WO2007073090A1

WO2007073090A1 - Method of simply digitizing a numeral value on a mechanical type meter into a digital value and apparatus for the same

Info

Publication number: WO2007073090A1
Application number: PCT/KR2006/005589
Authority: WO
Inventors: Yeonmi Kim
Original assignee: Yeonmi Kim
Priority date: 2005-12-23
Filing date: 2006-12-20
Publication date: 2007-06-28
Also published as: KR20070067451A; CN101389968A; JP2009521057A; KR100848037B1

Abstract

Disclosed are an apparatus for and a method of automatically digitizing an indication value of a meter. A light emitter emits a light towards the outer circumferential face of a target number wheel of which rotation numbers are to be counted. A light receiver receives and converts the reflected light into an optical detection signal. The optical detection signal is converted into a digital data, which is provided to a metering computer unit. A determination result as to whether the supplied goods are currently being consumed is provided to the metering computer unit. The metering computer unit counts an increase by T only if the stabilized state is caused by use of the supplied goods. Further, a temperature and pressure compensation unit is further adopted, which compensates for the meter reading errors caused by a difference between reference temperature and pressure at the gas-supplying point and the temperature and pressure values of the gas passing through the gas meter, i.e., calculates a temperature and pressure compensation coefficient. The metering computer unit reflects this compensation coefficient on the automatic read value to provide a more precise digitalized read value.

Description

METHOD OF SIMPLY DIGITIZING A NUMERAL VALUE ON

A MECHANICAL TYPE METER INTO A DIGITAL VALUE

AND APPARATUS FOR THE SAME

Technical Field

[1] The present invention relates to automatic meter reading (AMR), more specifically, to such techniques which can automatically read consumption indication value of a mechanical meter and convert the read value into a digital value, thereby using the digitized read value in remotely reading the meter. Background Art

[2] (1) Conventional Digitizing Techniques

[3] In a typical mechanical meter, consumed amount of the supplied goods, such as gas, water or electricity, is displayed as numeral values of a rotation needle on a number plate or of a number wheel train (hereinafter, referred to as an "indication value"). In order to remotely and automatically read the indication value from a mechanical meter, the indication value (analogue value) is required to be converted into a digitized value.

[4] Representative prior art for the automatic reading techniques includes an optical automatic reading, magnetic automatic reading, acoustic automatic reading, image- recognition automatic reading, and the like. In case of the optical automatic reading, an optical sensor is used for counting rotation number of a particular number wheels or rotation needle of the number plate of a meter to thereby read the indication value of the meter. In the magnetic automatic reading technique, a magnetic sensor is used for the same purposes, instead of the optical sensor. The acoustic reading technique generates a unique mechanical sound every time when a certain number wheel or rotation needle rotates and detects the sound to count the rotation number of the number wheel or rotation needle. In addition, the image-recognition automatic reading method takes a picture of the values indicated by the number wheels and these images are recognized as a digital value using an optical character recognition technique. All these techniques convert the analogue indication value of a mechanical meter into a digitized value in different ways. Among them, the present inventor addresses in particular the optical automatic reading technique.

[5] Typical examples for the optical automatic reading technique includes Korean

Patent Application Laid-open No. 10-2000-52048 entitled "Signal generator for consumption of a meter using an optical sensor," No. 10-2000-66245 entitled "Rotation counter for the number wheel in a meter" and Korean Utility Model Registration No. 20-273026 entitled "Rotation counter for the number wheel in a meter," which were filed by VentureKorea. In these inventions of VentureKorea, an optical sensor is used to count rotation numbers of a particular number wheel in the number wheel train of a mechanical meter and digitize indication values of the meter. Figs. 1 to 3 show a conventional automatic reading apparatus in connection to this technique. As shown in Fig. 1, consumed amount of the supplied goods is indicated by numeral values displayed in a number wheel train 12 of a consumption indicator 14 in a meter 2. Among the number wheels forming the number wheel train 12, a number wheel 12a to be counted its rotation number (hereinafter, referred as to a "selected or target number wheel") is selected. A certain portion of the outer circumferential face of the target number wheel is formed as a light reflecting region 20 (for example, by hot- pressing a material having a high reflectivity on the certain portion). In addition, an optical sensor unit 30 made up of a light emitter 32 and a light receiver 34 housed in a case 35 is mounted in a housing 40. The housing is attached to the consumption indicator 14. In this way, the light emitter 32 and the light receiver 34 are oriented towards a certain area on the rotating path of the light reflecting region 20. The light emitter 32 receives a driving signal from a power supply and emits a light, and the light is incident on the outer circumferential face of the target number wheel 12a. In case where the light is incident on the light reflecting region 20 on the outer face of the target number wheel 12a, most of the light is reflected to provide a high intensity of light. When the light is incident on the remaining area except for the light reflecting region 20, the reflected light has a weaker intensity due to the lower reflectivity of the surface. This reflected light is incident on the light receiver 34 and converted into an electrical signal. While the target number wheel 12a is rotating as the supplied goods are consumed, the light reflecting region 20 and the other remaining region alternately pass a certain area towards which the light emitter 32 and the light receiver 34 are oriented, so that light detection signal output from the light receiver 34 alternates a higher level and a lower level. This optical detection signal of the light receiver 34 is converted into a digital signal and behavior in the level change of the signal is analyzed to determine where or not the target number wheel 12a has completed one revolution. These operations are made into a program, which is executed in a computer such as a microcomputer to count revolution number of the target number wheel 12a. The counted revolution number for the target number wheel 12a is equivalently related to the indication value of the meter and thus the indication value can be known from the revolution number. In other words, a light reflecting region is formed in the target number wheel 12a. The light reflecting region has a light reflectivity considerably different from the remaining region thereof such that light reflected by these two regions has different intensities. [6] The above-explained invention by VentureKorea requires necessarily a light reflecting region provided on the outer peripheral surface of a target number wheel. Without the light reflecting region, a high frequency of metering errors occurs. When manufacturing the number wheel train, provision of the light reflecting region on the outer face of a target number wheel is also cumbersome. In particular, in order to provide a light reflecting region in numerous exiting meters already installed in the consumers, the meters are to be recollected. This is very inconvenient and nearly impossible in practice.

[7] In order to solve this problem in the VentureKorea techniques, Korean Patent Application Laid-open No. 10-2005-66073 discloses a method of and apparatus for remote-reading a meter through analysis of the pattern change in output signals from multiple photoelectric devices. As shown in Figs. 4 to 6, this approach enables automatic reading by counting revolution numbers of a target number wheel 12a, without necessity of providing a separate light reflecting region on the outer surface of the target number wheel 12a.

[8] According to this invention, the optical sensor unit 30a, which detects rotation of the target number wheel 12a, includes at least one light emitter 32a, 32b and a light receiver array 34a. The light emitter radiates an incident light towards a certain particular area on the outer face of the target number wheel 12a. The light receiver array 34a is made of multiple light receiver elements clustered in a certain area. The light receiver element receives light reflected from the target number wheel 12a and outputs a corresponding electrical signal. These components are housed in a case 36 to form an integrated piece. Numerals from '0' to '9' are engraved or printed on the outer circumferential face of the target number wheel 12a. Here, in order for the numerals to be easily distinguished, typically the outer face is made of a black material and the numerals are formed in white, so that the background and the numerals have different light reflectivity and also each numeral has its own light-reflection pattern. The present invention has been perceived from these points. Output signal (optical detection signal) from each light receiver element of the light receiver array 34a is converted into a digital signal. A computer such as a microcomputer is used to analyze changing pattern with time in the level of the digital signals and to determine whether or not the target number wheel 12a has completed one revolution.

[9] In this technique, however, instead of not providing a separate light to the target number wheel, a large number of light receiver elements are required to form the optical sensor unit 30a and accordingly multiple light emitter elements are required. Thus, manufacturing cost for the optical sensor unit 30a increases. In addition, since the microprocessor must have a higher capability to process a relatively large amount of data acquired from the multiple light receiver elements, the cost for the microprocessor increases. Further, determination as to whether one revolution of the target number wheel has been completed is preformed by pattern comparison of the reflected lights and thus higher precision optical sensor unit is required as another burden.

[10] (2) Compensation for Temperature and Pressure Error in Gas Meter

[11] In general, a supply and charge system of household and industrial gases is determined, between wholesalers and retailers, based on the gas weight. Between the retailers and individual consumers, however, it is determined based on the gas volume (assuming that the gas meter installed in the consumers is a volumetric gas meter). For example, in Korea, the gas transaction between each local gas company (retailer selling gas directly to consumers) and the Korea Gas Corporation (wholesaler supplying gas to the retailers) is made for liquefied gas and the gas charge is calculated based on the gas weight. Conversely, when each local gas company sells gas to consumers, the gas is supplied in gaseous state through a gas pipe. Thus, the amount of supplied gas is measured in the unit of volume.

[12] Here, it has been found out that there is a significant difference between the gas amount purchased by each local gas company (retailer) from the Korean Gas Corporation (wholesaler) and the gas amount sold to the entire consumers by the retailer. The reasons therefor are that there is a difference between the reference temperature and pressure at a gas-supplying position (at the position of a pressure regulator) established by the gas company and the actual temperature and pressure of the gas passing through the gas meter of each consumer, leading to a difference in the gas volume in-between. This difference is hereinafter referred to as a temperature and pressure error.

