JP4825441B2 - Number reading method - Google Patents

Description

  The present invention relates to a number reading method in which an image of a display number of a measuring instrument in which usage amounts of power, gas, water, and the like are displayed by a number is acquired with an electronic camera, and the display number is electronically read based on the image.

  Conventionally, meter-readers have directly measured the amount of usage of electricity, gas, water, etc., by using a meter for usage meter attached to each consumer. However, there are also misreading of the instrument, mistakes in filling in the form, input mistakes in the computer, etc., and labor is required to perform accurate processing, resulting in lower efficiency. For this reason, a method of acquiring a display number displayed on the instrument as video data by using an electronic camera for reading the instrument, and outputting and reading the display number by comparing the video data with dictionary data stored in advance It has been known. Note that the video data obtained by the electronic camera is acquired when the camera is fixedly installed in the vicinity of the instrument (see, for example, Patent Document 1) or taken by a meter reader (see, for example, Patent Document 2).

  FIG. 13 (A) shows an example of a metering display unit used for metering the amount of power used disclosed in the above-mentioned Patent Document 1, and “0” to “9” are displayed on a flat cylindrical surface. A plurality of rotating pieces 3 each having a number are arranged side by side. Each of the above numbers can be read from the outside through the display window 2 of the panel 1. For example, the half mirror 4 can be used as a video image by the electronic camera 5 in addition to visual recognition by human eyes. Has been.

  In the display with a plurality of rotating pieces, when the rotating piece 3 rotates in conjunction with weighing and the rotating piece of one digit becomes “9”, it engages with the rotating piece 3 one digit above and When the lower rotating frame 3 changes from “9” to “0”, the rotating frame 3 one digit higher is rotated by 1/10 and the displayed number increases by one. FIG. 13B shows an example of a state in which the display number changes from “8” to “9” with this carry mechanism. If one number is displayed in the display frame 6, “ When “8” starts to move out of the display frame 6, “9” appears in the display frame 6.

When the number in the display frame 6 changes from “8” to “9”, FIG. 13 (B) shows an example with 10 types of video patterns. However, since the display usually changes every 1/100 rotations, There are 100 patterns. That is, when 10 numbers from “0” to “9” are obtained, 1000 kinds of video patterns are displayed in the display frame 6. This pattern is captured by the electronic camera 5 and acquired as an image, and compared with a pattern stored in advance in the reading device, a number with a high degree of coincidence is read.
JP 2001-101380 A JP-A-6-150069

The reading device needs to store a video pattern that changes as the rotating frame rotates as dictionary data. In order to improve the reading accuracy, it is necessary to store the above-mentioned many image patterns as dictionary data. However, this increases the capacity of the storage device, which increases the size of the reading device and the cost. It becomes.
The present invention has been made in view of the above-described circumstances, and can read a display number with high accuracy by reducing the storage capacity of dictionary data when reading a measured value using a rotating frame with an electronic camera. An object is to provide a number reading method.

The number reading method according to the present invention is a measuring instrument in which a plurality of rotating pieces representing numbers “0” to “9” are provided corresponding to the number of displayed digits, and the rotating pieces rotate by weighing to display a measured value. The display number image is acquired by an electronic camera, and the display number of the measuring instrument is read by comparing the image acquired by the electronic camera with the number image stored in advance in the dictionary data. The video acquired by the electronic camera is extracted as a video of a predetermined comparison range for each digit of the displayed number, and the rotation of the rotating frame stops from the extracted video and the reference line of the position of one number displayed in the comparison range The degree of mobility from is detected. The dictionary data stores a video in which the numbers written on the rotating frames are expanded, and sequentially extracts videos in a comparison range corresponding to the number mobility from the dictionary data. The video extracted from the dictionary data is sequentially compared with the video acquired and extracted by the electronic camera, and the number with the highest degree of coincidence is read.

