

[0046] Figure 2 This is a schematic flowchart of the reading method of the anti-interference coded reading sensor described in this invention;

[0047] Figure 3 This is a schematic diagram of the surface electrical structure of the high-position encoder disk described in this invention;

[0048] Figure 4 This is a schematic diagram of the electrical structure of the low-position encoder surface described in this invention;

[0049] Figure 5 This is a schematic diagram of the surface of the encoder board of the anti-interference coded reading sensor described in this invention;

[0050] Figure 6 This is a schematic diagram of the first wheel structure of the anti-interference coded reading sensor gear carry structure described in this invention;

[0051] Figure 7 This is a schematic diagram of the middle gear structure of the anti-interference coded reading sensor gear carry structure described in this invention;

[0052] Figure 8 This is a schematic diagram of the last gear structure of the anti-interference coded reading sensor gear carry structure described in this invention. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to specific embodiments:

[0054] like Figure 1 As shown, an anti-interference coded reading sensor for water meters includes a main control board, a flexible circuit board, and sensing units corresponding to each water meter digit wheel. Multiple sensing units are arranged in descending order of the number of bits.

[0055] The sensing unit includes: multiple digit wheels (units, tens, hundreds, etc.) and a code disk (divided copper foil on a PCB substrate) corresponding to each digit wheel. See appendix. Figure 3 Or 4, each code disk (e.g.) Figure 2 The number is divided into 10 regions (S0-S9), representing the numbers 0-9 respectively.

[0056] Each region is connected to a resistor (R0-R9), which contacts the code disk through brushes on the character wheel. The size of the brushes is within a region and does not exceed the space of the divided code disk. Each divided code disk corresponds to three states: connected to the previous code disk, completely within the current character wheel code disk, and connected to the next character wheel code disk.

[0057] Correspondingly, each code disk has three resistance states for its reading: parallel with the upper part, independent of itself, and parallel with the lower part.

[0058] When the area of ​​contact of the low-position brush corresponds to the number "9", it is in the state of forward carry connection of the high-position character wheel code disk circuit;

[0059] When the area of ​​contact of the low-position brush corresponds to the numbers "0" to "9", it presents an independent state;

[0060] When the area of ​​contact of the low-position brush is in the boundary area of ​​the digit "0" close to "9", it presents the state of the high-position character wheel code disk circuit reversing carry connection.

[0061] See appendix Figure 5 The schematic diagram of the encoding table board shows that the resistors of multiple code disks are connected in parallel to a common terminal. The resistors are selected to meet the recognition requirements, and adjacent resistor values ​​cannot be close. The brush is a gold-plated copper sheet that connects to the common terminal and to the marked area on the code disk. See Figure 6 or Appendix. Figure 8 The diagram shows a spring plate mounted on the surface of the character wheel (body). The spring plate acts as a position detection unit for the character wheel, outputting pulses or switching signals to detect the position of the character wheel, facilitating decoding and reading. The brush is a current transmission element, serving as a signal output terminal connected to a signal processing circuit. The signal processing circuit uses AD sampling to read the reading corresponding to the position of the character wheel, converting the mechanical reading into an electronic reading, saving it, and outputting it for display.

[0062] AD sampling acquires voltage signals, with a sampling accuracy of no less than 10 bits. The sampling resolution is determined by the number of bits in the ADC and the reference voltage, and the calculation formula is: resolution = (Vref) / 2^N.

[0063] Where: Vref represents the reference voltage of the ADC (unit: volts V), and N represents the resolution bits of the ADC (unit: bits).

[0064] The number of bits N determines how many discrete levels the reference voltage range is divided into. For example, a 12-bit ADC would divide the voltage range into 2¹² = 4096 levels. The reference voltage is the base voltage used by the ADC for quantization, determining the entire range. Sampling resolution represents the smallest voltage change that the ADC can recognize, measured in volts (V) or millivolts (mV).

[0065] The water meter uses a decimal system, and the carry-over mechanism is achieved through a non-continuous gear carry-over structure. Each digit wheel only rotates one tooth pitch when it turns from "9" to "0", by using an isolated convex tooth on its shaft to drive the gear of the adjacent higher-level digit wheel to rotate by one tooth pitch, thus achieving "carry-over when reaching ten".