[13] Inherently, gas volume per unit weight varies with the temperature and pressure thereof. The gas supplier (retailer) supplies gas through a gas pipe to each individual consumer from the gas-supplying position, where a pressure regulator is installed, with a reference temperature and pressure (In Korea, e.g., O⁰C and 1 ATM). At this time, the gas is supplied from the pressure regulator with a gauge pressure of about 20~25mbar, considering reduction in the gas pressure between the pressure regulator and each consumer's gas meter. In a volumetric gas meter, the volume-measuring container is formed of a membrane having flexibility, which causes fluctuations in the gas volume (i.e., the gas consumption measured at the gas meter) by the changes in the ambient temperature and pressure even through the gas mass is same. During the course of transportation of gas to the consumers through a gas pipe, it is affected by ambient temperature and pressure, and the like. Thus, the gas temperature and pressure at the volumetric gas meter of each consumer is not necessarily identical to the above reference supply temperature and pressure. In this way, the temperature and pressure differences between both positions lead to a change in the gas density, and thus a gas volume measured in the gas meter of each consumer becomes different from a gas volume, which corresponds to the gas mass supplied from the gas supply reference point, thereby causing difference and fluctuation in the consumed gas volumes measured from the gas meter. Because of this, there is a difficulty in charging a precise and consistent gas price between the gas supplier and the consumers. For instance, unreasonably consumers in hot areas or highlands may pay the same gas fees as those in cold areas or lowland, in spite where they consumes less calories (the calories are in proportion with the mole numbers of gas, not the gas volume.).

[14] The inventor has found causes for the temperature and pressure error and filed a patent application for some solutions (refer to Korean Patent Application No. 10-2003-0053627 entitled "Remote reading apparatus of gas meters having temperature and pressure compensation function"). In the temperature and pressure compensator disclosed in the above application, each gas meter is equipped with one temperature-measuring device. For example, a temperature sensor is attached inside of the gas pipe or on the surface thereof, or attached to the inner side or surface of the gas meter or near the gas meter. With respect to pressure, however, a single pressure- measuring device is installed with respect to multiple gas meters installed in a unit area and measures the atmospheric pressure, not the gas pressure. Then, measured information on the atmospheric pressure is transmitted to and shared with multiple gas meters through a wireless network (for remote reading).

[15] However, the temperature and pressure of gas passing through the gas meter of each consumer may be different for the respective consumers. In addition, the gas temperature and pressure at the individual consumer's gas meter are also different from the reference temperature and pressure at the gas-supplying position. Therefore, in order to minimize the temperature and pressure error, the best information is the instantaneous temperature and pressure values of gas passing through each consumer's gas meter. In the above invention of Koran Patent Application Laid-open No. 10-2003-0053627, however, atmospheric pressure information, not the pressure value of gas itself, is used for compensating the pressure difference. Furthermore, the atmospheric pressure value is measured at a certain point within a unit area, not from each consumer's gas meter, and then the measured pressure value is applied to all the gas meters within the unit area, thereby resulting in inaccurate compensation for the pressure differences. In addition, according to the conventional technique, a pressure- measuring unit (a unit for measuring atmospheric pressure) and a temperature- measuring unit are installed at different places. Accordingly, these units must be separately made and installed, thus incurring inefficiency and in convenience. Disclosure of Invention Technical Problem [16] Accordingly, the present invention has been made in order to solve the above problems in the prior art. It is an object of the invention to provide a method of and an apparatus for digitizing an indication value displayed through the number wheel train of a mechanical meter, using a simplified optical sensor and without necessitating a change or modification to the structure and construction of the meter.

[17] Another object of the invention is to provide a method of and an apparatus for digitizing an indication value, in particular, of a volumetric gas meter in order to automatically read the indication value, and for compensating temperature and pressure errors contained in the indication value and thus acquiring a temperature & pressure compensated digital data for the consumption indication value. Technical Solution

[18] In order to accomplish the above objects, according to one aspect of the invention, there is provided an apparatus for digitizing an indication value for consumption of supplied goods in a mechanical meter, the meter including a number wheel train having a plurality of number wheels disposed adjacently in a row, the indication value being a combination of number values engraved or printed on the number wheels, the apparatus comprising: a light emitter emitting a light towards a certain desired area on the outer circumferential face of a target number wheel of which rotation number is to be counted, the light emitter generating light by a power supply; a light receiver disposed towards the certain desired area so as to receive the light of the light emitter reflected from the outer circumferential face of the target number wheel, the light receiver converting the received light into an electrical optical detection signal corresponding to the intensity of the received light and outputting the electrical optical detection signal; an analog-to-digital converter converting the optical detection signal output from the light receiver into a digital signal; and a metering computer unit reading the indication value of the meter in such a manner to monitor in real-time the digital signal being provided by the analog-to-digital converter and determine that the number value of the target number wheel has increased by T every time when the magnitude of the digital signal remains uniform for more than a certain period of time and thereafter fluctuate irregularly.

[19] In case of a volumetric gas meter where the gas consumption is measured in a unit of volume and which includes a number wheel train having a plurality of number wheels disposed adjacently in a row and the indication value is displayed as a combination of number values engraved or printed on the number wheels, a temperature and pressure error needs to be removed from the digitized read value. For this purpose, according to another aspect of the invention, there is provided a digitizing apparatus having a function of compensating for the temperature and pressure errors. The apparatus comprise: a light emitter emitting a light towards a certain desired area on the outer circumferential face of a target number wheel of which rotation number is to be counted, the light emitter generating light by a power supply; a light receiver disposed towards the certain desired area so as to receive the light of the light emitter reflected from the outer circumferential face of the target number wheel, the light receiver converting the received light into an electrical optical detection signal corresponding to the intensity of the received light and outputting the electrical optical detection signal; an analog-to-digital converter converting the optical detection signal output from the light receiver into a digital signal; a temperature and pressure compensation unit measuring an instantaneous temperature value and an instantaneous pressure value of gas inside of the gas meter or inside of a gas pipe connected to the gas meter at regular time intervals or whenever gas -consumption reaches a certain value, and calculating a temperature and pressure compensation coefficient at intervals of a first desired time, which occurs due to a difference between the measured instantaneous temperature and pressure values and a reference temperature and pressure at a gas-supplying point; and a metering computer unit reading the indication value of the meter in such a manner to monitor in real-time the digital signal being provided by the analog-to-digital converter and determine that the number value of the target number wheel has increased by T every time when the magnitude of the digital signal remains uniform for more than a certain period of time and thereafter fluctuate irregularly, and reflecting the temperature and pressure compensation coefficient computed by the temperature and pressure compensation unit on the read indication value for the first desired time to calculate a temperature and pressure compensated read value. [20] For precise automatic reading, preferably the digitizing apparatus may further comprise an in-use detector unit for determining whether or not the supplied goods are currently being consumed and providing the determination result in real-time to the metering computer unit. In this case, the metering computer unit is configured such that, when the magnitude of the digital signal remains uniform for more than the certain period of time, using the determination result, the metering computer unit determines whether the uniform state is caused by use of the supplied goods or by interruption of use of the supplied goods without an increase by T in the number value of the target number wheel, and counts the increase by T in the number value of the target number wheel only in case where the uniform state is incurred by use of the supplied goods or ignores the uniform state in case where it is incurred by interruption of use of the supplied goods. The determination result is acquired in such a manner to be decided as being 'non-use' when the lowest place wheel in the number wheel train remains stopped without rotation for more than a certain period of time and to be decided as being 'non-use' when the lowest place wheel rotates within the certain period of time. The determination result provided from the in-use detector unit can be used to check and see if the stable state of the magnitude of the optical detection signal for more than a certain time period is incurred by interruption of use of the supplied goods, without an increase by T in the number value of the target number wheel. Thus, the increase in the number value of the target number wheel can be prevented from being doubly counted.

[21] According to another aspect of the invention, there is provided a method of digitizing an indication value for consumption of supplied goods in a mechanical meter including a number wheel train having a plurality of number wheels disposed adjacently in a row, in which the indication value is a combination of number values engraved or printed on the number wheels. The method comprises: a first step in which a light emitter and a light receiver are disposed towards a certain desired area on the outer circumferential face of a target number wheel of which rotation number is to be counted, the output light of the light emitter is incident on and reflected from the outer circumferential face of the target number wheel, and the light receiver receives and converts the reflected light into an optical detection signal and outputs the optical detection signal; a second step in which the optical detection signal is converted into a digital signal through an analog-to-digital converter; and a third step in which the indication value of the meter is read in such a manner to monitor in real-time the digital signal being provided by the analog-to-digital converter and determine that the number value of the target number wheel has increased by T every time when the magnitude of the digital signal remains uniform for more than a certain period of time and thereafter fluctuate irregularly.

[22] Furthermore, for purpose of more precise reading, the digitizing method may further include a fourth step which determines whether or not the supplied goods are currently being consumed, thereby providing the determination result. In this case, in the third step, when the magnitude of the digital signal remains uniform for more than the certain period of time, the determination result is used to determine whether the uniform state is caused by use of the supplied goods or by interruption of use of the supplied goods without an increase by T in the number value of the target number wheel, and count the increase by T in the number value of the target number wheel only in case where the uniform state is incurred by use of the supplied goods or ignore the uniform state in case where it is incurred by interruption of use of the supplied goods. In addition, the determination result is acquired in an indirect way in such a manner to use a sensor to detect whether or not a lowest place wheel in the number wheel train is rotating and, as result of the detection, to be decided as being 'non-use' when the lowest place wheel remains stopped without rotation for more than a certain period of time and to be decided as being 'non-use' when the lowest place wheel rotates within the certain period of time.

[23] Further, in case where the supplied goods are a gas, the determination result is acquired in such a manner to use a sensor to detect directly whether or not the gas is flowing in the meter or inside a gas pipe near the meter.

[24] Furthermore, in case where the supplied goods are a gas, the digitizing method may further comprise: a fifth step which measures an instantaneous temperature value and an instantaneous pressure value of gas inside of the gas meter or inside of a gas pipe connected to the gas meter at regular time intervals or whenever gas-consumption reaches a certain value, and calculates a temperature and pressure compensation coefficient at intervals of a first desired time, which occurs due to a difference between the measured instantaneous temperature and pressure values and a reference temperature and pressure at a gas-supplying point; and a sixth step which reflects the temperature and pressure compensation coefficient on the read indication value for the first desired time to calculate a temperature and pressure compensated read value.

Advantageous Effects

[25] As described above, the digitizing apparatus of the invention can be installed in existing meters by simply attaching it thereto, without incurring any structural change. Thus, its application is very convenient, as compared with convention techniques where a light reflector must be provided in the target number wheel.