In the present invention, the comparison range is a rectangular region that touches the outer edge of a number having the widest occupied range when the rotation of the rotary piece is stopped in the display window and one number is displayed. It is set so that the upper and lower edges of all numbers touch the upper and lower sides of the area. Then, the rectangular region as the reference coordinates, that gives extract a specific portion of the image corresponding to the position of the reference coordinates. The degree of mobility of the number can be detected by the distance between the upper end or the lower end of the number in the rectangular area and the upper or lower side of the rectangular area as a reference line . In addition, when extracting the video of the comparison range corresponding to the number mobility for each number from the dictionary data, the image when the detected number mobility is changed back and forth is extracted, acquired by the electronic camera and extracted The result of reading can also be confirmed by comparing with the recorded video.

  According to the present invention, the display number of the measuring instrument is acquired as an image by the electronic camera, and when reading the number compared with the data of the dictionary data, it is only necessary to store a minimum amount of data, High-precision reading can be realized. Thereby, for example, a reading device composed of an electronic camera can be attached near the display window of an existing meter such as an integrating wattmeter or a gas meter, and meter reading data can be easily obtained.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1A shows an example of a display unit that performs measurement display using a rotating piece according to the present invention, and FIG. 1B shows a state in which the rotating piece is expanded. In the figure, 11 is a panel, 12, 12a and 12b are display windows, 13 is a rotating frame, 14 is a display number, 15 is a scale line, and 16 is a mark line.

  As shown in FIG. 1 (A), the number reading method according to the present invention includes a display window 12a for displaying a number of digits on the panel 11 of the measuring instrument, and a display window 12b for displaying the decimal part as necessary. It is intended to read a display in which display numbers 12 are provided and display numbers 14 move according to the measurement. The display number 14 is generally written on the circumferential surface of the thin cylindrical rotary piece 13, but can also be written on a rotary moving body such as an endless tape. In the present invention, the term “rotary frame” will be used as a generic term for expression, including such tape-like ones.

  On the peripheral surface of the rotary piece 13, numbers “0” to “9” are written at equal intervals, as shown in a developed view in FIG. This display number 14 is written in white, for example, and the background (the peripheral surface of the rotating frame) is formed in black, or formed in the opposite color scheme. The rotary frame 13 is provided side by side so that each display numeral 14 is displayed on the display window 12a of multiple digits or the display window 12b of decimal point display. Note that a scale line 15 is attached to the rotary frame 13 for displaying the decimal point, and a portion that coincides with the mark line 16 provided on the panel 11 can be read to display less than the decimal point. The portions of the display windows 12a and 12b in FIG. 1A are captured by an electronic camera (also referred to as a digital camera) in the same manner as shown in FIG.

  FIG. 2 is a diagram for explaining an example in which a video acquired by an electronic camera is digitized. FIG. 2A is a diagram illustrating an example of determining reference coordinates of the acquired video, and FIG. 2B is dictionary data. It is a figure which shows an example of the data memorize | stored as. In order to compare the acquired video with the dictionary data, a comparison range 17 is set as shown by a dotted line in FIG. 2A, and the features of the video in the comparison range 17 are converted into numerical data. In the numerical value conversion of the image, the feature of the image may be converted into a numerical value corresponding to the position on the reference coordinate using the comparison range 17 as the reference coordinate. Note that, as feature information to be digitized, for example, brightness, area, display pattern, and the like can be considered.

  The comparison range 17 can be set to any size as long as one display number 14 is displayed, and accommodates at least all the contours of the display number “8” having the largest occupied display area. It is necessary to set it within a possible range. In other words, when the rotating top is stopped and in a stationary state, display numbers with the same normal size are displayed on the rotating top, so the range where the upper and lower sides of each number touch is the minimum comparison range. 18 Using this minimum comparison range 18 as reference coordinates, the feature information can be extracted by quantifying the video features for each coordinate position of (X0, Y0) to (Xn, Ym).