[0066] Specifically, when the lower-position character wheel rotates from "0" to "8", its protruding teeth idle next to the driven gear of the higher-position character wheel without contact, and the higher-position character wheel remains completely stationary. When the lower-position character wheel rotates to the end of "9" and is about to jump to the critical position of "0", its protruding teeth rotate to the position where they align with the tooth groove of the driven gear of the higher-position character wheel. With the last bit of rotation of the lower-position character wheel (from 9 to 0), the protruding teeth engage with the tooth groove of the higher-position gear.

[0067] See appendix Figure 6 Appendix Figure 7 Appendix Figure 8 The diagrams provided show the structure of the first, middle, and last gears in the gear shifting mechanism. Each gear has a toothed groove for easy shifting.

[0068] After the convex tooth engages, it continues to rotate with the lower-position digit wheel, driving the higher-position gear to rotate exactly one tooth pitch. Each tooth pitch rotation of the higher-position gear corresponds to the higher-position digit wheel advancing to "1" (e.g., jumping from 3 to 4). Simultaneously, the lower-position digit wheel completes the jump from "9" to "0".

[0069] After the carry-over is completed, the convex tooth disengages from the tooth groove of the higher gear, and the higher gear is locked in the new numerical position (usually by a locating pin or the gear itself), waiting to be driven by the lower gear next time.

[0070] In one embodiment or other implementation, the sensing unit is configured as a code disk that corresponds one-to-one with the character wheels, with the spacing width between adjacent character wheel numbers on the code disk being equal, centered on the axis of the character wheels.

[0071] The other ends of all the resistors on the sensing unit corresponding to the highest bit wheel are connected in parallel to serve as the first signal terminal, which is led out through the first trace of the flexible circuit board.

[0072] The brush of the sensing unit corresponding to the highest-ranking character wheel serves as the second signal terminal, and is connected to the parallel terminal of all resistors in the sensing unit corresponding to the adjacent lower-ranking character wheel through the second trace of the flexible circuit board.

[0073] Connect all the sensor units corresponding to the character wheels in a daisy chain manner, up to the lowest character wheel;

[0074] The brush of the sensing unit corresponding to the least significant word wheel is connected to a common reference level via a flexible circuit board.

[0075] The ADC measurement point of the main control board is connected to the first signal terminal of the highest bit wheel through a flexible circuit board. The other end is connected to a common reference level (e.g., ground (GND)). The measurement is the total resistance or voltage between the two signal (pin) terminals. If the total resistance is measured, the resistance value is determined by the resistance connected to the area currently contacted by the brush of each bit wheel from high to low. Based on the voltage or resistance value obtained by the measurement, the readings of all bit wheels are decoded.

[0076] The reading conversion is completed by using the resistance or voltage information corresponding to each code wheel, ensuring that each character wheel can be identified by only two pins on the corresponding circuit board. The counter and the main board are connected by a simple ribbon cable FPC cable, which facilitates production.

[0077] When the digit wheel is in the 0-8 state, the digit wheel does not consider the state of other digit wheels. However, in the carry state, the reading of the digit wheel itself may affect the reading of the previous digit wheel. When carrying from 9 to 0, the previous digit wheel also needs to start carrying. Since the existing water meter digit wheel reading is a mechanical non-continuous gear structure, the non-continuous gear used to drive the rotation of the next digit wheel to the previous digit wheel has mechanical intervals. When carrying from a higher position (such as carrying from 1 to 2), there are three states: not yet carrying, carrying during the carrying process, and carrying completed. At the same time, the lower digit wheel is also in one of the three states: 9, 9-0, and 0.

[0078] Typically, the reading in the carry state is marked as the reading of the carry state, such as 2 for 1-2, 3 for 2-3, and 0 for 9-0; if the previous digit is in the carry state, the next digit is marked as 0, so that the readings will not be confused.

[0079] When the water meter is rotating forward, under special circumstances, if the reading is 99 / 999 / 9999 / 99999, and the code is evenly distributed, if the reading exceeds two digits and is in a 9-0 carry-over state, such as reading 199, the reading state is 1, 9-0, 9-0. If the last two digits are recorded as 0 according to the previous rules, and the first digit is not carried over and is recorded as 1, the actual reading is 100. However, if the state is 199 or 200, then a reading error has occurred.