[26] In addition, the digitizing apparatus of the invention has a simplified optical sensor unit, as compared with conventional techniques where the optical sensor unit is formed in the form of matrix array requiring a larger number of light emitters and receivers, instead of providing a light reflector to the target number wheel. In the conventional optical sensor unit of matrix array type, the number of light receivers to be adopted is limited due to its limited installation space. The invention can provide a complete solution to this problem.

[27] Further, according to the present invention, a function of compensating for temperature and pressure errors is provided to the digitizing apparatus of a meter. Thus, the consumption read value can be precisely digitized, without being affected by fluctuation in the gas temperature and pressure values.

Brief Description of the Drawings

[28] Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

[29] Figs. 1 to 3 show a conventional automatic reading apparatus where a light reflecting region is provided on the outer circumferential face of a target number wheel and an optical sensor unit is used to count revolution number of the target number wheel, more specifically Figs. 1 and 2 show the apparatus before and after the optical sensor unit is assembled to a meter, and Fig. 3 is a sectional view taken along the line

A-A in Fig. 2; [30] Figs. 4 to 6 show a conventional automatic reading apparatus where, without a light reflecting region, an optical sensor unit formed of multiple light receiver elements is used to count revolution number of a target number wheel, more specifically Figs. 4 and 5 show the apparatus before and after the optical sensor unit is assembled to a meter, and Fig. 6 is a sectional view taken along the line B-B in Fig. 5; [31] Fig. 7 schematically illustrates an apparatus for digitizing an indication value of a meter according to the first embodiment of the invention, in which the digitization is carried out through analysis of waveform from a simplified optical sensor unit, without providing any separate light reflecting region to the target number wheel; [32] Fig. 8 shows a pattern of level change in the optical detection signal from the light receiver while the target number wheel is rotating in the digitizing apparatus of Fig. 7; [33] Fig. 9 shows a pattern of level change in the optical detection signal from the light receiver when use of the supplied goods is interrupted while the target number wheel is rotating in the digitizing apparatus of Fig. 7; [34] Fig. 10 illustrates a digitizing apparatus further including an 'non-use' detector unit according to the second embodiment of the invention where the in-use detector unit determines whether or not the supplied goods are being used; [35] Fig. 11 illustrates a digitizing apparatus having an exemplary in-use detector unit in

Fig. 10; [36] Fig. 12 is a schematic diagram explaining a method for detecting gas-flow using a differential pressure sensor; [37] Fig. 13 illustrates a digitizing apparatus according to the third embodiment of the invention where a temperature and pressure compensation unit is further provided to the apparatus of Fig. 10 to enable to acquire digitized read value compensated for temperature and pressure errors;

[38] Fig. 14 shows an installation of the digitizing apparatus of Fig. 13 into a meter; and

[39] Figs. 15 to 18 is a sectional view taken along the line C-C in Fig. 14, showing exemplary temperature and pressure measuring devices according to embodiments of the invention.

Best Mode for Carrying Out the Invention [40] Exemplary embodiments of the present invention will be hereafter described in detail with reference to the accompanying drawings. [41] ( 1 ) Rotational Mode of Number Wheel Train [42] A number wheel train 12 of a meter includes multiple number wheels adjacently disposed one after another. In most commercialized meters, the number wheel train 12 is made up of 6 to 8 number wheels, which correspond to 4 to 6 integer number places and two decimal places. Each number wheel is formed typically of a flat disk made of black plastic resin. Engraved along the outer circumferential face of the number wheel are integer numbers of from 0 to 9, which are white-colored thereinside. Adjacent number wheels are related to each other to have a rotation ratio of 10: 1. Therefore, if the rotation numbers of anyone of the number wheels are counted, the indication value of higher number places than the counted number wheel can be found out.

[43] On the other hand, each number wheel of the number wheel train 12 revolves in the manner as follows. Among the entire number wheels, the lowest place wheel moves continuously while the supplied goods (gas, water, or electricity) are being consumed. Other number wheels, however, remain stopped. Then, when the adjacent lower place wheel moves from '9' to '0' it rotates by 36°to increase its indication value by T from the previous one. That is, the other number wheels, excepting the lowest place wheel, do not perform a continuous rotation, but an 'intermittent rotation'.

[44] The indication value of a meter can be automatically read by counting the rotation numbers of a certain particular place wheel in the meter. In selecting a particular number place wheel to be counted, the lowest place wheel needs to be precluded, in view of the above rotational mode of number wheel train 12. In addition, it is necessary to preclude number places being effectively considered in the calculation of indication value for consumption of supplied goods (typically, integer places before the decimal point). In view of these points and securing an accurate read value, it is preferable to select, as a particular number place wheel 12a to be counted (hereinafter, referred to as a "selected or target number wheel"), a number wheel immediately before the lowest place wheel. A typical number wheel train 12 has two or three decimal place wheels after the decimal point. Thus, most preferably, the target number wheel employs the first or second decimal place wheel after the decimal point.

[45] (2) First embodiment

[46] Fig. 7 shows the configuration of a digitizing apparatus 100 according to the first embodiment of the invention. In Fig. 7, the digitizing apparatus 100 is applied to a conventional meter 2. The digitizing apparatus 100 can be applied to any type of meters without limitation as long as they display an indication value using a number wheel train. When applied, the meters are not required to be structurally modified (e.g., provision of a light reflector to the number wheel, etc.). In addition, in application of the digitizing apparatus 100, a number wheel immediately before the lowest place wheel is selected as the target number wheel 12a.

[47] The digitizing apparatus 100 includes an optical sensor unit 30. The optical sensor unit 30 includes a light emitter 32 and a light receiver 34, which are mounted inside of two receptacle cavities 38a and 38b provided at one side of a roughly rectangular case 35. The case 35 is mounted inside of a holder 48, which is provided in the inner space of a housing 40. A latch member 46 of the housing 40 is latched into a flange 16 provided at the lateral side of a consumption indication unit 14. The portion in the housing 40 that covers a number wheel train 12 of the meter is made of a transparent window to clearly show the indication values. In this case, preferably, the transparent window is configured to have an optical noise shielding function such that optical noises are prevented from entering into the housing from the outside.

[48] The housing 40 is attached to the meter 2 such that the optical sensor unit 30 is disposed above the outer circumferential face of the selected target number wheel 12a. Here the two receptacle cavities 38a and 38b are formed to be inclined such that exits of both cavities 38a and 38b are oriented towards a certain desired area (hereinafter, referred to as a "Target area") on the outer circumferential face of the target number wheel 12a. Hence, light being emitted from the light emitter 32 is incident on the target area and then reflected to be incident back on the light receiver 34. The above two receptacle cavities 38a and 38b provided in the case 35 are isolated from each other. Thus, the output light from the light emitter 32 can not be incident directly towards the light receiver 34, but reflected by the target area and the input into the light receiver 34.

[49] The digitizing apparatus 100 may include a power supply 50. The light emitter 32 generates light by means of a driving power provided from the power supply 50. In case where the power supply 50 employs a battery, preferably the driving power is provided in the form of pulse signals to minimize power consumption. In case of using a pulse signal as the driving power, it is preferable that duration time of the pulse signal is longer than response time of the photoelectric elements and the duty ratio thereof is not beyond 1/100. Further, preferably the period of the pulse signal is no more than 250 ms. A timer 56 sends a clock signal to the power supply 50 to generate a driving pulse signal for the light emitter 32. The light generated from the light emitter 32 is radiated on the radiated area on the outer circumferential face of the target number wheel 12a and then reflected therefrom. Most of the reflected light is incident back on the light receiver 34. Then, the light receiver 34 converts the incident light into an electrical signal corresponding to the intensity of the light and then outputs the electrical signal.

[50] Further, the digitizing apparatus 100 has an analog-to-digital converter (ADC) 52 coupled to the output terminal of the light receiver 34 and a metering computer unit 54 coupled to the ADC 52. The metering computer unit 54 is configured to include an element, such as a microcomputer, having capabilities for storing programs and data, and for data operation and processing, which will be described hereafter. A clock signal required for operation of the metering computer unit 54 is provided by the timer 56. For example, the metering computer unit 54 includes a memory element for storing data and programs implemented with a metering logic according to the invention, and a central processing unit for executing the programs to perform data operations required for measuring the indication values and to store the operation results into the memory element, etc.

[51] The digitizing apparatus 100 is configured to count revolution (rotation) numbers of the target number wheel 12a to thereby automatically read the indication values of a meter. For the purpose of explanation, first, it is assumed that the supplied goods are continuously being used or consumed. In this case, the lowest number wheel 12b is continuously rotated, but the selected target number wheel 12a, placed at a number place right before the lowest number wheel 12b, is revolved intermittently (discontinuously), as previously described. That is, while the lowest place wheel moves from '0' to '9' the target number wheel does not rotate. Only when the lowest place wheel switches its value to '0' from '9' the target number wheel rotates to increase its displayed value by one (T) from the previous value. In this embodiment, this rotational mode of number wheel is employed to count revolution number of the target number wheel 12a.

[52] While the target number wheel 12a is rotating, light from the light emitter 32 is incident on the outer circumferential face of the target number wheel 12a, and then reflected towards and input into the light receiver 34. The light receiver 34 outputs an electrical signal (optical detection signal) in proportion to the intensity of the incident light. At this time, since the driving force for the light emitter 34 is provided in the form of pulses, the output electrical signal from the light receiver 34 appears as a pulse form, as shown in Fig. 8. According to observation of the intensity of light reflected from the target number wheel 12a through the ADC 52, the intensity of reflected light varies with the respective numerals on the target number wheel 12a. However, in recognizing rotation of the target number wheel 12a, direct use of this variation may lead to a wrong result. This is because the variation in reflected light varies with the types of meters and with the assembled state even in the same type of meters. Instead, it is preferable to utilize the intermittent rotation of the target number wheel 12a while the lowest place wheel 12b continues to rotate.