  Further, when the rotating frame rotates, the display character 14 moves through the upper and lower sides of the display window, so the upper and lower sides of the display window are detected for the degree of rotation of the rotating frame, that is, the degree of movement of the display numbers. It can be a reference line. In the embodiment of the present invention, for example, the upper side 18a and the lower side 18b of the above-mentioned minimum comparison range 18 are used as a reference line, and the upper side 18a is used as a passage check line for the display number 14.

  On the other hand, as shown in FIG. 2 (B), the dictionary data 19 stores an image corresponding to a developed view of display numbers (see FIG. 1 (B)) expressed at equal intervals on the circumference of the rotating frame. It becomes. The developed view of the dictionary data 19 is an image in which the stored numbers 20 from “0” to “9” are arranged vertically at equal intervals sequentially with a blank portion interposed therebetween. The dictionary data 19 is stored as an image that is continuous at equal intervals with “0” at the top after “9” at the bottom. In this case, a copy video of “0” may be added to the lower part of “9” with a blank portion interposed therebetween.

  As shown in FIG. 2A, the image acquired by the electronic camera described above is in a stationary state in which the rotation of the rotating frame is stopped, and the upper end and the lower end of one display numeral 14 are the comparison range 18 (reference coordinates). ) Are in contact with the upper side 18a and the lower side 18b. In order to read the display number 14, the same coordinates as the reference coordinates of the comparison range 18 are set for the image on the dictionary data 19 side shown in FIG. In this case, the stored numeral 20 on the dictionary data 19 side is set to have the same positional relation as the positional relation of the display numeral 14 acquired by the electronic camera with respect to the reference coordinates. Specifically, the upper ends P0, P1, P2,... Of the stored numbers 20 of “0” to “9” of the dictionary data 19 are in contact with the upper side of the reference coordinates set in the dictionary data 19. .

  In contrast to the display number 14 extracted in the reference coordinates of the comparison range 18 in the video acquired by the electronic camera, in the dictionary data 19, the upper ends P0, P1, P2 of “0” to “9” of each stored number 20 ... Are extracted as numerical data within the range of the reference coordinates set from the position of. The numerical data of the dictionary data 19 is sequentially compared with the numerical data extracted and digitized by the reference coordinates acquired by the electronic camera, and the numerical value with the highest degree of coincidence is read. In the example of FIG. 2, since the numerical value acquired by the electronic camera is “8”, the numerical value with the highest degree of coincidence is shown when compared with the numerical data “8” in the dictionary data 19.

Next, a description will be given of reading in a case where two display numerals are partially displayed on the display window or one display numeral is partially omitted while the rotating frame is rotating. .
FIG. 3 shows a moving state in which the display numeral 14 in the comparison range 18 passes through the reference line when the rotation piece rotates and the upper side 18a of the comparison range 18 is set as the reference line (passage check line). It is shown.

  As shown in FIG. 3, a first pattern in which the display number 14 overlaps the reference line and a second pattern in which the display number 14 does not overlap the reference line are generated. In FIG. 3, the three patterns on the left are the first patterns, and the one pattern on the right is the second pattern. Note that the patterns at both ends indicate patterns in which the rotation of the rotary piece described with reference to FIG. 2A stops and the entire display numeral 14 is within the comparison range 18. In the present invention, when the display number 14 is in a moving state, the distance S1 or S2 between the upper side 18a or the lower side 18b of the comparison range 18 described later and the upper end or the lower end of the display number 14 is detected.

  The first and second patterns can be discriminated, for example, by extracting the brightness on the reference line of the upper side 18a as shown in FIG. That is, as shown in FIG. 4A, when a part of the display number 14 is on the reference line of the upper side 18a, for example, the brightness detected from the coordinates on the reference line increases on the dark side. On the other hand, as shown in FIG. 4B, if a part of the display numeral 14 is not on the reference line 18a, the brightness detected from the coordinates on the reference line becomes smaller on the bright side.

  FIG. 5 is a diagram for explaining the detection of the distance S between the upper side 18a or the lower side 18b of the comparison range 18 and the upper end or lower end of the display numeral 14, and FIG. 5 (A) is a diagram for explaining the first pattern. FIG. 5B is a diagram for explaining the second pattern. This distance S serves as an index indicating the degree when the rotating piece rotates and the displayed number moves and switches. In the present invention, this distance S will be described as “number moving degree”.

