CN1017933B - Pencil-type precise ph-meter with automatic temp. compensation - Google Patents
Pencil-type precise ph-meter with automatic temp. compensationInfo
- Publication number
- CN1017933B CN1017933B CN 89101111 CN89101111A CN1017933B CN 1017933 B CN1017933 B CN 1017933B CN 89101111 CN89101111 CN 89101111 CN 89101111 A CN89101111 A CN 89101111A CN 1017933 B CN1017933 B CN 1017933B
- Authority
- CN
- China
- Prior art keywords
- meter
- electrode
- diode
- thermal compensation
- integrated circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Investigating Or Analyzing Materials Using Thermal Means (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
The present invention relates to a precision pen type pH meter with the function of automatic temperature compensation, which uses only one integrated circuit. The present invention is suitable for the precision measurement of the pH value of various water solutions, and the instrument accuracy is superior to 0.01pH(+/-)1 words. Due to the adoption of a novel structure design, a glass pH electrode, a reference electrode and electronic lines are integrated with each other; an A/D conversion integrated circuit is used, and the pH value is digitized through the display of a miniature LCD. The pH meter forms a pen shape and can be carried in a jacket pocket like a pen, and the pH meter is suitable for environmental protection, field precision measurement and on-site precision measurement.
Description
The present invention relates to integrated circuit of a kind of usefulness, and accurate pen type PH meter with auto thermal compensation function, it can be applicable to the micrometric measurement of various aqueous ph values, especially be fit to environmental protection, field and on-the-spot precision measurement, give and to carry and use brings great convenience, accuracy of instrument is better than 0.01PH ± 1 word.
At home and abroad the kind of PH surveying instrument is a lot, but adopts the instrument of auto thermal compensation to use in higher laboratory, and the manufacturing cost height, costs an arm and a leg.Other has one to be the meter of the PH known to the public, it is characterized in that the A/D converter of a high input impedance, and its output is added on the digital indicator, and its reference voltage is obtained from the voltage source that voltage produces the loop.Connect with the glass electrode output voltage and be added to A/D converter again in this voltage generation loop simultaneously.So sensitivity (slope) of reference voltage recoverable glass electrode, the output voltage of this voltage generator asymmetrical potential of recoverable glass electrode (location) also simultaneously.But owing to lack the efficient temperature compensation system, the precision that causes instrument is very limited, and precision is 0.2PH.
The objective of the invention is to provide a kind of usefulness an integrated circuit, and the accurate pen type PH that possesses the auto thermal compensation device counts, its glass PH electrode, contrast electrode and electronic circuit are combined into one, profile is lip pencil, and it can carry in pen hangs coat pocket, can measure aqueous ph value exactly again, precision can reach 0.01PH ± 1 word, and cost is extremely low, and stable performance is easy to operate.
Invention is achieved in that with glass PH electrode and Ag-AgCl contrast electrode makes the PH survey sensor, semiconductor diode is made temperature sensor, PH electrode and contrast electrode are formed primary element in solution, its electrode potential inputs to the simulation input end of A/D integrated circuit, the signal of temperature sensor is delivered to the reference voltage of this integrated circuit and is brought in the converting sensitivity of adjusting the A/D integrated circuit, to offset the influence of solution temperature, reach the purpose of accurate measurement pH value, and show pH value with 4 bit digital.
This instrument can guarantee that one of key of enough accuracy is correctly to select both to meet the requirement of Nai Site (Nernst) formula, the semiconductor diode that is fit to the integrated circuit operating characteristic is made sensor again, and apply a constant working current, utilize diode PN junction forward voltage drop to reach the purpose of fine compensation with the variation of temperature rule.
The invention will be further described below in conjunction with accompanying drawing:
Figure 1A and 1B are the outside drawings of accurate pen type PH meter.
Fig. 2 A, 2B and 2C are the structural drawing of accurate pen type PH meter.
Fig. 3 is the principle calcspar.
Fig. 4 is an electrical schematic diagram.
Realize accurate pen type PH meter of the present invention by electrode protection cover (1), pocket hook (2), " location " regulator (3), in fill solution replenisher (4), contrast electrode (5), handwriting (6), " slope " corrector (7), power supply (8), switch (9), display circuit (10), glass PH electrode (11), auto thermal compensation device (12), water-absorbing sponge (13) and form.The pocket hook is positioned at the back side of instrument, can hang in the coat pocket as pen, and display is positioned at the instrument front, so that open-air and on-the-spot precision measurement pH value.
Electronic circuit is by glass PH electrode IE, contrast electrode RE and detected solution are formed a primary element, its electrode potential Ux is as the simulation input signal of A/D converter, make the conversion performance of A/D converter meet the Nai Site formula by " slope " corrector R4 that regulates the instrument back side, and show corresponding pH value with numeral.The effect of " location " regulator R5 is to offset the liquid junctionpotential, phase boundary potential of electrode or the like asymmetrical potential.The auto thermal compensation device is to provide a suitable continuous current to supply temperature sensor diode line sex work by field effect transistor V1, biasing resistor R7, the reference voltage of A/D integrated circuit is in time being controlled in the variation of diode PN junction forward voltage, the variation of reference point REFLO (being the variation of reference voltage) is adjusted the A/D converting sensitivity with temperature value, reaches the purpose of auto thermal compensation.