[53] As the lowest place wheel 12b continues to rotate, the output electrical signal sampled from the light receiver 34 takes a waveform, for example as shown in Fig. 8 (a). Each region P , P , P , where the target number wheel 12a remains stopped at the numbers 5, 6, 7 respectively, corresponds to a time period during which the lowest place wheel 12b rotates from '0' to '9'. The regions P 9 and P 4 , where the target number wheel 12a moves from '5' to '6' and from '6' to 7' respectively, correspond to a time period during which the lowest place wheel 12b moves from '9' to '0'. In the regions P , P , P where the target number wheel 12a remains stopped, the light reflecting surface does not move and thus the sampled signal has a constant amplitude m , m or m .

Ii 7i 13i

However, when the target number wheel 12a rotates to change its number value, for example, from '5' to '6' or from '6' to 7' (region P or P ), the light reflecting surface moves or changes. Accordingly, the light reflectivity and reflection patterns change such that the intensity of reflected light being incident on the light receiver 34 changes. As the result, the sampled output signals from the light receiver 34 ([m , m , m , m , m 1 or [m , m , m , m , m 1) have non-uniform magnitudes. This behavior occurs

8 9 10 11 12 ^& commonly for all the numerals engraved or written in the target number wheel 12a whenever its number value increases by T. In the non-uniform amplitude regions, for example, the regions P and P , the signals have fluctuations large enough to be easily sensed or detected, nearly regardless of the printed states or assembled states of the number wheels. At the region P 2 or P 4 where the target number wheel 12a stops at a certain number value (e.g., at '5' or '6'), if the supplied goods are being consumed, a lower place wheel, i.e., the lowest place wheel 12b, continues to rotate. The duration time for the respective regions P , P , P , P and P varies according to instantaneous consumption of the supplied goods.

[54] As shown in Fig. 8(b), the metering computer unit 54 analyzes digital signal values provided by the ADC 52 to discriminate the regions P , P , P and the regions P and P from each other and then provides a 'logic low' and a 'logic high' respectively. In the regions P , P , P , the digital signal values fluctuate within a certain limit within a certain period of time. In the regions P and P , the digital signal values go beyond the certain limit. That is, while monitoring in real-time the magnitude of digital signals output from the ADC 52, whenever the magnitude changes non-uniformly after it has been maintained uniformly for more than a certain time period, a 'logic low' and a 'logic high' are allotted for the uniform region and the non-uniform region respectively. Then, it is determined that the number value of the target number wheel 12a has been increased by T. In other words, the region having a 'logic high' corresponds to an increase by T in the number value of the target number wheel 12a. Thus, the number of logic high' occurrences can be counted and, when the count becomes 10, the target number wheel 12a is considered to have completed one rotation.

[55] These metering procedures are implemented into a program, which is then installed in the metering computer unit 54. The metering computer unit executes the program to enable to automatically digitize indication value (consumption) of the meter 2. Here, theoretically, all the sampled signals during the region P , P , P where the target number wheel 12a remains stopped are to have the same amplitude, but practically may have slight fluctuations due to noises and the like. Therefore, the above- mentioned limit is to be determined so as to be higher than the above fluctuation range. In addition, if the limit is selected to be overly large, the regions P and P where the target number wheel 12a moves cannot be distinguished. These points are to be considered in choosing the maximum limit.

[56] (3) Third Embodiment

[57] 1) Incident of "erroneous reading"

[58] In the above first embodiment of the invention, however, the revolution number of the target number wheel 12a, counted through the metering computer unit 54, may be inaccurate, in case where the supplied goods are being intermittently used, i.e., the consumption of the supplied goods is interrupted during rotation of the target number wheel 12a. It is assumed that use of the supplied goods is stopped or interrupted from a time point t when the target number wheel 12a is being rotated, and, after a certain period of time, the use of supplied goods is resumed. In this assumption, a signal sampled from the ADC 52 takes a waveform, for example, as shown in Fig. 9(b). In case where the supplied goods are being used without intermission, the sampled signal from the light receiver 34 exhibits a waveform, for example, as shown in Fig. 9(a). However, at the above-assumed situation, if the use of supplied goods has been stopped, for example at the time point t , after the metering computer unit 54 has recognized sufficiently that the target number wheel 12a was during the course of rotation (i.e., in the region P or P ), the intensity of the reflected light becomes

2 4 uniform or constant (e.g., signals m , m , m , m , m , m , m in Fig. 9(b)) in spite

41 42 43 44 45 46 47 of incompletion of numeral switch in the target number wheel 12a. This is because, at the region Q where the use of supplied goods is interrupted, the lowest place wheel 12b and the target number wheel 12a both remain stopped and thus the intensity of light being incident on the light receiver 34 is nearly uniform or constant. [59] According to the logics of first embodiment, the metering computer unit 54 will accept the rotation of the target number wheel 12a as an increase by T in the numeral value thereof and thus assign a logic high R for this course of happening, i.e., for the course of incidents where a sampled signal m of uniform level is followed by sampled

Ii signals m and m of non-uniform level and thereafter a stable uniform signals m ~m

^& 2 3 ^& 41 47 appear. In fact, however, the target number wheel 12a did not complete a rotational movement corresponding to an increase by T in its numeral indication value. Under this circumstance, if the use of supplied goods is resumed after a certain period of time (i.e., from a time point t ), the intensity of reflected light being incident on the light receiver 34, i.e., the optical detection signal of the light receiver 34 appears nonuniform (e.g., sampled signals m 5 and m 6 ). Accordingly, the target number wheel 12a completes its rotational movement for an increase by T in its numeral value and then the optical detection signal level of the light receiver 34 is stabilized again (e.g., signal m ). At this time, again the metering computer unit 12a will accept this movement of

7i the target number wheel as an increase by T in the numeral value thereof and thus assign a logic high R for this course of incidents. Consequently, the revolution number of the target number wheel 12a counted as above comes to contain an error. As a matter of fact, in spite that the numeral value of the target number wheel 12a is increased by T the metering computer unit 54 may erroneously recognize as being increased by '2' (hereinafter, referred to as an "erroneous reading or erroneous reading incident").

[60] In order to avoid this erroneous reading incident, the second embodiment of the invention proposes a digitizing apparatus as illustrated in Fig. 10. Dissimilar to the digitizing apparatus 100 according to the first embodiment, the digitizing apparatus 100-1 of second embodiment is further provided with an in-use detector unit 58, which makes detection in real-time as to whether or not the supplied goods are currently being used or consumed and provides the detection result to the metering computer unit 54.

[61] The erroneous reading occurs as follows. When the intensity of reflected light being incident on the light receiver 34 (i.e., the magnitude of the optical detection signal of the light receiver 34) appears as being stable for more than a certain period of time, the number value of the target number wheel is considered as having been increased by T. However, in case where the stable state occurs by interruption of the use of the supplied goods, the target umber wheel is erroneously determined as having completed its rotational movement for an increase by T in its number value, in spite of not an increase in its actual number value. Therefore, based on information provided by an in- use detector unit 58 in real-time as to whether or not the supplied goods are currently being consumed, the metering computer unit 54 makes a decision as to whether the stable (uniform) state of the magnitude of optical detection signal output from the light receiver 34 is caused by use of the supplied goods or by non-use of the supplied goods. As the result of the decision, the former case is counted as the target number wheel 12a having completed it rotation corresponding to an increase by T in the number value thereof, and the latter case is ignored. That is, this logic is implemented in the metering program to be installed in the metering computer unit 54. More specifically, as one approach to avoid the double count, a logic can be prepared so as to ignore either one of the ^r pulses R 1 and R 2.

[62] 2) Specific Examples for In-use Detector Unit 58

[63] The lowest place wheel 12b continuously rotates while the supplied goods are being consumed, and remains stopped when the supplied goods are not used. The lowest place wheel 12b can be detected as to whether it is rotating or not, in order to determine whether or not the supplied goods are currently being used. Fig. 11 illustrates one exemplary configuration for the in-use detector unit 58a. The in-use detector unit 58a is configured such a manner that an optical sensor unit is employed to detect whether or not the lowest place wheel 12b is being currently rotated and thus to determine whether or not the supplied goods are currently being consumed.

[64] The in-use detector unit 58a includes an optical sensor unit 30-1 having a detection light emitter 32-1 and a detection light receiver 34-1 housed in a case 35-1. The optical sensor unit 30-1 has the same construction as the optical sensor unit 30. The former unit is for detecting and the latter one is for metering. In practice, two optical sensor units are disposed adjacently one after another such that one is used for detecting and the other one is used for metering. Alternatively, two light emitters and two light receivers may be housed in a single case and then one pair can be used for detecting and the other pair can be used for metering. A power supply 50- 1 is coupled to the detection light emitter 32-1 and provides a driving pulse thereto. An ADC 52-1 is coupled to the detection light receiver 34-1 and receives an optical detection signal therefrom. A detection computer unit 54-1 is coupled to the ADC 52-1 and receives sampled signal values. Coupled to the power supply 50-1 and the detection computer unit 54-1 is a timer 56-1 to provide a clock signal.

[65] According to real-time observation of the intensity of reflected light being input to the detection light receiver, i.e., the sampled signal output from the ADC 52-1, the sampled signal values are fixed for more than a certain time period when the supplied goods are not being used. On the contrary, when the supplied goods are being consumed, the sampled signal values keep fluctuating. If the lowest place wheel 12b remains stopped for a certain period of time, it is determined that the supplied goods are not being used currently. According to these decision criteria, the detection computer unit 54-1 analyzes sampled signals provided from the ADC 52-1 to determine whether or not the supplied goods are currently being used. The determination from the detection computer unit 54-1 is provided in real-time to the metering computer unit 54. The metering computer unit 54 uses the determination results to distinguishes the following two cases i) and ii) from each other. I) The target number wheel 12a has completed its rotational movement corresponding to an increase by T in the number value thereof. II) Use of the supplied goods is interrupted during rotational movement of the target number wheel 12a, and thus the intensity of the reflected light being incident on the light receiver 34 becomes constant or uniform. Thus, the above-mentioned erroneous reading can be prevented.