  FIG. 5A is a diagram showing the mobility of numbers in the first pattern in which two display numbers 14 exist in the comparison range 18 and one of the display numbers 14 overlaps the reference line of the upper side 18a of the reference coordinates. It is. When the first pattern is determined, the line K1 (for example, the coordinate (X0) that touches the lower end (the lower end of “8” in the figure) of the display numeral 14 that overlaps the reference line of the upper side 18a from the lower side 18b of the reference coordinate. , Yk), (Sn) to (line connecting (Xn, Yk)). The distance S1 indicates the degree of mobility of numbers as described above. Note that the position of the line K1 can be detected by the same technique as that for detecting the overlapping state of the numbers used in FIG.

  FIG. 5B shows the numbers in the second pattern that are present in the comparison range 18 with one display number 14 partially missing, and that the display number 14 does not overlap the reference line of the upper side 18a of the reference coordinates. It is a figure which shows a mobility. When the second pattern is determined, the distance S2 from the upper side 18a of the reference coordinates to the line K2 that is in contact with the upper end of the display numeral 14 (the upper end of “8” in the drawing) is detected. This distance S2 indicates the degree of mobility of numbers as in S1 described above. Note that the position of the line K2 can also be detected by the same method as that for detecting the overlapping state of the numbers used in FIG.

3 to 5, after the rotating piece rotates and the mobility S1 or S2 of the display number 14 within the comparison range 18 is detected, the stored number 20 on the dictionary data 19 side is Set the reference coordinates for the comparison range.
FIG. 6 is a diagram for explaining a method of extracting a video comparison range on the dictionary data 19 side when the video of the comparison range acquired by the electronic camera is the first pattern. As described with reference to FIG. 2 (B), the dictionary data 19 corresponds to a developed view of the display numbers written on the circumference of the rotating frame, and the stored numbers 20 from “0” to “9” are sequentially added. It is stored as images arranged vertically at equal intervals across the blank.

  When the vertical length of the reference coordinates for the image acquired by the electronic camera is equal to the height of the display number, the detected distance S1 as shown in FIG. 5A is from the upper end of the display number to the upper side of the reference coordinates. Is equal to the distance. When this is made to correspond to the image of the dictionary data 19, the reference coordinates serving as the comparison range of the image are set at a position advanced by the distance S1 from the upper end (P0, P1, P2,...) Of the stored number 20. . That is, P0 + S1, P1 + S1, P2 + S1,... Advanced from the upper end of each stored numeral 20 by the distance S1 is the comparison start position with the video acquired by the electronic camera.

  FIG. 7 is a diagram showing an example of comparing the video acquired and extracted by the electronic camera with the video extracted from the dictionary data in the first pattern. FIG. 7A is a video acquired and extracted from the electronic camera, and is a case where the display number is moving from “8” to “9” as described in FIG. 5A. In the illustrated example, there are two display numbers 14 of “8” and “9” in the comparison range 18, and the mobility of the distance S1 from the lower side 18b to the lower end of the display number 14 overlapping the reference line of the upper side 18a. Is detected. FIG. 7B is an image extracted from the dictionary data 19. As described with reference to FIG. 6, the position where S <b> 1 indicating the mobility of the display number 14 is advanced from the upper end of each stored number 20 of the dictionary data 19. A comparison range is extracted as a comparison start position.

  Next, as shown by a comparison image in FIG. 7C, the comparison range image acquired and extracted by the electronic camera is compared with the comparison range image extracted from the dictionary data. The comparison between the two is performed for all of “0” to “9” of the stored numeral 20 in the dictionary data 18 and the degree of coincidence is obtained. FIG. 8 is a diagram illustrating an example in which the degree of coincidence is detected at this time. As shown in FIG. 8, when the stored number is “8” → “9” (comparison start position is P8 + S1), the degree of coincidence is the highest at 91%, and the stored number is “3” → “ 4 ”(comparison start position is P3 + S1) and when the stored number is“ 9 ”→“ 0 ”(comparison start position is P9 + S1), the degree of coincidence was 84%. Therefore, in this case, the display number 14 is read as “8”.