[0080] Therefore, in another embodiment or other implementation of the present invention, the sensing unit is configured such that: the sensing unit is configured such that: on the code disk, the carry area corresponding to the digit "9" turning to the digit "0" has a physical width. Larger than the width of the separator lines between other numbers The expanded isolation zone.

[0081] In detail, increase the distance between the separator line between 9 and 0 on the code disk area; that is, increase the width of the separator line between the marked digits 9 and 0. Larger than the width of the separator lines between other numbers Furthermore, during the critical process of the brush turning from 9 to 0, the signal for effective contact in the "0" region arrives with a delay relative to the mechanical action, and the time it takes for the brush to pass through the region between 9 and 0 is shorter, ensuring that when the previous bit carries over, the next bit must be in the 9-0 carry-over state.

[0082] Widen the isolation zone Width of other number separator lines The ratio satisfies: For example, in a specific embodiment, 0-9 widens the isolation zone. Compared to other number separator widths The widening ratio is 60% ( =1.6).

[0083] By widening the space between 9 and 0, when the tens digit wheel begins its carry-over action as the units digit changes from 9 to 0, the units digit brush has already stably fallen into the "0" area or a clear "9-0 critical" signal has been identified. This avoids the problem of reading errors caused by the evenly divided code disk and non-continuous gear structure, which rotates in the forward direction, thus ensuring accurate reading.

[0084] In addition, due to the discontinuity of the gears, in actual operation of the water meter, the water meter will rotate in both directions due to the combined effect of water hammer and air in the pipeline. When the high-position digit wheel rotates forward to advance, the low-position digit wheel rotates backward and to the position of 9. The high-position digit wheel does not rotate backward due to the discontinuous teeth, which can easily lead to incorrect readings.

[0085] For example, if the reading is 200 after a carry-over, the higher digit becomes 2, the second digit is 0 (carry-over state), and the lowest digit is 9-0 (reverse carry-over state). According to conventional logic, the reading should be 210, which is inconsistent with the reading 200, indicating an error in the reading.

[0086] However, by increasing the distance between the separator line between the lowest bit 9 and 0 on the code wheel, and making the state time of the low-bit critical bit shorter, the problem of reading errors caused by the low-bit word wheel reversing is avoided.

[0087] The signal processing circuit includes a microprocessor and a signal acquisition unit / bus, and its internal storage contains, for example,... Figure 2 The reading logic algorithm shown is as follows:

[0088] a. Measure the different resistance values ​​between the signal output terminal and the common terminal;

[0089] b. Calculate the candidate state combinations for each word wheel based on the pre-stored mapping relationship. The states include a determined digital value and a carry-critical state.

[0090] c. Apply verification rules based on discontinuous gear carry rules and water flow physical constraints to perform legality verification and screening of candidate state combinations;

[0091] d. Output the verified and valid reading.

[0092] The microprocessor is an MCU. During operation, the MCU's ADC pin measures the voltage at the brush leads (proportional to the total resistance). The MCU first queries a preset "resistance value-state combination" mapping table to obtain a set of possible state combinations. For example, the resistance value corresponds to two candidates: a tens digit of "3" and a units digit of "9" (critical state) and a tens digit of "2" and a units digit of "0".

[0093] Subsequently, the algorithm uses a rule base for verification. The core rule is: if a high-order word wheel is decoded as "carried from the number n to n+1", then its immediately adjacent low-order word wheel must be decoded as "9→0 carry-critical state or just completed carry" 0.

[0094] According to this rule, the tens digit is "3" and the units digit is "9", which is at the critical position and this combination is valid (indicating that it is carrying from "29" to "30"); while the tens digit is "2" and the units digit is "0", which is invalid in the context of "29" (because the tens digit does not show a carry action, the units digit should not be 0). The algorithm eliminates the invalid combination.

[0095] For instantaneous reversals caused by water hammer, the algorithm identifies them by recording a short sequence of states. For example, if the reading jumps from "200" to "199" within milliseconds, an impossible reversal event is identified. The reading logic algorithm will ignore this jump and maintain the output "200" until the next stable state conforming to a positive accumulation pattern is confirmed.