[66] It is most preferable that the detection optical sensor unit 30-1 is disposed correspondingly to the lowest place wheel 12b. However, it may be installed towards a number wheel at a number place right before the lowest place wheel. For example, among number wheels after the target number wheel 12a, the number wheels, excepting the lowest place wheel, have the following characteristics (in this case, the target number wheel is at least a third number wheel from the lowest place wheel, or a number wheel before the third one.). That is, whenever the target number wheel changes its number value, a number wheel right after the target number wheel has completed one revolution and changes its number value to '0' from '9'. Here, it is assumed that 12a and 12c in Fig. 4 are adopted as a detection number wheel and a target number wheel respectively. An optical sensor unit having a detection light emitter and a detection light receiver is installed at the above detection number wheel. Then, the above-mentioned erroneous reading can be avoided according to the following logics. That is, when the reflected light of the target number wheel fluctuates (i.e., fluctuation in the optical detection signal of the light receiver 34 or in the output digital signal of the ADC 52) and then becomes stabilized, the following two phenomena occur.

[67] First, in case where the intensity of reflected light of the detection number wheel remains constant for a certain period of time and then starts fluctuation, it means that the supplied goods are being continuously used. In this case, if the detection computer unit 54-1 confirms this case, it provides to the metering computer unit 54 a detection information of the supplied goods being currently used. In addition, stabilization of the reflected light of the target number wheel can be considered as having completed an increase in the number value thereof. Therefore the metering computer unit 54 counts an increase by T in the number value of the metering computer unit 54. Here, the certain period of time is a time period from the stabilized state to the fluctuation of the reflected light of the detection number wheel when the supplied goods are minimally used. This time period varies with the types of the supplied goods or the types of the meters and thus need to be acquired experimentally.

[68] The second case is that the intensity of the reflected light of the detection number wheel remains constant, not changing even after the certain period of time has lapsed. This phenomenon occurs in case where the use of the supplied goods is interrupted. Thus, the detection computer unit 54-1 notifies the metering computer unit 54 that the supplied goods are not currently used. Of course, at this time, the reflected light of the target number wheel appears stabilized, but actually the target number wheel has not completed an increase by T in its number value. Thus, the metering computer unit 54 takes an appropriate measure so as not to doubly count the movement of the target number wheel. For example, the current fluctuation in the reflected light of the target number wheel is ignored, or the next-occurring first fluctuation is ignored.

[69] The in-use detector unit 58 may be formed of a magnetic sensor unit (not shown) made up of a permanent magnet and a magnetic sensor (e.g., a lead switch, hall sensor or the like), in stead of the optical sensor unit. That is, a permanent magnet is attached to for example the lowest place wheel 12b so as to be rotated together with it. A magnetic sensor is disposed on the rotating path of the permanent magnet. Excepting for replacing the optical sensor unit with the magnetic sensor unit, the remaining of the in-sue detector unit 58 is constructed in the same manner. With this in-use detector unit using a magnetic unit, whenever the lowest place wheel 12b completes one rotation while the supplied goods are continuously being used, the magnetic sensor enters the magnetic field of the permanent magnet and then escapes therefrom. Every time when the magnetic sensor enters and escapes from the magnetic field of the permanent magnet, accordingly the magnetic sensor outputs a switching signal (e.g., an on/off signal). The post-processing for this output signal from the magnetic sensor unit is the same as in the optical sensor unit.

[70] The above two types of in-use detector units can be applied regardless of the types of supplied goods. For example, in case where the supplied goods are a gas, a flow sensor may be installed in a gas meter or in a gas pipe near the gas meter to thereby detect gas-flowing. Specifically, as shown in Fig. 12, a differential pressure sensor unit can be used for detecting gas-flowing. The differential pressure sensor unit is made up of an orifice 6 inside of a gas pipe 90 connected to the meter and a differential pressure sensor 98 for sensing a difference in the pressure between before and after the orifice 6 and generating corresponding electrical signal. If the differential pressure sensor 98 outputs an electrical signal corresponding to the sensing result, the output electrical signal is converted into a digital signal by the ADC 52-1, and the detection computer unit monitors in real-time the digital signal values. Similar to the previously mentioned optical sensor unit or the magnetic sensor unit, if the level of the digital signal remains in a constant or uniform value for a certain period of time, it is determined that the gas is not currently being used. Otherwise, the gas is determined as being currently consumed.

[71] The above logics, i.e., the digitizing methods according to the second embodiment is implemented as a program, which is then stored in a memory. The CPU executes the program to carry out the method or logics. The in-use detector unit 58 and the metering computer unit 54 may employ a microprocessor having for example a memory and a CPU.

[72] (4) Third Embodiment

[73] Fig. 13 shows a digitizing apparatus 100-2 according to the third embodiment of the invention. This digitizing apparatus 100-2 further comprises a temperature and pressure compensation unit 60, in addition to the construction of the digitizing apparatus 100-1, such that a temperature and pressure error can be removed from the digitized read value for a consumption indication value. [74] The temperature and pressure compensation unit 60 (hereinafter, referred to as a "T

&P compensation unit") includes a temperature measuring device 62 and a pressure measuring device 64. The temperature measuring device 62 and the pressure measuring device 64 measure instantaneous temperature and pressure values of a gas meter 2 or inside of a gas pipe 90 connected to the gas meter 2 at regular time intervals or whenever the amount of consumed gas reaches a certain predetermined value. The T &P compensation unit 60 includes a temperature and pressure compensator 66 (hereinafter, referred to as a "T&P compensator") for computing an instantaneous temperature and pressure compensation coefficient K (hereinafter, referred to as an "Instantaneous T&P compensation coefficient"), which occurs due to a difference between a measured instantaneous temperature and a reference temperature and between a measured instantaneous pressure and a reference pressure.

[75] The T&P compensation coefficient K computed by the T&P compensation unit 60 is provided to the metering computer unit 54. In the metering computer unit 54, the T& P compensation coefficient (computed by the T&P compensation unit 60) is reflected on the actually read indication value for the amount consumed for a certain period of time, according to the logics of the above two embodiments, thereby computing a temperature and pressure error and a consumption read value compensated for the temperature and pressure error.

[76] The T&P compensation unit 60 may be configured such that the measured instantaneous temperature and pressure values are averaged every one hour, every two hours or every day to calculate average temperature and pressure values for the respective periods. Further, the metering computer unit 54 may use the consumption read value as a 'weight factor' to calculate a weighted average value for the instantaneous gas temperature or gas pressure.

[77] Fig. 14 illustrates an automatic reading apparatus employing a digitizing apparatus having a T&P compensation function according to the third embodiment of the invention. In the volumetric (membrane-type) gas meter 2 of Fig. 14, the temperature measuring device 62 and the pressure measuring device 64 are housed in a case 68 capable of screw-assembling and combined integrally with the gas pipe 90. The gas pipe 90 is hermetically coupled between the existing gas supply pipe 94 and the gas meter 2, using couplings 92a and 92b. The optical sensor unit 30 is mounted in front of the indication unit of the meter. The remaining components of the digitizing apparatus 100-2, i.e., the power supply 50, the ADC 50, the timer 56, the metering computer unit 54, the T&P compensation unit 66, the communications unit 70 and the like, are implemented in a printed circuit board (not shown), which is then housed in a circuit box 150. The optical senor unit 30 and the temperature and pressure measuring devices 62 and 64 are connected to the printed circuit board through an electric wire 82. The functions of the T&P compensation unit 66, the metering computer unit 54 and the in- use detector unit 58 are implemented into a program, which is stored in a memory. The functions are performed by executing the program by the CPU. Thus, hardware for the T&P compensation unit 66, the metering computer unit 54 and the in-use detector unit 58 may be implemented by using a microprocessor 80 having a memory and a CPU. Further, the circuit box 150 may be further provided with operation buttons 152 through which a user can input instructions required for an automatic reading, a T&P compensation or the like, and with a display unit 154 for displaying various information acquired or computed by the CPU. In this case, the user operation button 152 and the display unit 154 are coupled to the CPU so that the user's instructions are transferred to the CPU and the CPU provides the metering results.

[78] The digitizing apparatus 100-2 is installed at each gas consumer. For the purpose of efficient meter-reading, preferably a gas supply company divides its own gas- supplying region into several unit areas and installs a local wireless collector 72 for every unit area. The local wireless collector 72 installed in each unit area are connected to a computer 76 of the gas supply company via a wired communications network or wireless communications network (e.g., data communications using a mobile phone communications network) or the like. Digital consumption information such as automatic read value, T&P compensation coefficient, compensated consumption or the like), which is computed by the metering computer unit 54 and compensated for temperature and pressure error, is transmitted to the local wireless collector 72 or a local wireless communications relay, along with each consumer information, via the communications unit 70. Then, the local wireless communications relay 72 transmits the information, collected from the consumers of the allotted unit area, to the computer 76 of the gas supply company through a communications network 74. In this way, the gas supply company can read automatically and precisely the gas meter of each consumer remotely located.

[79] On the other hand, when it is assumed that T, P, T , and P are an instantaneous temperature (⁰K), an instantaneous pressure (hPa), a reference temperature (⁰K) and a reference pressure (hPa) respectively, K = T -P/T-P . The reference temperature and pressure are typically 0°K (=273°C) and 1 ATM (=1013hPa). Thus, the instantaneous temperature and pressure compensation coefficient K is expresses as the following equation (1). [80]

P x 273

^K™ ⁼ 1013 x (273 + T) (1) [81] The instantaneous temperature and pressure compensation coefficient K can be calculated from the equation (1) or any other equations equivalent to the physical principle of the equation (1). The equation (1) is determined using the Boyle-Charles's law. More specifically, gas volume is expressed by the following equation (2) according to temperature and pressure.

[82] P-V = Z-n-R-T (2)

[83] Here, P and V denote absolute pressure and volume of gas respectively. Z denotes compressibility factor being affected by pressure. T and N denote mole number of gas and absolute temperature of gas (°K). Pressure and temperature of the gas passing through a gas meter 2 are relatively low, i.e., about 1013~1399hPa in absolute pressure and near room temperature. Thus, Z=I make no significant difference. Using the equation (2), gas volume at an arbitrary temperature T and pressure P can be expressed by the following equation (3), in which T and P are reference temperature and pressure at the gas-supplying location of a gas-supply company (in case of Korea, usually 0°C(273°K) and 1 ATM (1013hPa)), and V is gas volume at the T and P .