At glass PH contact conductor end one Miniature plug is installed, be convenient to the aging back of this electrode or damage after dismounting and change, leave an injection orifice in the lower end of contrast electrode, be convenient to instrument and use through long-term, in replenishing after filling solution and exhausting, to prolong the serviceable life of instrument.In protective sleeve, post a water-absorbing sponge, be beneficial to electrode activation, be convenient to quick measurement.
The integrated circuit that adopts among the present invention is 3 1/2 monolithic a/d converters of dual integration, after the numerical value of the basic peripheral cell of integrated circuit is determined, circuit just has a fixing sampling integral time (1000 pulse), by to electrode potential Ux forward integration (sampling integration) with to the quadratic integral of reference voltage Uab reverse integral (relatively integration), electrode potential Ux in the sampling time is converted to and the numerical value that relatively accurately is directly proportional integral time, and measure clock pulses number in comparison integral time with counter, just can obtain the digital value relevant with electrode potential (being pH value), the converting sensitivity of circuit changes simultaneously when changing reference voltage.
Electrical schematic diagram R1, R2, C2, C3, C4, C5 are the basic peripheral cell of integrated circuit, and R1, C2 determine the circuit clock frequency.C3 is a reference capacitance, and just memory is on this capacitor for reference voltage when comparing integration, and C4 is an automatic zero set (AZS) electric capacity, and before each work period, automatic zero set (AZS) is once drifted about with the work of eliminating each operational amplifier in the integrated circuit.R2 and C5 are integrating resistor and electric capacity.V2 is a temperature sensor, and V1, R7 provide a suitable constant working current.C1 does the filter capacitor of sorrow for eliminating high frequency.
Voltage about a stable 2.8V is provided in the integrated circuit chip, has formed three dividing points by R3, R4, R5, R6.The Ua point provides the reference voltage of converter, can not make electrode slope obtain proofreading and correct because the actual slope of electrode is Nai Site theoretical value, adjusting R4, promptly determines A/D(mv/PH) converting sensitivity.The Uc point provides adjusts " location " voltage that the electrode zero potential needs.The Ub point is the reference voltage reference point, the reference point is being controlled in variation along with the forward voltage drop of diode V2 when solution temperature changes automatically, promptly adjusting A/D(mv/PH automatically) converting sensitivity, with of the influence of accurate compensation temperature to electrode slope, and with LCD demonstration pH value.
Claims (1)
1, a kind of accurate pen type PH meter of auto thermal compensation comprises:
(1) the PH sensor that constitutes by glass electrode and contrast electrode,
(2) A/D converter ic,
(3) auto thermal compensation circuit,
(4) digital indicator,
(5) slope correction device,
(6) positioning regulator,
It is characterized in that described auto thermal compensation device is that reference voltage terminal by semiconductor diode that applies a constant working current and the A/D converter institute that is connected constitutes, field effect transistor V1 and biasing resistor R7 provide a suitable continuous current to make diode V2 linear work to diode V2, the reference voltage of A/D integrated circuit is in time being controlled in the variation of diode PN junction forward voltage, the variation of reference point REFLO (being the variation of reference voltage) is adjusted the A/D converting sensitivity with temperature value, reaches the purpose of auto thermal compensation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 89101111 CN1017933B (en) | 1989-02-24 | 1989-02-24 | Pencil-type precise ph-meter with automatic temp. compensation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 89101111 CN1017933B (en) | 1989-02-24 | 1989-02-24 | Pencil-type precise ph-meter with automatic temp. compensation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1045183A CN1045183A (en) | 1990-09-05 |
| CN1017933B true CN1017933B (en) | 1992-08-19 |
Family
ID=4854148
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 89101111 Expired CN1017933B (en) | 1989-02-24 | 1989-02-24 | Pencil-type precise ph-meter with automatic temp. compensation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1017933B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013112767A1 (en) * | 2012-01-25 | 2013-08-01 | Senova Systems, Inc. | Analyte sensor |
| CN105092653A (en) * | 2014-05-23 | 2015-11-25 | 翰信科技股份有限公司 | Detector for detecting sodium hypochlorite concentration |
| CN104990970A (en) * | 2015-06-24 | 2015-10-21 | 中山欧麦克仪器设备有限公司 | Dissolved oxygen sensor with automatic temperature compensating |
| US10436736B2 (en) * | 2015-12-08 | 2019-10-08 | Endress+Hauser Conducta Gmbh + Co. Kg | Measurement device for measuring a property of a fluid |
| CN109187704A (en) * | 2018-09-29 | 2019-01-11 | 嘉善县惠民小学 | A kind of written examination PH tester |
-
1989
- 1989-02-24 CN CN 89101111 patent/CN1017933B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CN1045183A (en) | 1990-09-05 |
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| C14 | Grant of patent or utility model | ||
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| CF01 | Termination of patent right due to non-payment of annual fee |