[0096] Through the coordinated operation of the aforementioned hardware and software, the sensor of this invention can output a stable electronic reading that is highly consistent with the mechanical indication in the complex working environment of a non-continuous gear water meter, thus solving the problem of critical ambiguity and resulting reading errors.

[0097] Based on the encoder described above, the present invention also provides a reading method for an anti-interference coded reading sensor for a water meter, comprising:

[0098] Obtain the total resistance value of the anti-interference coded reading sensor;

[0099] Based on the pre-stored code disk resistor arrangement mapping table, the total resistance value is calculated into a combination of candidate reading states for each character wheel. The states include: determined digital value, 9-0 carry critical positive, and 9-0 carry critical negative.

[0100] The candidate combinations are filtered using state transition verification rules: if the state of the higher-order word wheel is "carried", then the state of its adjacent lower-order word wheel must be "9-0 carry critical positive" or its result; illegal combinations that do not conform to the state transition verification rules and other illegal combinations that do not conform to physical laws (such as invalid reverse sequences) are eliminated.

[0101] After filtering, if only one valid combination remains, the corresponding reading for that valid combination will be output; if multiple combinations remain, the combination with the smallest change in the previous historical reading will be selected for output.

[0102] Store the valid reading of this output for use in the next logical judgment.

[0103] This invention provides an anti-interference coded reading sensor and reading method for water meters. Targeting the non-continuous gear carry-over structure of the meter, it uses resistance partitioning and three connection states for encoding. Furthermore, a widened isolation zone, with a physical width greater than the separation width between other digits, is set on the code disk corresponding to the carry-over critical position where the digit "9" turns to "0". During carry-over, the previous digit will only change if the next digit is in a forward 9-to-0 carry-over state or a reverse 0-to-9 carry-over state. This design results in a shorter and later triggering time window for the brush to change contact state when passing through this critical area, providing a clear timing distinction window for the carry-over action of higher digit wheels and effectively avoiding misjudgments when multiple digits carry over simultaneously.

[0104] Furthermore, in practice, the states of reading 99 / 999 / 9999 / 99999 are listed separately. Impossible states are eliminated during forward rotation, reverse rotation, and repeated forward and reverse rotation. States that are prone to misjudgment are corrected by software logic algorithms to prevent the reading from jumping and ensure the accuracy of the recognized reading.

[0105] This invention establishes a state validity verification rule based on the carry-over rules of the discontinuous gears in water meters (e.g., when the previous digit carries over, the next digit must be in a "9→0" critical state) and the physical constraint of irreversible water flow (although there is reversal, the total volume accumulates in one direction). Impossible state combinations (e.g., the higher digit has carried over while the lower digit is not in a critical state) are eliminated or corrected, ultimately outputting a stable and correct reading. This overcomes the problem in existing direct-reading sensors that cannot effectively handle the critical state of discontinuous gear carry-over in water meters and the reading jumps, incorrect codes, and misreadings caused by water hammer reversal.

[0106] Furthermore, the present invention provides a water meter, including the above-described anti-interference coded reading sensor for a water meter.

[0107] Furthermore, the present invention provides a meter reading system, including the water meter described above and a meter reading terminal or concentrator that is communicatively connected to the water meter.

[0108] The above embodiments are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