[84]

P V B₁ V₀

(3) [85] The equation (3) is well-known as Boyle-Charles's Law clearly defining gas behavior. The gas volume V at the reference temperature T and pressure P , i.e., a compensated gas consumption (V ), can be derived from the equation (3), using the gas volume V measured at the arbitrary temperature T and pressure P. The equation (3) can be rewritten as follows, in terms of the compensated gas consumption (V ). [86]

T - P₀ (4)

[87] The consumed gas amount V at the reference temperature and pressure (e.g., at T =

0°C = 273°K and P =1013hPa) can be calculated using the following equation (5). In the right side of the equation (5), the remainder except for V is the instantaneous temperature and pressure compensation coefficient K expressed by the equation (1). That is, V = K x V .

0 TP

[88] T⁷ IO H (5)

[89] A method for compensate for T&P error using the instantaneous T&P compensation coefficients K is explained.

TP

[90] The instantaneous T&P compensation coefficient is used to compensate the T&P errors. By way of an example, instantaneous temperature and pressure values are measured at certain time intervals to compute an instantaneous T&P compensation coe fficient K corresponding thereto. A gas consumption V during the time interval is measured and then the gas consumption V is multiplied by the instantaneous T&P coefficient K to calculate a compensated gas consumption V . As an alternative, a daily T&P compensation coefficient is computed by averaging the entire instantaneous T&P compensation coefficients being calculated during a day. The daily T&P compensation coefficient is multiplied by the read value of gas amount consumed during the day, thereby calculating a compensated daily amount of consumed gas (referred to as a "compensated daily consumption"). The compensated daily amounts of consumed gas are accumulated monthly to determine a compensated monthly amount of consumed gas (referred to as a "compensated monthly consumption"). In addition, a monthly T& P compensation coefficient is determined by averaging the entire instantaneous T&P compensation coefficients or the entire daily T&P compensation coefficients being computed during one month. Then, a compensated monthly consumption can be determined by multiplying the monthly T&P compensation coefficient by the read value of consumed gas for the month. Here, the automatic read value V for gas consumption, which is to be compensated, can be acquired from rotation numbers of the target number wheel 12a. The rotation numbers are digitized by the metering computer unit 54, using output signals from the ADC 52.

[91] On the other hand, in order to more precisely compensate for T&P errors using the above T&P compensation coefficients, when the T&P compensation unit 66 computes the T&P compensation coefficient or the compensated gas consumption, it is preferable to check whether gas is consumed or not at the time of measuring the temperature and pressure or during the measuring time interval. It is also preferable to apply a weighted value depending upon the amount of gas consumption. As one method of applying the weighted value, the time intervals of measuring the temperatures and pressures, in other words, the time intervals of calculating instantaneous T&P compensation coefficients are to be related with and thus variably adjusted according to whether or not gas is consumed or the amount of consumed gas. Since the information as to whether the gas is being used or not is generated by the in-use detector unit 58, the metering computer unit 54 uses the information from the in-use detector unit 58 to provide a weighted value. In one embodiment for the application of a weighted value, the temperature and pressure compensation unit 66 analyzes the fluctuation pattern with time for temperature values being acquired from the temperature-measuring device 62 and for pressure values being acquired from the pressure-measuring device 64, to thereby determine whether gas is currently being consumed. In case where the gas is currently being consumed, the T&P compensation coefficient is calculated at short time intervals, relative to the case where the gas is not currently being consumed. Thus, in order to obtain daily or monthly T&P compensation coefficients, these instantaneous T&P compensation coefficients calculated as above can be simply arithmetic- averaged to thereby automatically reflect a weighted value according to whether or not gas is being consumed or the consumed amount of gas.

[92] Figs. 15 to 18 are sectional views taken along the line C-C in Fig. 14 and showing a temperature measuring device 62 and a pressure measuring device 64 according to embodiments of the invention. Referring to the temperature and pressure measuring device of Fig. 15, in order to measure pressure, the pressure measuring device includes a gas pipe 90, a body 68a, 68b, 68c, a pressure sensor 220, an isolator means, and a pressure signal processor 230a. The gas pipe 90 is coupled between the gas supply pipe 94 and the gas meter 2 and constitutes part of the gas supply pipe 84. The body 68a, 68b and 69c is secured to the gas pipe 90 using screws 246a and 246b, and provided with a pressure pipe path 242 passing through a receptacle cavity one end of which communicates with the gas pipe and the other end of which is closed. The pressure sensor 220 is disposed inside of a receptacle cavity of the body 68b and generates an electrical signal corresponding to the ambient pressure. The isolator means is formed of for example a membrane 224, which is disposed in the pressure pipe path 242 inside of the body 68b so as to transverse the pressure pipe path 242, such that gas pressure inside of the gas pipe is transmitted to the gas pressure sensor 220, but the gas is not allowed to contact directly the gas pressure sensor 220. The pressure signal processor 230a is disposed outside of the body 68b and coupled to the output terminal of the pressure sensor 220 through an electric wire 222. The pressure signal processor 230a processes the output electrical signal from the pressure sensor 220 and converts it to a digital signal corresponding to the gas pressure. As long as it can measure pressure and convert the measured pressure value into an electrical signal in the form of a digital value, the pressure sensor may employs various types such as a capacitor pressure sensor, a strain gauge pressure sensor, a semiconductor pressure sensor, a piezoelectric pressure sensor, and the like.

[93] Furthermore, for temperature measurement, the temperature and pressure- measuring devices include a temperature sensor 210 installed inside or outside of the gas pipe 90. The temperature sensor 210 measures ambient temperature and converts into an electrical signal corresponding to it. A temperature signal processing unit 230b is connected to the output terminal of the temperature sensor 210 through an electric wire 212. The temperature signal processing unit 230b processes the output electrical signal from the temperature sensor 210 and converts into a digital signal corresponding to the ambient temperature. The figures illustrate the pressure signal processing unit 230a and the temperature signal processing unit 230b as being implemented on a same printed circuit board 230c. An O-ring 250a, 250c is mounted around the membrane 224 and the pressure sensor 220 to thereby prevent the gas from leaking to the outside. The gap occurred for installing the pressure sensor 220 is finished with a sealant 228. As long as it can measure ambient temperature and convert into an output electrical signal, the temperature sensor may employ various types such as a metallic thermistor such as thermocouples or platinum, a non-metallic thermistor, a semiconductor temperature sensor, a radiation temperature sensor, a metal-core type temperature sensor, or the like.

[94] Figs. 16 and 17 shows a temperature and pressure measuring unit further modified to prevent direct contact between the pressure sensor 220 and the gas inside the gas pipe member 90. In case of Fig. 16, two membranes 224a and 224b sealed with O- rings 250a and 250b are dispose in a pressure pipe path 242- 1 formed inside the body 68b. A U-shaped pressure tube is formed between the two membranes 250a and 250b and a liquid material 226 is filled inside the U-shaped pressure tube. In order to fill the liquid material 225, the body 68b is provided at its side with a groove formed to be connected with the U-shaped pressure tube. After the liquid material is injected through the groove, the groove is closed with a plug 244 sealed with an O-ring 25Od. Fig. 17 illustrates a pressure pipe path 242-2 having a V-shape. In Figs. 16 and 17, either one of the membranes 224a and 224b or the liquid material 226 may be adopted.

[95] Fig. 18 shows a temperature and pressure measuring unit having a different mode of temperature-measuring device. Specifically, a pressure pipe path 242-3 is formed inside of the body 68a, 68b, and 68c. Part of the pressure pipe path 242-3 is formed in vertical direction. One end of the pressure pipe path 242-3 is fluid-communicated with the gas pipe 90 and the other end thereof is closed. The vertical section of the pressure pipe path is filled with a liquid material 226 up to a desired level. A permanent magnet 248 is rested on a float, which is to be floated in the liquid material 226. The liquid material 226 changes the height of liquid column, in response to change in the pressure inside of the gas pipe 90. In addition, a magnetic field sensor 252 is disposed outside of the body 68b so as to be placed approximately at the intermediate of the level- fluctuation range of the liquid material 226, which corresponds to the expected range of pressure fluctuation inside of the gas pipe 90. The magnetic field sensor 252 outputs an electrical signal corresponding to the intensity of magnetic field of the permanent magnet 248. The electrical signal output from the magnetic field sensor 252 is transmitted to a pressure signal processing unit 230a and converted into a digital signal corresponding to the gas pressure. The liquid material 226 is sealed with a plug 244 and an O-ring 25Od. [96] Hereafter, T&P compensated gas consumption is calculated according to the following procedures. First, a basic mode will be explained. The T&P compensator 66 acquires an instantaneous temperature T and an instantaneous pressure P from the temperature-measuring device 62 and the pressure-measuring device 64, for example every 10 minutes from 0:00AM in real time. A T&P compensation coefficient K is calculated using the above equation (1). Tnstant_T/P/K (instantaneous T&P compensation coefficient)' is stored in the memory inside of the microprocessor 80. At 24:00PM, the microprocessor 80 averages Tnstant_T/P/K of 24 hours to calculate a 'daily_T/P/K ' which is stored in the memory inside of the microprocessor 80 together with the date information. In addition, a 'monthly T/P/K TP ' up to that date is calculated and stored. Everyday, a 'monthly_T/P/K ' up to that date is stored. Then, at the end of the month, a 'monthly_/P/K ' up to that date is copied and stored as a 'monthly_T/P/K ' of that month separately in the memory inside of the microprocessor 80. However, the 'mmonthly_T/P/K ' for each date is updated everyday. Here, the 'monthly_T/P/K ' is an average from the current time (24:00PM) to the last one month. At this time, the days of that month is calculated according to the month to which the current date belongs. That is, in case of the average to 24:00PM on February 3, the days of the month is 28 days and thus 'daily_T/P/K 's for 28 days from January 7 to February 3 are arithmetic- averaged to calculate the 'monthly_T/P/K ' for February 3. The above procedures are repeated. In case where a user inputs an instruction through the user operation unit 152, the following special modes are performed according to the user's instruction.