  FIG. 9 is a diagram for explaining a method of extracting a video comparison range on the dictionary data 19 side when the video of the comparison range acquired by the electronic camera is the second pattern. If the length in the vertical direction of the reference coordinates for the image acquired by the electronic camera is equal to the height of the display number, the detected distance S2 as shown in FIG. 5B is from the upper end of the display number to the upper side of the reference coordinates. Is equal to the distance. If this is made to correspond to the image of the dictionary data 19, the reference coordinate serving as the comparison range of the image is set at a position that is a distance S2 before the upper end (P0, P1, P2,...) Of the stored number 20. . That is, P0-S2, P1-S2, P2-S2,... Returned from the upper end of each stored numeral 20 by the distance S2 is the comparison start position with the video acquired by the electronic camera.

  Next, as described with reference to FIG. 7C, the comparison range image acquired and extracted by the electronic camera is compared with the comparison range image extracted from the dictionary data. The comparison between the two is performed for all of “0” to “9” of the stored numeral 20 in the dictionary data 19, and the degree of coincidence is obtained. FIG. 10 shows an example in which the degree of coincidence is detected when the image of the display number 14 in the comparison range acquired and extracted by the electronic camera is “8” with a part missing as shown in FIG. FIG. In this case, as shown in FIG. 10, when the stored number 20 is “7” → “8” (comparison start position is P8-S2), the degree of coincidence is the highest at 93%, and the stored number is the next rank. When “2” → “3” (comparison start position is P3-S2), the degree of coincidence was 86%. Therefore, in this case, the display number 14 is read as “7”.

  10, the degree of coincidence when the stored number 20 on the dictionary data 19 side is “7” → “8” is 93%, and the stored number 20 is “2” → “3”. The degree of coincidence at that time is 86%, and the degree of coincidence between them is a close value. In the present invention, sufficient discrimination is possible by reading numbers from the data. However, when two or more values with close coincidence occur, when extracting the comparison range from the dictionary data, extraction with the value of S indicating the degree of mobility of the displayed number is performed, and the comparison range by S ± Δ is set. The degree of coincidence can be calculated by extraction.

  FIG. 11 is a diagram showing a state in which the degree of coincidence in the range of ± Δ before and after S indicating the degree of mobility of the displayed number is compared. As can be seen from this figure, in the case of a true value (correct value), the decrease in the degree of coincidence in the range of S ± Δ tends to be smaller than that in the case of not being a true value. Therefore, if the degree of coincidence is high and close to each other, the comparison range is obtained by extracting the video when the degree of mobility of the displayed numbers is changed back and forth as described above, and acquiring and extracting with the electronic camera. Compared with the video, the true value of the read result can be confirmed, and the reliability can be improved.

  FIG. 12 is a diagram showing a flow of the above-described number reading method according to the present invention. First, in step S1, an image of a display number displayed on the measuring instrument is acquired by an electronic camera. Next, in step S2, a predetermined digit of the image acquired by the electronic camera is selected, and an image in the display range comparison range is extracted. In step S3, it is detected whether or not the displayed number within the comparison range is moving. If there is no movement in the displayed numbers within the comparison range, the digits are read by the method described with reference to FIG. 2 in step S4. It is determined whether or not the digit read in the next step S5 is the last digit. If it is not the last digit, the process returns to step S2 to read the next digit in step S6, and the next digit to be read is determined. Extract the video of the comparison range of the displayed numbers. If it is the last digit, reading of the numerical value read in step S4 is terminated and finalized.