Claims

1. An anti-interference coded reading sensor for water meters, comprising a main control board, a flexible circuit board, and a sensing unit corresponding to each water meter digit wheel, characterized in that, The sensing unit includes a digit wheel and a code disk that are set one-to-one on the water meter, and a brush mounted on the base plate and rotating with the digit wheel; multiple sensing units are arranged in descending order of the number of digits. Each of the code disks is divided into N regions, and each region is connected to a resistor. The brushes follow the character wheel and contact a region of the code disk corresponding to the current character wheel. Each of the code wheels and its connected resistors is configured such that the resistance value presented when the brush contacts different areas represents three mechanical connection states of the character wheel relative to the adjacent higher character wheel: a state connected to the higher character wheel code wheel circuit, an independent state, and a state connected to the lower character wheel code wheel circuit. The resistors of the multiple code disks are connected in parallel to a common terminal; the brush serves as a signal output terminal and is connected to a signal processing circuit, which reads the reading corresponding to the position of the character wheel through AD sampling; The three mechanical connection states specifically correspond to the following operating conditions of the water meter's discontinuous gear mechanism: When the area of ​​contact of the low-position brush corresponds to the boundary area from the digit "9" to "0", it is in the state of forward rotation and carry connection of the high-position character wheel code disk circuit; When the area of ​​contact of the low-position brush corresponds to the numbers "0" to "9", it presents an independent state; When the area of ​​the brush contact is in the boundary region of the digit "0" close to "9", it presents a state of high-order character wheel code disk circuit reversal carry connection; The sensing unit is configured such that, on the code disk, the carry-in area corresponding to the digit "9" turning into the digit "0" has a physical width. Larger than the width of the separator lines between other numbers The widened isolation zone; The width of the widened isolation zone Width of other number separator lines The ratio satisfies: .

2. The anti-interference coded reading sensor for a water meter according to claim 1, characterized in that, The sensing unit is configured as follows: a code disk that corresponds one-to-one with the character wheel, with the axis of the character wheel as the center, and the spacing width between adjacent character wheel numbers on the code disk is equal. The other ends of all the resistors on the sensing unit corresponding to the highest bit wheel are connected in parallel to serve as the first signal terminal, which is led out through the first trace of the flexible circuit board. The brush of the sensing unit corresponding to the highest-ranking character wheel serves as the second signal terminal, and is connected to the parallel terminal of all resistors in the sensing unit corresponding to the adjacent lower-ranking character wheel through the second trace of the flexible circuit board. Connect all the sensor units corresponding to the character wheels in a daisy chain manner, up to the lowest character wheel; The brush of the sensing unit corresponding to the lowest bit wheel is connected to a common reference level through the flexible circuit board.

3. The anti-interference coded reading sensor for a water meter according to claim 1, characterized in that, The signal processing circuit includes a microprocessor, which performs the following reading logic: a. Measure the different resistance values ​​between the signal output terminal and the common terminal; b. Calculate the candidate state combinations for each word wheel based on the pre-stored mapping relationship, wherein the state includes a determined digital value and a carry critical state; c. Apply verification rules based on discontinuous gear carry rules and water flow physical constraints to perform legality verification and screening of candidate state combinations; d. Output the verified and valid readings.

4. The anti-interference coded reading sensor for a water meter according to claim 3, characterized in that, The verification rules include at least the following: when a certain high-order word wheel is found to be in the "carried" state, the state of its adjacent low-order word wheel is either the "carried critical state" or the result state after the carried critical state is completed.

5. The anti-interference coded reading sensor for a water meter according to claim 3, characterized in that, The microprocessor is also used to: when a state jump that does not conform to the volume cumulative monotonicity is detected in a short period of time, determine it as a water hammer reversal interference, and maintain the previous stable reading unchanged.

6. A reading method for an anti-interference coded reading sensor for a water meter, used in any one of claims 1-5, characterized in that, include: Obtain different resistance values ​​of an anti-interference coded reading sensor; Based on a pre-stored mapping table of encoder resistance arrangement, the total resistance value is calculated into a combination of candidate reading states for each character wheel. The states include: determining the digital value, 9-0 carry critical positive, and 9-0 carry critical negative. The candidate combinations are filtered using state transition verification rules: if the state of the higher-order word wheel is "carried", then the state of its adjacent lower-order word wheel must be "9-0 carry critical positive" or its result; illegal combinations that do not conform to the state transition verification rules and other combinations that do not conform to physical laws are eliminated. After filtering, if only one valid combination remains, the corresponding reading for that valid combination will be output; if multiple combinations remain, the combination with the smallest change in the previous historical reading will be selected for output. Store the valid reading of this output for use in the next logical judgment.

7. A water meter, characterized in that, Including the anti-interference coded reading sensor for water meters as described in any one of claims 1-5.

8. A meter reading system, characterized in that, It includes a water meter as described in claim 7, and a meter reading terminal or concentrator that is communicatively connected to the water meter.

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