[97] In a special mode, whether or not the gas is currently being consumed is confirmed.

In this mode, first, the microprocessor 80 confirms whether the gas is being consumed, for example every 30 seconds from 0:00AM in real time, using the determination result of the in-use detector unit 58. At a 'gas not being consumed' state, the microprocessor 80 acquires the temperature and pressure from the temperature-measuring device 62 and the pressure-measuring device 64, for example every 60 minutes from 0:00AM in real time, to store an 'instant_T/P/K ' in the memory inside of the microprocessor 80. At a 'gas being consumed state', the microprocessor 80 acquires the temperature and pressure from the temperature-measuring device 62 and the pressure-measuring device 64, for example every 6 minutes from 0:00AM in real time, to store an 'instant_T/P/K inside of the microprocessor 80. By repeating the above procedures, at 24:00PM the 'instant T/P/K 's for 24 hours are averaged to calculate a 'daily T/P/K '. In

^~ TP ^{& J ~} TP calculating the average value, all the data of that day is arithmetic-averaged, regardless of the state of 'gas being consumed' or 'gas not being consumed'. The number of data varies, but not exceed 240(=10 x 24) at maximum. Since the sampling period is 60 minutes or 6 minutes, the weighted value will be automatically reflected as much. Even in the state of 'gas not being consumed', the weighted value is reflected as much as 1/10, to thereby enable to respond to mal-operation of the function of confirming whether or not the gas is currently being consumed. Consecutively, as in the basic mode, the microprocessor 80 stores the 'daily_T/P/K ' in the memory inside of the microprocessor 80 along with the date information, and then calculates a 'monthly_T/P/K

' up to that date and stores it in the memory inside of the microprocessor 80. Everyday, a 'monthly_T/P/K ' up to that date is stored. Then, at the end of the month, a 'monthly /P/K ' up to that date is copied and stored as a 'monthly T/P/K ' of that month separately in the memory inside of the microprocessor 80. However, the 'monthly_T/P/K ' for each date is updated everyday.

[98] Another alternative special mode confirms the amount of consumed gas. In this mode, first, the microprocessor 80 operates the in-use detector unit 58 to confirm whether the gas is being consumed, for example every 2 seconds from 0:00AM in real time. In case where the in-use detector unit 58 confirms using a photo-sensing mode whether gas is being consumed, it is confirmed whether one rotation of a particular number wheel is completed. The microprocessor 80 acquires the temperature T and pressure P from the temperature-measuring device 62 and the pressure-measuring device 64 to calculate and store an 'instant_T/P/K ', for example every one, two, four

TP or eight rotations of the particular number wheel. Consecutively, the microprocessor 80 averages the 'instant T/P/K 's of 24 hours at 24:00PM to calculate and store a

^~ TP

'daily_T/P/K ' and a 'daily consumption'. All the data of that date is arithmetic- averaged. The 'daily consumption' is used as a weighted value when calculating a monthly average value. The microprocessor 80 stores the 'daily_T/P/K ' in the memory inside of the microprocessor 80 with the date information and then calculates a 'monthly_T/P/K ' up to that date and stores it in the memory inside of the microprocessor 80. The 'monthly_T/P/K ' up to that date continues to be updated every day. [99] The T&P compensation coefficient obtained through the above modes is reflected on the automatic read values provided by the metering computer unit 60 to thereby enable to calculate a T&P compensated gas consumption. These operational modes are programmed to the temperature and pressure compensation unit 66. Industrial Applicability [100] As described above, the digitizing method of invention has been explained illustrating a mechanical meter, but can be applied to various other types of meters without restriction as long as they are mechanical meters displaying the consumption of supplied goods in the form of analog values. In this digitizing method, the consumption read value of a mechanical meter is converted into a digital data. The converted digital data can be used for remotely and automatically reading a meter. Further, when applied to a gas meter, it can easily compensate for temperature and pressure errors, which occur due to a difference between the reference temperature and pressure at the gas supplying location and the actual temperature and pressure at the gas meter of each individual consumer, thereby enabling a precise remote automatic reading of meters.

[101] Although the present invention has been described with reference to several preferred embodiments, the description is illustrative of the invention and not to be construed as limiting the invention. Various modifications and variations may occur to those skilled in the art without departing from the scope and spirit of the invention, as defined by the appended claims.

[102]

Claims

[1] An apparatus for digitizing an indication value for consumption of supplied goods in a mechanical meter, the meter including a number wheel train having a plurality of number wheels disposed adjacently in a row, the indication value being a combination of number values engraved or printed on the number wheels, the apparatus comprising: a light emitter emitting a light towards a certain desired area on the outer circumferential face of a target number wheel of which rotation number is to be counted, the light emitter generating light by a power supply; a light receiver disposed towards the certain desired area so as to receive the light of the light emitter reflected from the outer circumferential face of the target number wheel, the light receiver converting the received light into an electrical optical detection signal corresponding to the intensity of the received light and outputting the electrical optical detection signal; an analog-to-digital converter converting the optical detection signal output from the light receiver into a digital signal; and a metering computer unit reading the indication value of the meter in such a manner to monitor in real-time the digital signal being provided by the analog- to-digital converter and determine that the number value of the target number wheel has increased by T every time when the magnitude of the digital signal remains uniform for more than a certain period of time and thereafter fluctuate irregularly.

[2] The apparatus as claimed in claim 1, further comprising: an in-use detector unit for determining whether or not the supplied goods are currently being consumed and providing the determination result in real-time to the metering computer unit, wherein the metering computer unit is configured such that, when the magnitude of the digital signal remains uniform for more than the certain period of time, using the determination result, the metering computer unit determines whether the uniform state is caused by use of the supplied goods or by interruption of use of the supplied goods without an increase by T in the number value of the target number wheel, and counts the increase by T in the number value of the target number wheel only in case where the uniform state is incurred by use of the supplied goods or ignores the uniform state in case where it is incurred by interruption of use of the supplied goods.

[3] The apparatus as claimed in claim 2, wherein the determination result is acquired in such a manner to be decided as being 'non-use' when the lowest place wheel in the number wheel train remains stopped without rotation for more than a certain period of time and to be decided as being 'in-use' when the lowest place wheel rotates within the certain period of time.

[4] The apparatus as claimed in claim 2, wherein the in-use detector unit comprises: a detection light emitter emitting a light towards a certain desired area on an outer circumferential face of a detection number wheel, the detection number wheel being a number wheel at a number place lower than the target number wheel, the detection light emitter generating light by application of a drive power; a detection light receiver disposed so as to receive the light of the detection light emitter reflected from the outer circumferential face of the detection number wheel, the detection light receiver converting the received light into an electrical optical detection signal corresponding to the intensity of the received light and outputting the electrical optical detection signal; an analog-to-digital converter sampling and converting the optical detection signal output from the detection light receiver into a digital signal; and a detection computer unit monitoring in real-time the digital signals being provided by the analog-to-digital converter, and determining that the supplied goods are being used when the magnitude of the digital signal remains uniform for more than a certain period of time and otherwise determine that the supplied goods are being used.

[5] The apparatus as claimed in claim 2, wherein the in-use detector unit comprises: a permanent magnet attached to and rotating with a detection number wheel to generate a magnetic field around the rotating path, the detection number wheel being a number wheel at a number place lower than the target number wheel; a magnetic sensor unit disposed on the rotating path of the permanent magnet, the magnetic sensor unit generating a desired detection signal when it is affected by the magnetic field of the permanent magnet by the rotation of the detection number wheel; an analog-to-digital converter converting the electrical signal output from the detection light receiver into a digital signal; and a detection computer unit monitoring in real-time the digital signals being provided by the analog-to-digital converter, and determining that the supplied goods are being used when the magnitude of the digital signal remains uniform for more than a certain period of time and otherwise determine that the supplied goods are being used.

[6] The apparatus as claimed in claim 4 or 5, wherein the target number wheel is a second or third number wheel from the last number wheel in the number wheel train, and the detection number wheel is a number wheel which is not the last number place among number wheels at lower number places than the target number wheel.

[7] The apparatus as claimed in claim 2, wherein in case where the supplied goods are a gas, the in-use detector unit comprises; an orifice installed inside of a gas pipe connected to the meter, and a differential pressure senor unit sensing a pressure difference between before and after the orifice and generating an electrical signal corresponding to the pressure difference; an analog-to-digital converter converting the electrical signal output from the differential pressure sensor into a digital signal; and a detection computer unit monitoring in real-time the digital signals being provided by the analog-to-digital converter, and determining that the gas is being used when the magnitude of the digital signal remains uniform for more than a certain period of time and otherwise determine that the gas is being used.

[8] The apparatus as claimed in claim 1 or 2, further comprising a power supply providing a drive power required in the light emitter, wherein the drive power is a drive pulse signal having a period of no more than 250 ms, the duration time of the drive pulse signal being longer than the response time of the photoelectric device and the duty ratio thereof being no more than 1/100.

[9] An apparatus for digitizing an indication value for consumption of supplied goods in a mechanical meter, the meter being a volumetric gas meter measuring gas consumption in a unit of volume, the meter including a number wheel train having a plurality of number wheels disposed adjacently in a row, the indication value being a combination of number values engraved or printed on the number wheels, the apparatus comprising: a light emitter emitting a light towards a certain desired area on the outer circumferential face of a target number wheel of which rotation number is to be counted, the light emitter generating light by a power supply; a light receiver disposed towards the certain desired area so as to receive the light of the light emitter reflected from the outer circumferential face of the target number wheel, the light receiver converting the received light into an electrical optical detection signal corresponding to the intensity of the received light and outputting the electrical optical detection signal; an analog-to-digital converter converting the optical detection signal output from the light receiver into a digital signal; a temperature and pressure compensation unit measuring an instantaneous temperature value and an instantaneous pressure value of gas inside of the gas meter or inside of a gas pipe connected to the gas meter at regular time intervals or whenever gas -consumption reaches a certain value, and calculating a temperature and pressure compensation coefficient at intervals of a first desired time, which occurs due to a difference between the measured instantaneous temperature and pressure values and a reference temperature and pressure at a gas-supplying point; and a metering computer unit reading the indication value of the meter in such a manner to monitor in real-time the digital signal being provided by the analog- to-digital converter and determine that the number value of the target number wheel has increased by T every time when the magnitude of the digital signal remains uniform for more than a certain period of time and thereafter fluctuate irregularly, and reflecting the temperature and pressure compensation coefficient computed by the temperature and pressure compensation unit on the read indication value for the first desired time to calculate a temperature and pressure compensated read value.