  If the displayed number in the comparison range is moving in step S3, a (S) value indicating the number mobility is detected in step S7. This detection can be performed by the method described with reference to FIGS. When the number mobility (S) is detected, the number mobility according to the number (S) according to the method described in FIG. 6, FIG. 7 or FIG. Set the reading start position and extract the comparison range. Next, in step S9, the video acquired and extracted by the electronic camera is sequentially compared with the video extracted from the dictionary data. In the next step S10, a number having a high degree of coincidence is selected from the comparison data of FIG. 8 or FIG.

  Next, it is determined whether or not the digit read in step S12 is the last digit. If it is not the last digit, the flow returns to step S2 to read the next digit in step S13, and the next digit to be read is determined. Extract the video of the comparison range of the displayed numbers. If it is the last digit, the reading of the numerical value read in step S12 is confirmed and terminated.

It is a figure which shows an example of the display part which carries out the measurement display made into reading object by this invention. It is a figure explaining the method of determining a reference coordinate with respect to the image | video acquired by this invention, and carrying out a numerical conversion process. In this invention, it is a figure which shows the movement state when a display number passes the reference line of a comparison range. In this invention, it is a figure which shows an example which detects the specific position of a display number. It is a figure which detects the mobility of the display number in this invention. It is a figure explaining the method to extract the image | video by the side of the dictionary data in the 1st pattern in this invention. It is the figure which showed an example which compares the image | video acquired and extracted with the child camera in this invention, and the image | video extracted from dictionary data. It is a figure which shows the coincidence in the case of the image | video comparison shown in FIG. It is a figure explaining the method to extract the image | video by the side of the dictionary data in the 2nd pattern in this invention. It is a figure which shows the coincidence degree of the image comparison in the case shown in FIG. It is a figure which shows the change state of a coincidence degree when the (S) value of FIG. 10 is changed. It is a flowchart of the number reading method of this invention. It is a figure explaining the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Panel, 12, 12a, 12b ... Display window, 13 ... Rotation top, 14 ... Display number, 15 ... Scale line, 16 ... Mark line, 17, 18 ... Comparison range, 18a ... Upper side, 18b ... Lower side, 19 ... Dictionary data, 20 ... memorized numbers.

Claims (5)

The electronic display of the display of the number displayed on the weighing instrument that displays the measured value by rotating the rotating piece according to the number of digits corresponding to the number of digits for displaying the rotating pieces representing the numbers “0” to “9” A number reading method for reading a display number of a measuring instrument by comparing the image acquired by a camera and the image acquired by the electronic camera with a number image of dictionary data stored in advance,
A video of a predetermined comparison range is extracted from the video acquired by the electronic camera for each digit of a displayed number , and the position of one number displayed in the comparison range after the rotation of the rotating frame is stopped from the extracted video Detecting the degree of mobility from the reference line
The dictionary data stores an image obtained by expanding a number written on the rotating frame, and sequentially extracts the image of the comparison range corresponding to the mobility of the number from the dictionary data for each number,
A number reading method comprising: sequentially comparing a video extracted from the dictionary data and a video acquired and extracted by the electronic camera, and reading a number having the highest degree of coincidence.   The comparison range is a rectangular region in contact with the outer edge of the number having the widest occupied range when the rotation of the rotary piece is stopped in the display window and one number is displayed, and the upper side of the rectangular region 2. The number reading method according to claim 1, wherein the upper side and the lower end of all the numbers are set in contact with the lower side.   The number reading method according to claim 2, wherein the rectangular area is used as a reference coordinate, and a specific portion of an image corresponding to the position of the reference coordinate is extracted. And the upper end or the lower end of the number of the rectangular region, the distance from the said reference line and reference line upper or lower side of the rectangular region, according to claim 2, characterized in that for detecting the movement degree of the numbers or 4. The number reading method according to 3 . When extracting the image of the comparison range corresponding to the degree of mobility of the number for each number from the dictionary data, the image when the detected degree of mobility of the number is changed back and forth is extracted, and the electronic camera obtained extracted and compared with the video, number reading method according to any one of claims 1 to 4, characterized in that to check the read result in.

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