[10] The apparatus as claimed in claim 9, further comprising: an in-use detector unit for determining whether or not the supplied goods are currently being consumed and providing the determination result in real-time to the metering computer unit, wherein the metering computer unit is configured such that, when the magnitude of the digital signal remains uniform for more than the certain period of time, using the determination result, the metering computer unit determines whether the uniform state is caused by use of the supplied goods or by interruption of use of the supplied goods without an increase by T in the number value of the target number wheel, and counts the increase by T in the number value of the target number wheel only in case where the uniform state is incurred by use of the supplied goods or ignores the uniform state in case where it is incurred by interruption of use of the supplied goods.

[11] The apparatus as claimed in claim 10, wherein the in-use detector unit is configured so as to i) detect rotation of a detection number wheel to determine as 'non-use' if non-rotation of the detection number wheel continues for more than a second desired time and determine as 'in-use' if the detection number wheel rotates within the second desired time, the detection number wheel being a number wheel at a number place lower than the target number wheel, or ii) monitor in real-time whether or not gas is flowing inside the meter or inside a gas pipe connected to the meter to determine whether or not the gas is being used.

[12] The apparatus as claimed in claim 9 or 10, further comprising a communications unit for transmitting information on the compensated gas consumption calculated by the metering computer unit to a designated receiver regularly or in response to an external request.

[13] The apparatus as claimed in claim 9, wherein the instantaneous temperature and pressure compensation coefficient K is computed according to following equation or other equations equivalent to the physical principle of the following equation, in which P and T denote the instantaneous temperature and pressure values respectively.

_ P X 273

Λ ⁱ r^TFp —^~ 10l3 x (2T3 + T)

[14] The apparatus as claimed in claim 13, wherein, in calculating the temperature and pressure compensation coefficient, the temperature and pressure compensation unit considers a weighted value corresponding to whether or not gas is consumed or the amount of consumed gas when the gas temperature and pressure are measured or during the measuring-time interval.

[15] The apparatus as claimed in claim 9 or 10, wherein the temperature and pressure compensation unit includes: a temperature measuring device for measuring gas-temperature inside the gas meter or inside a gas pipe near the gas meter and converting the measured temperature value into an electrical signal corresponding thereto; a pressure measuring device for measuring gas-pressure inside the gas meter or the gas pipe and converting the measured pressure value into an electrical signal corresponding thereto; and a temperature and pressure compensator measuring an instantaneous temperature value and an instantaneous pressure value of gas at regular time intervals or whenever gas -consumption reaches a certain value, using the electrical signals provided by the temperature and pressure measuring devices, and calculating a temperature and pressure compensation coefficient at the first desired time intervals according to following equation or other equations equivalent to the physical principle of the following equation, P and T denoting the instantaneous temperature and pressure values respectively.

+ T)

[16] The apparatus as claimed in claim 15, wherein the pressure measuring device includes a pipe member connected between the gas supply pipe and the gas meter and constituting part of the gas supply pipe; a body fixed to the pipe member and having a pressure pipe path formed inside thereof, one end of the pressure pipe path being fluid-communicated with the pipe member and the other end thereof being ended with a closed receiving cavity; a pressure sensor disposed inside of the receiving cavity of the body and generating an electrical signal corresponding to ambient pressure; an isolation means disposed at the intermediate of the pressure pipe path within the body, the isolation means allowing the gas pressure inside of the pipe member to be transmitted to the pressure sensor and preventing the gas from contacting directly the pressure sensor; and a pressure signal processing unit disposed outside of the body and electrically connected with output terminal of the pressure sensor, the pressure signal processing unit processing the output electrical signal to convert into a digital signal corresponding the gas pressure.

[17] The apparatus as claimed in claim 16, wherein the isolation means is at least one of at least one membrane disposed at a desired position in a way to cross the pipe member and a liquid material filled in a U-shaped or V-shaped pipe path to a desired height thereof.

[18] The apparatus as claimed in claim 15, wherein the pressure measuring device includes a pipe member connected between the gas supply pipe and the gas meter and constituting part of the gas supply pipe; a body fixed to the pipe member and having a pressure pipe path formed inside thereof, one end of the pressure pipe path being fluid-communicated with the pipe member and the other end thereof being closed, part of the pressure pipe path being upright; a liquid material filled in the upright portion of the pressure pipe path to a desired level thereof, the column height of the liquid material changing in response to changes in the gas pressure inside of the pressure pipe path; a pressure sensor generating an electrical signal corresponding to the magnitude of gas pressure, the pressure sensor including a permanent magnet rested on a float floating in the liquid material and a magnetic field sensor disposed outside of the body to output an electrical signal corresponding to the intensity of magnetic field formed by the permanent magnet, the magnetic field sensor being placed approximately at the intermediate of the range of level change of the liquid material corresponding to an expected range of pressure fluctuation inside the pipe member; and a pressure signal processing unit converting the output electrical signal from the pressure sensor into a digital signal corresponding to the gas pressure.

[19] The apparatus as claimed in claim 15, wherein the temperature measuring device includes a temperature sensor installed inside or outside of the pipe member and converting into an electrical signal corresponding to ambient temperature, and a temperature signal processing unit electrically connected with output terminal of the temperature sensor and processing the output electrical signal from the temperature sensor and converting into a digital signal corresponding to the ambient temperature, the temperature signal processing unit being installed outside of the temperature sensor.

[20] An apparatus for digitizing an indication value for consumption of supplied goods in a mechanical meter, the meter being a volumetric gas meter measuring gas consumption in a unit of volume, the meter including a number wheel train having a plurality of number wheels disposed adjacently in a row, the indication value being a combination of number values engraved or printed on the number wheels, the apparatus comprising: a light emitter emitting a light towards a certain desired area on the outer circumferential face of a target number wheel of which rotation number is to be counted, the light emitter generating light by a power supply; a light receiver disposed towards the certain desired area so as to receive the light of the light emitter reflected from the outer circumferential face of the target number wheel, the light receiver converting the received light into an electrical optical detection signal corresponding to the intensity of the received light and outputting the electrical optical detection signal; an analog-to-digital converter converting the optical detection signal output from the light receiver into a digital signal; a temperature and pressure compensation unit measuring an instantaneous temperature value and an instantaneous pressure value of gas inside of the gas meter or inside of a gas pipe connected to the gas meter at regular time intervals or whenever gas -consumption reaches a certain value, and calculating an averaged temperature value and an averaged pressure value at intervals of a first desired time, using the measured instantaneous temperature and pressure values; and a metering computer unit reading the indication value of the meter in such a manner to monitor in real-time the digital signal being provided by the analog- to-digital converter and determine that the number value of the target number wheel has increased by T every time when the magnitude of the digital signal remains uniform for more than a certain period of time and thereafter fluctuate irregularly, and computing a weighted average value for the instantaneous temperature and pressure values using the read indication value as a weight factor.

[21] A method of digitizing an indication value for consumption of supplied goods in a mechanical meter, the meter including a number wheel train having a plurality of number wheels disposed adjacently in a row, the indication value being a combination of number values engraved or printed on the number wheels, the method comprising: a first step in which a light emitter and a light receiver are disposed towards a certain desired area on the outer circumferential face of a target number wheel of which rotation number is to be counted, the output light of the light emitter is incident on and reflected from the outer circumferential face of the target number wheel, and the light receiver receives and converts the reflected light into an optical detection signal and outputs the optical detection signal; a second step in which the optical detection signal is converted into a digital signal through an analog-to-digital converter; and a third step in which the indication value of the meter is read in such a manner to monitor in real-time the digital signal being provided by the analog-to-digital converter and determine that the number value of the target number wheel has increased by T every time when the magnitude of the digital signal remains uniform for more than a certain period of time and thereafter fluctuate irregularly.

[22] The method as claimed in claim 21, further comprising a fourth step which determines whether or not the supplied goods are currently being consumed, thereby providing the determination result, wherein, in the third step, when the magnitude of the digital signal remains uniform for more than the certain period of time, the determination result is used to determine whether the uniform state is caused by use of the supplied goods or by interruption of use of the supplied goods without an increase by T in the number value of the target number wheel, and count the increase by T in the number value of the target number wheel only in case where the uniform state is incurred by use of the supplied goods or ignore the uniform state in case where it is incurred by interruption of use of the supplied goods.

[23] The method as claimed in claim 22, wherein the determination result is acquired in an indirect way in such a manner to use a sensor to detect whether or not a lowest place wheel in the number wheel train is rotating and, as result of the detection, to be decided as being 'non-use' when the lowest place wheel remains stopped without rotation for more than a certain period of time and to be decided as being 'in-use' when the lowest place wheel rotates within the certain period of time.

[24] The method as claimed in claim 22, wherein, in case where the supplied goods are a gas, the determination result is acquired in such a manner to use a sensor to detect directly whether or not the gas is flowing in the meter or inside a gas pipe near the meter.

[25] The method as claimed in claim 21 or 22, in case where the supplied goods are a gas, further comprising: a fifth step which measures an instantaneous temperature value and an instantaneous pressure value of gas inside of the gas meter or inside of a gas pipe connected to the gas meter at regular time intervals or whenever gas -consumption reaches a certain value, and calculates a temperature and pressure compensation coefficient at intervals of a first desired time, which occurs due to a difference between the measured instantaneous temperature and pressure values and a reference temperature and pressure at a gas-supplying point; and a sixth step which reflects the temperature and pressure compensation coefficient on the read indication value for the first desired time to calculate a temperature and pressure compensated read value.